Outline of Agronomy - Agriculture Science
Agronomy is the branch of agriculture sciences dealing with principles and practices of crop production and field management. Agronomy is mainly based on following basic principles Agrometerology, Soils and Tillage, Soil and Water Conservation, Dryland Agriculture, Mineral Nutrition of Plants, Manures and Fertilizers, Irrigation Water Management, Weed Management, Cropping and Farming Systems, Sustainable Agriculture.
Agrometerology: Agrometerology is the branch of meteorology, which investigates the relationship of plants and animals to the physical environment. Agrometerology describes Agrometerological Observatory, Atmosphere, Wind, Clouds and Precipitation, Solar Radiation, Air Temperature, Soil Temperature, Humidity and Evaporation, Weather Hazards and their Mitigation, Weather and Crop Productivity, Weather Relations of crops, Weather Forecasting and Classification of Climate and Agroclimate in relation to agriculture.
Soils and Tillage: Soils and tillage are necessary to know how soils should be managed and conserved for sustainable crop production. Under this principle of agronomy we can learn Physical Properties of Soil, Chemical Properties of Soil, Biological Properties of Soil, Soil Organic Matter, Salt Affected Soils, and Tillage.
Soil and Water conservation: We must conserve soil and water because these are the most critical resources. In this principle we will touch to Soil Erosion, Water Erosion, Wind Erosion, Soil and Water Conservation Measure.
Dryland Agriculture: Dryland farming is cultivation of crops in regions with annual rainfall more than 750 mm. Under this we need to read History of Dryland Agriculture, Problems of Dryland Agriculture, Monsoon and Length of Crop Growing Season, Drought, Moisture Conservation in Drylands, Water Harvesting and Protective Irrigation, Crops and Cropping Systems, Mitigating Adverse Effect of Aberrant Weather, Alternate Land Use Systems, Watershed Management and Improved Dryland Agricultural Implements.
Mineral Nutrition, Manures and Fertilizers: Nutrient Management is one of the most important principles in agronomy which includes Essentials in Plant Nutrition, Nutrient Uptake by Plants, Soil Fertility Evaluation, Manures, Fertilizers in Indian Agriculture, Nitrogen Fertilizers, Phosphatic Fertilizers, Potassic Fertilizers, Calcium, Magnesium and Sulphur, Micronutrients, Mixed Fertilizers, Fertilizer Application, and Fertilizers & Environment.
Irrigation Water Management: Irrigation Water Management is very important for success of agriculture. In irrigation management we need to read Irrigation in Indian Agriculture, Water Resource & Their Development, Systems of Irrigation, Soil – Water Relationships, Plant – Water Relationship, Evapotranspiration, Water Requirements of Crops, Measurement of Irrigation Water, Scheduling Irrigation, Methods of Irrigation, Irrigation & Water Use Efficiency, Irrigation Practices for Major Crops, Quality of Irrigation Water, Drainage, Cropping Pattern in Command Areas, Pricing Irrigation Water.
Weed Management: Weed is a plant grown at place & time which is not desire. Understanding of Common Weeds, Losses and Benefits, Weed Ecology & Classification, Crop – Weed Association & Competition, Methods of Weed Control, Classification of Herbicides, Herbicide Formulation, Herbicide Application, Absorption & Translocation of Herbicides, Mode of action of Herbicide, Selectivity of Herbicide, Herbicide Combination, Rotations & Interactions, Persistence of Herbicides in Soils, Herbicide Resistance, Chemical Weed Control in Different Crops, Parasitic & Aquatic Weed Control.
Cropping Systems: Cropping systems is gaining more importance in this day and includes Various Terminology, Major Cropping Systems, Agronomy of Rainfed Cropping Systems, Agronomy of Irrigated Cropping Systems, Evaluation of Cropping Systems, Farming Systems and Farming Systems Research
Sustainable Agriculture: Sustainable agriculture can be define as the form of agriculture aimed at meeting the food and fuel needs of the present generation without endangering the resource base for the future generations. It includes study of Impact of Improved Crop Production Technology, Factors Affecting Ecological Balance, Evaluation of Sustainable Agriculture, Components of Sustainable Agriculture, Sustainable Utilization of Land Resources, Sustainable Utilization of Water Resources, Sustainable utilization of Biodiversity, Integrated Nutrient Management, Integrated Nutrient Management, Integrated Plant Protection, Enhancing Sustainability of Dryland Agriculture, Enhancing Sustainability of Irrigated Agriculture, Agricultural Sustainability and Farming Systems.
Water Management Including Micro Irrigation
Water Resources & Irrigation Development in India and M.S
Water (H2O):
Water is indispensable for human, animals and plant life. It is a part of all organisms, some of which contain more than 90 percent. Water is essential part of protoplasm. It is an important ingredient in photosynthesis. About 400 to 500 liters of water is necessary for production of a one kilogram of plant dry matter. Water is also required for translocation of nutrient and dissipation of heat.
Properties of water:
Water molecule contains two hydrogen ions and one oxygen ions. The space occupied by each water molecule is mainly due to oxygen ions while two hydrogen Ions do not occupy practically any space. The shape of the water molecule is sphere and the position of two hydrogen ions is at the corners of a tetrahedron that exists within a sphere.
The positive valences of hydrogen ions are partially neutralized by negative valency of oxygen ion. Thus, one, end of water molecule has positive charge and another end has negative charge. This makes water molecules a dipole.
Water molecules do not exist in individually. Hydrogen in water serves as connecting link from one molecule to the other and it is known as hydrogen bonding. Water sticks to it self with great energy and this property is called cohesion, where as water attaches itself to surface of many substances and this property is known as adhesion. By adhesion, water is held tightly at the soil water interface and water is retained in the soil by adhesion and cohesion. The water molecules hold other water molecules by cohesion forces. Because of these forces, water fills small pores in the soil and is in fairly thick film in large pores.
Hydrological Cycle:
The earth’s outer solid crust is called Lithosphere. Most of the earth’s total water is contained in Oceans (96%), small portion (2%) as snow and ice and rest (2%) in the water bodies of the continents. Oceans, lakes, rivers and other water bodies of the Earth are called Hydrosphere.
Continuous circulation of water between hydrosphere, atmosphere and lithosphere is known as hydrological cycle. This has neither a beginning nor an end.
The physical and biological processes in the environment are sustained by the Hydrological cycle. Water from various water bodies evaporates due to energy provided by solar radiation and enters the atmosphere as water vapour. Oceans account for 85% of worldwide evaporation. Evaporation is the chief source of water vapour in atmosphere. Water vapour in the atmosphere constitutes only 0.001 percent of the total global water. Even if all water vapour present in the atmosphere at any amount could be precipitated, an average depth of only about 2.5 cm of water is added to the oceans. Though the quantity of water vapour present in the atmosphere is small, it provides vital hydrological link between oceans land.
Clouds are formed as the water vapour rises above in to the atmosphere. When condensation takes place in the atmosphere, water precipitates mainly as rain or to some extent as snow. Thus, water is constantly added to the atmosphere through evaporation and lost through precipitation. The annual average world precipitation is
1000 mm. As Oceans, occupy 2/3 of the total surface of earth, most of the precipitation that falls over oceans. Of the precipitation that falls over continents, about 65% is returned to Atmosphere through evapo-transpiration and the rest goes as a surface run off into the rivers and finally into the oceans. Thus, water occurs on earth in three forms viz solid, liquid and gaseous.
Water resources of the world:
About 97 percent of worlds in the oceans and this are not useful for irrigation. Of The total quantity of water, only 2.6 percent is fresh water, which is in the form of ice caps, icebergs and glaciers and only small fraction of water is present in the ground, rivers and atmosphere that can be harvested for irrigation of crops.
Water resources of India:
The average rainfall of India is 1194 mm. When considered over geographical area of 328 million hectares, this rainfall amounts to 392 million hectare meters (m. ha. m). This may round off to 400 (m. ha. m) by including the contribution of snowfall which is not yet fully determined. Out of 400 (m. ha. m) of rainfall, 75% is received during South-West Monsoon period (June to September) and rest in remaining months as shown below. A Major portion of water (215 m. ha. m) soaks into the soil, while 70 (m. ha. m) is lost as an evapo-transpiration.
Sources of Water & Functions of Water
Sources of water:
The major sources of water available either for agriculture or for human consumption is obtained from the precipitation in the form of rainfall or snowfall. Run-off from precipitation drains through streams and rivers or collects in surface depressions forming tanks or ponds. Water of streams stored in reservoirs or is diverted directly through canal system for irrigation. Run-off water stored in tanks or ponds is also regulated for irrigation through suitable conveyance system. Part of rainfall is stored as a Ground water. Of the annual rainfall of 400 (m. ha. m) about 215 (m. ha. m) infiltrates into the soil. A major part of it amounting to about 165 (m. ha. m) is retained as a soil moisture, which is essential for growth of vegetation. It is only after the soil has absorbed water to field capacity that water starts percolating down to water table and adds to ground water reservoir.
Functions of water:
Ecological importance:
The distribution of vegetation over the surface of earth is controlled by the availability of water than any other single factor. In heavy rainfall area, flush vegetation (forest) is observed.
Physiological importance:
The ecological importance of water is result of physiological importance.
· It is a constituent of protoplasm:
Water is as important quantitatively as qualitatively Constituting 80 to 90 Percent of fresh weight of most herbaceous plant parts and 50 percent of the fresh weight of woody plant.
· It is a very good solvent:
Water acts as a solvent in which gases, minerals (plant Nutrients) and other solutes are dissolved. The dissolved plant nutrients are absorbed by Plant through soil solution. It acts as a carrier of food nutrients.
· It is a reagent:
Water acts as a reagent in many important processes, such as photosynthesis and hydrolysis of starch and sugar.
· It maintains turgidity of plant:
Maintenance of turgidity is essential for cell Enlargement and growth. Turgidity is also important in opening of the stomata, movement of leaves, flower, petals etc.
· It controls the temperature of plant and soil.
· It is a major part of plant body
Classification of Soil Water or Kinds of Soil Water
When water is added to dry soil either by rain or irrigation, it is distributed around the soil particles, where it is held by adhesion and cohesive forces. It displaces air in the pore spaces and eventually fills the pores. When all the pores, large and small are filled, soil is said to be saturated and it is at its maximum retentive capacity.
Although the soil water cannot be sharply demarcated, yet for sake of understanding and as per utility of water to plant it is mainly classified into following categories.
· Hygroscopic water
· Capillary water a) Inner capillary b) outer capillary
· Gravitation water
· Water vapour
Hygroscopic water:
It is that part of soil water which is very tightly held on the surface of soil particles in very thin film by adsorption forces such as adhesion and cohesion. It is mostly in vapour form and forces with which it is held on surface of soil particles is estimated about 10,000 atmosphere towards the inner side and about 31 atmosphere at the outer side of hygroscopic water film. (One atmosphere at sea level is about 15 pounds per square inch, which means the force holding the water at one atmosphere is equal to about 15 pounds pre square inch or 1023 centimeters of water column height). This water is not any use to the plants.
Capillary water:
It is the water held by the forces of surface tension and continuous film around soil particles and in the capillary spaces. When soil particles absorb water even after the hygroscopic coefficient is reached, additional water is also held around the particles in the form thin film. This retension of water film continues until the film becomes quite thick and micro pores inside the soil mass get filled with water. A stage is then reached when the force of gravity becomes stronger and any further addition of water is pulled down by gravity and flows down as free water.
The capillary water is that water, which is held in the soil in excess of hygroscopic water but is up to the point where the gravity pull begins to move the water down wards, when free drainage conditions exist in the soil.
Capillary water is rather loosely held water (from 31 atmosphere to 1/3 atmosphere tension) and is capable of movement within the soil. The plant food nutrients are dissolved in it and therefore, it is most useful water for plants. The capillary water itself can be divided into two parts though there is no clear-cut line division.
· Inner Capillary Water:
It is that part of capillary water, which is nearest to the hygroscopic water and is in the form of a thinner film, held more tightly and moves rather very slowly than outer capillary water.
· Outer Capillary water:
It is that part of capillary water which is not very tightly held in the soil and there after moves readily from place to place. It is the most useful water for plants as it is very quick available.
A soil which has a finer texture and granular structure indicating larger proportion of micro pores than macro pores holds more amount of capillary water than a single grained sandy soil having more percentage of macro pores. Soil rich organic matter content also holds much grater quantity of capillary water.
Gravitational water:
It is that part of soil water, which moves freely in response to gravity and drains out of the soil. When the maximum capillary capacity of a soil gets satisfied and further addition of water comes under the force of gravity. This water starts moving as free water through the macropores and it is called gravitational water.
It is superfluous and as such, it is of no use to the plants. Gravitational water is held at zero atmosphere tension. When down ward movement of gravitational water is more, some plant nutrients are leached out and when it is slow, it will adversely affect the aeration of soil.
Vapour form:
In this category, the water is present in gaseous form in the soil atmosphere but it is not directly used by plants and is therefore, not important unlike the first three kinds.
Kinds of soil water (classification of soil water)
· Hygroscopic water (Water of adhesion)
· Capillary water (water of cohesion)
· Gravitational water
· Water Vapour
Absorption and Movement of Water in Soil
The movement of water from the soil surface into and through the soil is called water intake. It is the expression of several factors including infiltration and percolation.
Infiltration:
Infiltration is the term applied to the process of water entry into the soil generally (but not necessarily) through the soil surface and vertically downward. This process is of great practical importance since its rate determines the amount of run-off over the soil surface.
In other words, infiltration refers to the entry and downward movement of water in to the soil surface. Infiltration is a surface characteristic of a soil.
Infiltration rate:
It is the rate at which the water enters from the surface to the soil. Initially the infiltration rate is more but afterwards it decreases because the soil gets wet. According to the rate of entry of water from surface to the soil, infiltration rate is grouped in to four categories.
1. Very Slow: soils with less than 0.25cm per hour e.g. - very clay soils.
2. Slow: infiltration rate of 0.25cm to 1.25cm per hour e.g. Soils with high clay.
3. Moderate: infiltration rate of 1.25 to 2.5cm per hour. e.g. - sandy loam/ silt loam soils.
4. Rapid: infiltration rate is more than 2.5cm per hour e.g. deep/sandy silt loam soils.
Factors affecting the rate of infiltration:
· Compactness of soil surface: A compact soil surface permits less infiltration whereas more infiltration occurs from loose soil surface.
· Impact of rain drop: the force (speed) with which the rain drop falls on the ground is said to be impact of rain drop. Ordinary size varies from 0.5 to 4mm in diameter. The speed of raindrop is 30ft per second and force is 14 times its own weight. When impact of raindrop is more then it causes sealing and closing of pores (capillaries) especially in easily dispensable soils resulting in infiltration rate
· Soil cover: Soil surface with vegetative cover has more infiltration rate than bare soil because sealing of capillary is not observed.
· Soil Wetness: If soil is wet, infiltration is less. In dry soil, infiltration is more.
· Soil temperature: Warm soil absorbs more water than cold soils.
· Soil texture: In coarse textured soils, infiltration rate is more as compared to heavy soils. In coarse textured soil, the numbers of macro-pores are more. In clayey soils, the cracking caused by drying also increases infiltration in the initial stages until the soil again swells and decreases infiltration.
· Depth of soil: Shallow soils permit less water to enter into soil than too deep soils.
A coarse surface textured, high water stable aggregates, more organic matter in the surface soil and greater number of micro pores, all help to increase infiltration. As it is a dynamic and quite variable character of soil, it can be controlled by management practices. Cultivation practices that loosen the surface soil make it more receptive for infiltration e.g. course organic matter mulches increases infiltration.
Permeability:
It is defined as the characteristic that determines how fast air and water move through the soil describes what is known as permeability.
Once the water has entered into the top layer, its subsequent slow or rapid movement within the soil indicates its rapid or slow permeability. The permeability basically depends upon pore size distribution in the soil. Larger the number of macro pores (non-capillary pores), the greater is the permeability. The movement of water becomes slow in subsoil layers due to their compactness and low organic matter content but with deep-rooted plants, there is an increased permeability even in such sub soil layers. Permeability increases with the increasing fine texture.
Permeability depends up on:
· Number of micro pores: More the number of macro pores higher is the permeability.
· Soil aggregates: Larger the size of capillary pores, greater is the permeability.
· Depth of soil: Permeability decreases with the depth, as the sub soil layers are more compact and have less organic matter.
· Coarseness of soil texture: In coarse textured soil, permeability is more, however fine textured soil is less.
· Salt concentration: Salt concentration affects permeability adversely. If the sodium is high in water; it would cause ready dispersion of soil and thus reduces permeability.
· Soil moisture status: Permeability decreases as the soil becomes drier and increases when soil becomes wet.
· Organic matter content: more organic matter in the soil results in more permeability.
The permeability is considered slow, if it is less than 2.5 cm per hour, moderate if it is about 5.0 cm per hour. Like infiltration, permeability can be also controlled to a extent by suitable management practices. Continuous tillage reduces permeability, while the growth of deep-rooted crops like pulses or legumes, grasses and tress increases permeability. The permeability of soil varies with its moisture status and usually decreases as the soil becomes drier because air enters in to soil and reduces the permeability.
Percolation:
The down ward movement of water through saturated or nearly saturated soil due to the forces of gravity is known as percolation. Percolation occurs when water is under pressure or when the tension is smaller than about 1/3 atmosphere.
Percolating water goes deep into the soil until it meets the free water table. Percolation studies are important for two reasons-
1)Percolating water is only source of recharge of ground water, which can be again be profitably used through springs and wells for irrigation.
2)Percolating water carries plant nutrients like Calcium, Magnesium deep into lower layers and depositing them beyond the reach of roots of common field crops. In sandy or open textured soils, there is a rapid loss of water through percolation.
Percolation depends up on:
(i) Climate: If the rainfall is more than evaporation, then there will be appreciable amount of percolation. In dry region, percolation is almost negligible.
(ii) Nature of soil: sandy soils permit more percolation as these occupy large number of macro-pores. The macro-pores serve as the main channels of the gravitational flow. However, clayey soil permits less water to percolate.
Capillary movement:
Once the flow due to gravitational forces has been ceased (stopped), the water moves in the form of thin or capillary film from a wet region to dry region. This type movement goes through the finer or micro-pores and it continues until the thickness of moisture film surrounding the soil particles is equal to both the regions (wet and dry regions). Capillary may be in all directions i.e. it may be downward, lateral or upwards from a low tension to high-tension area, since thicker film have lower tension; water from thicker film around the soil particles flows to thinner film. The greater the difference between the thicknesses of the film, the quicker is the capillary movement up to certain point and as difference narrows, the movement of water film also becomes slow and may cease (stop).
Forces Causing Water Movement and Retention of Water in Soil
Force Causing Water Movement:
The forces which cause the water movement in soil are:
(1) Gravitational force or gravity tension: The flow of water due to gravity is very marked when the soil is in saturated condition and generally, the direction of such flow is downward although a little lateral flow takes place. The large pores i.e. macro-pores serve as the main channels for gravitational flow.
(2) Capillary force or capillary tension: In the soil, water is held by the forces of surface in the capillary spaces and around the soil particles. The movement of water under unsaturated soil conditions is due to force of surface tension. Once the flow due to gravitational force has ceased the water moves in the form of thin or capillary film from a wet region to a dry region through finer or micro-pores. The surface or capillary tension is responsible for the capillary movement of water to all directions from low tension to high tension.
(3) vapour tension: If the soil is not water logged, the movement of water vapour may take place to a very little extent from soil layers which gets more heated towards the cooler soil layers particularly when difference between their temperatures are very wide.
(4) Osmotic pressure: The movement of water takes place due to difference in osmotic pressure of the soil solution. the situation is only observed in only saline soil which has excessive salts.
In all these four forces, the gravitational and capillary forces are important because their significance in the movement of water in the soil is more. However, vapour transfer and osmotic pressure are less important because of their negligible significance in case of normal soils.
Retention of water in soil:
Water that enters in the soil is retained by means of the following three forces:
i) Force of adhesion: It is the attraction of solid surface of water molecules (It is the attraction of unlike materials to each other). Due to the force of adhesion, the water molecules are attached to the surface of soil particles and thus a thin film of water is tightly held around the soil particles. Finer the soil particles, greater the surface area and consequently, the water film is held or retained more tightly.
ii) Force of cohesion: It is attraction between similar molecules of like characteristics. Cohesion is attraction of water molecules for each other. When more water is added to the moist soil, the cohesive force comes into action and the freshly added molecules get attracted towards already existing water molecules. This results in thickening of water film around the soil particles.
iii) Soil colloids: (Clay or humus particles): The water is also retained in the soil due to soil colloids like clay or humus particles. The water thus retained in the soil is called imbibitional moisture.
Such retention of moisture is different in different soils. Fine textured soils having greater aggregation and more organic matter or humus retain much more quantity of water than those coarse textured single grained soils which are poor in organic matter.
Soil Moisture Constant
Soil Moisture Constant:
Water contents under certain standard conditions are referred as soil moisture constants.
Under field conditions, water content of soil is always changing constantly with time and depth of soil and is not static or constant. However, the concept of soil moisture constants greatly facilitates in taking decision in irrigation.
Important Soil Moisture Constant:
While studying soil water and discussing its availability or other wise to plant, some specific terms called as soil moisture constants are used. A brief explanation of some important and commonly used terms is given below and the methods of expressing them are indicated in the table below.
Appearance
of soil
Type of Soil
Soil Moisture Constant
Moisture Tension
in Atmosphere
Wet soil
Gravitational water
Maximum water
0.001
Moist soil
Available water
Field capacity
0.33 (1/3)
Water held in micro pores
Wilting point
15
Dry soil
Unavailable water tightly held
Hygroscopic coefficient
31
Air dry
1000
I
Oven dry
10,000
Important soil moisture constants:
1. Oven dry weight: This is the basis for all soil moisture calculations. The soil is heated in an oven at 105 degree Celsius until it looses no more water and final weight is recorded as oven dry weight. Equivalent moisture tension at this stage is 10,000 atmospheres.
2. Air-dry weight: Unlike oven dry weight, this is a variable constant. Soil exposed in humid atmosphere will have a higher weight than the same soil, if put in dry atmosphere. Under average conditions, moisture at air dryness is held with a force of about 1000 atmosphere.
3. Hygroscopic coefficient: It is the maximum quantity of water absorbed by any soil in a saturated atmosphere (i.e. at 99 percent relative humidity) at 25 degree Celsius temperature. The hygroscopic coefficient varies with the type of soil, its texture and organic matter content. This constant is equal to a force of about 31 atmospheres and determined by placing the soil in a saturated atmosphere at 25oC temperature. Water held by the soil at this constant is not available to plants because it is mostly in vapour form but it is useful to certain bacteria.
4. Permanent Witling Point (PWP): The wilting point is also known as a wilting coefficient or permanent wilting point or permanent wilting percentage.
After using the water from outer capillary portion, the plant roots begin to utilize although with difficultly the inner capillary water. Thus, as the moisture film becomes thinner, it is held more and more tightly and it is difficult for plant roots to remove each successive portion of the water film. But later on, a stage is reached at which plants cannot obtain enough water to meet transpiration requirement and remain wilted even under saturated atmosphere, unless water is added to soil. The soil moisture constant at this stage (wilting is called as wilting co-efficient or permanent wilting percentage. Water at this constant is with force of a 15 atmosphere. The wilting co-efficient differs in different soils. It is as low as 4 to 6 percentage in sandy soils and as high as about 16 to 20 percent in clayey soils which are rich in organic matter. The wilting point is a lower limit of available soil moisture.
5. Field Capacity (F.C.): Field capacity is the moisture content in percentage of a soil on oven dry basis, when it has been completely saturated and down ward movement of has practically ceased.
With 2 to 3 days after a heavy rains or irrigation, the gravitational or free water is drained. The moisture content at this stage in the soil is said to be at field capacity. The field capacity is the upper limit of available soil moisture range in the soil moisture and plant relations. The moisture tension at this stage is about 1/3 atmosphere. The fine textured granular soil with high organic matter content more soil moisture than sandy soil at field capacity.
6. Moisture equivalent: According to the modified technique, moisture equivalents is the amount of moisture in percentage on oven dry weight basis held by 30 grams of dry soil when subjected to 1000 times the gravitational force in a centrifuge for 30 minutes.
For practical purpose, field capacity may be considered as equal to the moisture equivalent. The value (moisture content may be considered as equal to the moisture equivalent are nearly equal in loamy soil but for sandy soils, the moisture equivalent is slightly higher than filed capacity.
7. Maximum capillary capacity: When water is added to the soil whose field capacity is already reached, that water goes on thickening the moisture film. A stage is then reached after which any further additional of water will get percolated down by the force of gravity. This is the point of maximum capillary capacity.
8. Maximum water holding capacity: Any further addition of water to the soil after its maximum capillary capacity is reached will start moving down by force of gravity, if it is a well drained soil but when drainage is restricted, maximum amount of water can be held until all micro and macro pores are filled with water. This stage is called the maximum water holding capacity. It is only in case of poorly drained soils or soils having hard pan near the surface that maximum water is retained in the soil for a long period.
The values of different soil moisture constant (moisture percent) differ according to soil type. The values for these moisture constant for some the soils are given below.
Table: Moisture constants for few typical Indian soils (in percent of oven dry soil)
Soil type
Air dry
moisture
Hygroscopic
co-efficient
Wilting
Coefficient
Moisture
equivalent
Maximum
water holding capacity
Heavy black
3.8
20.7
29.9
53.2
79.7
Medium black
2.1
13.3
20.6
45.6
66.6
Alluvial
1.6
7.6
13.5
40.4
48.7
Sandy
0.5
1
5.3
21.8
25.2
Laterite
0.8
2.8
5.5
32.9
39.6
Available and Unavailable Soil Water
It is evident that all the water present in the soil profile is not available for the use of plants. Even the capillary water which is considered to be loosely held by the soil particles is not utilized by plants.
Three tentative divisions of the soil water may be made on the basis of availability
i) Unavailable water
ii) Desirably available water
iii) Superfluous or excess of water not needed by plants.
Available and unavailable water
Type of water
Atmospheric Pressure
Status
Oven Dry
10000
Unavailable Water
Air Dry
100
Hygroscopic Co-efficient
31
Difficultly Water
Wilting Point
15
Field Capacity
0.33
Available Water
Ground Water
0.001
Unavailable Water
Unavailable soil water:
Types of water are not available to the plants are
a) Hygroscopic water
b) Fraction of inner capillary
c) Water vapour
Water below the hygroscopic co-efficient is held so tenaciously above 31 atmosphere that is unavailable to plants. The water held between the hygroscopic co- efficient (31 atmosphere) and the wilting point (15 atmospheres) is inner capillary water. Its movement is extremely sluggish and is only difficultly available to plants. Only certain type of plants under arid conditions make its use. So also some bacteria and fungi use the inner capillary water. It includes whole of the hygroscopic water plus a part of inner capillary water being below the wilting point.
Available or Desirably available water:
The range of water between the limits of field capacity and wilting point (co- efficient) is considered as the desirably or available water. The soil moisture between field capacity (1/3 atmosphere) and wilting point (15 atmosphere) is readily available moisture.
Superfluous water:
It includes gravitational water (excess of field capacity). This water is also unavailable to the use of plants because it is lost due to deep percolation. The preference of superfluous water in soil for longer period is harmful to plant growth.
Absorption of Moisture by Crops
Absorption of water is not dependent of process but it is related to transpiration. Absorption is controlled by rate of water loss in transpiration at least when water is readily available to the roots. Absorption and transpiration are linked by the continuous water column in xylem system of plants. Due to the loss of water in transpiration, it produces the energy gradient which causes the movement of water from soil in to the plants and from plants to atmosphere. In the maintenance of water column in xylem, the cohesive and adhesive properties of water play important role.
Moisture enters in to plant roots by process of osmosis (movement of liquid through semi permeable membrane caused by unequal concentration on the two sides). The concentration of soluble material in cell sap of roots is increased because of loss of water through transpiration. When concentration of soluble material in cell sap within roots is greater then the soil moisture, the water passes in the roots to equalize the concentration. A more correct view to consider the concentration of water molecule in cell sap reduced because of quantity of soluble substances present and hence the number of water molecules in the soil solution is greater. As a result more water molecules strike against cell wall and water passes into the roots from the zone of higher concentration of water to a zone of lower concentration of water.
When the concentration of soluble substances in the soil moisture exceeds that cell sap, situation will be reserved and water will pass out of the roots to the soil. Plants growing in saline soils with high concentration of soluble salts absorb water with difficulty due to high osmotic pressure of the soil solution.
The absorption of water by plants is closely related with transpiration. The sun provides energy for vaporization of water from leaves. Loss of water from leaf cells cause an increase in interior osmotic pressure which causes water to move in to them from xylem vessels. The xylem vessels of leaf are continuous with that of stem and roots and cause a tension created by loss of water from leaf to be transmitted to roots. Increased osmotic pressure in root cells occurs and uptake of water is encouraged. The absorption of water takes place in terminal portion of roots but the maximum absorption takes place in the zone of root hairs, 1 to 10cm behind root tip.
In other words, water is absorbed mainly through roots hairs. Root absorbs water both passively and actively.
Passive absorption takes place when water is drawn into the roots by negative pressure in the conducting tissues created by transpiration.
Under the conditions during which there is little transpiration, the roots of many plants absorb water by spending energy that is called active absorption. Under normal conditions of transpiration, the contribution of active absorption to the water supply of plant is negligible and it is usually less than 10 percent of total absorption.
Certain plants are able to absorb moisture from the atmosphere when soil is at permanent wilting point. This is known as aerial absorption or negative transpiration. Direct absorption of water by leaves that are wetted by rain, dew or overhead irrigation can help to resaturate dehydrated leaf tissue.
The leaves are borne through out the stem in all plants which are mainly responsible for the loss of water. The leaf surface shows small pores surrounded by two cells. The pores are called stoma and cells surrounding them are called guard cells. The stoma (stomata) regulates the loss of water as vapour and exchange of CO2 in leaf and other organs. It is thus the efficiency of these structures which possibly determine water loss from plant. The efficiency of the stomata up on their size and number per unit area.
Factors Affecting Absorption of Water
Factors affecting absorption of water:
A) Physical factors: The soil and atmosphere are the chief physical factors which determine the flow rate of water through plant.
Soil factors:
i) Soil water content: The plant roots can easily absorb the soil moisture in between field capacity and permanent wilting point. When the soil moisture decrease below the wilting point, plant roots have to exert more pressure and thus rate of absorption decreases. On the other hand, when the soil is completely saturated with water, then soil temperature and aeration are poor and this condition also affects the absorption of water.
ii) Soil temperature: Soil temperature is known to influence water absorption and ultimately transpiration to a considerable extent. In many plants, water absorption below a soil temperature of 10 oC is reduced sharply and 25 oC soil temperature up take of water is slowed down. In most instances, temperature above 40 oC does not support water absorption and plant can show signs of wilting. A freezing temperature reduces water absorption because of following causes.
a) Decreased root growth
b) Increased viscosity of water
c) Increased resistance to movement of water in to roots. thus is caused by decreased permeability of cell membrane and the increased viscosity.
iii) Soil aeration and flooding: Most of crop plants are not able to water while standing under water logged conditions. The following are the possible reasons of flood injury.
a) Poor availability of oxygen and occurrence if higher CO2 concentration around roots.
b) Accumulation of toxic substances either in the submerged roots or around them.
c) Changes in pattern of ion up take resulting in the accumulation of some toxic ions.
In water logged condition, the availability of oxygen is reduced which affects respiratory actively of roots. In addition, CO2 concentration is increased and it affects permeability of membranes and adversely influences water up take. Reduced oxygen also affects root growth adversely.
B) Atmospheric factor:
Classification of Crops According To Root Depth, Rooting Characteristic And Moisture Use Of Crops.
The amount of soil moisture that is available to a plant is determined by the moisture characteristics of the soil, the depth to which the plant roots extend and the proliferation or density of the roots. Soil moisture characteristics, such as field capacity and wilting percentage are peculiar to a soil and are a function of the texture and organic matter. Little can be done to alter these limits to any great extent. Greater possibilities lie in changing the characteristic of the plant enabling it extend its rooting system deeper into the soil, thereby enlarging its reservoir of water. The density of roots proliferation is important.
Water is an unsaturated soil moves very slowly, and only a distance of a few cm. To utilize effectively the moisture stored in the soil profile, roots must continue to proliferate into unexploited zones throughout the plants growth cycle. During favorable growing periods, roots often elongate so rapidly that satisfactory moisture contacts can be maintained even when the soil moisture content declines. Where transpiration is effected due to the different atmosphere factors such as wind velocity, humidity, sunlight, etc when temperature and wind velocity are more sunlight for longer period and humidity are less, under such conditions, transpiration is more. The increased rate of transpiration results more water uptake.
C) Biological factors:
Root system is the plant factor which is directly related to the absorption of water from soil. Under favorable soil water, potential soil temperature, aeration, and roots system of the plants strongly influence the uptake of water. When growth of roots (root system) is more, uptake of water is also more under favorable soil conditions. Root growth is influenced by soil and more therefore agronomic management practices can help to improve root growth.
Other plant factors such as morphology of leaves, stomatal mechanism and growth stage of the crop influence the rate of transpiration. The increased rate of transpiration results more water absorption.
Good root system has developed during favorable growing periods; a plant can draw its moisture supply from deeper soil layers.
Plants vary genetically in their rooting characteristics. Vegetable crops such as onions and potatoes have a spare rooting system and are unable to use all the soil water within the root zone. Forage grasses, sorghum, maize and such other crops have very fibrous, dense roots. Lucerne has a deep root system. Whether plant is an annual or perennial is another factor affecting its its moisture relations. An annual plant must extend its roots down into the soil to make availability root depth, and needs only to extend its small roots and hairs to be able to utilize the entire amount of available soil water.
Plants may be limited in their rooting by factors other than genetic. High water table, shallow soils and an impermeable formation near the ground surface restrict the depth rooting. Fertility and salt status of the soil influence the rooting of plants crop management practices, such as cutting the top growth at different physiological stages and the cultivation and cutting of surface roots after rooting habits. The rooting pattern of common and crop plants vary widely from soil. For example, roots of maize crop have been found to extend as deep as 1.5 meters in medium to textured soils, while in a fine textured soil the crop has a shallower root system.
Effective Root zone: Effective root zone is the depth from which the roots of average mature plant are capable of reducing soil moisture to the extent that it should be replaced by irrigation. It is not necessarily to have maximum root depth for ant given plant especially for plants that have a long taproot. Root development of any crop varies widely with the type of soil and other factors.
Table: Effective root zone depth of some crops and their classification.
Rooting Characteristic
Shallow Rooted
Moderately Deep Rooted
Deep Rooted
Very Deep Rooted
Rice
Wheat
Maize
Sugarcane
Potato
Castor
\Cotton
Citrus
Cauliflower
Ground Nut
Sorghum
Coffee
Cabbage
Pea
Bajara
Apple
Lettuce
Bean
Soybean
Grape Vine
onion
Chili
Sugar Beet
Safflower
Tobacco
Tomato
Lucerne
Moisture extraction pattern within root zone
The moisture extraction pattern shows the relative amounts of moisture extracted from different depths within the crop root zone.
It is seen that about 40 percent of the total moisture used is extracted from first quarter of the root zone, 30 percent from the second, 20 percent from third and only 10 percent from last quarter.
This indicates that the need for making soil moisture measurements at different depths within the root zone in order to have estimate of soil moisture status.
Methods of Soil Moisture Estimation Laboratory & Field Methods
By measuring soil moisture at regular interval and at several depths within the root zones, information can be obtained as to the rate at which moisture is being used by the crops at different depths. This provides the base for determining when to irrigate and how much water to be applied.
For practical purpose, irrigation should be given when about 50 percent of available moisture in the root zone is depleted. The amount of water to be applied is directly related to the water already present in the soil. The methods of measuring soil moisture are divided in to:
A) Direct method: Measurement of moisture content in the soil (wetness)
B) Indirect methods: Measurement of water potential or stress or tension under which water is held by the soil.
A) Direct methods:
I) Gravimetric methods: In the gravimetric method, basic measurement of soil moisture is made on soil samples of known weight or volume. Soil sample from the desired depths are collected with a soil auger. Soil sample are taken from desired depth at several locations of each soil type. They are collected in air tight aluminum containers. The soil samples are weighed and they are dried in an oven at 105 oC for about 24 hours until all the moisture is driven off. After removing from oven, they are cooled slowly to room temperature and weighed again. the difference in weight is amount of moisture in the soil. The moisture content in the soil is calculated by the following formula:-
Moisture content Wet weight –Dry weight
On weight basis = ----------------------------- X 100
Dry weight
PROBLEMS: Wet weight of a soil sample with can is 210 gms and weight with
can is 180 gms weight of empty container is 40 gms calculated moisture content of
soils sample?
Solution:
Weight of wet soil sample = wet weight – weight of empty can
= 210-40
= 170
Dry weight of soil sample = Dry weight – weight of can
=180-40
=140
Wet weight of soil- Dry weight of soil
Moisture content (%) = --------------------------------------- X 100
Dry weight of soil
170-140
= ----------------------------- X100
140
30
= ------ X 100
140
= 21.4%
II) Volumetric Method: Soil sample is taken with a core sampler or with a tube auger whose volume is known. The amount of water present in soil sample is estimated by drying it in the oven and calculating by following formula.
Moisture content = Moisture content (%) by weight x Bulk Density (%) by volume.
PROBLEM: Undisturbed soil sample was collected from a field, two days after irrigation when the soil moisture was near field capacity. The inside dimension of core sampler was 7.5 cm diameter and 15 cm deep. Weight of core sampling cylinder weight of the core-sampling cylinder was 1.56 kg. Determine the available moisture holding capacity of soil and the water depth in centimeter per meter depth of soil.
Solution:
Weight of moist soil = 2.76-1.56 = 1.20kg
Weight of oven dry soil = 2.61-2.56 = 1.05 kg
1.20-1.05
Moisture content = ------------- X 100
1.05
= 14.28%
Volume of core sampler = ----------------------------X d2 x h
= ------------X7.5X7.5X15
4
= 662 cu. Cm
Wt. of dry soil in grams
Apparent specific gravity = --------------------------------
Volume of soil in cu. Cm
1.05
= ------ = 1.58
662
Available moisture = Ap. Sp. Gr. X moisture content
= 1.58 X 14.28
= 22.56 cm / m depth of soil
The method is though accurate and simple it is used mainly for experimental purpose. Sampling, transporting & repeated weighing give errors. It is also laborious and time consuming. The errors of the gravimetric method can be reduced by increasing the size and number of samples. however the sampling disturbs the experimental plots and hence many workers prefer indirect methods.
III) Using Methyl Alcohol: Soil sample is mixed with a known volume of methyl alcohol and then measure the change in specific gravity of school with a hydrometer. This is a shot cut procedure but it is no in common use.
IV) Using calcium chloride: Soil sample is mixed with a known amount of calcium chloride. calcium chloride reacts with water and removes it in the form of acetylene gas. The moisture is determined has come in common use.
B) Indirect methods:
In those methods, no water content in the soil is directly measured but the water potential or stress or tension under which the water is held by the soil is measured. The most common instrument used for estimating soil moisture by indirect method is:
1) Tensiometer
2) Gypsum block
3) Neutron probe
4) Pressure plate and pressure membrane apparatus
In all these methods, the reading from above instruments and corresponding soil moisture content is determined by oven drying method are plotted on a graph. Subsequently, these calibration curves are used to know soil moisture content from the reading of these instruments.
1) Tensiometer: Tensiometer is also called irrometers since they are used in irrigation scheduling. Tensionmeters provide a direct measure of tenacity (tension) with which water is held by soil. It consist of 7.5 cm porous ceramic or clay cup, a protective metallic tube, a vacuum gauge and a hollow metallic tube holding all parts together. At the time of installation, the system is filled with water from the opening at the top and rubber corked when set up in the soil. moisture from cup moves out with drying of soil, creating a vacuum in the tube which is measured with the gauge. Care should be taken to install tensiometer in the active root zone of the crop. When desired tension is reached, the soil is irrigated. The vacuum gauge is graduated to indicate tension values up to one atmosphere and is divided in to fifty divisions each of 0.2 atmosphere value. The tensiometer works satisfactory up to 0.85 bars of atmosphere.
Merits of tensiometer:
1. It is very simple and easy to read soil moisture in situ.
2. It is very useful instrument for scheduling irrigation to crops which require frequent irrigations at low tension.
Limitations:
Sensitivity of a tensiometer is only up to 0.85 atmospheres while available soil moisture range is up to atmosphere and hence is useful more on sandy soils wherein about 80% of available water is held within 0.85 ranges.
2) Gypsum Blocks: Gypsum blocks or plaster of Paris resistance units are used for measurement of soil moisture is situ. These were first invented by Bouycos and Mick in 940. the blocks are made of various materials like gypsum, nylon fiber, glass, plaster of Paris or combination of these materials. The blocks are generally rectangular shaped. A pair or electronics is usually made of 20 mesh stainless steel wire screen soldered to copper lead wire. The common dimensions of screen electrodes are 33.75 cm long and 0.25 cm wide. The usual spacing between the electrodes is 2 cm. A similar block is 5.5 cm long, 3.75 cm wide and 2 cm thick.
Principal of working: It works on principal of conductance of electricity. When two electrodes A and B are placed parallel to each other in a medium and then electric current is passed, the resistance to the flow of electricity is proportional to the moisture content in the medium. Thus, when the block is wet, conductivity is high and resistance is low. Generally these read about 400 to 600 ohms resistance at field capacity and 50,000 at wilting point. the readings are taken with portable Wheatstone Bridge Bouycos water Bridge operated by dry cells.
While placing the gypsum block in soil, care should be taken that the blocks must have close contact with undisturbed soil. After placing, the blocks get wetted with soil moisture due to capillary movement. Pure gypsum block sets in about 30 minutes. The gypsum block is sensitive to soil to moisture from 1.0 atm tension to 20.0 atm. How ever, the gypsum blocks are not reliable in wet soils.
3) Pressure membrane and pressure plate apparatus: Pressure membrane and pressure plate apparatus (developed primarily by Richards) is generally used to estimate field capacity, permanent wilting point and moisture content at different pressures. The apparatus consists of air tight metallic chamber in which porous ceramic pressure plate is placed. The pressure plate and soil samples are saturated and are placed in the metallic chamber. The required pressure, say 0.33 bar or 15 bars is applied through a compressor. The water from the soil sample which is held at less than the pressure, Applied trickles out of the outlet till equilibrium against applied pressure is achieved after that, the soil samples are taken out and oven dried for determining the moisture content.
4) Neutron meter (neutron scattering method): Soil moisture can be estimated quickly and continuously another with neutron moisture meter without disturbing the soil. Another advantage is that soil moisture can be estimated from large volume of soil. This meter scans the soil to about 15 cm. diameter around the neutron probe in wet soil and 50 cm in dry soil. it consists of a probe and a scalar or rate meter. The probe contains fast neutron source, which may be a mixture of radium and beryllium or Americium and beryllium. Access tubes are aluminum tubes of 50 to 100 cm length and are placed in the field where moisture to be estimated.
Neutron probe is lowered into access tube to the desired depth. fast neutrons are released from the probes, which scatter into the soil. When neutrons encounter nuclei of hydrogen atom of water, their speed is reduced. the scalar or the rate meter counts the number of slow neutrons, which are directly proportional to water molecules. Moisture content of soil can be known from the calibration curve with counts of slow neutrons.
Limitations: The two drawbacks of the instruments are that it is expensive and moisture content from shallow top layers cannot be estimated. The fast neutrons are also slowed down by other source of hydrogen (present in the organic matter). Other atoms such as chlorine, boron and iron also slow down the fast neutrons, thus overestimating the soil moisture content.
5) Gama Ray absorption method: it is the technique of measurement of changes in soil water content by change in amount of gamma radiation absorbed. The amount of radiation passing through soil depends on soil destiny which varies chiefly with change in water content. This is suitable where change in bulk destiny is very small.
6) Feel and appearance method: A practical estimate of moisture content is obtained by the feel and appearance of soil samples taken from the desired depths. the soil sample is squeezed in the hand and its feel and appearance are taken into consideration. In this method, actual moisture content is not determined.
7) Soil moisture characteristic curve: The energy status of water and amount of water in the soil are related with the soil moisture characteristic curve. As the energy status of water decreases (moisture towards more negative values) soil water content also decreases. In other words, as soil moisture content deceases, more energy has to be applied to extract moisture from the soil. the relation between suction (externally applied force) and water content of the soil are represented graphically by a curve which is known as a soil are moisture characteristic curve.
Hysteresis:
The relation between energy status and moisture content can be obtained in two ways, (i) in absorption by taking an initially saturated soil sample and applying increasing suction to dry the soil gradually and (ii) in absorption by gradually wetting an initially dry soil. The measurement of energy status and moisture content during this process are taken and plotted on graph. The curves obtained through desorption and sorption is different for the same soil sample. the moisture content at a given suction is greater in desorption than in absorption and this phenomenon is known as hysteresis.
Evaporation, transpiration, evapo-transpiration, factors influencing ET
Rainfall and irrigation water are the main source of water. rainfall is the basic source of water. However, ground water can also be made available to crops. After precipitation or application of irrigation water, it is lost from soil in four ways.
1. Surface run-offs
2. Percolation (downward movement of excess water).
3. Evaporation from the soil surface
4. Transpiration
1) Surface run off: The loss of water through run-offs is the largest and is almost damaging because it causes soil erosion. The rate of loss of water through run-off depends upon the soil type, intensity of precipitation or quantity of irrigation water. When the intensity of rainfall is more for longer period, the loss of water from the soil surface through run-off is greater. The infiltration capacity of sandy soil is more than heavy soils and hence in sandy soil, loss of water through run-off is low.
2) Percolation: When rainfall is high and water-holding capacity of soil is less, the losses due percolation are very great. Such losses are very rapid particularly when the soils are sandy and porous. In heavy soils, percolation is low because of more water holding capacity. Besides rapid percolation of water, there is also heavy loss of plant nutrients viz. Ca, Mg, S, K etc. resulting in soil becoming acidic. Percolation losses are maximum in humid climate. When high rainfall is received, the loss of water through percolation is necessary otherwise, poor drainage conditions and water logging may develop in heavy soils. When water is in excess of water holding capacity of soils, it percolates through the soil due to gravity.
3) Evaporation losses: Evaporation is the process during which a liquid changes into a gas. The process of evaporation of water in nature is one of the fundamental components of the hydrological cycle by which is one of the vapour through absorption of heat energy. This is the only form of moisture transfer from land and oceans into the atmosphere.
Considerable quantity of water is lost by evaporation from the soil surface. Sunlight, temperature, wind velocity and humidity are the main climate factors influencing the rate and extent of evaporation. More the fine aggregates of black soil, more the heat absorbed resulting in more loss of water.
Man can do maximum control over such losses by adopting suitable soil management practices. The basic principle is to cover the soil with vegetation, mulching, keeping soil surface loose by tillage operation, use of wind brake etc. that can help to reduce evaporation losses.
4) Transpiration losses: Transpiration is the process by which water vapour leaver the living plant body and enters the atmosphere. It involves continuous movement of water from the soil into roots, through the stem and cut through the leaves to the atmosphere. The process include cuticular transpiration or direct evaporation in to the atmosphere from moist membranes through the cuticle, and stomatal transpiration or outward diffusion into the atmosphere through the stomata and lenticels vapour previously evaporated from imbibed membranes, into intracellular space within the plant.
Transpiration is an evaporation process. However, unlike evaporation from a water surface, plant structure and stomata behavior in conjunction with the physical principles governing evaporation modify transpiration.
The loss of water through transpiration is governed by temperature, humidity, wind velocity, moisture content in the soil and inherent characteristic of the plant. Since transpiration is a physiological process, which must continue, if the plant has to grow, the only way to save this loss is by growing such crops and their varieties whose transpiration co-efficient is low. Transpiration can be checked to some chemicals. Transpiration produces energy gradient, which causes movement of water into through plants.
Effective rainfall:
Effective rainfall is a part of rainfall available for the consumptive use of the crop.
Part of the rain may be lost as a surface run-off, deep percolation below the root zone of the crop or by evaporation of rain intercepted by foliage. When rainfall is of high intensity, only a portion of rainfall can enter the soil and stored in the root zone. In case of light rains of low intensity depending on the amount of moisture already present in the root zone of the crop, even the amount and intensity of rainfall, rate of consumption use, moisture storage capacity of soil, initial moisture content and infiltration rate of the soil. It is difficult to predict effective rainfall because of variation of soils, crops, topography and climate. However, in India it is assumed that 70% of the average seasonal rainfall to be effective in arid and semi-arid regions while 50% considered effective humid regions.
Water table:
The upper surface of the zone of saturation is called the water table. At the water table, the water in the pores of the aquifer is at atmospheric pressure. The hydraulic pressure at any level within a water table aquifer is equal to the depth from the water table point and is referred to as the hydraulic head. When a well is dug in a water table aquifer, the static water level in the well stands at the same elevation as the water table. The water table is not a stationary surface moves up and down rising when more water is added to the saturated zone by vertical percolation, and dropping during drought periods when the previously stored water flows out towards springs, streams, well and other points of ground water discharge.
Water Requirement and Irrigation Requirement
Water Requirement of Crop:
Water requirement of crop is the quantity of water regardless of source, needed for normal crop growth and yield in a period of time at a place and may be supplied by precipitation or by irrigation or by both.
Water is needed mainly to meet the demands of evaporation (E), transpiration (T) and metabolic needs of the plants, all together is known as consumptive use (CU). Since water used in the metabolic activities of plant is negligible, being only less than one percent of quantity of water passing through the plant, evaporation (E) and transpiration (T), i.e. ET is directly considered as equal to consumptive use (CU). In addition to ET, water requirement (WR) includes losses during the application of irrigation water to field (percolation, seepage, and run off) and water required for special operation such as land preparation, transplanting, leaching etc.
WR = CU + application losses + water needed for special operations.
Water requirement (WR) is therefore, demand and the supply would consist of contribution from irrigation, effective rainfall and soil profile contribution including that from shallow water tables (S)
WR = IR + ER + S
Under field conditions, it is difficult to determine evaporation and transpiration separately. They are estimated together as evaportranspiration (ET). IR is the irrigation requirement.
Factors influencing Evapotranspiration (ET):
ET is influenced by atmospheric, soil, plant and water factors.
A) Atmospheric factors:
1) Precipitation
2) Sunshine
3) Wind velocity
4) Temperature
5) Relative humidity
B) Soil factors:
1) Depth of water table
2) Available soil moisture
3) Amount of vegetative cover on soil surface.
C) Plant factors:
1) Plant morphology
2) Crop geometry
3) Plant cover
4) Stomatal destiny
5) Root depth
D) Water factors:
1) Frequency of irrigation
2) Quality of water ET.
Water requirement of any crop depends on crop factors such as variety, growth stage, and duration of plant, plant population and growing season. Soil factors such as temperature, relative humidity, wind velocity and crop management practices such as tillage, fertilization, weeding, etc. Water requirement of crops vary from area to area and even field to field in a farm depending on the above-mentioned factors.
Estimation of Evapotranspiration (ET):
Climate is the most important decides the rate of ET. Several empirical formulas are available to estimate ET from climate date. FAO expert group of scientists has recommended four methods for adoption of different regions of world.
1) Blaney and Criddle method
2) Radiation method
3) Pan evaporation method
4) Modified penman method
Estimation of ET Involves Three Important Steps:
a) Estimation of PET or evapotranspiration (ET) by any four above methods.
b) Estimation of crop co-efficient (KC) and
c) Making suitable adjustments to local growing conditions.
a) Reference Evapotranspiration (ETO): ETO can be defined as the rate of evapotranspiration of an extended surface of an 8 to 15 cm tall, green cover, actively growing completely shading the ground and not short of water.
Selection of a method for estimation of ETO depends on availability of metrological data and amount of accuracy needed. Among four methods for estimation of ETO, modified Blaney-Criddle method is simple, easy to calculate and requires data on sunshine (S.S.) hours, wind velocity (WV), relative humidity (RH) in addition to temperature (T).
Among these methods, modified penman method is more reliable with a possible error of 10% only. The possible errors for other methods are 15, 20 and 25% of pan evaporation, radiation and modified Blaney-Criddle methods respectively.
Modified Blaney method:
ETO = C [P (0.46 T + 8)] mm/day
Where ETO = Reference crop ET in mm/day for the month considered
T = Mean daily temperature in oC over the month considered
P = Mean daily percentage of total annual day time hours of a given month and latitude (from standard table)
C = Adjustment factor depends on minimum R.H., Sunshine hours and day time wind estimates.
Pan evaporation method:
ETO = Kp | Epan Where Kp = Crop factor
Epan = mean pan evaporation (Epan pan evaporation)
Modified penman method:
ETO = C [W.Rn + (1-w). f (U). (ea – ed)]
Where Rn = Net radiation in equivalent evaporation expressed as mm/day
W = temperature of altitude related factor
F (U) = Wind related function
Ea – ed= Vapour pressure deficit (mili bar)
C = the adjustment factor (ratio of U day to U night)
Rn (0.75-Rns)
Ea =Saturated vapour pressure (m.bar)
Ed = Mean actual vapour pressure of the air (m. bar)
Crop Coefficient:
Crop co-efficient is the ratio between evapotranspiration of crop (Etc) and potential evapotranspiration and expressed as T (crop) = Kc X ETo
Irrigation requirement:
Irrigation requirement is the total quantity of water applied to the land surface in supplement to the water supplied through rainfall and soil profile to meet the water needs of crops for optimum growth.
IR = WR – (ER + S)
Net irrigation requirement:
The net irrigation requirement is the amount of irrigation water just required to bring the soil moisture content in the root zone depth of the crops to field capacity. Thus, net irrigation requirement is the difference between the field capacity and soil moisture content in the root zone before application of irrigation water.
Gross irrigation requirement:
The total amount of water inclusive of water in the field applied through irrigation is termed as gross irrigation requirement, which in other words is net irrigation requirement plus application and other losses.
Consumptive use of water:
Sr. No
Crop
Consumptive Use ( cm )
Place
1
Jawar (Rabi )
450
Pune
2
Wheat
550
Pune
3
Sugarcane ( Suru )
2500
Padegoan
4
Sugarcane ( Adsali )
3300
Padegoan
5
Groundnut
560
Pune
6
Gram
250
Rahuri
7
Sunflower
350
Rahuri
Irrigation requirement of some common crops grown in India:
Crop
Growing Period ( No. of days )
Total Water Requirement
Daily Water Requirement
in cm
in inches
in cm
in inches
Jawar
114
64.25
25.70
0.575
0.23
Maize
100
44.50
17.80
0.450
0.18
Rice
93
104.50
41.80
1.075
0.43
Wheat
88
37.00
14.80
0.425
0.17
Groundnut
124
65.25
26.10
0.525
0.21
Linseed
88
31.71
12.68
0.350
0.14
Cotton
202
105.50
42.20
0.525
0.21
Sugarcane
365
237.50
95.00
0.650
0.26
Tobacco
132
98.00
39.20
0.750
0.30
Onion
120
75.00
30.00
0.625
0.25
Potato
88
30.00
12.00
0.750
0.30
Pea
88
30.00
12.00
0.350
0.14
Mustard
88
25.20
10.08
0.300
0.12
Barley
88
25.20
10.08
0.400
0.16
Oat
88
36.00
14.40
0.400
0.16
Ragi
127
74.50
29.80
0.575
0.23
Quantity of Irrigation Water or How Much to Irrigation
The net quantity of water to be applied depends upon magnitude of moisture deficit in the soil, leaching requirement and expectancy of rainfall. When no rainfall is likely to be received and soil is not saline, net quantity of water to be applied is equal to the moisture deficit in the soil i.e. the quantity required to fill the root zone to filed capacity. The moisture deficit (d) in the effective root zone found out by determining the field capacity moisture content and bulk density of each layer.
Problem: Find out the net quantity of irrigation water to be applied to wheat field with the following moisture status.
Sr. No.
Depth of Soil Layer ( cm )
Moisture % on oven dry basis
Apparent specific gravity g/cc
Field Capacity
Actual
1
0 - 15
25.0
16.4
1.39
2
15 - 30
24.0
17.8
1.47
3
30 - 60
22.3
19.2
1.51
4
60 - 90
22.2
20.5
1.53
Solution: Moisture deficit in the different layers will be as follows,
25.0 – 17.8
1. First Layer = ----------------- X 1.39 X 15 = 1.79
100
24.0 – 17.8
2. Second Layer = ----------------- X 1.47 X 15 = 1.36
100
22.3 – 19.2
3. Third Layer = ------------------ X 1.81 X 30 = 1.40
100
22.2 – 20.5
4. Forth Layer = ----------------- X 1.53 X 30 = 0.78
100
Therefore, net quantity of water to be applied is 5.33 cm to fill the root zone to field capacity again.
Requirement of irrigation water:
Units for water measuring:
Water is measured under two conditions. Water at rest measured in units of volume such as liter, cubic meter, hectare meter. Water in motion is expressed in rate off low units such as liters per hour and meters per day.
Liter: One liter is equivalent to 0.22 imperial gallons or 0.0353 cubic feet or 1/1000cubic meters.
Cubic meters: A volume of water equal to that of one cubic meter in length, one meter in breadth and one meter in thickness. One cubic meter of water = one kilo liters or 100 liters or 220 gallons or 35.3 cubic feet or one ton (approx)
Gallon: A gallon is 0.1602 cubic foot. One gallon of water weighs about 10Ib
Cubic foot: A volume of water equal to that of a cube 1 foot in length, 1 foot in breadth and 1 cubic foot in thickness. One cubic foot of water = 28.37 liters or 6.23 gallons or 0.0283 cubic meters or 0.028 ton.
Hectare centimeters: A volume of water necessary to ci\over an area of one hectare (10,000 aq. meters) surface to a depth of one centimeters (1hectare centimeter = 100 cubic meters = 100,000 liters)
Acre inch: the volume of water necessary to cover one-acre (43,560 sq. feet) surface to a depth of one inch. One hectare inch = 3630 cubic feet or 101 ton.
Acre foot: The volume of water necessary to cover one acre to a depth of one foot.
(One acre feet = 43,560 cubic feet)
Cusec: It is the quantity of water flowing at the rate of one cubic foot per second. As one cubic feet of water weighs about 62.4 Ib or 28.37 kg. One cusec of water flowing for one hour is equal to 62.4 Ib X 60 X 60 = 22464 gallons, 101 tons, or one- hectare inch (28.37 liter X 60 X 60 = 101952 liters or one-acre inch.
Duty of water: It denoted the number of acres covered by one causes of water flowing continuously through out the growing season of a crop. It is therefore varies with kind of crop, season, nature of soil, method of irrigation and method of cultivation.
Delta: It is the total depth of water required by a crop.
Problem: A pump with an average discharge of 15 liters/second irrigates one-hectare wheat crop in 12 hours. What is an average depth of irrigation?
Solution:
Discharge in 12 hours = 15 X 60 X 60 X 12
= 648000 liters
= 648 M^3
Volume of water (Cu. m)
Depth of irrigation (cm) = -------------------------------------- X 100
Area of land (sq. m)
648
= --------------- X 100
10,000
= 6.48 cm
Problem: Wheat crop requires 40 cm of irrigation water during 120 days irrigation period. How much land can be irrigation with a flow of 20 liters per second for 12 hours a day?
Solution:
20 X 60 X 60 X 12 X 120
Total discharge during irrigation period = ------------------------------------- M3
1000
= 1, 03,680 M3
40
Irrigation requirement per hectare = ------- X 10,000 M3
100
= 1, 03,680 M3
40
Irrigation requirement per hectare = ----------- X 10,000 M3
100
= 4000 M3
Volume of available water
Area irrigated = ------------------------------- X 10,000 M3
Volume of water required/ha (M3)
1, 03,680
= ---------------
40
= 25.92 hectare land can be irrigated
Devices Used for Measuring Irrigation Water
Several devices are commonly used for measuring irrigation water. They grouped into four categories
1) Volumetric Measures
2) Velocity-Area Methods
a) Float Method
b) Water Meters
3) Measuring Structures
a) Orifices
b) Weirs
c) Flumes
4) Tracer Methods
1) Volumetric methods (Using a container)
A simple method of measuring a small irrigation stream is to collect the flow in container of known volume for a measured period. An ordinary bucket or barrel is used as container. The time required to fill the container is recorded with a stopwatch or with seconds on wristwatch. The rate of flow is measured as below
Volume of container (liters)
Discharge rate liter/second = -----------------------------------
Time required to fill (seconds)
PROBLEM: A 24 liter capacity bucket is filled in 10 seconds by discharge from a Persian wheel. What is rate of flow?
24
Solution: Discharge ratio liter/second = -----
10
= 2.4 liter/second or 144 liter/minute
2) Velocity area method:
a) Float method:
The float method of making of rough estimates of the flow in a channel consists of nothing the rate of movement of a floating body. A long necked bottle partly filled with water or black wood, an orange or lemon may be used as float. A straight section of the channel about 30 meters long with uniform cross section is selected. Several methods of depth and width are made within the trial section to arrive at average cross sectional area. A string is stretched across each end of section at right to the direction of flow. The float is placed in the channel a short distance up stream from the trial section. The float needed to pass from upper end to lower end of the section is recorded. Several trials are made to get average time of travel.
To- determine the velocity of water at the surface of the channel, the length of the trial section is divided by the average time taken by the float to cross it. Since the Velocity of the float on the surface of the water will be greater than the average velocity of the stream; it is constant factor, which is usually assumed to be 0.85. To obtain the rate of flow , this average velocity ( measured velocity x co-efficient) is multiplied by the average cross sectional area of the stream.
Discharge or rate of flow = area x velocity
Q = A X V where Q= discharge rate in m3/sec. v = velocity of flow in m/s
a = cross section al area of channel in m2
b) Water meters:
Water meters utilize a multi blade propeller made of metal, plastic or rubber, rotating in a vertical or horizontal plane and geared to a tataliser in such a way that a numerical counter can totalize the flow in any desired volumetric units, water meters are available for a range of sizes suiting the pipe size commonly used on the farm. There are basic requirements for accurate operation of the water meter.
(1) The pipe must flow full at all times.
(2) The rate of flow must exceed the minimum for the rated range.
Meters are calibrated in the factory and field adjustments are usually not required. When water meters are installed in open channels, the flow must be brought through the pipes of known cross sectional area. Care must be taken that no debris or other foreign materials obstruct the propeller.
3) Water measuring devices:
a) Orifices:
Orifices in open channel are usually circular or rectangular openings in vertical bulk head through which water flows. The edges of opening are sharp and often constructed of metal. The cross sectional area of orifice is small in relation to the stream cross section. Orifice may operate under free flow or submerged flow conditions. The types of orifices are
I) Orifices below the level of inlet: The discharge through a closer orifice in which the orifice is situated below the level of inlet is calculated by the equation.
Q = Ca x under root (2gh)
Where, Q = Quality of flow in C. ft/Sec.
a+ Cross sectional area of water, the canal or orifice in sq. ft.
c = A constant which varies from 0.6 to 0.8 or more depending upon the position of orifice relative to the sides and bottom of vessels or the degree of roundness of the edge of orifice.
g= Acceleration due to gravity. (32 feet / sec/sec)
h= Height of water level in cistern from the middle of the orifice in feet.
II) Discharge through an orifice situated at higher level than inflow pipe: When the orifice is situated at a higher level than the inflow pipe, the discharge is calculated according to the equation.
Q = CLh1.5
Where D= Length of orifice in feet and
C= 2C 2g
H= head of water.
III) Discharge through submerged orifice:The discharge through a submerged orifice is given by the equation.
Q=0.61 LH 2gh
E.g. if L=1.0 H=0.5ft. h=0.25 ft. and g=Acceleration due to gravity (32ft/sec/sec) then Q=1.22 C, ft/sec.
b) Discharge through Weirs:
A wear means a notch in a well built across a stream. The notch may be (a) rectangular (b) Trapezoidal and (c) 90 degree V (Triangular) notch or weir.
(a) Rectangular notch or weir: The length of a weir may be equal to width of the upstream channel or less than it. The discharge through a rectangular weir, in case of complete end, contraction is given by the equation.
Q = 3.33 (L-0.2 H) H^1.5
Where L= measured length of the weir
L= effective length of weir in feet.
L= L-0.2H)
(b) Trapezoidal or Cipolletti Weir:
The discharge of water is given by the equation
Q= 3.367 LH ^ 1.5
L1 + L2
Where = --------------
2
(c) Discharge through 90oV notch:
The discharge is given by the equation:
Q= 2.49 H ^ 2.48 = 2.5H^2.5
c) Parshall flume or (Venturi flume):
Parshall (1950) has decided a device in which the discharge is obtained by measuring the loss in the head caused by forcing a stream of water through a throat or converged section of a flume with a depressed bottom. The loss in head is very small in this device. The accuracy of measurement in the Parshall flume is within allowable limits of 5% the flumes ranging from 3 inches to 10 feet throat width are used, which gives the range of discharge of 1/30 to 200 ousecs. The flumes of 3, 6 and 9 inch size are generally used in field measurement.
The ration between the reading at Hb and Ha point should be carefully studied. This ratio should not exceed 0/3 for 3 inch, 6 inch 9 sized Parshall flumes otherwise correction needs to be applied. When the ratio is less than 0.6, it is termed as free flow and exceeds 0.6, it is called submerged flow.
CUT THROAT FLUMES: Skogerboe eqal. (1967) have developed cutthroat flumes for measurement of water. Since there is no throat section (Zero throat flumes), the flumes have been given the name as out throat flumes by the designers.
The flumes have a level floor as apposed to the inclined floor in the throat and exit section in the partial flumes. it is placed in a concrete lined channel or on a channel bed conveniently. Every flume has the same all lengths in both the entrance and exit sections. These flumes consist of converging inlet section and diverging outlet section, under free flow conditions. The discharge Q through a cutthroat flume depends upon the upstream depth of flow Ha. The basic form of the free flow equation is-
Q=CH a 1.56
Where C=3.50 W 1.025 (W=throat d width infect)
4) Tracer Methods:
These methods are independent of stream cross section and are suitable for field measurements with out installing fixed structures. In these methods, a substance (tracer) is concentration form is introduced into flowing water and allowed to thoroughly mix. The concentration of the tracer is measured at down stream section. Since only the quantity of water is necessary to accomplish the dilution is involved, there is no need to measure velocity, depth, and head, cross sectional or any other hydraulic factor usually considered in discharge measurement. The relationship between size of stream, time of application, area to be irrigated and depth of water to applied is as below.
Qt=ad
Where Q=Size of stream or discharge (liter/second) or (ha. cm per hour)
t=the time of application of water (seconds or hour)
a=area (sq. m or hectare)
d=Depth in cm that the volume of water used would cover the land irrigated, if quickly spread uniformly over its surface.
Criteria for Scheduling Irrigation or Approaches for Irrigation Scheduling
An ideal irrigation schedule must indicate when to apply irrigation water and how much quantity of water to be applied; several approaches for scheduling irrigation have been used by scientist and farmers. These are as under
1) Soil moisture depletion approach:
The available soil moisture in the root is a good criterion for scheduling irrigation. When the soil moisture in a specified root zone depth is depended to a particular level (which is different for different crops) it is too replenished by irrigation.
For practical purpose, irrigation should be started when about 50 percent of the available moisture in the soil root zone is depleted. The available water is the soil moisture, which lies between field capacity and wilting point. The relative availability of soil moisture is not same field capacity to wilting point stage and since the crop suffers before the soil moisture reaches wilting point, it is necessary to locate the optimum point within the available range of soil moisture, when irrigation must be scheduled to maintain crop yield at high level. Soil moisture deficit represents the difference in the moisture content at field capacity and that before irrigation. This is measured by taking into consideration the percentage, availability, tension, resistance etc.
2) Plant basis or plant indices:
As the plant is the user of water, it can be taken as a guide for scheduling irrigation. The deficit of water will be reflected by plants itself such as dropping, curling or rolling of leaves and change in foliage colour as indication for irrigation scheduling. However, these symptoms indicate the need for water. They do not permit quantitative estimation of moisture deficit.
Growth indicators such as cell elongation rates, plant water content and leaf water potential, plant temperature leaf diffusion resistance etc. are also used for deciding when to irrigate. Some indicator plants are also a basis for scheduling irrigation e.g. sunflower plant which is used for estimation of PWP of soil is used in Hawaii as an indicator plant for irrigation sugar cane.
3) Climatological approach:
Evapotranspiration mainly depends up on climate. The amount of water lost by evapotranspiration is estimated from Climatological data and when ET reaches a particular level, irrigation is scheduled. The amount of irrigation given is either equal to ET or fraction of ET. Different methods in Climatological approach are IW/CPE ratio method and pan evaporimeter method.
In IW/CPE approach, a known amount of irrigation water is applied when cumulative pan evaporation (CPE) reaches a predetermined level. The amount of water given at each irrigation ranges from 4 to 6 cm. The most common being 5 cm irrigation. Scheduling irrigation at an IW/CPE ratio of 1.0 with 5 cm. Generally, irrigation is given at 0.75 to 0.8 ratios with 5 cm of irrigation water.
Problem: Calculate cumulative evaporation required irrigation at 0.5 0.6 0.75 0.8 with 5 cm of irrigation water.
Solution:
Cumulative pan evaporation at IW/CPE ratio of 0.5=IW/CPE=0.5
5 5 50
= ---------- = 0.5, CPE X 0.5 = 5 CPE = ------ = ------ 10cm
CPE 0.5 5
Irrigation of 5 cm is given when CPE is 10 cm
CPE at 0.6 ratio = 5/0.6 = 8.33cm
CPE at 0.75 ratio = 5/0.75 = 6.66cm
CPE at 0.8 ratio = 5/0.8 = 6.25cm
In IW/CPE ratio approach, irrigation can also be scheduled at fixed level of CPE by varying amount of irrigation water.
Problem: Calculate the amount of water for each irrigation for scheduling irrigation at 0.5 and 0.8 IW/CPE with 10cm of CPE.
Solution:
Amount of water to be given at IW/CPE ratio of 0.5=IW/10=0.5
IW=0.5 X 10= 5cm
Amount of water to be given at IW/CPE ratio of 0.8 =IW/10=0.8, IW=10 X 0.8=8cm
Estimating Evapo-Transpiration from Evaporation Data:
It is been observed that a close relationship exists between the rate of CU by crops and the rate of evaporation from a well-located evaporation pan. The standard United States weather bureaus class A pan evaporimeter or the sunken screen pan evaporimeter may be used for measurement of consumption use.
U.S class A evopometer:
It is most widely used evaporation pan. It is made of 20 gauge galvanized iron sheet 120 cm. in diameter by 25cm. in depth and is painted white and exposed on a wooden frame in order that air may circulate beneath the pan. It is filled with water to depth of about 20 cm. The water surface level is measured daily by means of hook gauge in a still well. Difference between two daily readings indicates the evaporation if there is no rainfall. When there is rainfall, record it separately with a rain gauge. Add that value to the initial water level in the still well. Difference between this reading and subsequent reading of the water would indicate evaporation. Water is added each day to bring the level to fixed point in the still well. A measuring cylinder can also be used for this purpose.
Sunken Screen Evapometer:
The sunken screen pan evaporimeter developed by Sharma and Dastane (1968) at the I.A.R.T., New Delhi provides a simple device to make reasonable estimate of CU. The ratio between evapo-transpiration and evaporation from U.S.W. class A pan (ET/E) is about 0.5 to 1.3 after establishment of the crop. the same ratio is the sunken screen pan evaporimeter was observed i.e. 0.95 to 1.05. in other words, it is claimed that the evaporation value obtained from it closely approximates the evapo-transpiration.
It consists of three parts, namely an evaporation pan, a stilling well and a connecting tube. The evaporation is 60 cm. in depth, is made of 20ngague galvanized iron sheet, and is painted white. it is fitted with a screen of 1/24 or 6/20 mesh, which is held tight over the pan by bending it at the rim and pressing hard. The stilling well is 15 cm. in diameter 45 cm. in depth and is fitted with a screen cover of the same mesh as that of the evaporation pan. It has a pointer to its side of the wall and bent upward in the center at right angle. The evaporimeter is installed by digging a pit of suitable size placing the pen and back filling the earth with due to compaction the top edge of the protrudes (sickout) 10 cm. over the soil surface. This is necessary to avoid run-off from the surrounding area entering the pan. The water level is maintained at same height as the soil level outside. Thus, the tip of the pointer free water surface in the pan and the pan and soil surface are at the same level.
The water level in the pan is brought in level with the pointed tip and pan is set at work. Observations of falling water level are recorded at suitable intervals say 24 hours. This is done by adding water with a measuring cylinder and recording the quantity of water added to bring the water level back to the pointer tip. The volume of water (ml) added is converted in to depth (mm) by dividing the area of pan plus that of stealing well.
The evaporimeter is installed in duplicate to enable leakage detection. The minimum distance between two evaporimeter is 3 meter. The pan is cleaned occasionally and painted white once in a year and cheeked scrupulously for leakages. The evaporimeter is located under natural conditions in a field, which does not provide obstruction to wind. It is aligned perpendicular to the main direction of wind to avoid mutual interference.
4) Critical growth approach:
In each crop, there are some growth stages at which moisture stress leads to irrevocable yield loss. These stages are known as critical periods or moisture sensitive periods. If irrigation water is available in sufficient quantities, irrigation is scheduled whenever soil moisture is depleted to critical moisture level. Say 25 or 50 percent of available soil moisture. Under limited water supply conditions, irrigation is scheduled at moisture sensitive stages and irrigation is skipped at non-sensitive stages. In cereals, panicle initiation, flowering, and pod development are the most important moisture sensitive stages.
Table: Moisture sensitive stages of important crops.
Sr. No.
Crop
Important Moisture Sensitive Stages
1
Rice
Panicle Initiation, Flowering
2
Wheat
Crown Root Initiation, Jointing, Milking
3
Sorghum
Seedling, Flowering
4
Maize
Silking. Tasseling
5
Bajara
Flowering, Panicle Initiation
6
Nachani
Panicle Initiation, Flowering
7
Ground Nut
Rapid Flowering, Pegging, Early Pod Formation
8
Red Gram
Flowering & Pod Formation
9
Green Gram
Flowering & Pod Formation
10
Black Gram
Flowering & Pod Formation
11
Sugarcane
Formative Stage
12
Sesamum
Blooming stage to Maturity
13
Sunflower
Two weeks before & after flowering
14
Safflower
From rosette to flowering
15
Soybean
Blooming & seed formation
16
Cotton
Flowering & Ball Formation
17
Tobacco
Transplanting to Full Bloom
18
Chilies
Flowering
19
Potato
Tuber Initiation to Tuber Maturity
20
Onion
Bulb Formation to Maturity
21
Tomato
From the Commencement of Fruit Set
5) Plant water status it self:
This is the latest approach for scheduling of irrigation. Plant is a good indicator of a soil moisture and climate factors. The water content in the plant itself is considered for scheduling irrigation. It is however, not yet common use for want of standard and low cost technique to measure the plant water status or potential.
Simple Technique for Scheduling Irrigation
Soil cum sand mini plot technique:
In this method, one cubic meter pit is dug in the middle of field. About five percent of sand by volume is added to the dug soil, mix well and pit is filled in the natural order. Crops are grown as usual in the entire area of the field including the pit area. The plants in the pit show wilting symptoms earlier than the other plants in the remaining area. Irrigation is scheduled as soon as wilting symptoms appear on the plants in the pit.
Sowing high seed rate:
In an elevated area, one square meter plot is selected and crop is grown with four times thicker than natural seed rate. Because of high plant density, plants show wilting symptoms earlier than in the area indicating the need for scheduling irrigation.
Feel and appearance method:
Moisture content can be roughly estimated by taking the soil from root zone in to hand and making in to small ball. It requires lot of experience to estimate the soil moisture by this method.
Irrometers or tensiometer:
Tensiometer is also called irrometers since they are used in irrigation scheduling. Tensionmeters provide a direct measure of tenacity (tension) with which water is held by soil. It consist of 7.5 cm porous ceramic or clay cup, a .0protective metallic tube, a vacuum gauge and a hollow metallic tube holding all parts together. At the time of installation, the system is filled with water from the opening at the top and rubber corked when set up in the soil. Moisture from cup moves out with drying of soil, creating a vacuum in the tube which is measured with the gauge. Care should be taken to install tensiometer in the active root zone of the crop. When desired tension is reached, the soil is irrigated. The vacuum gauge is graduated to indicate tension values up to inch atmosphere and is divided in to fifty divisions each of 0.2 atmosphere value.
Merits of tensiometer:
1. It is very simple and easy to read soil moisture in situ.
2. It is very useful instrument for scheduling irrigation to crops which require frequent irrigations at low tension.
Limitations:
Sensitivity of a tensiometer is only up to 0.85 atmospheres while available soil moisture range is up to atmosphere and hence is useful more on sandy soils wherein about 80% of available water is held within 0.85 ranges.
Plant indices:
As the plant is the user of water, it can be taken as a guide for scheduling irrigation. The deficit of water will be reflected by plants itself such as dropping, curling or rolling of leaves and change in foliage colour as indication for irrigation scheduling. However, these symptoms indicate the need for water. They do not permit quantitative estimation of moisture deficit.
Growth indicators such as cell elongation rates, plant water content and leaf water potential, plant temperature leaf diffusion resistance etc. are also used for deciding when to irrigate. Some indicator plants are also a basis for scheduling irrigation e.g. sunflower plant which is used for estimation of PWP of soil is used in Hawaii as an indicator plant for irrigation sugar cane.
Infra red thermometer:
Canopy temperature is measured with infrared thermometer. It also simultaneously measures canopy temperature (Tc) and air temperature (Tq) and displays Tc-Tq value. Tc-Tq values can be used for scheduling irrigation. When transpiration is normal, due to its cooling effect canopy temperature is less than air temperature. The negative values of Tc-Tq indicate the plants have sufficient amount of water. When Tc-Tq values are zero or positive, which indicates stress irrigation is scheduled. Stress degree days (SDD), useful for scheduling irrigation are summed in a manner that is analogous to growing degree days SDD = (Tc-Tq) canopy temperature is measured during midday when air temperature is maximum. Yield reduction is maximum, when total number of cumulative SDD’s exceeds 10 to 15 between irrigations.
Remote sensing:
In projects areas, where a single crop is grown on large area, irrigation scheduling can be done with the help of remote sensing data. Reflectance of solar radiation by the plants with sufficient amount of water is different from that of stressed plants. This principle can be used for scheduling irrigation. The following methods can be recommended to farmers for scheduling irrigation.
· Soil -Cum-Sand Mini Plot Technique
· Increased Plant Population
· Pan Evaporimeter
· Methods of Irrigation- Surface, Surge, Subsurface, Sprinkler, Raingun Sprinkler
·
· There are three principle methods of irrigation viz. surface, sub surface and aerial, overhead or sprinkler irrigation.
· A. Surface irrigation: There are four variations under this method viz.
· (1) Flooding,
(2) Bed or border method (Saras and flat beds),
(3) Basin method (ring and basin) and
(4) Furrow method (rides and furrows, broad ridges or raised beds)
· Flooding: It consist of opening a water channel in a plot or field so that water can flow freely in all directions and cover the surface of the land in a continuous sheet. It is the most inefficient method of irrigation as only about 20 percent of the water is actually used by plants. The rest being lost as a runoff, seepage and evaporation. Water distribution is very uneven and crop growth is not uniform. It is suitable for uneven land where the cost of leveling is high and where a cheap and abundant supply of water is available. It is unsuitable for crops that are sensitive to water logging the method suitable where broadcast crops, particularly pastures, alfalfa, peas and small grains are produced.
· Adaptations:
· (1) An abundant supply of water
(2) Close growing crops
(3) Soils that do not erode easily
(4) Soils that is permeable
(5) Irregular topography
(6) Areas where water is cheap.
· Advantages:
· (1) Can be used on shallow soils
(2) Can be employed where expense of leveling is great
(3) Installation and operation costs are low
(4) System is not damaged by livestock and does not interfere with use of farm implements.
· Disadvantages:
· (1) Excessive loss of water by run of and deep percolation
(2) Excessive soil erosion on step land.
(3) Fertilizer and FYM are eroded from the soil.
· Bed or border method (Sara and Flat beds or check basin): In this method the field is leveled and divided into small beds surrounded by bunds of 15 to 30 cm high. Small irrigation channels are provided between two adjacent rows of beds. The length of the bed varies from 30 meters for loamy soils to 90 meters for clayey soils. The width is so adjusted as to permit the water to flow evenly and wet the land uniformly. For high value crops, the beds may be still smaller especially where water is costly and not very abundant. This method is adaptable to most soil textures except sandy soils and is suitable for high value crops. It requires leveled land. It is more efficient in the use of water and ensures its uniform application. It is suitable for crops plant in lines or sown by broadcast. Through the initial cost is high requires less labour and low maintenance cost. This may also be called a sort of sara method followed locally in Maharashtra but the saras to be formed in this method are much longer than broader.
· Adaptations:
· (1) A large supply of water
(2) Most soil textures including sandy Loam, loams and clays
(3) Soil at least 90 cm deep
(4) Suitable for close growing crops.
· Advantages:
· (1) Fairly large supply of water is needed.
(2) Land must be leveled
(3) Suited only to soils that do not readily disperse.
(4) Drainage must be provided
· Basin irrigation: This method is suitable for orchids and other high value crops where the size of the plot to be irrigated is very small. The basin may be square, rectangular or circular shape. A variation in this method viz. ring and basin is commonly used for irrigating fruit trees. A small bund of 15 to 22 cm high is formed around the stump of the tree at a distance of about 30 to 60 cm to keep soil dry. The height of the outer bund varies depending upon the depth of water proposed to retain. Basin irrigation also requires leveled land and not suitable for all types of soil. It is also efficient in the use of water but its initial cost is high.
· There are many variations in its use, but all involve dividing the field into smaller unit areas so that each has a nearly level surface. Bunds or ridges are constructed around the areas forming basins within which the irrigation water can be controlled. Check basin types may be rectangular, contour and ring basin.
· Adaptations:
· 1) Most soil texture
2) High value crops
3) Smooth topography.
4) High water value/ha
· Advantages:
· 1) Varying supply of water
2) No water loss by run off
3) Rapid irrigation possible
4) No loss of fertilizers and organic manures
5) Satisfactory
· Disadvantages:
· 1) If land is not leveled initial cost may be high
2) Suitable mainly for orchids, rice, jute, etc.
3) Except rice, not suitable for soils that disperse easily and readily from a crust.
· Furrow method (rides and furrow, broad ridges, counter furrow etc.): Row crops such as potatoes, cotton, sugarcane, vegetable etc. can be irrigated by furrow method. Water is allowed to flow in furrow opened in crop rows. It is suitable for sloppy lands where the furrows are made along contours. The length of furrow is determined mostly by soil permeability. It varies from 3 to 6 meters. In sandy and clay loams, the length is shorter than in clay and clay loams. Water does not come in contact with the plant stems. There is a great economy in use of water. Some times, even in furrow irrigation the field is divided into beds having alternate rides and furrows. On slopes of 1 to 3 percent, furrow irrigation with straight furrows is quite successful. But on steeper slopes contour furrows, not only check erosion but ensure uniform water penetration.
· Adaptations:
· 1) Medium and fine textured soils.
2) Variable water supply
3) Farms with only small amount of equipment.
· Advantages:
1) High water efficiency
2) Can be used in any row crop
3) Relatively easy in stall
4) Not expensive to maintain
5) Adapted to most soils.
· Disadvantages:
· 1) Requirement of skilled labour is more
2) A hazard to operation of machinery
3) Drainage must be provided.
· B. Subsurface method:
· Subsurface irrigation or sub-irrigation may be natural or artificial. Natural sub surface irrigation is possible where an impervious layer exists below the root zone. Water is allowed in to series of ditches dug up to the impervious layer, which then moves laterally and wets root zone.
· In artificial sub surface irrigation, perforated or porous pipes are laid out underground below the root zone and water is led into the pipes by suitable means. In either case, the idea is to raise the water by capillary movement. The method involves initial high cost, but maintaince is very cheap. There is a risk of soil getting saline or alkaline and neighboring land damaged due to heavy seepage.
· It is very efficient in the use of water as evaporation is cut off almost completely. The plant roots do not suffer from logging, there is no loss of agricultural land in laying out irrigation system and implements can be worked out freely. This method is however rarely noticed in our country but followed in other countries like Israel.
C. Drip or trickle irrigation:
· It involves slow application of water to the root zone. The drip irrigation system consist of
· 1) Head
2) Main line and sub line
3) Lateral lines
4) Drip nozzles.
· The head consists of a pump to lift water and produce the desired pressure (about 2.5 tmosphere) and to distribute water through nozzles. A fertilizer tank for applying fertilizer solution directly to the field along with the irrigation water and filter which cleans the suspended impurities in irrigation water to prevent the blockage of holes and passage of drip and nozzles
· Mains and sub mains are normally of flexible material such as black PVC pipes. Laterals or drip lines are small diameter flexible lines (usually 1 to 1.25 cm diameter black PVC tubes) taking off from the mains or sub mains. Laterals are normally laid parallel to each other. Lateral lines can be up to about 50 meters long and are usually 1.2 cm diameter black plastic tubing. There is usually one lateral line for each crop row. By laying the main line along the center line of the field, it is possible to irrigate either side of the field alternately by shifting the laterals. A pressure drop of 10 percent is permitted between the ends of lateral.
· Drip nozzles are also known as emitters or values and are fixed at regular intervals in the laterals. These PVC values allow water to flow at the extremely slow rates, ranging from 2 to 11 liters per hour and they are of different shapes and design.
· The spacing between laterals is controlled by the row-to-row spacing of the crop to be irrigated. Drip laterals laid on soil surface are buried underground at the depth of 5 to 10 cm.
· Advantages:
· 1) The losses by drip irrigation and evaporation are minimized
2) Precise amount of water is applied to replenish the depleted soil moisture at frequent intervals for optimum plant growth.
3) The system enables the application of water fertilizers at an optimum rate to the plant root system.
4) The amount of water supplied to the soil is almost equal to the daily consumptive use, thus maintaining a low moisture tension in soil.
· Disadvantages:
· The initial cost of the drip irrigation for large-scale irrigation is its main limitation. The cost of the unit per hectare depends mainly on the spacing of the crop. For widely spaced crops like fruit trees, the system may be even more economical than sprinkler.
· D. Sprinkler or overhead irrigation:
· This method consists of application of water to soil in the form of spray, somewhat as rain. It is particularly useful for sandy soils because they absorb water too fast. Soils that are too shallow, too steep or rolling can be irrigated efficiently with sprinklers.
· This method is suitable for areas having uneven topography and where erosion hazards are great.
· In sprinkler irrigation, water is conveyed under pressure through pipes to the area to be irrigated where it is passed out through or sprinklers the system comprises four main parts
i. Power generator
ii. Pump
iii. Pipeline and
iv. Sprinkler
· The power generator may be electrical or mechanical. A centrifugal pump may be used for suction lift up to 37 to 50 cm. A piston type pump is preferable where water is very deep. The pipe consists of two sections, the main line and the laterals.
· The main line may be permanently buried underground or may be laid above ground, if it is to be used on a number of fields. The main pipes are usually made of steel or iron.
· The laterals are lightweight aluminum pipes and are usually portable. The sprinkler nozzles may be single or double, revolving or stationery and mounted or riser pipes attached to riser. Each sprinkler head applies water to circular area whose diameter depends up on the size of water, which varies from ¼ to ¾ inch per hour is determined by selecting the proper combination of nozzles.
· Adaptations:
· 1) A dependable supply of water
2) Uneven topography
3) Shallow soils.
4) Close growing crops.
· Advantages:
· 1) It ensures uniform distribution of water
2) It is adaptable to most kinds of soil.
3) It offers no hindrance to the use of farm implements
4) Fertilizers material may be evenly applied through sprinklers. This is done by drawing liquid fertilizer solution slowly in to the pipes on the suction side of the pump so that the time of application varies from 10 to 30 minutes.
5) Water losses are reduced to a minimum extent
6) More land can be irrigated
7) Costly land leveling operations are not necessary and
8) The amount of water can be controlled to meet the needs of young seedling or mature crops.
· Disadvantage:
· 1) The initial cost is rather very high.
2) Any cost of power to provide pressure must be added to the irrigation charges.
3) Wind interferes with the distribution pattern, reducing spread or increasing application rate near lateral pipe.
4) There is often trouble from clogged nozzle or the failure of sprinklers to revolve.
5) The cost of operations and maintaince is very high. Labour requirement for moving a pipe and related work approximately nearly one hour per irrigation.
6) It requires a dependable constant supply of water free slit and suspended matter and 7) It is suitable for high value crops
Micro Irrigation
Micro irrigation is defined as the methods in which low volume of water is applied at low pressure & high frequency usually an irrigation interval is in the ranges of 1 to 4 days. The system has extensive network of pipes at operated at low pressure. At pre-determined spacing outlets are provided for emission water generally known as emitters.
Drip irrigation:
In drip irrigation the required quantity of water is applied by means of mains, sub mains, manifolds & plastic laterals in the with equally spaced emitters usually laid on the ground surface at low pressure & at low discharge at the root zone of the crop.
Advantage of drip irrigation
1. Water saving is up to 40 to 60%
2. Enhance the plant growth & increases the crop yield
3. Savoring in level & energy most. Suitable for poor soil.
4. Weed infestation is minimum
5. Economy in cultural practices & easy operations.
6. Chance of using saline water.
7. Improve efficiency of fertilizers.
8. Very flexible in operation
9. No soil erosion.
10. Easy installation, no land preparation.
11. Minimizing quantity of produce.
12. Enhances the maturity of the crop.
Limitations
1. High maintenance requirement.
2. Salinity hazard
3. Economy limitations (40,000Rs/ha)
4. High technical know-how is required.
Irrigation
Definition: irrigation is artificial application of water to soil for the purpose to access the crop production. It is supplied supplementary to water available from rainfall & ground water.
Types of irrigation – (classification)
1. Flood
2. Surface
3. Sub surface
4. Sprinkle
5. Drip irrigation.
Surface irrigation:
Water is applied directly to the soil from channel located at upper ridge of the field proper land preparation adequate control of water is necessary for uniform distribution of water border. The entire field is divided into strips separated by low ridge of the strip to lower in form of sheet guided by the low ridges. Border should have uniform gentle slope in direction of irrigation. Each strip is independently by turning stream of water at upper ridge. Suitability-suitable for close growing crops some row crop & orchards under favorable soil & topographic condition. Not recommended for extremely low or extremely high infiltration rate soils.
Advantage:
1. Easy construct & operate
2. Person can irrigation more compares to check basin.
3. If properly designed use uniform distribution & high water use efficiency.
4. Large streams can be effectively used.
5. If can provide excellent drainage (surface) if have proper outlet facility at the lower end.
Disadvantages:
1. Required precise land leveling
2. Required large irrigation streams.
Check basin:
It is used in extreme condition of soil. It is well known method generally used for heavy soils with low infiltration rate or high permeable soil like deep sand. Used for orchards grain & folder production.
Disadvantages:
1. Labor requirement for land preparation is high.
2. Operation cost is more.
3. The ridges cause hindrances to implements by field operations.
Furrow method:
Furrow is preferably used for row crops like maize, sugarcane, potato, groundnut & other vegetable crops. Water is applied in small furrows betureoil the row crops. Water infiltrated into soil & spread within the root zone. Large as well as small sized stream can be effectively used for irrigation. It also acids for safe disposal of excess water i.e. facilitates drainage. Only 1/5 to ½ of land surface is in contact with water (wet). There by reducing the evaporation losses. Method is specially situated to crops like maize which are sensitive to water in contact with their strength. The cost of land preparation is reduced & there is no wastage of land under field channels. In clay or deep clay soils shadow furrow are made along with guiding ridge to take care of soil cracking behavior such furrow are called corrugated furrow.
Subsurface irrigation:
Water is applied below the ground surface by maintaining artificial water table at some depth depends upon the soil characteristic & root zone of crop. Water moves through capillaries within soil to meet plant requirement deep trenches & underground piper are the two ways for sub-surface irrigation.
Adaptability: Soils having low W.H.C. soil having very high-high infiltration rate. Soils surface method is not possible where sprinkle method of irrigation proves to be expensive.
Advantage:
1) Evaporative losses are minimum.
Disadvantage:
1) Salty water can not be used.
Sprinkler Irrigation
Definition: It is methods in which water is spread into air and allowed to fall on the ground surface some what resembling.
Water is forced under pressure through small nozzle/orifice which gets broken up to into droplets and fall back on the ground. Slow circular revolution is impacted to the nozzle uniformally covered the ground surface. The rate of application should not be more than the infiltration rate of the soil.
Adaptability of sprinkler irrigation
1. Sprinkler irrigation can be adopted where land reveling is uneconomical and other method of surface irrigation cant carried out.
2. Adapted to soils to pours highly avoidable or relatively impermeable which are difficult to irrigate by other methods like furrow, border etc.
3. Where it is designed to go for frequent irrigation.
4. It is designed to minimum cost towards labours, fertilizer, and irrigation.
Advantages of Sprinkler Irrigation:
1. It can be used for almost crops expect paddy & jute.
2. System can be adopted under varied topographic condition and especially suitable to steep-slope and irregular topography.
3. Soils-method is particularly suited for sandy soils having high infiltration rate.
4. It can eliminate surface run off of irrigation water (run off elimination)
5. To protect the crop against frost & high temp.
6. To reduce labour cost for irrigation as compared with surface method.
7. Savings in land construction of channel to the field.
8. It saves fertilizer & water as ferti-irrigation can be carried out.
9. Land leveling is not essential for sprinkle irrigation.
10. Gives higher water use efficiency.
Limitations of sprinkle irrigation:
1. Not suitable for very fine texture soil (<4mm/her)
2. Uneven distribution of water due to distortion by high water.
3. More evaporation losses.
4. Require clean, water free from debris sand slit & clay particles.
5. Saline water can no be used.
6. Initial cost is high.
7. High operating power is high (5-10kg/cm)
8. Unsuitable climate condition sprinkling may be encouraging spread of disease.
9. Ripening softy fruits need protection from the spray.
10. Systems of Sprinkle Irrigation
Systems of Sprinkle Irrigation
Based on Spraying Arrangement
Based on Portability
1
Fixed Head
1
Portable
2
Rotating Head
2
Semi Permeable
3
Perforated Pipes
3
Semi Portable
i) Dancing Water
4
Solid Structure
ii) Oscillating Arms
5
Permanent
11. Portable system:
12. In sprinkle irrigation system in which main line, sub main line, lateral and the pumping units all are the portable generally the pipers are made up of light weight aluminum to facillate easy transportation such system can be shifted from place to another.
13. Semi-portable system:
14. This system is parallel to portable except that location of water source and pumping unit is fixed.
15. Semi-permanent:
16. In this system the main and sub-main are fixed, usually buried under the ground where as the laterals are portables.
17. Solid straight system:
18. These have enough laterals present to eliminate their movement from one place to another. The system is fixed at the beginning of system of season and remains through out the season for short & frequent irrigation.
19. Permanent irrigation system:
20. The permanent system is suited to automation using soil moisture sensor and are generally preferred in orchard. The sub main, lateral are permanently buried below the ground level.
21. Based on spraying arrangement fixed head:
22. The fixed head type of sprinkler arrangement system sprays water in one direction.
23. Rotating head:
24. Rotating head removes slow rate to distribute water in a circular fusion. They may be single, double, multiple nozzle sprinkler head. Single nozzle sprinkles system are referred for their low application rate however the double nozzle sprinkle head gives good uniformity of application at low pressure.
25. Multiple nozzle type of sprinkler also called as giant sprinkler are used to covered more area with single set. The operating pressure required for such sprinkler may be more than 10kg/cm2.
26. Perforated Pipes:
27. Such systems are preferred for application of water under lower operating pressure usually between 0.5 to 2.5 kg/cm2. The system is not recommended under heavy winds as the jets are distorted more easily.
28. Generally pipes are provided with holes, perforated along the upper 1/3rd perimeter in a proper designated to covered with between 6 to 15m such system are preferred on plains moderately high infiltration rate used for irrigation of lawns or vegetable crop where the plant height ranges between 40 to 60 cm.
29. Systems of Sprinkle Irrigation
Systems of Sprinkle Irrigation
Based on Spraying Arrangement
Based on Portability
1
Fixed Head
1
Portable
2
Rotating Head
2
Semi Permeable
3
Perforated Pipes
3
Semi Portable
i) Dancing Water
4
Solid Structure
ii) Oscillating Arms
5
Permanent
30. Portable system:
31. In sprinkle irrigation system in which main line, sub main line, lateral and the pumping units all are the portable generally the pipers are made up of light weight aluminum to facillate easy transportation such system can be shifted from place to another.
32. Semi-portable system:
33. This system is parallel to portable except that location of water source and pumping unit is fixed.
34. Semi-permanent:
35. In this system the main and sub-main are fixed, usually buried under the ground where as the laterals are portables.
36. Solid straight system:
37. These have enough laterals present to eliminate their movement from one place to another. The system is fixed at the beginning of system of season and remains through out the season for short & frequent irrigation.
38. Permanent irrigation system:
39. The permanent system is suited to automation using soil moisture sensor and are generally preferred in orchard. The sub main, lateral are permanently buried below the ground level.
40. Based on spraying arrangement fixed head:
41. The fixed head type of sprinkler arrangement system sprays water in one direction.
42. Rotating head:
43. Rotating head removes slow rate to distribute water in a circular fusion. They may be single, double, multiple nozzle sprinkler head. Single nozzle sprinkles system are referred for their low application rate however the double nozzle sprinkle head gives good uniformity of application at low pressure.
44. Multiple nozzle type of sprinkler also called as giant sprinkler are used to covered more area with single set. The operating pressure required for such sprinkler may be more than 10kg/cm2.
45. Perforated Pipes:
46. Such systems are preferred for application of water under lower operating pressure usually between 0.5 to 2.5 kg/cm2. The system is not recommended under heavy winds as the jets are distorted more easily.
47. Generally pipes are provided with holes, perforated along the upper 1/3rd perimeter in a proper designated to covered with between 6 to 15m such system are preferred on plains moderately high infiltration rate used for irrigation of lawns or vegetable crop where the plant height ranges between 40 to 60 cm.
48. Components of Sprinkler Irrigation System
49. 1. Prime mover/pump suction pipe, foot value:
50. Pumping sets or pump is required for lifting water from the source and push it through distribution system i.e. main, sub main, laterals and finally through the sprinkler head under sufficient pressure.
51. The pumping set consists of a centrifugal pump (volume) or turbine type pump with a driving unit suction line and a foot value. Centrifugal pump are generally used where the lift is less than 5m i.e. when source is river, shallow well etc. for higher lift or if water level fluctuates widely turbine pumps are recommended.
52. The electric motors are generally used driving unit for fixed installation diesel engines are generally recommended for portable units.
53. 2. Main line:
54. It carries water from the source (pumping unit) to the various parts in the field. It may fixed or portable. Permanent lines are generally buried below the working depth inside the ground. Light weight aluminum pipe with quick couples are preferred for portable lines something HDPF (high density pipes are also preferred because of its longer life. The fixed are generally of steel pipe or PVC pipe of suitable diameter). Te or L section is provided to connect the main with sub main or lateral.
55. 3. Sub main:
56. It carries water from main to lateral lines.
57. 4. Lateral Lines:
58. It carries water from main or sub main pipe line to the sprinkler head through the rise pipe. They are portable and equipped with quick coupling devices. Commonly they are available in 5,6 or 12m length are provided with U shaped rubber gasket in the female portion of coupling. The water pressure forces outside of ‘U’ gaskets to form water seal when the water is turned off the seal is broken and water is drained out from the pipe making it easy to uncouple and more.
59. Sprinkler head:
60. Sprinkler heads are used for spraying water on the fields they may be-
a) Rotating Head
b) Fixed head Type
c) Perforated Type
61. Fixed Head Type: Used in landscape
62. Sprinkler lead can be classified on basis of pressure
63. 1) Low operating pressure sprinkler (1.5 to 2.5kg/cm2)
2) Intermediate pressure sprinkler (2.5 to 5kg/cm2)
3) High pressure sprinkler (5 to 10kg/cm2)
64. Problems:
65. Find the fertilizer does per settings of the sprinkler system if a lateral has 12 sprinkler 14m apart. Later lines are spaced 20m on the main line and the recommend does of fertilizer is 80kg/ha.
66. Solution:
Ds x DL X Ns X WP
WF = ---------------------
10,000
67. 14 X 20 X 12 X 80
DL 20 = --------------------
10,000
68. Irrigation Efficiency
69. Irrigation water is an expansive input and has to be used very efficiently. The main losses that occur during irrigation of fields as conveyance, run off, seepage and deep percolation. Irrigation efficiency can be increased by reducing these losses. Uneven spreading and inadequate filling of root zone are the other causes for low irrigation efficiency. Irrigation efficiency at the field level can be increased by selecting suitable method of irrigation, adequate land preparation and engaging an efficient irrigator. At the project level, it can be increased by proper conveyance and distribution system. Irrigation efficiency is the ratio usually expressed as percent of the volume of irrigation water transpired by plants, plus that evaporate from the soil, plus that necessary to regulate the salt concentration in the soil solution and that used by plants in building plant tissue to total volume of water diverted, stored or pumped for irrigation.
Wt + Ws - Rs
Ei = -------------------- X 100
Wi
70. Where,
71. Ei = Irrigation efficiency (percent)
Wt = the volume of irrigation water / unit area of land transpired by plants, evaporation from the soil during the crop period.
Ws = the volume of irrigation water per unit area of land to regulate the salt Content of soil solution.
Re = Effective rainfall
Wi = the volume of water per unit area of land that is stored in reservoirs or diverted for irrigation. Irrigation efficiency indicates how efficiency the available water supply is being used. The efficiency of irrigation projects in India is as low as 20 to 40%.
72. Water Conyenance Efficiency & Water Use Efficiency
73. Water Conyenance Efficiency:
74. It indicates the efficiency with which water is conveyed from source of supply to the field. It estimates the conveyance losses. It is expressed as
75. Wf
Ec = --------- X 100
Ws
76. Where,
77. Ec = Water conveyance efficiency (percent)
Wf= Water delivered at the field
Ws= Water delivered at the source
78. Water Application Efficiency:
79. Irrigation water applied to the field is lost due o surface run off and deep percolation. Surface run off occurs due in long furrow or long border strips if ridges are weak. The water moves from one plot to another due to weak bunds giving way to water which may collect in large quantities even to break strong bunds. In furrows, water is allowed most of the time at the beginning of furrow till the flow reaches the other end of the furrow. It results in deep percolation of water in the first quarter of furrow. Water application efficiency is the measure of efficiency with which delivered to the field is stored in the root zone.
80. Water stored in the root zone
Water application efficiency = ------------------------------------ X 100
Water delivered to the field
81. Water Storage Efficiency:
82. This parameter estimates whether the amount of water necessary for the crop is stored in the root zone or not. It is expressed as the percentage of water needed in the root zone prior to irrigation to that stored in the root zone during irrigation.
83. Water stored in the root zone
Water storage efficiency = ------------------------------------- X 100
Water needed in the root zone
84. Water Distribution Efficiency:
85. Water distribution efficiency is defined as the percentage of difference from unity of the ratio between the average numerical deviations from the average depth stored during the irrigation.
Water distribution efficiency = {1-Y/d} X 100
86. Where,
d = Average depth of precipitation along the run off during irrigation
Y = Average numerical deviation from –d
87. Water distribution efficiency indicates uniformity in distribution of water over the entire root zone.
88. Water Use Efficiency (WUE):
89. Water use efficiency is defined as yield of marketable crop produced per unit of water used in evapotranspiration.
90. WUE = Y / ET
91. Where,
92. WUE = Water use efficiency (kg/ha/mm of water)
Y = marketable yield (kg/ha)
ET= Evapotranspiration (mm)
93. If yield is proportional to ET, water use efficiency has to be constant but it is not so. Actually, Y and ET are influenced independently by crop management and environment. Yield is more influenced by crop management practices, while ET is mainly dependent on climate and soil moisture. Fertilization and other cultural practices for high yield usually increase in water use accompanying fertilization is often negligible. Crop production can be increased by judicious irrigation without markedly increasing ET. Under optimum water supply, ET is not dependent on kind of plant canopy provided the soil is adequately covered with crop.
94. Increasing the amount of plant canopy has there fore little or no effect on ET. Obviously, any practice that promotes plant growth and more efficient use of sunlight in photosynthesis without causing a corresponding increase in ET will increase WUE.
95. Factors affecting WUE:
96. 1. Nature of the plant: There are considerable between plant species to produce a unit dry matter per unit amount of water used resulting in widely varying values of WUE.
97. Water use efficiency of different crops:
Crop
Water Requirement mm
Grain Yield kg/ha
WUE kg/ha/mm
Rice
2000
6000
3.0
Sorghum
500
4500
9.0
Bajara
500
4000
8.0
Maize
625
5000
8.0
Groundnut
506
4680
9.2
Wheat
280
3534
12.6
Finger Millet
310
4137
13.4
98. There is also difference in WUE between varieties of the same crop. Selection of properly adopted crop, with good rooting habit ,low transpiration rates increase. WUE
99. 2. Climatic Conditions:
100. Weather affects both Y and ET. Manipulation of climate to any extent is possible at present. However, ET can be reduced by mulching, use of antitranspirant etc. To limited extent , but may not be economical or practical. Weed control is the most effective means of reducing ET losses and increasing the amount of water available to the crop thereby increasing WUE.
101. 3. Soil Moisture Content:
102. In adequate supply of soil moisture as well as excess moisture supply to the crop have an adverse effect on plant growth and production and therefore conductive to low WUE. For each crop combination of environment conditions, there is a narrow range of soils moisture level at which WUE is higher than with lesser or greater supply of water, proper scheduling of irrigation will increase WUE.
103. 4. Fertilizers:
104. Irrigation improves a greater demand for plant nutrients. Nutrient availability is highest for most of the crops when water tension is low. All available evidences indicate that under adequate irrigation suitable fertilization generally increase yield considerably, with a relatively small increase in ET and therefore, markedly improve WUF.
105. 5. Plant population:
106. Higher yield potential made possible by the favorable water regime provided by irrigation, the high soil fertility level resulting from heavy application of fertilizers and genetic potential of new varieties and hybrids, could be achieved only with appropriate adjustments of the population. The highest yields and WUE are possible only through optimum levels of soil moisture regime, plant population and fertilization.
107. Frequency of Irrigation
108. Irrigation frequency refers to the number of days between irrigation during periods without rainfall. It depends on consumptive use of rate of a crop and on the amount of available moisture in the crop root zone. It is function of crop, soil and climate. Sandy soils must be irrigated more often than fine texture deep soils. A moisture use ratio varies with the kind of crop and climate conditions and increases as crop grows larges and days become longer and hotter.
109. In general, irrigation should start when about 50 percent and not over 60 percent of the available moisture has been used from the root zone in which most of the roots are concentrated. The stage of crop growth with reference to critical periods of growth is also kept in view while designing irrigation frequency.
110. The interval that can be safely allowed between two successive irrigations is known as frequency of irrigation:
111. Allowable soil moisture depletion
Irrigation interval = ---------------------------------------
Daily water use
112. Problem: Calculate irrigation interval when F.C=20.0% dry weight basis
PWP = 8.0 dry weight basis, BD = 1.4 g/cc
Root depth = 60cm ET ratio = 0.5 cm/day
113. Allowable soil water depletion is equal to 25% of available soil water
114.
115. Solution:
116. (20.0 – 8.0) X 1.40
Available water = ------------------------------- X 60
100
= 10.08cm
117. 25 X 10.08 2.52
Allowable soil water depletion = ---------------- = -------- = 5.04 = 5 days
10.0 0.5
118. Irrigation must be given at 5 days interval.
119. Water Quality Parameters
120. Irrigation water contains impurities in varying concentration. The suitability of irrigation water mainly depends up on the amount and type of salts present in the water. The main soluble constituents are calcium, magnesium, sodium as cations and chloride, sulphate, bicarbonates as anions. The other ions present in minute quantities are boron, selenium, molybdenum and fluorine which are harmful to animals fed on plants grown with excess of these ions. Quality of irrigation water is judged with three parameters
121. 1. Total salt concentration
2. Sodium absorption
3. Bicarbonate and boron content.
122. 1. Total Salt Concentration:
123. Salt content of irrigation water is measured as electrical conductivity (EC). Conventionally, water containing total dissolved salts to the extent of more than 1.5 m mhos / cm has been classified as saline. Saline waters are those which have sodium chloride as predominant salt. Brackish water is one that is contaminated with acid, bases, salts or organic matter, where as saline water contains mainly dissolved salts, Based on EC irrigation water is classified as below.
Class
EC
Quality Characterization
Soil for which suitable
C1
< 1.5
Normal Water
All Soils
C2
1.5 to 3.0
Low Salinity
Light and Medium Soils
C3
3.0 to 5.0
Medium Salinity
Light and Medium Textured Soils for Semi tolerant crops
C4
5.0 to 10.0
Saline
Light medium textured soils for Tolerant crops
C5
> 10
High Salinity
Not Suitable
124. 2. Sodium absorption ratio (SAR) and boron content:
125. In addition to EC which has been used as a main criterion to determine the quality of irrigation water, sodium absorption ratio (SAR), residual sodium carbonate (RSC) and boron content are also used to find suitability of irrigation water.
126. Irrigation water which contains more than 3 ppm boron is harmful to crops, especially on light soils.
127. Factors Affecting Frequency of Irrigation
128. Humidity:
129. In rainy season, the humidity is high and rains may be received just when the crop is in need of water. In such case, some irrigation turns could be stopped and frequency may be extended to 20 days. During winter season, also the frequency will be longer than in summer because of less evapotranspiration, dewfall, nighttime humidity, and less sunshine. The frequency may therefore be 15 to 20 days in winter and 6 to 8 days in summer. In summer irrigation, water is given more frequently and hence more frequency of irrigation in summer, medium in winter and less in rainy season.
130. Stage of Growth of Crops:
131. During certain stages particularly at flowering and fruit formation stages of crop requires much larges quantities of water than earlier stages. In earlier stage, even if a little less water than estimated daily use is provided, the crop will stand the strain without any harm, perhaps a slight moisture stress may encourage better root growth.
132. Type of Crop:
133. The frequency of irrigation will also depend up on the crop. A succulent leaf vegetable will require irrigation more often than cereal crop like Jowar. Crops which are doses of fertilizers need more water than those with a little or no fertilizers.
134. Soil Type:
135. Light soil requires more frequent irrigation than the loamy soils. Sandy loam soil need to be irrigated every fifth day while clay loam may be irrigated every tenth day. Time required to irrigate an area: The time required to irrigate an area depends up on magnitude of discharge, quantity of water applied, irrigation efficiency and area. The time required to irrigate an area is calculated by formula.
136. IQT = Ad
137. Where,
I= irrigation efficiency
Q= discharge in cusec
T= time in hours
A= area in acres
d= moisture deficit in soil.
Problem: Calculate the time required to irrigate 4 acres of sugar cane when soil moisture deficit is 2.5 inch, discharge from a weir is 2 cusec and irrigation efficiency is 80 percent.
Solution:
138. IQT = Ad
= 80/100 X 2 X t
= 4 X 5/2
= 6.25hours.
139. Common Problems that Result From Using Poor Quality Irrigation Water
140. Salinity:
141. Salinity problems related to water quality occurs if total quantity of salts in the irrigation water is high enough for the salts to accumulate in the crop root zone to the extent that yields are affected. If excessive quantity of soluble salts accumulate in the root zone, the crop has difficult in extracting enough water from the salty soil solution. This reduces the water up take by plant and usually results in slow or reduced growth.
142. Permeability:
143. This problem occurs when the rate of water infiltration in to and through the soil is reduced by the effect of specific salts in the water to such extent that the crop is not adequately supplied with water and yield is reduced. The poor soil permeability causes difficulty like crusting of seedbed, water logging, and attack of disease, salinity, weeds, oxygen and nutritional problems.
144. Toxicity:
145. A toxicity problem occurs when certain constituents in the water are taken up by the crop and accumulate in amounts that result in reduced yield. This is usually related to one or more specific ions in the water viz. boron, chloride and sodium.
146. Miscellaneous:
147. Various other problems related to irrigation water quality occur with sufficient frequency and should be specifically noted. These include excessive vegetative growth, lodging and delayed crop maturity from excessive nitrogen in water supply, white deposits on fruits or leaves due to sprinkler irrigation with high carbonate water and abnormalities by an unusual pH of the irrigation water.
Quality of Water from Different Sources
Water quality of most the Indian rivers are good with EC values less than 0.7 m mhos /cm except in Krishna (1.4), Hagari (1.6) and Tungbhadra (1.7) rivers. Quality of most the tanks, lakes etc. is good except in those which are fed by stream passing through salt affected areas. Quantity of ground water is affected by and arid regions are generally poor with high salt content.
Irrigation water with poor quality:
In an area where there is no alternative source of good quality irrigation water, it is inevitable to use the available water of poor quality. However, the yield potential of such areas can be increased by adopting proper management practices such as
Improvement of sodium and bicarbonates rich water by gypsum application.
Choice of salt tolerant crops and their varieties.
Optimum fertilizer application and manuring
Proper irrigation management
Breaking any impervious layer by deep ploughing and
Adopting other management practices suitable for area.
A. Gypsum application:
The harmful effect of irrigation water can be minimized to some extent by modifying its ionic composition by adding such chemicals which tend to precipitate the harmful constituents such as bicarbonate and carbonate in the form of less soluble salts or tend to create a favorable catonic Ca : Mg : Na ratio.
Gypsum should be powered up to 0.5 mm size or passed through a 30-mesh sieve. The gypsum requirement of water should be calculated depending upon the relative concentration of sodium, magnesium and calcium 8.6 Q of gypsum of 100 percent purity per hectare meter of water be necessary. Gypsum can directly be mixed in irrigation water.
B. Choice of salt tolerant crops:
Some crops and their varieties are more salt tolerant than others. Hence, salt tolerant crops are to be grown in salt affected areas till the soil are improved by vegetation or other reclamation procedures.
Salt Tolerant Crops: Barly, Dhainacha, Sugar beet, Tobacco, Turnips, Mustard, Cotton, Wheat, Sugarcane, Turnips, Beetroots, Spinach, Date palm coconut etc.
Semi Tolerant Crops: Oats, Rice, Sorghum, Bajara, Maize, Red gram, Green gram, Sunflower, Castor, Sesamum, Linseed, Senji Lucerne, Berseem, Cowpea, Tomato, Cabbage, Cauliflower, Lettuce, Potato, Carrot, Onion, Cucumber, Pumpkins, Bitter ground, Pomegranate, Grape, Guava, Mango, Apple, Orange, Lemon.
Sensitive Crops for Salts: Field beans, Gram, Peas and Guar, etc.
C. Use of Fertilizers:
Generally saline and alkali soils, or irrigated with poor quality waters are low in their fertility status, especially with reference to nitrogen or something phosphorus. Better crop can be grown by raising their fertility status. Nitrogen response to crop better when it is applied to soil along with manures. It has been observed that for wheat, barley, bajara, and maize the usual loses of fertilizers as applied up to an EC value of 6.5 m mhos/ cm and an E.S.P. of about 30. However, excessive fertilization or addition of fertilizers on a highly saline, alkali soil is of no value.
D. Soil Management Practices:
When poor quality water is to be applied, it is important to have the detailed analysis of soil profile for their physical, chemical, and morphological characteristic. Soil analysis should include its structure, texture, pH, lime content, location and amount of gypsum, T.T.S., exchangeable cations, etc Information on water transmission properties on soil and depth of water table should be obtained Data on rainfall, its intensity and distribution and evaporation are obtained. Saline area should be leveled properly for uniform spread of water and its downward movement.
Medium textured soils with Kankar layers pose a problem of sodicity. Such soils are managed by deep ploughing and growing green manuring crop like dhaicha. Application of gypsum under condition of low water table may improve land productivity. Use of optimum fertilizers and manures and improving the surface drainage systems will help in improving productivity.
E. Irrigation management:
Accumulation of salts increase with the fineness of soil texture, it is essential to adopt irrigation practices such that the salinity at the root zone is kept minimum. The quantity of water and the frequency of irrigation are so kept that they could met the leaching requirement of the soil and consumptive sue off the crop grown. Salts often accumulate in the top few centimeters of soil during non-crop period and hence both crop germination and yield can be seriously reduced. A heavy pre-sowing irrigation to leach these surface salts will improve germination and early growth. It is done well in advance to allow cultivation to remove weeds and prepare the seedbed. Sowing the seed in the center of a single row raised bed will place the seed exactly in the area where salts concentrate. Alternate furrow irrigation is often advantageous. Similarly increasing the depth of water in the furrow can also be an aid to improve germination the use of sleeping beds with seeds planted on the sloping sides and the seed row placed just above the water line can help in better salinity control. Large seeded crops like maize planted in water furrows can improve germination.
Effect of salts on plants growth is reflected by increasing the osmotic pressure in the soil solution. Accumulating certain ions toxic concentration in plant tissue and by altering the plants mineral nutritional characteristics resulting in poor stand of crop, stunted growth and yield. It may cause leaf burns in some crops and blue green colour in others. The germination of seed is delayed and retarded. In general, grain yield is affected more than the height of the plants.
F. Salt Tolerance of Crops:
The ability of a plant to tolerate salt in the root zone is known as salt tolerance. Studies are important in selecting it for a particular or its variety to suit the soil conditions and for determining the leaching requirements. The effect of soil salinity on crop growth is negligible when the EC of saturated extract is less than 2 m mhos/ cm. Many crops are affected when EC is in the range of 4 to 8 m mhos/cm. crops with high salt tolerance can grow satisfactorily when EC values are in between 8 to 16 m mhos/cm. Only a few survive at EC beyond 16 m mhos / cm.
Definition of Drainage, Causes of Water Logging Effects of Bad Drainage
Drainage means the process of removing water from the soil that is in excess of the needs of crop plants.
Drainage is the removal of excess gravitational water from the soil by artificial means to enhance crop production.
A soil may need artificial drainage for one or two reasons.
When there is a high water table that should be lowered or
When excess surface water cannot move downward through the soil or ever the surface of the soil fast enough to prevent the plant roots from suffocating.
Advantages of drainage:
The field will net get waterlogged and crop can get sufficient water and air
After the rains are received, the soil comes in tilth earlier and it is possible to carryout agriculture operations properly and in time.
The structure of soil improves
There is good aeration and warmth in the root zone which are essential for proper growth.
Bacteria that change organic matter into plant foods get necessary air and warm temperature in the soil.
Desirable chemical reactions take place and nutrient become available to the plants easily.
There is proper root development and absorption of nutrients is accelerated.
Seeds germinate faster and better stand of crop is obtained.
Due to healthy growth of plants they can resist the attack of pest and diseases better.
Weed growth can be checked by timely weeding and inter culturing operations.
Roots go down deep and can draw up on moisture at greater depth and with stand periods of through better and
Good drainage permits the removal of many toxic salts and thus, reduces damage to crops.
Drainage problems:
Drainage problem occur on lands, which we consider as an arid. The causes of drainage problems are as follows. This is also termed as causes of bad drainage or why soils become water logged or ill drained.
1. Excessive use of water: Water that is plentiful and cheap often is used in excess. The result is general water logged condition. Wild flooding continuous irrigation or excessively long irrigation turns to promote water logging.
2. Seepage of canals laterals or ditches: The seepage enters underground strata at elevations higher than those of irrigated lands enter and often becomes a direct source of water logging of low lying areas.
3. Internal stratification or irrigated soils: The internal natural drainage of soils is often poor. The slowly permeable soils, which when irrigation water is applied, impede the percolation of the excess water. The water cannot move down wards fast enough and accumulate on the surface forming a thin layer and obstruct aeration.
4. Low lying area: The area is low lying and excess rain cannot be carried away as a surface runoff rapidly into the drain causing water logged condition.
5. The water table may be high and the additional gravitational water just accumulates and checks the air spaces and saturates the surface and sub soil.
6. There may be a hard pan that affects seepage of water to lower strata.
7. There may be salts affecting water absorption by roots.
Principles of drainage:
The main purpose of artificial draining is to remove the water that is harmful for plant growth. In areas with rolling topography, the excess water is carried away as a surface run off seepage water through natural depressions into the nalas and rivers. But in flat areas and in soils having an imperious substratum, the natural drainage system is not well developed and therefore water saturates and accumulates in low lying areas until evaporated or drained out slowly. The soils that remains saturated for long time needs artificial drainage.
The artificial of soil water consists of providing man made channels through which the free water is carried away to natural drains such as nalas, rivers. This can done either by digging open channels to the required depth or by laying underground tile pipelines of suitable dimensions at the proper intervals and at required depth. When such artificial openings are provided in saturated soil, the water in the underground water table is lowered until it reaches the bottom level of the drainage line. The surface line of the water table does not remain horizontal but it depress over the drains. This happens, because water over the drains has the shortest distance to travel and it has the least resistance to flow through the pore spaces of the soil.
The horizontal distance over which water will flow in the drains depends upon the type of soil. If the soil porous the distance is grater. Therefore, drainage must be at short intervals and at shallower depth if the soil is sandy and porous. Thus, it can be seen that the factors, which determine the depth and spacing of the drainage system, are the soil type and the desired of the water table.
Type of Drainage
Drainage is of two forms
A. Surface drainage and
B. Sub surface drainage or underground drainage.
A) Surface drainage (Natural system of drainage):
It may consist of open ditches that are laid out by eye judgment, leading from one wet spot to another and finally into a nala or river. This is often called natural system.
Open ditch drains: The pattern of ditches is regular. The method is adopted to land that has uniform slope.
Field ditches: Field ditches for surface drains may be either narrow with nearly vertical sides or V shaped with flat side slopes. V shaped ditches have the advantages of being easier to cross with large machinery.
Narrow ditches: Narrow ditches are most common where large farm machinery is not used.
In level areas, a collecting ditch may need to be installed at one side of the field and shallow shaped ditches are constructed to discharge into the collecting ditch. The field ditches should be laid out parallel and spaced 15 to 45 meters or more apart as required by the soil surface conditions and crop to be grown. They should be 30 to 60 cm deep depending upon the depth of the collecting ditch.
Farming operations should be parallel to the field ditches. The care that a ditch will drain satisfactorily depends up on how quickly water runs into the ditch how much rain falls on the land, slope, and the condition of the soil and plant cover.
B) Sub surface or under ground drainage:
A sub surface or underground drainage will remove excess soil water. It percolates in to themselves, just like open drains. These underground drains afford the great advantages that the surface of the field is not cut off, no wastage of lad and do not interfere with farm operations. On the other hand, they are costly to lie and are not effective in slowly permeable clay soils.
Underground drains may be classified as:
1. Tile or pipe drain
2. Box drains
3. Rubble (coarse stones or gravels filled) drains
4. Mole drains and
5. Use of pumps for drainage.
1. Tile drain: It consists of digging a narrow trench, placing short section of tiles at the bottom and covering the tiles with earth. The loose joints between two section of the tiles serve as a place where drainage water may enter into the drainage system. Water moves by gravity into the joins between tiles and through tile walls.
Porous tile gives no better drainage than tiles that water does not percolate and porous tile can easily broken or crushed. the drains are two types of tiles in use. Tile should be always placed at least 75 cm deep to prevent breakage by heavy machinery.
2. Box drains: Instead of pipes, underground drains may be made in V shaped cut or trench, sides of which are reverted with soil, restoring the surface of the field. Depth may be 90 cm below ground.
3. Rubble drains: A somewhat equally substitute for tile drains is made by cutting narrow V shaped drains or rectangular in section, as for box drains, filling them up with rough stones large and small and then covering the whole up with soil level with surface field soil. Depth may be 90 cm.
4. Mole drains: They are often used in clay, clay loam soils. A moling machine is one that draws a bullet nosed cylinder; usually 10-15 cm in diameter is therefore formed. A mole drain should be at least 75 cm below the surface to prevent closing of the holes by compaction from farming operations. Mole drains are extremely used in Europe.
5. Use of pumps for drainage: The pumps are used in U.S.A. and many other countries for drainage. River bottoms, lakes and costal plains, peat lands and irrigated lands are the main types of lands reclaimed by pump drainage. The subsequent must be sufficiently permeable for the ground water to move to the pipes enough for effective pumping.
Agro Technique under ill Drained Soils, Reclamation of Damaged Soils
The damaged lands comprise of
1) Water logged soils
2) Salt affected areas
Remedial measures to reclaim each of soil comprise of Preventive and Curative measures:
1. Preventative measures to control damage to lands:
Lining of canals and distributaries: Water percolating from canals and distributaries contribute a great deal to sub soil causing a rise in soil water table. Lining of canals prevents percolation of water largely and is being taken in the new canals.
Pre-irrigation soils surveys: Soil surveys prior to irrigation are quite necessary to select proper types of soils for perennial crops where by the utilization of irrigation for crops is maximum and contribution to the sub is the least. It is therefore, helps a remedy.
Fixing limits for perennial: Sugar cane is the most important crop under the canals in Maharashtra where it has acquired almost semi aquatic habitat. It makes splendid growth, if liberally supplied with soil moisture and the irrigation generally inclined to give water even to the extent of over irrigation with the result that it raises the sub soil water table where the drainage is obstructed. In many places, the soil water makes its appearance just below the ground level or appears as free water at the surface. Medium soils to 8’’ in depth are not suitable for sugarcane unless artificially drained.
Introduction of Block System: In a Block system a supply of water is provided for carrying on irrigated agriculture under conditions through out a block for a period of years. Block areas are de metered areas for which water is sanctioned for a term of years and within which any crops may be grown in the mansoon and Rabi season, subject to the provision that no more than one third of area shall be under sugar cane. During the hot season only allowed i.e. 11/2 acres of other perennial equal to 1 acre of sugarcane. Under block system, water is guaranteed for 6 years. Cane blocks allow 1/3 area under sugarcane and 2/3 area under seasonal crops.
Volumetric Supply of Irrigation to Sugarcane Factory Areas: The volumetric basis consists of the quantity of water to which the factory is entitled. It is fixed on acre-inches basis/acre of sugarcane area guaranteed. The inch depth fixed was 124’’ measured at distribution head. The volumetric rate is Rs 124/ acre-inches. The sugar owners have a freedom to arrange their programmer of plantation, harvesting within the guaranteed area. This system of volumetric supply of water has resulted in economic use of water and effective measures to control water logging.
2. Curative Measures:
Surface and Sub Surface Drainage: On construction of drainage scheme the sub soil water level go down the damaged areas are dried up and are brought back to cultivation after adopting reclamation methods.
Intensive well irrigation to keep the sub soil water level water under check: Another effective measure to improve the damaged areas is to have a network of working wells in suitable locations. Well irrigation forms an alternative solution where drainage cannot be adopted at economic cost.
Reclamation Method to Bring the Fertility of Soils for Growing Normal Crops: In a sound system of management, good tilth deserves first consideration. Regulation of the depth of water table by careful application of water and the disposal of surplus water by efficient drainage, natural or artificial are the very primary needs in the management of soils with a view to preserving soil fertility permanently. Agriculture practices, governing the maintenance of optimum amounts of basic factors such as soil moisture control etc. are not attended to maintain good surface and sub surface drainage therefore becomes very essential.
Partly water logged and fully water logged areas can be reclaimed by lowering sub soil water table to more than 4’ by artificial drainage. Preliminary agricultural operations are carried out on drying of the surface soil. The following sequence of operations is generally followed, of damaged lands due to water logging.
Effect of Excess Water on Soil and Plant Growth / Effect of Poor Drainage on Crop and Soil:
Drainage is the removal of excess gravitational water from the soil by artificial means to enhance crop production. If this water is not removed from the soil, the water logged or poor drainage condition occurs. Due to such condition, the soil as well as crop and soil are explained as below
Soil Aeration: Proper aeration in the root zone is necessary for development of healthy growth. The water air ratio in the pores of root zone of crop is such that it will not affect the yield. The increase in water content in soil pores is filled and the oxygen supply is reduced.
Effects on Plant Growth and Root Development: The crops become stunted with yellowing of leaves when the soil si saturated. In excess water, the plants usually die because of root damage caused by reduced supply of oxygen and accumulation of carbon dioxide with the related effects on the soil plant relationship. The adverse effects are not from direct presence of excess water, because crops will not suffer even in total from direct presence of excess water, because crops will not suffer even in total water culture, if they can get air. the root growth in such cases is also poor due to lack of aeration and they tend to remain largely near the surface and be subject to wilting when the surface becomes dry and even through there may be enough moisture below.
Anaerobic conditions in soil:
Nitrification: Crops depend for their growth on an adequate supply of nitrogen in the form of nitrates. The process of nitrification is carried out by bacteria, which requires oxygen from air in soil pores for their activity. Under anaerobic condition, marsh gas and hydrogen are formed. These gases reduce the nitrates. The nitrogen so released, escapes into the atmosphere alone with the hydrogen or converted into some form in which it is not available to crops. Thus, the suspension of microbiological activity in water logged soils directly.
Study of Water Table
Drainage investigation: It consists of getting necessary information regarding sources of water logging and ground water characteristics, extent and severity of water logging to decide the proposed line of caution and economical feasibility of soil. It includes topographical and ground water survey.
Contour map of the field:
Observation well: It gives depth of water table below the ground surface in water bearing strata. Water is at atmosphere pressure. An uncased an auger hole can be used for observation wells. However in sandy soils perforated casing may be provided to prevent collapsing of side wall.
Generally 2.5 cm diameter pipe with 3 mm diameter perforations are sufficient for the observation well however the perforation of stream depends upon particle size distribution of the surrounding formation.
Piezometer: When the soil strata, ground water character can be studied by installed piezometer. It indicates hydrostatic pressure of ground water at lower end of the part. The water enters through the opens bottom & there is no leakage through the sides.
Depending upon precisions required such observation well/piezometer are installed in grid of 30 to 300 m no of such piezometers can be installed at grid point, installed at different depth called as battery (piezometer battery.) The distance between individual piezometer should be minimum 60cm.
Observation of Data:
1. Record elevation of ground level at the piezometer / obs. well station with reference to the permanent bench mark on the farm.
2. Height of the pipe pre the level is to be noted (for observation wells piezometer)
3. Electrical depth gauge or tapes with chalked ends are used for measuring the depth of water table.
4. Observation are to be recorded periodically e.g. daily weekly seasonal etc. to study the water fluctuation etc.
e.g. R.L = 98.2m
Piezometer / obs. well is fixed at this height of pipe = 0.5m
Total height from ground = 98.2 to 0.5 = 98.7 m
If the height is measured by tape & if it obtain as 2m
Then the elevation of water table is 98.7-2 = 96.7m
Like this calculate for all points.
Water table contours:
In which direction water is flowing under the ground is known by water table contours. There are the lines of equal water table elevation above the datum. They are plotted similar to the ground surface contours on the base of map of the field it gives:
1) Visible (visual) information slope of water table
2) Information for analysis & solution of drainage problem.
Isobaths: Isobaths are the lines of equal depth from the ground level or they are the lines of equal depth to the ground water table lines.
These lines are plotted on map just like the controls & it helps to decide the surface drainage
1) Method of surface drainage
2) Method of sub surface drainage
3) Problems of conductivity drainage design in practical.
Surface drainage:
The process of removal of excess water from surface of field is termed as surface drainage. Generally the flat lands with low depressions & low infiltration rate requires surface drainage to remove the excess rainfall/excess irrigation water. Drainage can be achieved.
Land Smoothening for Surface Drainage:
Land smoothening also known as land grading is to produce plane land surface with uniform grade or slope. The finished surface is smooth & free from all minor depressions to prevent impounding of water & facilitate easy disposal of excess water along the slope within non-erosive velocity. The land smoothening is carried out two methods
1) Rough Grading-Bulldozers or Scrapers
2) Smoothening or Finishing-Float, Levelers
Drainage for pounded areas:
Low level sots accumulates run off water from adjoining areas can be removed out of the field by construction of fitted drainage. These drains are shallow with side field. Slop of 8:1 or more to facilities the crossing ditches by farm implements. This method is called random ditch system.
When the field operation (tillage) are performed parallel to ditch. The side slope of 4:1 for ditch can be preferred.
Drainage of flat lands (slope is less than 1.5%):
Bedding: In this method of surface drainage excess drains laterally from the crown strip of the land into the dead furrow & finally into the outlet. Area between two adjacent dead furrow is called bed.
The bed should be laid out dead furrow running in direction of greatest slope. Bed with is depends upon drainage characters of soil
i) 7-11-for very slow intend drained soil.
ii) 13-15-for slow internal drained soil.
Depth bed = 15-45cm.
Type of Land Requiring Drainage
1. Land having water table is high
2. Water logging lands. (When the water stands on the land surface for long period e.g. 2-4 hours for vegetable)
3. Excessive moisture content above the field capacity.
4. Humid regions where rainfall is less than evaporation.
5. Humid regions having high rainfall continuous or intermittent.
6. Lands with fine textured soils.
Drainage Properties of Soil:
1. The artificial drainage is required to be provided for two reasons
2. Lowering of high table.
3. Removal of excess accumulated water
Soil parameters plays imp. Role in deciding the extent & type of drainage system required. This includes following:
1. Permeable soils do not require artificial drainage unless the water table is high slow permeable soil often requires drainage specially when rainfall is high & field is leveled.
2. Texture: fine texture soil requires artificial drainage where as coarse textured soils may not require the artificial drainage.
3. Structure: platy structure soils poor drainage characteristics whereas blocky & granular soil structure exhibits good drainage property.
Soils having low infiltration rate & soils horizontal having less permeability require the drainage facility.
Types of drainage:
1) Surface drainage
2) Sub surface / internal drainage
The direction of ploughing should be paralleled to dead furrow, whereas tillage operation likes sowing, planting, perpendicular to dead furrow.
The collected drains collect the water from dead furrows to carry them out from the field. The spacing of collected drains is generally 90m for flat land to 300m for sloppy lands.
Parallel field ditch system:
Ditch is speed further apart and has greater capacity than the dead furrows. The ditches are not at equidistant and such system is adapted to flat. Poorly drained soil with numerous shallow depressions
Generally, ‘V’ shaped trapezoidal or parabolic drains are constructed having minimum depth 22.5 cm & cross at area 0.5 m2. The spacing is around 360m when water is moving towards both the sides in the drains.
Surface drainage: flat sloppy
Surface drainage: 1) flat flow 2) interminable strata with pervious soil
Subsurface drainage: 1) tile drains 2) open ditch
Subsurface drainage will essentially required when the land is flat or when surface drainage is not possible also if is pervious, underlined by impervious strata, subsurface-drainage is required.
Deep trenches or tile drainage are the two essential means for subsurface drainage. Many times under field condition combination of surface & subsurface drainage may be required.
Types of subsurface drainage:
1. Random
2. Herring bone
3. Grid iron
4. Interceptor drain/interception
Random subsurface drainage:
This method issued to drain the scattered wet spots in the field. The lines (drained files) are laid some what randomly to drain these depressions generally the main line follows largest natural depression of the field and sub main & lateral connects the scattered spot with the main.
For drainage areas, individual low depressions, spots can be drained using herringbone or grid iron system.
Herring bone system: it consists of parallel laterals that enter the main from either side at angle. The main line or sub main lies in the narrow depression, particularly suitable where laterals are long & required area to be thoroughly drained.
Laterals enters the main only from one direction hence the cost of this system is comparatively less. This system is used on flat land/regularly shaped field on uniform soil.
Placing the main on each side of depression serves a dual purpose intercept the seepage & provide outlet for the laterals.
Interceptor: Deep drenches are tiles, are used to intercept seepage water from the hillside. The interceptor should be laid along bottom of permeable layer.
Factors affecting flow into tile drains:
1) Hydraulic conductivity of soil horizons
2) Depth of drain below the ground surface
3) Spacing of the drain
4) Diameter of the drain
5) Joint spacing between tile drains (generally3 mm)
6) Depth of impervious layer below the ground surface.
Hooghouts for spacing of subsurface drain:
4 kh (2d + H)
S2 = ----------------------
V
Where,
k = hydraulic conductivity
d = depth of impervious layer below the drain
V = rate of replenishment of water by irrigation or rainfall in cm/sec
H = maximum water table from base of drain as shown in fig
S = spacing between drain
Benefit of drainage:
1. Provides better environmental for plant growth
2. Depth of plant rooting zone increased hence have larger rooting system
3. Improves the soil structure & infiltration rate of soil
4. Reduces soil erosion
5. Provides opt. tillage condition even in rainy season
6. Crop damage harvest can be reduced by removal of water from the wet lands
7. Makes the soil well created, maintains the soil temp, which enhances microbial activities.
8. Promotes leaching of undersible salts beyond the root zone of the crop.
9. Provides leaching climate & contributes for general prosperity of the region.
Material used Drip System Design (Manufacturing of Drip)
· PVC = Poly Vinyl Chloride
· LDPE = Low Density Polyethylene
· HDPF = High Density Polyethylene
· LLDPE = Linear Low Density Polythene
· PP = Polypropylene
· F.R.P. = Fiber Glossed Reinforced Plastic
· PP = Polysterrlene polyamide
Use of Above Mentioned materials:
· Plastic = thermoplastic, thermosetting plastic
· PVC = forcipes
· LDPE = for laterals drippers
· HDPE = pipes
· For laterals
· Values etc. drip components
· F.R.P. = fertilizer tanks
Two types of plastic are generally used.
Thermoplastic: It consists of material that can be molded in desired shape under hard & pressure and also be used for remolding after.
Definitions & Terms used in Irrigation
· Hydroscopic Water: That water is adsorbed from an atmosphere of water vapour because of attractive forces in the surface of particles.
· Hysteresis: It is the log of in one of the two associated process or phenomena during reversion.
· Indicator Plant: It is the plant, which reflects specific growing condition by its presence or character of growth.
· Infiltration Rate: It is the maximum rate at which a soil under given condition and at given time can absorb water when there is no divergent flow at borders
· Intake Rate or Infiltration Velocity: It is the rate of water entry into the soil expressed as a depth of water per unit area applicable or divergence of flow in the soil.
· Irrigation Requirement: It refers to the quantity of water, exclusive of precipitation, required for crop production. This amounts to net irrigation requirement plus other economically avoidable losses. It is usually expressed in depth for given time.
· Leaching: It is removal of soluble material by the passage of water through the soil.
· Leaching Requirement: It is the fraction of water entering the soil that must pass through the root zone in order to prevent soil salinity from exceeding a specific value.
· Oasis effect: It is the exchange of heat whereby air over crop is cooled to supply heat for evaporation.
· Percolation: It is the down word movement of water through the soil.
· Permanent Wilting Point (PWP): Permanent wilting point is the moisture content in percentage of soil at which nearly all plants wilt and do not recover in a humid dark chamber unless water is added from an outside source. This is lower limit of available moisture range for plant growth ceases completely. The force with which moisture is held by dry soil this point corresponds to 15 atmospheres.
· Permeability: Permeability is the property of a porous medium to transmit fluids It is a broad term and can be further specified as hydraulic conductivity and intrinsic permeability.
· PF: It is the logarithm of height in cm of column of water which represents the total stress with which water is held by soil.
· PH: It is the negative logarithm of hydrogen ion concentration.
· Potential Evaporation: It represents evaporation from a large body of free water surface. It is assumed that, there is no effect of addictive energy .It is primarily a function of evaporative demand of climate.
· Potential Evapo-transpiration: It is the amount of water evaporated in a unit time from short uniform green crop growing actively and covering an extended surface and never short of water. Penman prefers the term potential transpiration.
· Seepage: It is the water escaped through the soil under gravitational forces.
· Agricultural Drainage: It is removal of excess water known as free or ravitational water from the surface or below the surface of farm land to create favorable condition for proper growth and development of the plot.
· Surface Drainage: when the excess water saturates the pores spaces removal of water of water by downward flow through the soil is called subsurface drainage.
Principles of Agronomy
What is Agriculture?
· Agriculture is the backbone of our Indian Economy.
· Agriculture is a very broad term encompassing all aspects of crop production, livestock farming, fisheries, forestry, etc.
· Agriculture is the most important human economic activity.
· Agriculture is the activity of man for the production of food, fiber, fuel, etc. by the optimum use of terrestrial resource i.e. land & water.
Definition of Agriculture:
· The word agriculture comes from the Latin words ager, means the soil & cultura, means cultivation.
· “Agriculture can be defined as the cultivation and/or production of crop plants or livestock products.”
· Agriculture includes Crop Production, Animal Husbandry & Dairy Science, Agriculture Chemistry & Soil Science, Horticulture, Agril Economics, Agril Engineering, Botany, Plant Pathology, Extension Education and Entomology, which develops its separate and distinct branches of agriculture occupying now a days place in several Agril Universities in the country.
Conventional Agriculture:
· “Conventional Agriculture is the term for predominant farming practices and systems of crop production adapted by farmer in a particular region”
Agriculture can be termed as a science, an art & business altogether.
Science: because it provides new and improved strain of crop and animal with the help of the knowledge of breeding and genetics, modern technology of dairy science.
Art: because it is the management whether it is crop or animal husbandry.
Commerce (Business): because the entire agril produce is linked with marketing, which brings in the question of profit or loss.
Scope of Agriculture
Proverbially, India is known as “Land of Villages”. Near about 67% of India’s population live in villages. The occupation of villagers is agriculture. Agriculture is the dominant sector of our economy & contributes in various ways such as:
National Economy: In 1990 – 91, agriculture contributed 31.6% of the National Income of India, while manufacturing sector contributed 17.6%. It is substantial than other countries for example in 1982 it was 34.9% in India against 2% in UK, 3% in USA, 4 % in the Canada. It indicated that the more the more the advanced stage of development the smaller is the share of agriculture in National Income.
Total Employment: Around 65% population is working & depends on agriculture and allied activities. Nearly 70% of the rural population earns its livelihood from agriculture and other occupation allied to agriculture. In cities also, a considerable part of labor force is engaged in jobs depending on processing & marketing of agricultural products.
Industrial Inputs: Most of the industries depend on the raw material produced by agriculture, so agriculture is the principal source of raw material to the industries. The industries like cotton textile, jute, paper, sugar depends totally on agriculture for the supply of raw material. The small scale and cottage industries like handloom and power loon, ginning and pressing, oil crushing, rice husking, sericulture fruit processing, etc are also mainly agro based industries.
Food Supply: During this year targeted food production was 198 million tons & which is to be increased 225 million tons by the end of this century to feed the growing population of India i.e. 35 corer in 1951 and 100 corers at the end of this century. India, thus, is able to meet almost all the need of its population with regards to food by develop intensive program for increasing food production.
State Revenue: The agriculture is contributing the revenue by agriculture taxation includes direct tax and indirect tax. Direct tax includes land revenue, cesses and surcharge on land revenue, cesses on crops & agril income tax. Indirect tax induces sales tax, custom duty and local octri, etc. which farmer pay on purchase of agriculture inputs.
Trade: Agriculture plays and important role in foreign trade attracting valuable foreign exchange, necessary for our economic development. The product from agriculture based industries such as jute, cloth, tinned food, etc. contributed to 20% of our export. Around 50 % of total exports are contributed by agril sector. Indian agriculture plays and important role in roads, rails & waterways outside the countries. Indian in roads, rails and waterways used to transport considerable amount of agril produce and agro based industrial products. Agril products like tea, coffee, sugar, oil seeds, tobacco; spices, etc. also constitute the main items of export from India.
History of Indian Agriculture - Early Development:
The early Aryans (Bronze Age people)
Period: 1800 to 1600 of B.C
They depended on wheat, Barley, millets, pulses, sesame, mustard & Animal husbandry.
The Vedic age (1560-100B.C)
The profession of farming was regarded as only far the unlearned and those devoid of wisdom. It remained so far centuries.
The later Vedic period (1000-600B.C)
Wooden ploughs were provided with Iron ploughshares, their efficiency further improved. This Improvement helped the Aryans to cultivate the virgin land resulted to greater mastery over food production.
The Buddhist period (Sixth century BC)
Brahmans were found pursuing Village, Cow herding, goat keeping, trade, woodwork weaving, archery and carriage driving. The hired labour apparently was assigned a low social rank.
The Magadhan Empire (fourth century BC)
Formations of villages started in this period. Plantation of bushes & tree, collection of seeds, fruit, flowers, fiber etc started.
The Asoka Period
Promoted forestry & horticulture, encouraged plantation of trees in gardens and along roads in the farm of avenues
First century BC to second century AD
First plough agriculture to replace slash & burn cultivation. Knowledge of distant markets, origination of village settlements & breaded also some.
Age of the Guptas (300-500AD)
This period is called golden age of India. Provides information an agriculture besides other sciences. Deals with selection of land, manuring, cultivate, seed collection, sowing, planting & grafting. Amarasoka contains information on soil village & irrigation.
Empire of the Harshvardhana (606-647 AD)
The source of information on agriculture curling this period is writings of early Arab writers.
The Muslim Rule (1206-1761 Ad)
Land revenue system was improved. Taguai loans were given to cultivators in distressed circumstance for the purchase of seed & Cattle.
The British rule & free India (1757-1947)
History of Indian Agriculture - Historic Developments
The historic developments in agriculture during British rules and free India are:
Sr. No.
Year
Historic Developments
1
1871
Departments of Agriculture created
2
1878
Higher Education in agriculture at Coimbatore.
3
1880
Famine commission appointed.
4
1890
Higher Education in agriculture at Pune.
5
1891
Dr. J A Voekker report on improving Indian agriculture
6
1900
Forest research Institute
7
1901
First Immigration commission.
8
1905
Imperial (now Indian) Agricultural research institute at Pusa (Now at Delhi)
9
1921
Indian central cotton committee.
10
1926
Royal commission on agricultural headed by Lord Linlithgow.
11
1929
Imperial (now Indian) council of agricultural research at Delhi.
12
1936
Indian Central Jute committee.
13
1942
Department of Food created.
14
1942
Grow more food campaign.
15
1944
Indian central Sugarcane committee.
16
1945
Indian central tobacco committee.
17
1946
Directorate of planet projection & quarantine.
18
1946
Central Rice research institute.
19
1947
Food policy committee.
20
1947
Fertilizers & chemicals Travancore.
21
1956
Project for intensification of regional research on cotton, oil, seeds, millets(PIRRCOM)
22
1957
All India Coordinated maize improvement Project.
23
1960
Intensive Agriculture district programme( IADP)
24
1960
First agricultural University at Panthnagar.
25
1963
National seed corporation.
26
1965
Intensive Agriculture area programme( IAAP)
27
1965
National demonstration programme.
28
1966
High yielding Varieties programme.
29
1966
Directorate of Extension.
30
1966
Multiple cropping schemes.
31
1969
Second Immigration compassion.
32
1970
Drought prone area programme (DPAP)
33
1970
National commission on agriculture.
34
1971
All India coordinated project for dry land agriculture.
35
1972
ICRISAT
36
1973
Minikit trials programme.
37
1974
Command area development.
38
1976
Integrated Rural development programme (IRDP)
39
1977
Training & Visit system (T&V)
40
1979
National Agricultural research project (NARP)
41
1982
National bank for agriculture & Rural development (NABARD)
42
1985
National Agricultural extension project (NAEP)
43
1986
National Agricultural research project (Phase-II)
44
1990
National Agricultural Technology project (NATP)
Important Events in Early History of Agriculture
Period
Event
10000BC
Hunting & Gathering
8700BC
Domestication of sheep
7500BC
Wheat & Barley cultivation
6000BC
Domestication of Cattle’s & Pigs
4400BC
Maize Cultivation
3500BC
Potato cultivation
3400BC
Wheel invention
3000BC
Bronze tools
2900BC
Plough invention & irrigation
2700BC
Domestication of silkworm in China
2300BC
Cultivation of chickpea, Pear, sarson &cotton.
2200BC
Domestication of Fowl, Buffalo and elephant.
2000BC
Rice cultivation
1800BC
Finger millet cultivation
1725BC
Sorghum Cultivation
1700BC
Taming of horse
1500BC
Sugarcane cultivation & well irrigation.
1400BC
Use of Iron
15th Century
Cultivation of Oranges, Brinjal.
16th Century
Cultivation of several crops into India by Portuguese - Potato, Tomato, Chilles, Pumpkin, Papaya, Pineapple, Guava, Custard apple, groundnut, Tobacco, Cotton, Cashew nut.
History of Agriculture as a science
1. In pre scientific agriculture six persons could produce enough food for themselves and for four others. In years of bad harvest they could produce only enough for themselves, with the development of science and application of advanced technology five persons are able to produce enough food for nine others.
2. Van Helmet (1577-1644Ad): Experiments pertaining to plant nutrition in systematic way and concluded that the main “Principle” of vegetation is water.
3. Jethre Tull (1674-1741AD): Conducted several experiments and published a book “Horse Heeing Husbandry”. These experiments mostly on cultural practices and they led to the development of seed drill & horse drawn cultivation.
4. Aurthur young (1741-1820Ad): Conducted pod culture experiments to increase the yield of crops by applying several materials like poultry dung, litter, gun power, & publish his work-in 46 volumes at “Annals of agriculture”.
5. In 1809 soil science begin with the formulation of the theory of hums.
6. Research in plant nutrition & physiology was started in 18th century.
7. Sir Humphrey Davy published book “Elements of agri chemistry” in 1813
8. Sir John Bennet was begun to experiment on the effects of manures of crops.
9. Justus Libey on agriculture chemistry and physiology launched systematic development of agriculture in 1840.
10. 1842, Initiated the systematic fertilizers Industry by the patented process of hearting phosphate rock to produce super phosphate.
11. Gregor Johann Mendel (1866) discovers the law of heredity and the ways to mutations laid to modern plant breeding.
12. Charles Darwin Published the results of the experiments on cross and self ferlization in plants.
13. 1920, the application of genetics to develop new strains of plants and animals brought major charges of agriculture.
14. The first successful tractor was built in U.S in 1882 from implements & machinery was manufactured industrially on a large scale by 1930.
15. Due to economic pressure and decrease in labor availability, the application of electricity to agriculture was in 1920.
16. The first successful large scale conquest of a pest a chemical means was the control of grapevine powdery mildew in Europe in 1840.
17. The key date in history of argil research at education is 1862. When the US congress set up departments of agriculture & provided for colleges for agriculture in each state.
18. Scientific agriculture began in India when Sugarcane, cotton, & Tobacco were grown for purpose.
19. What is Agronomy?
20. The term agronomy is derived from Greek words “AGRO” meaning field & “NOMO” meaning to manage.
21. Definition of agronomy:
22.
1. Agronomy is branch of agril science which deals with principles & practices of soil, water & crop management.
2. It is branch of agril science that deals with methods which provide favorable environment to the crop for higher productively,
3. It deals with the study of principles and preaches of crop production and field management.
4. It is the study of planet in relation to soil and climate. It deals essentially with all aspects of soil, crop and water management to increase productively of crops.
23. Principles of agronomy deal with scientific facts in relations to environment in which crop are produced
24. Scope of agronomy:
25. Agronomy is a dynamic discipline with the advancement of knowledge and better understanding of planet & environment, agril. Practices and modified of new practices developed for high productively as follows:
1. Proper methods of filling the lands.
2. Suitable period for its cultivation.
3. Keeping farm implements in good shape and managing field crops in a efficient manner as experienced farmer.
4. Management of crops, live stock & their feedings.
5. Care and disposal of farm & animal products like milk & eggs.
6. Proper maintenance of accounts of all transactions concerning farm industry.
7. Availability of chemical fertilizers has necessitated the generation of knowledge on the method.
8. Availability of herbicides for control of weeds has led to development for a vast knowledge about selectivity, time & method of its application.
9. Water management practices.
10. Intensive cropping.
11. New technology to overcome the effect of moisture stress under dry land condition.
12. Packages of practices to explore full potential of new varieties of crops.
26. Restoration of soil fertility, preparation of good seedbed, use of proper seed rates, correct dates of sowing for each improved Variety, proper methods of conservation & management of soil moisture & proper control weeds are agronomic practices to make our finite land water resources more productive.
With the growth of other allied agril sciences, the present day agronomy not only embodies the act of soil management of crop production and obtaining maximum production at minimum cost but also establishing new facts and applying scientific knowledge to practical problems.
27. The emphasis of agronomy is now more towards the scientific study of the behavior of plant under the different environmental conditions like varing soils and climate, irrigation, fertilization etc. by conducting well laid out experiments in the fields, pots & laboratories.
28. It is also involves application of research in the field or forming suitable packages of practices under a given set of conditions.
29. Relationship of Agronomy with other Sciences
30. Agronomy is having relationship with both basis and applied sciences.
31. 1. Basic sciences are those which reveal the facts or secrets of nature and comprise subjects like chemistry, physics, math’s, botany, zoology.
2. Applied sciences are those in which the theories and laws propounded in basic sciences are applied to problems in agriculture and other fields. Agril chemistry comprising, soil, planet, fertilizer, and dairy chemistry developed from basic science of chemistry.
3. Agril Botany covers planet nutrition, plant physiology and planet breeding developed from botany & chemistry.
4. Planet pathology & economic entomology developed from botany & Zoology.
5. Agril extension developed from psychology, sociology and anthropology.
6. Agronomy is essentially an applied science and is largely dependent on basic and other applied science.
7. Knowledge of all the science is necessary to learn the basic facts, regardless, of whether they would be of any practical value of agriculture.
8. All the applied sciences are important for advancement of agriculture, which are closely related to each other and no branch can progress without to help of allied science branches.
9. Agronomy is synthesis of several disciplines like soil science, agril chemistry, crop physiology, planet ecology, biochemistry & economics. Agril chemistry & soil science deals with: a) Management of acidic, saline & alkali soils. b) Application of fertilizers. c) Effects of physical, chemical changes (modifications) on soil environment.
1. Physiology deals to meet their requirement.
2. Breeding deals with evolution of new verities & exploitation of hybrid vigor.
3. Economics deals for economically crop production.
4. Pathology & entomology deals with effective control of diseases & pests.
32. Coordinated Approach:
1. Since the applied sciences are so interrelated the specialists cannot work in isolation but have to work in coordination with each other to solve the problems of agriculture rapidly and efficiently.
2. For Example: the Planet breeder while evolving a HYV (High yielding Variety) of any crop must take the help of planet pathologist to test the resistant or susceptibility of the new strain to diseases, physiologist to make sure that the new strain has not developed any undesirable qualities and of the agronomist to test the behavior of variety under field condition.
33. Agronomist
34. An agronomist is called as an expert of agriculture except veterinary science. Also known as doctor of plant
35. Agronomist is a specialized scientist in agronomy, which deals with the science of utilizing plants for food, fuel, feed & fiber.
36. Agronomist are involved with many issues including food, feed & fuel production without impact on environmental.
37. Agronomist should be specializing in areas such as crop rotation, irrigation & drainage, planet breeding, soil science, weed control & disease & pest control.
38. Role of Agronomist:
1. Agronomist aims at an obtaining maximum production at minimum cost by exploiting the exploiting the knowledge developed by basic and allied/applied science.
2. In a board sense he is conceder with production of food and fiber to meet the needs of the growing population.
3. He has to test the suitability of research finding of others specialists in the field and accept them finally and also judge the reaction of the farming community.
4. He is a coordinator of different subject matter specialist and act as a physician who concern with other SMS.
5. He carries out research on scientific cultivation of crops taking into account the effect of factors like soil climate, variety of crops production techniques suitably depending on the situation.
6. He is person with working knowledge of all agril disciplines and coordinator of different subject matter specialists.
39. Introduction to Principles of Agronomy
40. “Principles of agronomy deals with basic concepts & common agronomic principles & much more than crop to crop management approaches”
41. This principle of agronomy is useful for the application with many crops.
42. The principle of agronomy is based on two major purposes:
1. To develop an understanding of the important principles underlying the management.
2. To develop the ability to apply these principles to production situations
43. Major Principles to Agronomy:
44. 1. Agrometerology: study of climatic factors in related to agriculture.
45. 2. Soils & Tillage: Tillage is the agricultural preparation of the soil by ploughing, ripping, or turning it. There are two types of tillage: primary and secondary tillage. Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics.
46. 3. Soils & Water conservation: Water conservation refers to reducing the usage of water and recycling of waste water for different purposes like cleaning, manufacturing, agriculture etc.
47. 4. Dry land Agriculture: Dry land farming is an agricultural technique for cultivating land which receives little rainfall.
48. 5. Mineral Nutrition of plants, Manures & Fertilizers: Plant nutrition is the study of the chemical elements that are necessary for plant growth.
49. 6. Irrigation & water management: Water management is the activity of planning, developing, distributing and optimum use of water resources under defined water polices and regulations
50. 7. Weed Management: Management of unwanted plant in field.
51. 8. Cropping & Farming systems.
52. 9. Sustainable Agriculture: Sustainable agriculture refers to the ability of a farm to produce fertile soil and cows, without causing severe or irreversible damage to ecosystem health
Divisions of Plant Kingdom
A crop is an organism cultivated & harvested for obtaining yield.
· According to the natural system the plant kingdom has been divided into two divisions. I.e. Cryptogams & Phanerogams.
· Phanerogams divided into two sub division i.e. Angiosperm & Gymnosperm.
· Angiosperm further divided into two classes i.e. Monocots & Dicots.
· Classes again divided into orders, orders into families, families into genera & species, some times species into varieties.
Divisions of Plant Kingdom:
Botanical Classification of Plant:
Dicotyledonous
(Embryo with two cotyledons)
Monocotyledonous
(Embryo with one cotyledon)
Importance of classifying the Crop Plants:
1. To get acquainted with crops.
2. To understand the requirement of soil & water different crops.
3. To know adaptability of crops.
4. To know the growing habit of crops.
5. To understand climatic requirement of different crops.
6. To know the economic produce of the crop plant & its use.
7. To know the growing season of the crop
8. Overall to know the actual condition required to the cultivation of plant.
Classification based on climate:
1. Tropical: Crops grow well in warm & hot climate. E.g. Rice, sugarcane, Jowar etc
2. Temperate: Crops grow well in cool climate. E.g. Wheat, Oats, Gram, Potato etc.
Classification Based on growing season:
1. Kharif/Rainy/Monsoon crops: The crops grown in monsoon months from June to Oct-Nov, Require warm, wet weather at major period of crop growth, also required short day length for flowering. E.g. Cotton, Rice, Jowar, bajara.
2. Rabi/winter/cold seasons crops: require winter season to grow well from Oct to March month. Crops grow well in cold and dry weather. Require longer day length for flowering. E.g. Wheat, gram, sunflower etc.
3. Summer/Zaid crops: crops grown in summer month from March to June. Require warm day weather for major growth period and longer ay length for flowering. E.g. Groundnuts, Watermelon, Pumpkins, Gourds.
Use/Agronomic classification:
1. Grain crops: may be cereals as millets cereals are the cultivated grasses grown for their edible starchy grains. The larger grain used as staple food is cereals. E.g. rice, Jowar, wheat, maize, barley, and millets are the small grained cereals which are of minor importance as food. E.g. Bajara.
2. Pulse/legume crops: seeds of leguminous crops plant used as food. On splitting they produced dal which is rich in protein. E.g. green gram, black gram, soybean, pea, cowpea etc.
3. Oil seeds crops: crop seeds are rich in fatty acids, are used to extract vegetable oil to meet various requirements. E.g. Groundnut, Mustard, Sunflower, Sesamum, linseed etc.
4. Forage Crop: It refers to vegetative matter fresh as preserved utilized as food for animals. Crop cultivated & used for fickler, hay, silage. Ex- sorghum, elephant grass, guinea grass, berseem & other pulse bajara etc.
5. Fiber crops: crown for fiber yield. Fiber may be obtained from seed. E.g. Cotton, steam, jute, Mesta, sun hemp, flax.
6. Roots crops: Roots are the economic produce in root crop. E.g. sweet, potato, sugar beet, carrot, turnip etc.
7. Tuber crop: crop whose edible portion is not a root but a short thickened underground stem. E.g. Potato, elephant, yam.
8. Sugar crops: the two important crops are sugarcane and sugar beet cultivated for production for sugar.
9. Starch crops: grown for the production of starch. E.g. tapioca, potato, sweet potato.
10. Dreg crop: used for preparation for medicines. E.g. tobacco, mint, pyrethrum.
11. Spices & condiments/spices crops: crop plants as their products are used to flavor taste and sometime color the fresh preserved food. E.g. ginger, garlic, chili, cumin onion, coriander, cardamom, pepper, turmeric etc.
12. Vegetables crops: may be leafy as fruity vegetables. E.g. Palak, mentha, Brinjal, tomato.
13. Green manure crop: grown and incorporated into soil to increase fertility of soil. E.g. sun hemp.
14. Medicinal & aromatic crops: Medicinal plants includes cinchona, isabgoli, opium poppy, senna, belladonna, rauwolfra, iycorice and aromatic plants such as lemon grass, citronella grass, palmorsa, Japanese mint, peppermint, rose geranicem, jasmine, henna etc.
Classification based on life of crops/duration of crops:
1. Seasonal crops: A crop completes its life cycle in one season-Karin, Rabi. summer. E.g. rice, Jowar, wheat etc.
2. Two seasonal crops: crops complete its life in two seasons. E.g. Cotton, turmeric, ginger.
3. Annual crops: Crops require one full year to complete its life in cycle. E.g. sugarcane.
4. Biennial crops: which grows in one year and flowers, fructifies & perishes the next year? E.g. Banana, Papaya.
5. Perennial crops: crops live for several years. E.g. Fruit crops, mango, guava etc.
Classification based on cultural method/water:
1. Rain fed: crops grow only on rain water. E.g. Jowar, Bajara, Mung etc.
2. Irrigated crops: Crops grows with the help of irrigation water. E.g. Chili, sugarcane, Banana, papaya etc.
Classification based on root system:
1. Tap root system: The main root goes deep into the soil. E.g. Tur, Grape, Cotton etc.
2. Adventitious/Fiber rooted: The crops whose roots are fibrous shallow & spreading into the soil. E.g. Cereal crops, wheat, rice etc.
Classification based on economic importance:
1. Cash crop: Grown for earning money. E.g. Sugarcane, cotton.
2. Food crops: Grown for raising food grain for the population and & fodder for cattle. E.g. Jowar, wheat, rice etc.
Classification based on No. of cotyledons:
1. Monocots or monocotyledons: Having one cotyledon in the seed. E.g. all cereals & Millets.
2. Dicots or dicotyledonous: Crops having two cotyledons in the seed. E.g. all legumes & pulses.
Classification based on photosynthesis’ (Reduction of CO2/Dark reaction):
1. C3 Plants: Photo respiration is high in these plants C3 Plants have lower water use efficiency. The initial product of C assimilation in the three ‘C’ compounds. The enzyme involved in the primary carboxylation is ribulose-1,-Biophospate carboxylose. E.g. Rice, soybeans, wheat, barley cottons, potato.
2. C4 plants: The primary product of C fixation is four carbon compounds which may be malice acid or acerbic acid. The enzymes responsible for carboxylation are phosphoenol Pyruvic acid carboxylose which has high affinity for CO2 and capable of assimilation CO2 event at lower concentration, photorespiration is negligible. Photosynthetic rates are higher in C4 than C3 plants for the same amount of stomatal opening. These are said to be drought resistant & they are able to grow better even under moisture stress. C4 plants translate photosynthates rapidly. E.g. Sorghum, Maize, napter grass, sesame etc.
3. Cam plants: (Cassulacean acid metabolism plants) the stomata open at night and large amount of CO2 is fixed as a malice acid which is stored in vacuoles. During day stomata are closed. There is no possibility of CO2 entry. CO2 which is stored as malice acid is broken down & released as CO2. In these plants there is negligible transpiration. C4 & cam plant have high water use efficiency. These are highly drought resistant. E.g. Pineapple, sisal & agave.
Classification based on length of photoperiod required for floral initiation:
Most plants are influenced by relative length of the day & night, especially for floral initiation, the effect on plant is known as photoperiodism depending on the length of photoperiod required for floral ignition, plants are classified as:
1. Short-day plants: Flower initiation takes plate when days are short less then ten hours. E.g. rice, Jowar, green gram, black gram etc.
2. Long day’s plants: require long days are more than ten hours for floral ignition. E.g. Wheat, Barley,
3. Day neutral plants: Photoperiod does not have much influence for phase change for these plants. E.g. Cotton, sunflower. The rate of the flowering initiation depends on how short or long is photoperiod. Shorter the days, more rapid initiation of flowering in short days plants. Longer the days more rapid are the initiation of flowering in long days plants.
Agricultural Seasons in India & Maharashtra
Agricultural Seasons in India
In India four agricultural four seasons are present in year as per Indian metrological department as follows:
1. Winter Season: This season is called as cold weather period. January & February months are the cold months in the most parts of the country. Temperature distribution over India shows a marked decrease from south to north. In north India average temperature during this season is about 10-15 degree and in south India is about 21-28 degree. Weather during this period is cool, dry & pleasant with dewfall during morning. This period is practically rainless except occasional drizzles.
2. Summer Season: This season is also called as hot weather period / premonsoon season. This period is characterized by high temperature. The temperature is higher in north compared south. March to May month is the summer season. The weather gets hotter steadily from the beginning of March. April & may are the hottest months of the year. The average temperature is 30-40C. The rainfall receives during this period are mainly useful for preparatory cultivation. In this period hot wind blows & sometimes dust storms also take place. Some time these dust storms create problems due to their intensity for considerable period.
3. Rainy Season: This season is also called as south west monsoon. This is the most important period major rainy period in India about 60 to 75% of total rainfall in a year is received during this period. During this period climate is warm, humid with bright sunshine except on rainy days. Rainy season or monsoon is result of wind movements. Which in turn are caused by difference in air pressure? In early summer the sun heats large landmass of central & southern Asia and warm air rises. As it rises suction is created & the moist air across the Arabian Sea & the Bay of Bengal is pulled from the south-west direction. This creates south-west monsoons.
4. Post Rainy Season: This season is also called as post monsoon season or North-East monsoon. Rainfall received during this period is 13% to 33% of annual rainfall. The temperature high up to the mid of October and later starts falling rapidly. The October to December month is the duration for the post rainy season in India.
Agricultural Seasons in Maharashtra: In Maharashtra whole year is divided into three seasons as follows:
1. Kharif / Monsoon/Rainy season: 15 June to 15 October.
2. Winter/Rabi/Cool season: 15 October to 15 February.
3. Summer season: 15 February to 15 June.
These four seasons are further subdivided into six seasons based on rules:
1. Shishir (Jan to Feb)
2. Spring/Vasant (March to April)
3. Summer (May to June)
4. Rains/Varsha (July to Aug)
5. Fall/Sharad (Sep to Oct)
6. Hemant (Nov to Dec)
Factors Governing Crop Production or Affecting Crop Growth
Crop production is concerned with the exploitation of plant morphological (or structural) and plant physiological (or functional) responses with a soil & atmospheric environment to produce a high yield per unit area of land. Growth is irreversible increase in size or weight.
Crop production provides the food for human beings, fodder for animals and fiber for cloths. Land is the natural resource which is unchanged & the burden of the population is tremendously increasing, thereby decrease the area per capita. Therefore it is necessary to increase the production per unit area on available land. This necessitates the close study of all the factors of crop production viz.
1. The soil in which crops are grown
2. The water which is the life of plant
3. The Plant which gives food to man & fodder to his animals
4. The skillful management by the farmer himself
5. The climate which is out of control of man & but decided the growth, development & production.
6. The genetic characters of crop plant which is the genetic makeup & can be exploited for crop production.
Broadly, the factors that influence the growth of crop or crop production can be classified as:
A. Internal or Genetic Factors
B. External or Environmental Factors
Internal or Genetic Factors
Genetic makeup decided the crop growth & its production. Crops vary in the genetic makeup which included desirable & undesirable characters as well. Breeders try to incorporate maximum desirable characters in one strain of crop & also try to exploit the hybrid vigour.
Desirable characters include:
1. High yielding ability under given environment condition.
2. Early maturity
3. Better resistance to lodging
4. Drought, flood & salinity tolerance
5. Greater tolerance to insect & diseases
6. Chemical composition of grains (Oil & Proteins)
7. Quality of grains (Fineness coarseness etc)
8. Quality of straw (Sweetness juiciness)
These characters are inherent in each individual and are transmitted from one generation to another by genes.
External or Environmental Factors
1. Edaphic or Soil Factors
2. Water
3. Plant Biotic Factor
4. Anthropic or Management
5. Climatic
1) Edaphic or Soil factors: Soil can be defined as: Soil is a thin layer of the earth’s crust which serves as a natural medium for the growth of plants. Soils are formed by the disintegrations & decomposition of parent rocks due to weathering and the action of soil organisms & also the interaction of various chemical substances present in the soil. Soil is formed from parent rock by the process of weathering over a long period by the action of rain water, temperature and plant & animal residues.
A vertical cut of 1.5 to 2 m deep soil indicates a layer varying from a few cm to about 30 cm of soil, called surface soil, elbow that a layer of sub soil & at the bottom, the unrecompensed material which is the parent rock.
Role of soil:
1. Soil is the natural media to grow the crop.
2. Soil gives the mechanical support & act as an anchor,
3. Soil supplies the nutrients to the crop plants,
4. Soil conserves the moisture which is supplies to the crop plants
5. Soil is an abode (house) of millions of living organisms which act on plant residues & release food material to plants
6. Soil provides aeration for growth of crop and decomposition of organic matter.
Soil profile: A vertical section of soil in the field extending up to the depth of the parent material shows the presence of more or less distinct horizontal layers such a section is called a profile & individual layers are regarded as horizon.
The depth of soil varies as shallow, medium & deep. The soil which remains where it is formed, known as soil in situ, the soil on the banks of river which is formed from the soil particles washed away by rains from hill slopes & deposited at lower levels is known as alluvial soil which is much deeper & more fertile.
Soil varies in their composition and the arrangement of soil particles depending upon the parent rocks from which they are formed. They also vary in physical properties such as texture & structure. Textural class decided its fitness, fertility & plant growth, infertile soil need to add the org. Matter & fertilizers. Problematic soils need addition of soil amendments (Lime-acid & Gypsum-alkali) and other management practices to correct them. The chemical properties of soil are decided by the parent rocks.
Soil is not an inert mass but an abode of millions of living organisms which act on plant residues & release food material to plants. The decayed OM also loosens the soil to allow circulation & retention of moisture, which are necessary for the life & growth of the plant, soil is not an ordinary mass of dead particles of rock but a medium humming with activity, responsive to the water, plant & management by the farmer.
External or Environmental Factors – Water and Plant or Biotic factors
Water:
Functions of water:
1. Major component of the plant body (90%).
2. Act as solvent for dissolving the nutrients & nutrient carrier.
3. Maintains/regulates the temperature of plant & soil as well
4. Maintains the turgidity of plant cells.
5. Essential for absorption of nutrients & metabolic process of the plants.
Plant tissues constitute about 90% of water. Rain and ground water are the sources of the water. Ground H2O is reused for irrigation through well, tank or canal, etc. Erratic rains are to be conserved properly so that plants make best use of it. Rainwater is to be supplemented by irrigation to meet the water requirement of crops for bumper yields.
Water Present in the soil helps the plants in many ways:
1. Supplies the essential raw material for production of carbohydrates by photosynthesis.
2. Promotes physical, chemical & biological activities in the soil.
3. Gaseous diffusion in soil for proper aeration.
Water is the life of plant & must be supplied in proper quantity. Too much water may suffocate the plant roots & too little may not be able to sustain the plant. The water requirement of crops differs from crop to crop & variety to variety as well, depending upon the growth habit, genetically & physiological make up, duration of the crop, etc. For example, sugarcane, rice, banana, wheat, groundnut, etc. are the high water requiring crops & Jowar, Mung, udid, Tur, gram, bajara etc. are the low water requiring crops.
Plant /Biotic factors: Biotic factors include plant, symbiosis & animals.
Plant: The soil & water are two variables which either has to be suitably adjusted for the plant to grow or the plant should be so bred & selected that it will adjust to a given soil & water condition, growing season, climatic requirement, etc. Some of the crops grow on only rain while some required irrigation water, Plant breeders are constantly at work to evolve varieties which will suit the given soil & water condition e.g. drought resistant, disease resistant, more nutrients absorbing capacity etc.
The unwanted plants, ‘weeds’ compete with crop plants fro solar energy, water nutrients & also for space which need to be controlled for better crop growth & production at proper time & methods.
Symbiosis: There are the some organisms which have mutual relationship with each other & with the prevailing environment of the place. This biological inter relationship among the organisms is termed as symbiosis. The symbiotic relationship between legumes & Rhizobia which results in ‘N’ fixation is of great significance to crop production. The legume bacteria use the carbohydrates of their host as energy & fixes up atmospheric ’N’ which in turn used by host plants. The free living organisms (Azotobacter) acquire their energy from soil OM, fix the free N & make it a part of their own tissue. When they die the ‘N’ available in their body tissues is used by the crop plants.
Animals: Soil organisms:
The soil organisms include:
1) Soil flora (plant kingdom) & 2) soil fauna (animal Kingdom).
Soil flora is of two types: i) Macro flora e.g. Roots of higher plants ii) Micro flora e.g. Bacteria, fungi, actinomycetes & algae.
Soil fauna is of two types: i) Macro flora e.g. earthworm, moles, ants, and ii) Micro fauna e.g. protozoa, nematodes. The soil fauna including protozoa, nematodes, rotifers, snails, insects constitute a highly important part of the environment for plant roots. All these organisms contribute decomposition, when using the OM for their living. Among these insects, nematodes cause considerable damage as crop pests.
Beneficial organisms: Insects like bees, wasp, moths, butterflies, beetles help in pollination of crops. Burrowing by earthworm facilitates aeration & drainage and the ingestion of OM & mineral matter results in a constant mixing of these materials in the soil & tends to make better plant growth.
Small animals: Like rabbits, squirrels, rats cause extensive damage to field & garden crops.
External or Environmental Factors- Anthropic or Management or Man or Skillful Mgt & climate
Anthropic or Management /Man or skillful management by the man:
Finally, man must so manage the soil-water-plant complex to produce efficiently food & fodder and for that purpose a number of mechanical devices & useful cultivation practices have been evolved such as ploughs for ploughing, harrows for seeded preparation, hoes for hoeing, seed cum fertilizer driller for sowing the seeds & application of fertilizers. Man has to perform the operations at proper time such as land preparation sowing, thinning & gap filling and also the plant protection measures, optimum plant population, recommended fertilizer application at right time & depth, proper water mgt Practices. The soil, water, plant& management are the four factors, which govern successful crop production.
Climate: Another factor that influences the growth, development, & production of crop is the climate which is out of control by the man but mgt. practices of the crops can be altered to harvest maximum yield. Climate is the most dominating factor influencing the suitability of a crop to a particular region. The yield potential of a crop mainly depends on climate. More than 50% of variation in yield of crops is solar radiation, temperature & rainfall Relative humidity & wind velocity also influence crop growth to some extent. Atmospheric factors which affect the crop plants are called climatic factors which include.
1. Precipitation,
2. Temperature,
3. Atmospheric humidity,
4. Solar radiation,
5. Wind velocity and atmospheric gases.
1. Precipitation: - It results from evaporation of water from sea water and land surfaces. The process involved in the transfer of moisture from the sea to the land & back to the sea again what is known as the hydrologic cycle. Continuous circulation of water between hydrosphere, atmosphere & lithosphere called as hydrologic cycle. Precipitation includes rainfall, snow or hail, Fog drip & dew also contribute to moisture. Fog consists of small water droplets while dew is the condensation of the water vapour present in the air. Precipitation influences the vegetation of a place. Most of crops receive their water supply from rainwater which is the source of soil moisture so essential for the life of a plant. The yearly precipitation, both in total amount & seasonal distribution greatly affects the choice of cultivated crops of a place.
2. Temperature: It is considered as a measure of intensity of heat energy. The range of maximum growth for most argil, plans is between 15 & 400C, every plant community has its own minimum, optimum & maximum temperature known as their cardinal points. Temperature is determined by the distance from the equator (latitude) and the altitude; Apart from the reduction in yield many injuries such as cold injury which included chilling injury, freezing injury, suffocation & heaving and heat injury.
Maize & sorghum (8-100C, 300C, 40ºC) Rice (10-110C, 35ºC) Wheat (50C, 25ºC, 30º-320C)
3. Atmospheric humidity: Water which is present in the atmosphere in the form of invisible water vapor, termed as humidity of the air, ET of crop plants increases with the temperature but decreases with high relative humidity affecting the quantity of irrigation water, Moist air favors the growth of many fungi & bacteria which affect seriously the crop.
4. Solar radiation: Solar energy provides two essential needs of plants:
a) Light required for photosynthesis & for many other functions of the plant including seed germination, leaf expansion, growth of stem & shoot, and flowering, fruiting & even dormancy.
b) Thermal conditions required for the normal physiological functions of the plant. Light helps in synthesis of chlorophyll pigment. Light affects the plants in four ways: intensity, quality (wave length), duration (Photoperiod) and direction.
5. Wind velocity: It affects growth mechanically (damage to crop) and physiologically (evaporation & transpiration), Hot dry winds may adversely affect photosynthesis & hence productivity, by causing closure of the stomata even when soil moisture is adequate. Moderate winds have a beneficial effect on photosynthesis by continuously replacing the CO2 absorbed by the leaf surfaces.
Tilth and Tillage
Soil is the medium in which crops are grown but in its natural state, it is not in an ideal condition to grow them satisfactorily. Surface soil in which seed are to be sown, should not be hard & compact, but soft & friable, so that tender shoots of germinating seeds can push above the soil surface without any difficulty and the young roots penetrate easily into the lower layers of soil in search of food, water & air, Soil should also be free from weeds which otherwise rob the crop of water & nutrients. It should also have sufficient water & air which are very necessary for plant growth.
Such ideal condition of soil can be achieved by manipulating the soil properly & bringing it in good filth through a series of mechanical operations like ploughing, clod crushing, dicing, harrowing, leveling, compacting, interculturing etc. by tillage implements.
Tillage: Tillage is as old as Agriculture, Primitive man used to disturb the soil for placing seed Jethro Till considered as ‘Father of Tillage’ Who Written’ Horse hocing Husbandry’ book. Tillage of the soil consists of breaking the hard compact surface to a certain depth and other operations that are followed for plant growth. Tillage is the physical manipulation of soil with tools & the tilling of land for the cultivation of crop plants i.e. the working of the surface soil for bringing about conditions favorable for Raising of crop plants. Tillage is the manipulation of soil with tools & implements for loosening the surface crust & bringing about conditions favorable for the germination of seeds and the growth of crops.
Soil Tilth: Soil Tilth is the term used to express soil condition resulting from tillage. Hence it is the resultant of the tillage. A soil is said to be in good Tilth when it is soft, friable & properly aerated. The Tilth is the physical condition of the soil brought out by tillage that influences crop emergence, establishment, growth and development. Tilth is a loose, friable, airy, powdery granular & crumbly structure of the soil with optimum moisture content suitable for working & germination or sprouting seeds & propagates Soil Tilth is that kind of physical condition of soil when it is loose. Not very powdery but granular & when these granules are felt between fingers they are soft, friable, & crumble easily under pressure, Such soils permit easy infiltration of water & are retentive of moisture for satisfactory growth of plants.
Characteristics of good tilth/Measurement of soil tilth: Tilth indicates two properties of soil, viz the size distribution of aggregates and mellowness or friability of soil.
Size distribution of soil aggregates: The relative proportion of different sized soil aggregates is known as size distribution of soil aggregates. Higher% of larger aggregates i.e. more than 5 mm are necessary for irrigated agriculture while higher% of smaller aggregates(1-2mm) are desirable for dry land agriculture. Theoretically, the best size of granules or aggregates ranges from 1 to 6 mm. However, it depends on soil, type, soil moisture content (at which ploughing is done) & subsequent cultivation.
Mellowness or friability: is that property of soil by which the clods when dry become more crumbly. They do not crumble into dust but remain as stable aggregates of smaller size.
A soil with good tilth is quite porous and has fee drainage up to water table. The capillary & non-capillary pores should be in equal proportion so that sufficient amount of water is retained in the soil as well as free air, The soil aggregates would be quite from or stable & would not be easily eroded by water or by wind.
Soil tilth: is easy to describe but rather difficult to measure/ Theoretically, best size of granules ranges from 1-6 mm differs with country e.g. England as more than 15mm and Russia 2-3 mm. Besides this, study of pore space, equal distribution of macro & micro pores is good tilth.
Ideal soil tilth : An ideal soil tilth is not the same for all types of crops & all types of soils e.g. small seeded crops like bajara, ragi, lucerne, Sesamum, mustard require a much finer seedbed, Jowar & cotton require a moderately compact & firm seed bed and not cloddy or loose. Bold seeded crops like gram, maize germinate even in cloddy seedbed.
As regards soil type, a very fine, powdery condition of the surface soil is decidedly bad for a heavy clay soil as it forms a caked surface under rainy condition and all the rain water is then liable to be lost by run-off, taking away also with loamy & lighter soils.
Tilth and Tillage - Objects of Tillage
Objects of Tillage: These can be summarized in brief as below.
1. To make the soil loose & porous: It enables rain water or irrigation water to enter the soil easily & the danger of loss of soil & water by erosion and run-off, respectively, is reduced. Due to adequate proportion of microspores (capillary), the water will be retained in the soil & not lost by drainage.
2. To aerate the soil: Aeration enables the metabolic processes of the living plants & micro organisms, etc. to continue properly. Due to adequate moisture and air, the desirable chemical & biological activities would go on at a greater speed & result in rapid decomposition of the organic matter and consequently release of plants nutrients to be used by crops. Similarly, the evolution of CO2 gas in this process will result in forming weak carbonic acid in the soil which will make more nutrients available to crops.
3. To have repeated exchange of air / gases: There should be an exchange of air during the growing period of crops. As the supply of O2 from the air that is being constantly utilized in several biological reactions taking place in the soil; should be continuously renewed. At the same time CO2 that is released should be removed & not allowed to accumulate excessively decomposition of org. residues by micro- organisms where O2 is utilized & CO2 released. Deficiency or excess of O2 may reduce the rate of reactions.
O2 in soil air & atm. Air is more or less same i.e. 20 to 21% CO2 in atmospheric air is about 0.03% & in soil air 0.2 to o.3% which is 8to 10 times more than atmospheric air. It is, therefore, very necessary to often introduce atmospheric air in the soil to keep the concentration of CO2 under by suitable tillage operations.
4. To increase the soil temperature: This can be achieved by controlling the air- water content of soil & also by exposing more of the soil to the heat of sun. This helps in acceleration of activities of soil bacteria & other micro organisms.
5. To control weeds: It is the major function of tillage; Weeds rob food & water required by crop & competition results in lowering of crop yield.
6. To remove stubbiest: Tillage helps in removing stubbles of previous crop and other sprouting materials like bulbs, solons etc in making a clean field/seedbed.
7. To destroy insect pests: Insects are either exposed to the sun’s heat or to birds that would pick them up. Many of the insect-pests remain in dormant condition in the form of pupae in the top soil during off season & when the host crop is again planted, they reappear on the crop. Some may harbor on stubbiest or other eminent of the crop. Grubs & cutworms can be destroyed by tillage.
8. To destroy hard pan: Specially designed implements (Chisel plough) are helpful to break hard pan formed just below the ploughing depth which act as barrier for root growth & drainage of soil.
9. To incorporate organic & other bulky manures: Organic manures should not only be spread but properly incorporated into the soil. Sometimes bacterial cultures or certain soil applied insecticides require to be drilled into the soil for control of pests like white grub. White ants, termites, cut worms e.g. Aldrin.
10. To Invert soil to improve fertility: By occasional deep tillage the upper soil layer rich in org. matter goes down thus plant roots get benefit of rich layer and lower layer which is less fertile comes to top.
Tilth and Tillage - Factors Influencing Preparatory or Tillage Operations
Factors Influencing Preparatory or Tillage Operations:
The preparatory cultivation of the lands done in various ways which is influenced by several factors but more important ones are:
1. The crop: The crop to be grown decides the type & preparatory tillage given to the land. Hardy crops like sorghum & other millets are not sensitive about tilth. Production of fine tilth will increase the cost of cultivation which is not economic. Small seeded or delicate crops like tobacco, chilli, coriander,sesamum, mustard etc. Require a fine seedbed for which land is repeatedly cultivated to get required fine tilth. Sugarcane & other root crops require deep cultivation of land to lose the soil to the required depth.
2. Type of soil: A clayey soil is amenable to cultivation only within a narrow range of moisture. Outside this range, the soil can’t be worked satisfactorily & increases the draft required. Too wet or to dry soils are difficult to cultivate. The lighter soils can be worked under a wide range of moisture & the draught required for their manipulation is much less. Loamy soils are easily brought to good tilt with little cultivation & expenditure of energy.
3. Climate: It in influences the moisture in the soil, the draught required for cultivation and depth & types of cultivation done, For example, in scarcity areas the rainfall is low & the moisture in the soil prior to sowing does not ordinarily permit deep cultivation which tends to dry up soil to a greater depth & reduce moisture available to the crops eventually (finally) Sowings cannot be done till depth of cultivated soil is properly moistened. This results in delayed sowing & consequently the effect on growth & yield of crop Deep cultivation is beneficial in regions having better rainfall, particularly temperate regions for promoting aeration, summer showers are received in South India which favors moist condition & ultimately beneficial for preparing the land for next season crops.
4. Type of farming: There are two types, irrigated & dry land/ rained farming. Under irrigated farming intensive farming is followed which includes cultivation of more than two crops. In a year continuously without much interval between them. During this narrow period of interval the land is to be cultivated repeatedly to bring required title without subjecting the soil for natural weathering for a long period. The frequency & extent of tillage operations increase the cost of cultivation which serious as the profitable crops is raised in an intensive manner. Dry land faming depends entirely on rains & in such areas only one crop is taken in a year. The interval between crops & successive cultivation operations is long. Weathering plays an important role than cultivation. Hence they are limited with wide intervals between them. The cost of cultivation is kept down & the low productivity of land does not warrant a higher investment.
Tilth and Tillage - Effects of Tillage on soil & Plant growth
Effects of Tillage on soil & Plant growth:
A) Effect on soil:
1) loosens the soil which favors the germination & growth of crop,
2) Improves the soil structure due to alternate drying and cooling,
3) Improves soil permeability, soil aeration & soil inversion,
4) Facilitates the movement of water in soil,
5) Results in soil & water conservation through higher infiltration, reduce run-off & increase depth of soil for moisture storage,
6) Holds more water in the soil,
7) Increased soil aeration helps in multiplication of micro-organisms,
8) Org. matter decomposition is hastened resulting in higher nutrient “availability,
9) Increase aeration helps in degradation of herbicide and pesticide residues & harmful allelopathic chemicals exuded by roots of previous crops or weeds.
Tillage operations also influence the physical properties of soil like:
1) Pore space: Tillage increase the pore spaces i.e. space between the soil particles, due to equal amount of capillary & non- capillary (Macro & microspores) pores. This facilities free movement of air & moisture in the soil & increases infiltration.
2) Soil structure: Soil with crumble & granular clods are considered as soil with good structure which can be achieved by proper tillage operations at optimum moisture. This reduces the soil loss due to erosion.
3) Bulk density: when soil is loosened, the soil volume increases without any effect on weight. Therefore, bulk density of tilled soil is less than untilled soil which is favorable in many ways for crop, micro organisms, etc.
4) Soil colour: Tillage increases oxidation and decomposition resulting in fading of colour The org. matter is mainly responsible for the dark brown to dark grey colour of soil.
5) Soil water: Tillage improves soil water in different ways which depends on soil porosity, soil depth & roughness. also increases rate of infiltration, water holding capacity (WHC) & hydraulic conductively.
6) Soil temperature: Tillage creates up to soil temperature for seed germination & seed establishment. Tillage loosens the soil surface resulting in decrease of thermal conductivity (rate of heat transfer at which the heat penetrates) and heat capacity (heat storage / unit area)
B) Effects on crop growth:
1) Tillage loosen the soil thereby favors the germination & establishment of seeding.
2) Tillage helps in maintaining the optimum plant stand,
3) Increases depth of root penetration,
4) Roots proliferate profusely in loose soil & increase the growth of seminal & lateral roots.
5) Reduce the competition within crop & weeds for light, water, nutrients & space thereby helps in better growth of crop,
6) Tillage reduce the pest attack on succeeding crop,
7) Tillage helps in availability of nutrients to crop in proper amount.
Tilth and Tillage: Types of Tillage Operations
Types of Tillage Operations: Tillage includes use of different kinds of implements at different times are classified on the basis of their timing into-3types:
1. Preparatory tillage: Tillage operations that are carried out from the time of harvest of a crop to the sowing of the next crop are known as preparatory cultivation/ Tillage. OR Operations carried out in any cultivated land to prepare seedbed for sowing crops are preparatory tillage. These are time consuming & costly but are to be performed at right stage of soil moisture & with right implements, otherwise it will not helps in good growth of crop. These includes in sequence, plouging, clod crushing, leveling, discing , harrowing, manure mixing & compacting the soil and implements to be used are ploughs, clod crushers, disc ploughs or harrow , bladed harrow etc.
It includes primary & secondary tillage:
a) Primary tillage: It mainly includes the ploughing operation which is opening of the compacted soil with the help of different ploughs. Ploughing is done to:
1) Open the hard soil,
2) Separate the top soil from lower layers,
3) Invert the soil whenever necessary and
4) Uproot the weeds & stubbles.
The cutting & inverting of the soil that is done after the harvest of the crop or untitled fallow or to bring virgin or new land under cultivation is called primary tillage. It may be done once or twice a tear in normal or settled agriculture or once in four to five years in dry land agriculture.
b) Secondary tillage : Lighter or finer operation performed on the soil after primary tillage are known as secondary tillage which includes the operations performed after ploughing, leveling, discing, harrowing etc.
2. Seedbed preparation: when the soil is brought to a condition suitable for germination of seeds & growth of crops, called as SEEDBED.
After preparatory tillage the land is to be laid out properly for irrigating crops if irrigation is available for sowing or planting seeding which are known as seedbed preparation: It includes harrowing, leveling, compacting the soil, preparing irrigation layouts such as basins, borders, rides & furrows etc. and carried out by using hand tools or implements like harrow, rollers plank, rider etc. After field preparation, sowing is done with seed drills. Seeds are covered & planking is done so as to level & impart necessary compaction.
3. Inter tillage/ Inter cultivation/ Interculture/ after care operation: The tillage operations that are carried out in the standing crop are called inter tillage operations. The tillage operation done in the field after sowing or planting and prior to the harvesting of crop plants known as inter cultivation. It includes gap filling , thinning , weeding , mulching, top dressing of fertilizers, hoeing, earthling up etc. unless these are carried out at right time, with suitable implements mainly hoes & hand tools the crop will not attain a vigorous growth. These operations are carried out in between the crop rows.
Tilth and Tillage- Tillage Operations and Implements
Tillage operations and implements:
A) Preparatory tillage:
i) Ploughing: It is considered to be the most essential operation for growing crops. It is done by different ploughs which are of 3 types:
1) Deshi or wooden or Indigenous plough
2) Iron mould board ploughs
3) Special purpose ploughs.
The iron mould board plough may be:
1) Reversible or Turn –wrest mould board plough and
2) Non-reversible or fixed mould board plough. Former is drawn by bullocks and later with the tractor. Depending up on the weight and no. of bullocks to be used the
Reversible I.M.B. plough s may be:
a) Light R.I. M.B. plough drawn by one bullock pair.
b) Medium R.I.M.B. Plough had drawn by two bullock pairs &
c) Heavy R.I.M.B. plough drawn by three bullock pairs.
The special purpose ploughs are
a) Disc plough used for discing or loosening of the soil.
b) Sub soil plough used to break hard layers or pans without bringing them to the surface.
c) Chisel plough used breaking hard pans & for deep ploughing (60-70cm) with less disturbance to the top layers.
d) Rider used to split the field in top ridges & furrows.
ii) Clod crushing: It is not always necessary. When there are the clods the rains received will soft & break the clods. It is necessary in Rabi season. Clods are broken by a plank, blade harrow or hand mallet, indigenous implement (a big log of wood) called maind. The best implement for this purpose is the Norwegian harrow which breaks the clods by piercing & breaking action.
iii) Leveling of land: It is required in irrigated area & carried out after ploughing to ensure even distribution of rain & irrigation water to avoid stagnation of water in low lying areas and also to stop soil erosion Implements such as bamboo petari, blade harrow tied with rope round the prongs, planker, plank- leveler, buck scraper, float, keni are used for leveling.
iv) Manure mixing: Manures are spread over the prepared bed by manually or with the help of country plough, shovel tooth cultivator, a blade harrow, disc harrow.
v) Compacting the soil: It is done by working an inverted harrow or single/ double plank.
vi) Cultivator: It is used to break & loose the soil.
B) Implements used for seedbed preparation:
i) Harrowing: is done by a blade harrow with the purpose of clod crushing, leveling, collecting stubbles, destroying germinating weeds and compacting the soil, a multipurpose implement commonly used by the farmer. Disc harrow drawn either by bullocks or tractor is an improvement which cuts & pulverizes the soil.
ii) Covering of seed: is carried by a light blade harrow or a plank.
iii) Ridging: Riders are used for opening ridges and furrows for sugarcane, vegetables, and irrigation layouts field channels
iv) Implements for sowing: Sowing may be done by putting the seeds behind plough, seed drills which may be doff an, tiff an or Chou fan, Seeding & fertilizer application are done at the same time by providing two separate bowls, called as feri-cum-seed drill. Seed may be sown mechanically to maintain row to row & plant to plant(R/R & p/p) distance. There may be sowing of seed and fertilizer application at the same time.
C) Implements for inter cultivation: Operations carried out in between the crop rows called
Intercultivation or inter tillage or inter culture operations.
These are necessary for destroying weeds, preventing cracking of soil, aerating the soil to absorb more moisture, pruning of roots, ear thing up of plants, destroying insects & thinning of crop plans.
1. Thinning & gap filling: These are done by manual labour/hand in which plants are uprooted from dense places and the gaps are filled to maintain the optimum plant population.
2. Wedding: It is done either by hand with the help of a khurpi/sickle or hoes drawn by hand or bullocks. Hoes may be of entire blade, slit blade, spring teeth or Akola hoe Japanese/Rotary paddy weeder, karjat hoe/Touchy gurma etc.
3. Ear thing up: may be done by country plough or rider in S.cane, banana,
Potato. Sometime it is done by manual labour with kudali.
4. Spraying: is done by sprayers which may be manually operated, mechanical/power drawn to control insects-pests & diseases.
5. Dusting: is done by duster used for dusting insecticides to control insect-pests.
D) Special purpose implements:
1) Reapers & harvesters used to harvest wheat or paddy.
2) Threshers used for threshing which may be bullock (olpad) drawn, tractor drawn, or electric motor driven.
3) Potato digger used to harvest potatoes
4) Groundnut digger used to harvest Gnat
5) Gnat Sheller used to separate kernels from the pods.
6) Maize Sheller used to separate maize grains from cobs.
7) Seed dressing drum used to treat the seed with chemicals.
8) Hand gin used to separate lint from seed cotton.
Tools used in agriculture: 1) Khurpi: To remove weeds
2) Kudali: To dig the pits & earthling up
3) Axe: To cut the wood & harvest sugarcane
4) Pickaxe: To dig out the pits.
5) Sickle: To cut the hardy weed & crop plants & forages.
6) Ghumella: To transport soil or produce from the one place to other.
7) Crop-bar: To open the hole in soil while fencing the thomy bushes.
8) Dibbler: For dibbling the seeds. (For other tools, refer practical manual)
Tilth and Tillage- Modern Concepts of Tillage
Modern Concepts of Tillage:
Tillage is time consuming, laborious & costly, owing to this new concepts like minimum tillage & zero tillage are introduced.
1. Minimum Tillage: It is aimed at reducing tillage operations to the minimum necessary for ensuring a good seedbed, rapid germination, a satisfactory stand & favorable growing conditions, Tillage can be reduced by:
1) Omitting operations which do not give much benefit when compared to the cost and
2) Combining agricultural operations like seeding & fertilizer application.
Advantages:
1) Improve soil condition due to decomposition of plant residues in situ,
2) Higher infiltration caused by decomposition of vegetation present on Soils & channels formed by decomposition of dead roots.
3) Less resistance to root growth due to improved structure.
4) Less soil compaction by reduced movement of heavy tillage vehicles.
5) Less soil erosion compared to conventional tillage.
Disadvantages:
1) Less seed germination,
2) More ‘N’ has to be added as rate of decomposition of organic matter is slow.
3) Nodulation may affect in some legumes.
4) Sowing operations are difficult with ordinary implements.
2. Zero tillage: It is an extreme form of minimum tillage. Primary tillage is completely avoided & secondary tillage is restricted to seedbed preparation in the row zone only.
It is followed where:
1) Soils are subjected to wind & water erosion,
2) Timing of tillage operations is too difficult &
3) Requirements of energy & labour for tillage are too high.
Advantages:
1) Soils are homogenous in structure with more no. of earth worms.
2) Organic matter content increased due to less mineralization.
3) Surface runoff is reduced due to presence of mulch. Several operations are performed by using only one implement. In these weeds are controlled by spraying of herbicides.
Disadvantages:
1) Higher ‘N’ is too applied due to slower mineralization of org. matter.
2) Large population of perennial weeds appears.
3) Build up of pests is more.
3. Stubble mulch tillage: The soil is protected at all times either by growing a crop or by crop residues left on the surface during fallow periods. It is year round system of managing plant residue with implements that undercut residue, loosen the soil and kill weeds. Soil is tilled as often as necessary to control weeds during the interval between two crops. However, it presents the practical problem as the residues left on the surface interfere with seedbed preparation & sowing operations. The traditional tillage & sowing equipment is not suitable under these conditions.
Modern methods of tillage are not practiced in Indian condition because:
a) Left over residue is a valuable fodder & fuel.
b) Limited use of heavy machinery & therefore problem of soil compaction is rare.
4. Peddling: Pudding is ploughing the land with standing water so as to create an impervious layer below the surface to reduce deep percolation losses of water and to provide soft seedbed for planting rice. This followed in rice as the growth and yield are higher when grown under submerged conditions. Maintaining standing water throughout the crop period is not possible without pudding. It aims at destroying soil structure and separates individual soil particles i.e. sand, silt & clay, during operation and settles later. The sand particles reach the bottom, over which silt particles settle & finally clay particles fill the pores thus making impervious layer over the compacted soil. It is done with several implements depending on the availability of equipment and the nature of land such as spade, wetland plough, worn out Dryland plough, mould board plough, wetland puddler, country plough, etc. It consists of ploughing repeatedly in standing water until the soil becomes soft & muddy. Initially, 5-10cm of water is applied depending upon the water status of the soil to bring saturation and above and the first ploughing is carried out after 2-3 days. By this operation, most of the clods are crushed and majority of the weeds are incorporated. Within 3-4 days, another 5cm of water is given & third ploughing is done in both the directions. Planking or leveling board is run to level the field.
5. Conservation tillage: It is disturbing the soil to the minimum extent & leaving crop residues on the soil. It includes minimum & zero tillage which can reduce soil loss up to 99% over conventional tillage. In most cases, it reduces soil by 50% over conventional tillage. Conventional tillage includes ploughing twice or thrice followed by harrowing & planking. It leaves no land unploughes & leaves no residues on the soil.
Seeds and Sowing
Seed is any material used for planning & propagation whether it is in the form of seed (grain) of food, fodder, fiber or vegetable crop or seedlings, tubers, bulbs, rhizomes, roots, cuttings, grafts or other vegetatively propagated material.
Seed is a fertilized ovule consisting of intact embryo, stored food (endosperm) and seed coat which is viable & has got the capacity to germinate.
As we say, “Reap as you sow”, the good quality seed must have following characters:
1. Seed should be genetically pure & should exhibit true morphological & genetical characters of the particular strain (True to type).
2. It should be free from admixture of seeds of other strains of the same crop or other crop, weeds, dirt and inert material.
3. It should have a very high & assured germination percentage and give vigorous seedlings.
4. It should be healthy, well developed & uniform in size.
5. It should be free from any disease bearing organisms i.e. pathogens.
6. It should be dry & not mouldy and should contain 12-14% moisture.
Seed is the basic input in the crop production which should be of good quality.
Seeds and sowing - Seed Germination
Seed Germination: Means the resumption of growth by embryo & development of a young seedling from the seed. Germination is an activation of dormant embryo to give rise to radical (root development) and plumule (stem development).Germination is the awakening of the dormant embryo. The proce4ss by which the dormant embryo wakes up & begins to grow is known as Germination.
Seed Emergence Means actually coming above and out of the soil surface by the seedling.
Changes During Germination:
1) Swelling of seed due to imbibition of water by osmosis.
2) Initiation of physiological activities such as respiration & secretion of enzyme.
3) Digestion of stored food by enzymes.
4) Translocation & assimilation of soluble food.
When seed is placed in soil gets favorable conditions, radical grows vigorously & comes out through micro Pyle & fixes seed in the soil. Then either hypo or epicotyls begins to grow.
Types of germination:
1. Hypogeal germination: The cotyledons remain under the soil. E.g.: cereals, gram.
2. Epigeal germination: The cotyledons pushed above the soil surface. E.g.: mustard, tamarind, sunflower, castor, onion.
Seed and Sowing- Factors Affecting the Germination
External Factors:
1.Moisture: It enables the resumption of physiological activities, swelling of seed due to absorption of moisture & causes bursting of seed coat & softening the tissue due to which embryo awakes & resumes its growth.
2. Temperature: A suitable temperature is necessary for proper germination. Germination does not take place beyond certain minimum & maximum temperature i.e. 0⁰C & above 50⁰C. Optimum temperature range for satisfactory germination of seed is 25 to 30⁰C.
3. Oxygen: It is essential during germination for respiration & other physiological activities which are vigorous during the process.
4. Light: It is not considered as essential for germination & it takes place without light. The seedlings grow more vigorously during darkness rather in light. However, for survival of germinating seedling, light is quite essential.
5. Substratum: It is the medium used for germinating seeds. In the laboratory, it may be absorbent paper (blotting paper, towel or tissue paper), soil & sand. Substratum absorbs water & supplies to the germinating seeds. It should be free from toxic substances & should not act as medium for growth of micro-organisms.
Internal Factors:
1. Food & Auxins: An Embryo feed on the stored food material until young seedlings prepares its own food. Auxins are the growth promoters, hence quite essential during the germination.
2. Viability: All seeds remain viable for certain definite period of time and thereafter embryo becomes dead. It depends on maturity of seed, storage conditions & vigour of parents and type of species. Generally, it is for 3-5 years and they remain for more than 200 years also as in lotus.
3. Dormancy: It is the failure of mature viable seed to germinate under favorable condition of moisture. Many seeds do not germinate immediately after their harvest, they require rest period for certain physiological activities.
Seeds and Sowing- Seed Dormancy
Seed Dormancy: Failure of fully developed & mature viable seed to germinate under favorable conditions of moisture & temperature is called resting stage or dormancy and the seed is said to be dormant.
Kinds of Dormancy in Seeds:
1. Primary dormancy: The seeds which are capable of germination just after ripening even by providing all the favorable conditions are said to have primary dormancy. E.g.: Potato.
2. Secondary dormancy: Some seeds are capable of germination under favorable conditions just after ripening but when these seeds are stored under unfavorable conditions even for few days, they become incapable of germination.
3. Special type of dormancy: Sometimes seeds germinate but the growth of the sprouts is found to be restricted because of a very poor development of roots & coleoptiles.
Causes of Dormancy:
The dormancy in seeds may be due to any single or a combination of more than one of the following causes.
1. Seed coats being impermeable to water: Some seeds have a seed coat which is impermeable to water. Such seeds even when fully matured & placed in favorable conditions; fail to germinate because of failure of water to penetrate into the hard seed coats. These seeds become permeable, if they are treated with H2SO4 or dipped in boiling water for few seconds. E.g.: Cotton.
2. Hard seed coat: Seeds of mustard, amaranths, etc. contain a hard & strong seed coat which prevents any appreciable expansion of embryo. Thus, if the seed coats fail to burst the embryo will remain dormant even after providing all the favorable conditions for germination.
3. Seed coats being impermeable to O: The seed coats are impermeable to O2 & if the seed coats do not rupture the seed fails to sprout.
4. Rudimentary embryo of seeds: The seeds which are apparently ripened contain a rudimentary or imperfectly developed embryo and the germination of such seeds naturally gets delayed until the embryo develops properly.
5. Dormant embryo: The seeds of an apple, peach, pinus, etc do not germinate even though the embryos are completely developed and all the favorable conditions for germination are provided. In such seeds, physiological changes called after ripening take place during the period of dormancy which enables the seeds for germination.
6. Synthesis & accumulation of germination inhibitors in the seeds: Plant organs synthesize some chemical compounds which are accumulated in the seeds at maturity and these chemicals inhibit the germination of their seeds.
Seed and sowing- Methods to Break the Dormancy
Methods to Break the Dormancy:
1. Scarification: The dormancy due to hard seed coat or impermeable seed coats can be broken by scarification of seed coats. It should be done in such a way that the embryo is not injured.
a. Chilling (Pre-chilling): The seeds are placed in contact with the moist substratum at a temperature of 5 to 10°C for 7 days for germination. E.g. Cabbage, Cauliflower, and Sunflower.
b. Pre-dying: Seeds should be dried at a temperature not exceeding 40°C with free circulation for a period of 7 days before they are placed for germination. E.g. Maize, Lettuce.
c. Pre-washing:In some seeds, germination is affected by naturally occurring substances which act as inhibitors which can be removed by soaking & washing the seeds in the water before placing for germination. E.g.: Sugar beet.
d. Pre-soaking: Some seeds fail to germinate due to hard seed coat. Such seeds should be soaked in warm water for some period so as to enhance the process of imbibitions. E.g. Chillar, Subabul.
e. Rubbing or puncturing seed coat: Some seeds are subjected to mechanical scarification either by rubbing them against rough surface or puncturing the seed coat with pointed needle. E.g.: Coriander, Castor.
f. Application of pressure to seeds: Germination of Medic ago sativa is found to be increased when a hydraulic pressure of 2000 atmosphere at 18°C is applied. It may be due to increase in permeability of seed coat to water and O2.
2) Stratification: In some seeds after ripening, low temperature and moisture conditions require in artificial stratification. Seed layer altered with layers of moist sand or appropriate material to store at low temperature. E.g.: Mustard & Groundnut.
3) Exposure of seeds to light: It also helps to break the dormancy & increase the germination.
4) Chemical treatments:
a. Potassium nitrate treatment (KNO3): The material used for placing the seeds for germination i.e. substratum, may be moistened with 2% solution of KNO3 (2g KNO3 + 100ml of water). E.g. rice, tomato, chilies.
b. Gibberellic acid treatment: The substratum used for germination may be moistened with 500 ppm solution of GA i.e. 500 mg in 1000ml water. E.g. Wheat, Oat.
c. Thio-urea treatment: Potato tubers are dipped in thio-urea solution (1%) for one hour when fresh harvested produce is to be used as seed material.
Seed and Sowing- The Indian Seed Act (1966)
It was enacted in 1966 and has been in force since Oct. 2, 1969 in all over states of India. This act aims at regulating the quality of seed sold for agricultural purpose through compulsory labeling and voluntary certification. Under compulsory labeling, any one selling the seed of a notified kind or variety, in the region for which it has been notified, should ensure that:
1. The seed confirms to the prescribed limits of germination purity.
2. The seed container is labeled in the prescribed manner, and
3. The label truly represents the quality of seed in the container.
Under voluntary certification, anyone interested in producing certified seed may do so by applying to the seed certification agency for the grant of certificate. The agency grants the certificate and certification tags after satisfying itself that the seed has been after satisfying itself that the seed has been produced according to the prescribed standards and procedures.
There are two bodies, viz., the central seed committee and the central seed certification board, which advise the central and the state governments in the matters related to the general administration of the seeds act and of seed certification, respectively.
Seed and Sowing- Multiplication & Distribution of Seeds:
In India, farmers depend for their seed supply primarily on the state department of Agriculture and the National Seeds Corporation. The Department of Agriculture in all states has a planned programme of seed multiplication.
Classes of Quality seeds: The various classes of seed that are used in a seed production programme are:
1. Breeder seed,
2. Foundation seed,
3. Registered seed and
4. Certified seed.
These different classes of seed have different requirements and serve different functions:
1. Breeder seed: It is the seed or the vegetative propagating material produced by the breeder who developed the particular variety. The production & maintenance of breeders stock on main research station is controlled by the plant breeder. It is produced by the institution where the variety was developed in case the breeder who developed the variety is not available. In India, it is also produced by other Agri. Universities under the direct supervision of the breeder of the concerned crop working in that University, this arrangement is made in view of the large quantities of the breeder seed required every year. It is generally pure having high genetic purity (100%). Off type plants are promptly eliminated and care is taken to prevent out crossing or natural hybridization & mechanical mixtures.
2. Foundation seed: It is the progeny of the breeder seed and is used to produce registered seed or certified seed. It is obtained from breeder seed by direct increase. It is genetically pure and is the source of registered and/or certified seed. Production of foundation seed is the responsibility of NSC. It is produced on Govt. farms (TSF), at expt. stations, by Agri. Universities or by component seed growers under strict supervision of experts from NSC. It should be produced in the area of adaptation of the concerned variety.
3. Registered seed: It is produced from foundation seed or from registered seed. It is genetically pure & is used to produce certified seed or registered seed. It is usually produced by progressive farmers according to technical advice and supervision provided by NSC. In India, often registered seed is omitted and certified seed is produced directly from foundation seed.
4. Certified seed: It is produced from foundation, registered or certified seed. This is so known because it is certified by a seed certification agency, in this case state seed certification agency, to be suitable for raising a good crop. The certified seed is annually produced by progressive farmers according to standard seed production practices. To be certified, the seed must meet the prescribed requirements regarding purity & quality. It is available for general distribution to farmers for commercial crop production.
Seed and Sowing- Seed Testing
The various classes of improved seeds are recognized to facilitate the maintenance of genetic purity of the variety and to ensure a continuous supply of good quality seed at a reasonable cost. It also helps in the multiplication of the seed rapidly while maintain its purity.
Seed Testing: Seed tests consist of a series of tests designed to determine the quality of seed. Seed tests are done in seed testing laboratories. Almost every state has a seed testing laboratory which performs the following function:
1. Conducting research on seed testing methods,
2. Training of personnel in seed testing,
3. Determining the standards for seed purity and seed quality for various crops,
4. Seed testing for certification and for implementation of seed laws of the country.
Following tests are conducted to determine the quality of seeds:
1. Purity test,
2. Germination or seed viability test and
3. Moisture content test.1.
1. Purity test: Purity denotes the percentage of seeds (by weight) belonging to the variety under certification.
Purity (%) = Weight of pure seed (g) x 100
Total weight of working samples (g)
2. Seed viability or Germination test: It is determined as per cent of seeds that produce or are likely to produce seedlings under a suitable environment.
The two tests most commonly used for the determination of seed viability are germination test and tetra zolium method.
3. Germination test determines the percentage of seeds that produce healthy root and shoot. Temperature requirement varies from 18 to 22°C. The duration of germination test varies from 7 to 28 days depending upon the crop species.
Germination % = Total no. of seeds germinated x 100
Total no. of seeds kept
For convenience, 100 seeds are planned in each sample. From each seed lot 4 or more samples are plated for a reliable germination estimate. If there is difference of 10% or more in the germination of different samples from the same lot, it is desirable to repeat the germination test.
Tetra Zolium Method: It determines the percentage of viable seeds which may be expected to germinate.
The chemical 2, 3, 5 – tetrazolium chloride in short, is colourless but it develops intense red colour when it is reduced by living cells.
Seeds are soaked in tap water overnight and are split longitudinally with the help of a scalpel so that a portion of the embryo is attached with such half of the seed. One half of each seed is placed in a Petridis covered with 1% aqueous solution of tetrazolium chloride for 4 hours. The seeds are then washed in tap water & the no. of seeds in which the embryo is stained red is determined.
Viable seed % = No. of half seeds stained red * 100
___________________________________
Total no. of half seeds.
The tetrazolium method is faster than the germination method and it does not require a controlled environment which is necessary for the germination test. It is relatively cheaper than earlier. Bu it cannot be applied to all the species, particularly to those species that have very small seeds & embryos, because splitting & examination of such seeds is tedius.
Real value of seed: It is the percentage of a seed sample that would produce seedlings of the variety under certification. This is also known as utility percentage of the seed & is a function of the Purity (P) and germination (G) percentage of the seed sample.
Real value of seed (%) = P x G / 100
1. Moisture content: It is determined as % water content of the seeds. Optimum moisture content reduces the deterioration during storage, prevents attack by moulds & insects and
Moisture content (%) = W1 – W2 x 100
W1
Where, W1 – Wt. of seed sample before drying
W2 – Wt. of seed sample after drying
Facilitates processing. It is determined by drying the seed in oven at 130°C temperature for 90 minutes. The loss in weight represents the weight of water lost due to drying.
Seed and Sowing- Seed Production Organizations
Seed Production Organizations: There are two types of Govt. / Public sector organizations responsible for seed production & certification in India. The first type of organization is represented by the National Seeds Corporation (NSC) which has responsibilities for the entire country. The second types of organizations are State Seeds Corporation (SSCs) and State Seed Certification agencies (SSCAs) that have state-wise responsibilities.
National Seeds Corporation: The NSC was initiated in 1961 under the ICAR. Later, on 7th March, 1963, it was registered as a limited company in the public sector. It was established to serve two main objectives:
1) To promote the development of seed industry in India and
2) To produce & supply the foundation seeds of various crops.
The present functions of NSC may be summarized as:
a. Production & supply of foundation seed,
b. To maintain improved seed stocks of improved varieties,
c. Interstate marketing of all classes of seed,
d. Export & import of seed,
e. Production of certified seed where required,
f. Planning the production of breeder seed in consultation with ICAR,
g. Providing technical assistance to Seeds Corporation & private agencies,
h. Coordinating certified seed production of State Seed Corporation,
i. Conducting biennial surveys of seed demand,
j. Coordinating market research & sales promotion efforts,
k. Providing training facilities,
l. Providing certification services to states lacking established and independent seed certification agencies.
Seed and Sowing- Seed Testing Laboratories:
Seed Testing Laboratories: A Central Seed Testing Laboratory is established at IARI, New Delhi. There are 18 State Seed Testing Laboratories spread over states of India. In M.S, it is located at the College of Agriculture, Nagpur. These have been provided with modern seed testing equipments & they are required to help in the seed certification & seed control programme.
Functions:
To analyze the seed samples for purity, moisture content, wed seeds (%) & germination, etc.
2. To assist the seed inspectors in determining whether correct labeling is being done as per requirements of the seed act.
13. Sowing Of Seed
Sowing Of Seed:
For cultivation of any field crop, one must follow the recommended practices of seeds and sowing to harvest maximum yield of the crop.
14. A. Seed Rate
B. Seed Treatment
C. Sowing Time
D. Depth of Sowing
E. Spacing & Plant Population
F. Methods of Sowing
15. Seed rate: The seed rate per unit area depends on germination of the seed, size of the seed, growing habit of the crop, etc. Extremes from the recommended seed rate (i.e. too high or too low) affect the plant population & then yield of crop. E.g. higher seed rate will influence higher plant population/unit area. It results in heavy competition within the crop plants and suppresses the crop growth. Lower seed rate will result lower plant population thereby lowers the yield/unit area. The seed rate is governed by the ultimate stand desired. Most crops are seeded at smaller rates under dry land than under irrigated condition. Seed rate depends on size, germination, growing habit, type of farming, time of sowing, variety, etc
16. Seed treatment: It is a process of application of chemicals or protectants (with fungicidal, insecticidal, bactericidal or nematocidal properties) to seeds that prevent the carriage of insect or pathogens in or on the seeds.
17. Objects of seed treatment: Some seeds need treatment with some specific objectives before sowing.
18. 1.To control disease: There are some seed borne or soil borne diseases, seeds are treated with fungicides or organo mercurial compounds like Thirum, captain, carbendazim, agrosan, cereson, etc. E.g. to control paddy blast, seed is to be treated with agrosan @ 3 g per kg (3g/kg) of seed).
19. 2.To have convenience in sowing: Difficulties are encountered in sowing certain crops due to special characteristics of the seed like fuzz of cotton seeds, coriander seeds, small seeds of chilli, ragi, bajara, etc. E.g.: coriander seed is to be splitted by rubbing it against hard surface. Seed of chilli, Sesamum, bajara are mixed with fine sand or soil.
20. 3. To have quick germination: Germination of certain leguminous crops is delayed due to thick seed coat which restricts water absorption. Such seed coats are broken to some extent by mixing them with coarse gritty sand & trampling or pounding it lightly in a morter with a wooden pestle for breaking the thick seed coat. Sometimes seeds are soaked in water for a specified time. E.g.: cotton seed or paddy seed is soaked in water before actual sowing. Seed of Lucerne and Indigo is pounded with pestle
.
4. To increase nitrogen fixation in legumes: Legume seeds are inoculated with a particular Rhizobium culture. This is mixed with jaggery solution & applied to seed and dried in shade. It increases nodulation & thereby N fixation.
21. 5. To protect the seed against insect pests: There are some insect pests like ants, white ants, in the soil which attack on seed and eat. Sometimes, seed may be picked up by birds after sowing. To avoid this, seed is treated with repellents like campor, kerosene or soil drenching with insecticides like BHC, heptachlor, etc. E.g.: the carbofuran treatment in Jowar.
22. 6. To induce earliness (Vernalization treatment): This is an important for breeding programme by vernalization treatment. As a result of this, life span is reduced. In this, seed is soaked in water & incipient germination is induced in the form of awakening of the dormant embryo & commencing the changes favoring germination in the endosperm. Such seeds are kept in cold storage for a specified time in which germination power remains intact but the process of germination is temporarily halted. Thus, the plant spends part of its vegetative period or phrase in the form of sprouted seed and the seed so treated as a dormant plant. The period from sowing to flowering is thus greatly reduced & with such adjustment, a variety which is normally a long duration one, can be made to flower early.
23. 7. To induce variation: Seed is treated to induce variation in its morphological & general structure by ‘X’ ray treatment. It changes the genetical make up & helps in selection of desired types.E.g. Sonora, a wheat variety, is the result of Sonora-64 treated with gamma rays.
24. 8. To break dormancy: Some crops are having seed dormancy in fresh harvested produce. Dormancy is the state of rest period of a seed in which it does not germinate even if all the favorable conditions are available for germination. Due to dormancy of seed we cannot use the fresh harvested produce for sowing. It is desirable if the crop get rains at maturity. E.g.: groundnut varieties. This dormancy is broken by treating seed with chemicals. E.g. Thiourea 1% treatment to potato tubers.
25. 9. Seed treatment for special purpose: In vegetatively propagated crops, planting material is treated with growth promoting hormones like colchicines, Gibberellic acid (GA), Indole acetic acid (IAA), Seradix, sometime cattle urine. These promotes sprouting & growth of plant. E.g.: onion bulbs or potato tubers are treated with Malic Hydrazine (MH) for avoiding sprouting and growth of sprouts and thereby reducing losses due to sprouting.
26. Seed treatment in important crops:
27. 1) Sorghum: Thirum or 300 mesh sulphur: Seed is coated in seed dressing drum or earthen pot @ 3.4 g/kg seed against smut disease.
2) Bajara: Brine solution treatment is given @ 20% against eat got and to discard light & diseased seed.
3) Paddy: Seed is treated with brine solution @ 3% against blast of paddy and to discard unfilled seed.
4) Cotton: a) Cow dung slurry treatment: Seed is rubbed with cow dung slurry in 1:1 proportion of dung and soil for convenience in sowing or Seed is delinted by treating the seed with conc. H2SO4 for 2 min. for convenience in sowing. b) Seed is treated with organo mercurial compound like ceresin, agrosan @ 3 g or Thirum @ 5g against seed borne disease like anthracnose.
5) Coriander & Garlic: Seed is rubbed to split the seed for even sowing.
6) Small seeded crops like Sesamum, bajara, tobacco, etc: Seed is mixed with fine sand or soil for even sowing of seed in the field.
7) Potato: a) Seed is dipped in 1% Thiourea solution for breaking the seed dormancy.
b) Seed is dipped in streptomycin solution @ 200 g in 100 lit. Water for 1 hour against Ring rots disease.
8) Legume crops like Mung, Udid, Soybean, Etc.
a) Seed is treated with Thirum @ 3 g/kg seed against seed borne disease.
b) Seed is treated with Rhizobium culture @ 250g/10kg seed for ‘N’ fixation & better nodulation.
9) Sugarcane: a) Hot water treat (500C) or hot air treat. (540C) is given to sets for 2 hrs. Against grassy shoot & other diseases.
b) Sets are treated with OMC 6% @ 500g in 100 lit. Water by dipping for 5 min. against smut & increase germination.
Or Bavistin @ 200g in 100 lit. For 5 min.
10) Wheat & Oilseed crops: Seed is coated with Thirum or Bavistin @ 5 g/kg seed against seed borne diseases.
28. Sowing Of Seed – Sowing Time, Depth of Sowing, Spacing and Plant Population
29. Sowing Time: It is the non monetary inputs which greatly influence the crop growth & yield. Therefore, sowing of crop should be done at recommended dates. Any fluctuation in optimum sowing time results in drastic yield reduction. E.g. Wheat.
30. Depth of Sowing: It is also non-monetary input which decides plant stand in the field. It influences the germination & emergence of seed. Sowing should be done at recommended depth. These vary with the kind of seed and its size. Bigger seeds may be sown at a greater depth while small sized seeds at shallow. Seed should be dropped in the moist zone. In Kharif, sowing should be shallow and in Rabi deeper except pre-sowing irrigation.
31. Spacing and Plant Population: Spacing between the row and within the plants decides the plant stand/plant population per/unit area. Optimum plant population results in normal crop growth & thereby yields. One can manipulate the R/R & P/P distance but care should be taken for maintaining the optimum plant population as per the recommendations. E.g.: Jowar & Bajara 1.37 – 1.5 lakh (45 x 15cm), cotton (irrigated) 12000 (90 – 120 x 60 – 0 cm), sugarcane 5000 (1 M R/R with 25000 sets.), Groundnut (bunch) 2 – 2.5 lakh (30 x 15 cm). A dense population results in competition for nutrients, moisture & light and thereby suppressed growth while less population results in low yield /unit area.
Yield of a crop is the result of final plant population which depends on the no. of viable seeds, germination % and survival rates. An establishment of optimum plant population is essential to get maximum yield. Yield/plant decreases gradually as plant population/unit are is increased. However, the yield/unit area is increased due to efficient utilization of growth factors. Optimum plant population depends on plant size, elasticity, foraging area, nature of the plant, capacity to reach optimum leaf area at an early date & seed rate used.
32. Sowing of Seed – Methods of Sowing
33. Methods of Sowing: The sowing method is determined by the crop to be sown. There are 6 sowing methods which differ in their merits, demerits and adoption. Those are:
1. Broad casting
2. Broad or Line sowing
3. Dibbling
4. Transplanting
5. Planting
6. Putting seeds behind the plough.
34. 1. Broad casting: It is the scattering of seeds by hand all over the prepared field followed by covering with wooden plank or harrow for contact of seed with soil. Crops like wheat, paddy, Sesamum, methi, coriander, etc. are sown by this method.
Advantages:
1) Quickest & cheapest method
2) Skilled labour is not uniform.
3) Implement is not required,
4) Followed in moist condition.
Disadvantages:
1) Seed requirement is more,
2) Crop stand is not uniform.
3) Result in gappy germination & defective wherever the adequate moisture is not present in the soil.
4) Spacing is not maintained within rows & lines, hence interculturing is difficult.
35. 2.Drilling or Line sowing: It is the dropping of seeds into the soil with the help of implement such as mogha, seed drill, seed-cum-ferti driller or mechanical seed drill and then the seeds are covered by wooden plank or harrow to have contact between seed & soil. Crops like Jowar, wheat Bajara, etc. are sown by this method.
Advantages:
1) Seeds are placed at proper & uniform depths,
2) Along the rows, interculturing can be done,
3) Uniform row to row spacing is maintained,
4) Seed requirement is less than ‘broad casting’
5) Sowing is done at proper moisture level.
Disadvantages:
1) Require implement for sowing,
2) Wapsa condition is must.
3) Plant to plant (Intra row) spacing is not maintained,
4) Skilled person is required for sowing.
36. 3. Dibbling: It is the placing or dibbling of seeds at cross marks (+) made in the field with the help of maker as per the requirement of the crop in both the directions. It is done manually by dibbler. This method is followed in crops like Groundnut, Castor, and Hy. Cotton, etc. which are having bold size and high value.
Advantages:
1) Spacing between rows & plants is maintained,
2) Seeds can be dibbled at desired depth in the moisture zone,
3) Optimum plant population can be maintained,
4) Seed requirement is less than other method,
5) Implement is not required for sowing,
6) An intercrop can be taken in wider spaced crops,
7) Cross wise Intercultivation is possible.
Disadvantages:
1) Laborious & time consuming method,
2) Require more labour, hence increase the cost of cultivation,
3) Only high value & bold seeds are sown,
4) Require strict supervision.
37. 4. Transplanting: It is the raising of seedlings on nursery beds and transplanting of seedlings in the laid out field. For this, seedlings are allowed to grow on nursery beds for about 3-5 weeks. Beds are watered one day before the transplanting of nursery to prevent jerk to the roots. The field is irrigated before actual transplanting to get the seedlings established early & quickly which reduce the mortality. Besides the advantages & disadvantages of dibbling method, initial cost of cultivation of crop can be saved but requires due care in the nursery. This method is followed in crops like paddy, fruit, vegetable, crops, tobacco, etc.
38. 5. Planting: It is the placing of vegetative part of crops which are vegetatively propagated in the laid out field. E.g.: Tubers of Potato, mother sets of ginger & turmeric, cuttings of sweet potato & grapes, sets of sugarcane.
39. 6. Putting seeds behind the plough: It is dropping of seeds behind the plough in the furrow with the help of manual labour by hand. This method is followed for crops like wal or gram in some areas for better utilization of soil moisture. The seeds are covered by successive furrow opened by the plough. This method is not commonly followed for sowing of the crops.
40. Systems Approach
41. Management practices are developed for individual crops and recommendations are made for individual crops. The residual effects of individual crops are not considered in crop based recommendations in which resources are not utilized efficiently. To a farmer, instead of a crop, land is a unit & mgt. practices should be for all crops that are to be grown on a piece of land. This approach is applied to agriculture for efficient utilization of at resources, maintaining stability in production and obtaining higher net returns. A system consists of several components which depend on each other.
42. A system is defined as a set of elements or components that are inter related & interacting among themselves.
43. Farming systems represent an appropriate combination of farm enterprises viz. Cropping system, live stock, poultry, fisheries, forestry, bee keeping, sericulture and the means available to the farmer to raise them for increasing profitability.
44. They interact adequately with environment without dislocating the ecological & socio-economic balance on the one hand attempt to meet the national goals on the other.
45. System Approach- Farming System
46. Farm resources – Land, labour, water, capital & infrastructure
Farm enterprises – Dairying, poultry, Honey bee keeping, sericulture, Laculture, Piggery, Sheep & Goat raising, Fishery.
47. Cropping system and Crop rotation: Cropping system represents crop’s (Cropping) patterns used on farm & their interactions with farm resources, other farm enterprises and available technology which determine their makeup. Crops pattern means the proportion of area under various crops at a point of time in a unit area. It indicates yearly sequence and spatial arrangement of crops & fallow in an area.
48. Types of cropping systems:
49. 1) Monocropping/ monoculture: It refers to growing of only one crop on apiece of land year after year. It may be due to climatologically, socio-economic conditions or due to specialization of a farmer in growing a particular crop. E.g.: Rice cultivation in A.P.
50. 2) Multiple cropping: Growing two or more crops on the same piece of land in one calendar year is known as multiple crops.
51. 3) Inter crops: It is growing of two or more crops simultaneously on the same piece of land with a definite row pattern. E.g.: Jowar + Tur, Cotton + Urd/Soyabean. Based on the percent of plant population used for each crop in inter crop’s system, it is divided into two types viz. additive series and replacement series.
a. Additive series: In this one crop is sown with 100% of its recommended population in pure stand which is known as the base crop. Another crop is known as intercrop, is introduced into the base Crop by adjusting or changing crop geometry. The population of intercrop is less than its recommended population in pure stand.
b. Replacement series: In these both, the crops are called component crops. By scarifying certain proportion of population of one component, another crop introduced.
Main objective of intercropping is higher productivity/unit area in addition to stability in production. It utilizes resources efficiently & their productivity is increased.
52. For successful intercropping there are certain important requirements:
1) The time of peak nutrient demands of component crops should not overlap.
2) Competition for light should be minimum among the component crops.
3) Complementary should exist between the component crops.
4) The difference in maturity of component crops should be at least 30 days.
53. System Approach- Types of Cropping
54. 1. Mixed cropping: It is growing of two or more crops simultaneously intermingled without any row pattern. It is a common practice that the seeds of different crops are mixed in certain proportion and are sown. E.g.: Kharif Groundnut + Jowar, Cotton + Mesta (Ambadi), Jowar + Mustard or Wheat + Mustard.
55. 2. Sequence cropping: It is growing of two or more crops in sequence on the same piece of land in a farming year. It Amy is doubles (2 crops), triple (3 crops) or quadruple (4 crops). E.g.: Cotton – Groundnut, Jowar – Wheat, Mung – Rabi Jowar, and Hy. Jowar – Gram. Etc.
56. 3. Relay Cropping: It refers to planting of succeeding crop before harvesting the preceding crop like a relay race where a crop hands over the land to next crop in quick succession. Ratoon cropping or rattooning refers to revising a crop with regrowth coming out of roots or stalks after harvest of the crop. E.g.: Sugarcane or Jowar rattooning.
57. 4. Efficient cropping systems: for a particular farm depend on farm resources, farm enterprises & farm technology. The farm resources include land, labour, water, capita; and infrastructure. When land is limited, intensive cropping is adopted to fully utilize available waer & labour. When sufficient and cheap labour is available, vegetable crops are also included in the cropping system as they require more labour. Capital intensive crops like sugarcane, banana, turmeric, ginger, etc. find a place in the cropping system when capital is not a constraint. In low RF (less than 750 mm/annum) monocropping is followed & when RF is more than 750 mm intercropping is practiced. With sufficient irrigation water, triple, quadruple cropping is adopted when other climatic factors are not limiting. When the farm enterprise includes dairy the cropping system should contain fodder crops as a component.
58. System Approach- Crop Rotation
59. Crop Rotation: It refers to recurrent succession of crops on the same piece of land either in a year or over a longer period of time. It is a process of growing different crops in succession on a piece of land in a specific period of time, with an objective to get maximum profit from least investment without impairing the soil fertility.
60. Characteristics of Crop rotation or Principles of Crop rotation:
61.
62. 1) It should be adaptable to the existing soil, climatic and economic factors.
2) The sequence of cropping adopted for any specific area should be based on proper land utilization. It should be so arranged in relation to the fields on the farm that the yields can be maintained and soil losses through erosion reduced to the minimum.
3) The rotation should contain a sufficient acreage of soil improving crops to maintain and also build up the OM content of the soil.
4) In areas where legumes can be successfully grown, the rotation should provide for a sufficient acreage of legumes to maintain the N supply of the soil.
5) The rotation should provide roughage and pasturage for the live stock kept on farm.
6) It should be so arranged as to help in the control of weeds, plant disease & insect-pests.
7) It should provide for the acreage of the most profitable cash crops adapted to the area.
8) The rotation should be arranged as to make for economy in production & labour utilization exhaustive (potato, sugarcane) followed by less exhaustive crops (oilseeds & pulses)
9) The crops with tap roots should be followed by those which have fibrous root system. This helps in proper & uniform use of nutrients from the soil & roots do not compete with each other for uptake of nutrients.
10) The selection of crops should be problem and need/demand base.
i) According to need of people of the area & family.
ii) On slop lands alternate cropping of erosion promoting and erosion resisting crops should be adopted.
iii) Under Dryland or limited irrigation, drought tolerant crops (Jowar, Bajra), in low lying & flood prone areas, water stagnation tolerant crops (Paddy, Jute) should be adopted.
iv) Crops should suit to the farmer’s financial conditions, soil & climatic conditions.
11) The crops of the same family should not be grown in succession because they act like alternate hosts for insect pests & disease pathogens and weeds associated with crops.
12) An ideal crop rotations is one which provide maximum employment to the family & farm labour, the machines and equipments are efficiently used so all the agril. Operations are done timely.
63. Advantages of Crop Rotation:
64. An ideal crop rotation has the following advantages:
65. 1. There is an overall increase in the yield of crops due to maintenance of proper physical condition of the soil and its OM content.
2. Inclusion of crops having different feeding zones and different nutrient requirements help in maintaining a better balance of nutrients in the soil.
3. Diversification of crops reduces the risk of financial loss from unfavorable weather conditions and damage due to pests & diseases.
4. It facilitates more even distribution of labour.
5. There is regular flow of income over the year.
6. The incidence of weeds, pests and diseases is reduced and can be kept under control.
7. Proper choice of crops in rotation helps to prevent soil erosion.
8. It supplies various needs of farmer & his cattle.
9. Agricultural operations can be done timely for all the crops because of less competition.
‘The supervisory work also becomes easier.”.
10. Proper utilization of all the resources and inputs could be made by following crop rotation:
66. Cropping systems & crop rotations followed in MS & Marathwada:
67. Maharashtra:
1. Cotton – Jowar/ Bjra, Cotton – Jowar – Groundnut.
2. Sugarcane – Rice – Gram.
3. Cotton – Groundnut, Cotton – Jowar/ Bajara – Groundnut.
4. Sannhemp – Sugarcane.
5. Pre Cotton – R.Jowar/ Wheat/ Gram.
6. Rice – Gram.
7. Groundnut – Cotton – Jowar.
Marathwada:
1. Mung – Jowar – Cotton + Tur
2. Sunflower – Jowar.
3.Soybean – Jowar/ Safflower/ Gram.
4. Hy. Jowar – Gram / Sunflower / Safflower.
5. Bajara – Gram, Mung/Urd/ Soybean – R.Jowar, Safflower.
Irrigated:
1. Cotton – Groundnut, Sannhemp – Sugarcane – Groundnut.
2. Rice – Gram/ Sunflower.
3. Hy. Jowar – Wheat/ Jowar/ Gram.
4. Jowar – Sunflower – Groundnut.
5. Sunflower – Potato – Groundnut.
6. Groundnut – Wheat – Vegetables.
7. Sorghum – Wheat – Green gram – Cotton – Groundnut.
8. Bajara – cabbage – Groundnut – Cotton – Groundnut.
68. Syatem Approach- Crop Mixtures or Mixed Cropping
69. It is the process of growing two or more crops together in the same piece of land simultaneously. The cereals are usually mixed with legumes viz. Jowar or Bajara mixed with Tur, udid, Mung, matki or kulthi. Wheat is mixed with peas, gram or mustard; Cotton is grown mixed with Tur or sunflower.
70. The objectives are:
71.
1) To get handy installments of cash returns especially in irrigated crops,
2) To achieve better distribution of labour throughout the year,
3) To utilize available space & nutrients to maximum extent possible,
4) To safe guard against hazards of weather, diseases & pests,
5) To secure daily requirements like pulses, oilseeds, fibers, etc.
6) To get balanced cattle feed.
In order to obtain the maximum benefit from the subsidiary crop mixed with the main crop, it should have the following characteristics: It should
i) Not abstract the growth of the main crop,
ii) Mature earlier or later than of the main crop,
iii) Preferably be a legume,
iv) Have diff. growth habits & nutrient requirements,
v) Have diff. rooting depths & ramification and
vi) Not be very exacting in climatic requirements.
72. Mixed cropping may be:
73.
1) Mixed crops: Mixing of seeds and raising two – three crops at the same time & in same field. E.g.: Jowar/wheat +mustard/ gram.
2) Companion Crops: Different crops are sown in different rows. E.g.: 6 to 8 rows of cotton + 2 to 3 lines of Tur, 4 – 6 rows of Jowar + 1 – 2 lines of Tur, Jowar + Mung/Urd, Jowar + Safflower.
i) Guard crops: Growing hardy or thorny crops (Mesta/Safflower) around the main crop (Jowar/Wheat)
ii) Augmenting crops: Growing sub-groups (augmenting) to maintain the yield of main crop. F. Jowar/Bajara + Cowpea.
74. Syatem Approach- Crop Mixtures or Mixed Cropping
75. It is the process of growing two or more crops together in the same piece of land simultaneously. The cereals are usually mixed with legumes viz. Jowar or Bajara mixed with Tur, udid, Mung, matki or kulthi. Wheat is mixed with peas, gram or mustard; Cotton is grown mixed with Tur or sunflower.
76. The objectives are:
77.
1) To get handy installments of cash returns especially in irrigated crops,
2) To achieve better distribution of labour throughout the year,
3) To utilize available space & nutrients to maximum extent possible,
4) To safe guard against hazards of weather, diseases & pests,
5) To secure daily requirements like pulses, oilseeds, fibers, etc.
6) To get balanced cattle feed.
In order to obtain the maximum benefit from the subsidiary crop mixed with the main crop, it should have the following characteristics: It should
i) Not abstract the growth of the main crop,
ii) Mature earlier or later than of the main crop,
iii) Preferably be a legume,
iv) Have diff. growth habits & nutrient requirements,
v) Have diff. rooting depths & ramification and
vi) Not be very exacting in climatic requirements.
78. Mixed cropping may be:
79.
1) Mixed crops: Mixing of seeds and raising two – three crops at the same time & in same field. E.g.: Jowar/wheat +mustard/ gram.
2) Companion Crops: Different crops are sown in different rows. E.g.: 6 to 8 rows of cotton + 2 to 3 lines of Tur, 4 – 6 rows of Jowar + 1 – 2 lines of Tur, Jowar + Mung/Urd, Jowar + Safflower.
i) Guard crops: Growing hardy or thorny crops (Mesta/Safflower) around the main crop (Jowar/Wheat)
ii) Augmenting crops: Growing sub-groups (augmenting) to maintain the yield of main crop. F. Jowar/Bajara + Cowpea.
Difference between - Inter Cropping & Mixed Cropping
Sr. No
Inter Cropping
Mixed Cropping
1
The main object is to utilize the space left between two rows of main crop
To get at least one crop under favorable conditions
2
More emphasis is given to the main crop
All crops are cared equally
3
There is no competition between both crops
There is competition between all crops growing
4
Inter crops are of short duration & are harvested much earlier than main
The crops are almost of the same duration
5
Sowing time may be same or different
It is same for all crops
6
Crops are sown in different rows without affecting the population of main crop when sown as sole crop
Either sown in rows or mixed without considering the population of either
System Approach- Fallow in Rotation
Fallow: is the practice of allowing crop land to lie idle during a growing season to build up the soil moisture & fertility content so that a better crop can be produced in the following year. A fallow year or season is one in which the field is not cultivated with any crop but left without a crop. The field may be left undisturbed in a ploughed condition or kept clean by frequent cultivations.
It is usually worked periodically to control weeds and improve moisture infiltration.
Points to be considered for planning the crop rotation:
Farmer should consider the following factors while planning the crop rotation
.
1. Net profit.
2. Growth habit & nutrient requirements of different crops.
3. Effect of one crop on the other hand that is succeeding.
4. Soil type & slope &
5. Infestation of weeds, diseases & pests.
These factors should be considered to set the good crop rotation based on these factors; one should also consider the following points:
1. A shallow rooted grain crop, a deep rooted cash crop and a restorative crop should be included in the rotation which will provide food, fodder & cash to the farmer & maintain soil productivity.
2. The selection of crops should be made, taking into consideration soil, climate & market demand.
3. In case of irrigated areas, the rotation should be fixed on the extent of availability of water supply so that 2 or more crops can be taken from the same field in one year.
4. In case of rain fed areas, if sufficient moisture is left over in the soil after the harvest of Kharif crops, some minor crops requiring less moisture like pulses may be grown.
5. Both wide row spaced crops & thickly planted crops should be included.
6. Crops of diverse botanical relationship should be alternated as an insect or disease will attack closely related species but will not injure unrelated species.
7. A logical sequence of crops should be set up making full use of all available information as to effect of each crop in rotation on the succeeding crops to ensure maximum yields & higher quality.
8. Ordinarily, the area devoted to each crop should be consistent acreage from year to year.
9. Enough elasticity may be kept in the rotation.
10. Depending upon the soil type, i.e. more or less fertile, low lying, acidic or alkaline soils, stress should be gien to the crop rotation considering its importance.
11. Importance, location of farm and region base crops should be included in the crop rotation.
12.Legumes should be included in the crop rotation with non-legumes as it is multi advantageous crop such as fixes atmospheric nitrogen, covers the land so prevent erosion, smother weeds.
“Cotton – Sorghum – Groundnut” Is The Best Crop Rotation
This crop rotation shows maximum characteristics of a good crop rotation, such as:
1. All these crops are of diverse botanical relationship which avoids the attack of pests & diseases.
2. It is a three course crop rotation followed in two years.
3. It provides food (Sorghum), fodder (Sorghum & groundnut) and cash (Cotton & Groundnut) to the farmer.
4. It includes a deep rooted cash crop, followed by a shallow rooted grain crop and a restorative crop which maintains the soil fertility.
5. It adds organic matter and there is maximum utilization of residual nutrients.
6. It gives higher net profit per hectare.
7. Nutrient requirement of these crops is different from each crop.
8. Groundnut fixes the atmospheric ‘N’ and increase the soil fertility by adding organic matter.
Criteria Determining Harvesting a Crop and Preparation for Marketing
Harvesting: It is the removal of entire plants or economic parts (grain, seed, leaf, root, or entire plant) after maturity from the field.
Time of harvesting: If the crop is harvested early the produce contains high moisture and more immature grains. Higher moisture results shriveling of seed and infestation of pests. The immature grains lead to low yields and reduce quality as well as germination %. Late harvesting results in shattering of grains, germination when it rains and breaking during processing. Hence, harvesting at correct time essential to get good quality grains & higher yield. Crops can be harvested at physiological or harvest maturity. Crop is considered to be at physiological maturity when the translocation of photosynthates is stopped to economic part. Physiological maturity refers to a developmental stage after which no further increase in dry matter occurs in the economical part. This is important only when a field is to be vacated for sowing another crop otherwise, one should go for harvesting the crop at harvest maturity. Harvest maturity generally occurs 7 dates after physiological maturity with following symptoms:
1. Loss of moisture in grains up to 12 to 14%.
2. Yellowing and dropping of leaves.
3. Drying and change in colour of grains or pods.
4. Life cycle completes which vary with crop to crop and variety.
5. General symptoms in various crops are:
A) CEREALS:
1) Lower leaves turn to yellow straw.
2) Lower & other leaves fall down.
3) Stem turn to straw colour.
4) Pith formation in stem takes place.
5) Grains become hard & fully developed.
6) Moisture % in grain becomes less than 20% on total weight basis.
7) In maize, drying of cob sheath and fibers take place.
B) COTTON: Picking of fully opened & bursted bolls is done in 3 – 4 stages.
C) PULSES:
1) Pods turn to brown,
2) Grains become hard,
3) Shedding of lower older leaves take place.
4) Yellowing of leaves.
D) SUGARCANE:
1) Yellowish colour to crop,
2) Flowers, if flowering variety is planted.
3) Swelling of eye buds,
4) Sweetness of juice,
5) Reads 21 to 24 Bricks Saccharometer reading.
E) GROUNDNUT:
1) Drying of vines.
2) Black colouring to the inner side of pods
3) Reddening or dark colouration to the seed coat,
4) Prominent margins on pod.
F) POTATO:
1) Dropping of leaves and drying,
2) Hardening of tuber.
Determination of harvesting date is easier for determinate crops and difficult for indeterminate crops as it contains flower, immature & mature pods. Therefore, such crop should be harvested when 75% maturity is achieved or periodical harvesting should be done.
Threshing & Winnowing
The threshing is the process of separating fruits or seeds from the plants or ears (cobs/panicle). It is followed by winnowing which consists of separating grain seed from chaff. Threshing methods vary with type of crop. In general these are:
1. Beating with sticks/mallets (safflower, green gram, Urd, etc.)
2. Beating against stone or hard material (harrow body). E.g. Arhar.
3. Trampling under the feet of bullocks or wheels of tractor or bullock cart. E.g. Cereals, pulses,
4. By using threshing machines bullock (olpad), tractor or electric motor drawn. E.g. almost all crops.
After threshing this material is winnowed. The grains are subjected for sun drying before storage or marketing. Sun drying is done by spreading the produce on floor in a thin layer (10cm) for 4 – 5 days and stirred at 2 hrs. Interval to have uniform & quick drying and to lower the moisture up to 12 to 14%. To fetch higher prices for the produce should be graded, baged and sent to market.
Weeds and Their Control
There are 3 serious pests of the crop plants which causes loss of yield, i.e.
1. Insect-pests,
2. Diseases,
3. Weeds.
The estimated losses in crop yields range from 5% in clean cultivated fields over 70% in neglected fields depending upon the degree of weed infestation. They compete with crop plants for nutrients, water, light and space. The loss of ‘N’ through weed is as high as 150 kg/ha.
WEED: Any plant not sown in the field by farmer is out of place, called weed.
The term, ‘weed’ used by Jethro Tull for the first time, suggested an useless and harmful plant that persistently grows where it is quite unwanted.
According to Robinson: Weeds are that species of plants which grow unwanted or are not useful, often prolific, persistent, interfere with agricultural operations, increase labour cost and reduce the crop yields.
Weed is a plant growing where it is not wanted, unwanted plant, out of place, extremely noxious, useless, and poisonous.
Characteristics of weeds:
Weeds are like any other crops plants in size, form, morphological & physiological characters but possess the following characteristics, on account of which they are considered as enemy of crops by the farmer.
1. The weed seeds germinate early and the seedlings grow faster. They being hardy, compete for light, moisture and nutrients.
2. They flower earlier, run to seed in profusion and mature ahead of the crop. They are difficult to control and it may be even impossible to eradicate some weeds completely.
3. They are non-useful, unwanted & undesirable.
4. They are harmful to crops, cattle and human beings.
5. They can thrive even under adverse conditions of soil, climate, etc.
6. They are prolific and have a very high reproduction capacity. E.g.: A plant of satyanashi (Argemone mexicana) produces over 5000 seeds while a plant of striga produces over half a million seeds.
7. Viability of weed seeds remains intact, even if they are buried deep in the soil. In some cases, the seeds may remain viable even after passing through the digestive tract of the animals.
8. The seeds may have special structures like wings, spines, hooks, sticky hair, etc. on account of which they can be easily disseminated over long distances.
9. Many weeds like Cynodon dactyl on are vegetatively propagated and spread rapidly all over the field even under adverse conditions.
Weeds & Their Control- Classification of Weeds
Weeds can be classified in many ways as:
A) Classification based on life cycle:
a) Annuals: Weeds complete their life cycle within a year.
i) Seasonal weeds:
1. Monsoon annuals or Kharif season weeds: Weeds complete their life cycle during Kharif or rainy season. E.g.: Hazardana, kurdu, Aghada.
2. Winter annuals or Rabi season weeds: Weeds complete their life cycle during rabi or during winter season. E.g.: Pisola
ii. Two seasonal weeds: Weeds complete their life cycle within two seasons. E.g.: Jungli gobhi Lunea sp.
b) Biennials: Weeds require two years for completion of their life cycle. E.g.: Wild carrot (Daucus carota)
c. Perennials: Weeds continue their life cycle for years together. E.g.: lavala, hariyali, Kans, lajalu.
B) Classification based on habitat or place of occurrence:
a. Weeds of cropped land: Bathua, Kurdu.
b. Weeds of pastures & grazing lands: Hariyali, Unhali, Kans.
c. Weeds along water channels: Jalkumbhi (Eichhornia crassipes).
d. Weeds along roadside: Tarota, Unhali.
e. Weeds of waste lands: Ber, Sarata, Reshimkata.
f. Weeds of lawn & orchards: Ganja, Ghaneri.g.
g. Weeds of forest lands: Ghaneri, Nagphana.
C) Classification based on dependence on other hosts:
a. Stem parasite: Amerbel
b. Root parasite: Striga on Jowar, Sugarcane, and Bambakhu on Tobacco, Brinjal or Chilli.
c. Independent: Chandvel.
D) Classification based on soil type:
a. Weeds of black soils: Hariyali, Kans, Kunda.
b. Weeds on sandy loam soil: Aghada, Kurdu.
c. Weeds of ill drained soil: Lavala, Panbibi.
d. Weeds in tank: It may be submerged, immersed or floating. E.g.: Aquatic weeds like water hyacinth, cattails.
E) Classification based on plant family:
a. Graminae: Hariyali, Kunda, Kans.
b. Commelinaceae: Kena, vinchu, Panbibi.
c. Cyperaceace: Nagarmotha.
d. Amaranthaceac: Aghada, math, Kurdu.
e. Euphorbiaceae: Dudhi, Pisola, Wild castor.
f. Composite: Gokhuru, Jakham Judi, Gajar Gawat.
g. Leguminous: Lajalu, wild Mung, Unhali.
h. Malvaceae: Petari, wild bhendi.
i. Tiliaceae: Wild jute.
j. Cruciferae: Wild mustard.
k. Chenopodiaceae: Chandan Bathua.
l. Solanaceae: Kamuni, Wild Brinjal.
m. Papaveraceae: Satyanashi, Dhatura.
n. Portulacaceae: Ghol
o. Orobanchaeceae: Bambakhu
p. Cactaceae: Nagphana
Damages Or Losses Caused By Weeds or Disadvantages of Weeds
1. Reduction in crop yield:
Weeds compete for water, nutrients & light. Being hardy & vigorous in growth habit, they soon outgrow the crops & consume large amounts of water & nutrients, thus causing heavy losses in yield. E.g.: 40% reduction in yield of groundnut & 66% reduction in yield of chilli. The loss of N through weeds is about 150 kg/ha.
2. Increase in the cost of cultivation: One of the objects of tillage is to control weed on which 30% expenditure is incurred and this may increase more in heavy infested areas & also cost on weed control by weeding or chemical control. Hence, reduce margin of net profit.
3. Quality of field produce is reduced: Weed seeds get harvested & threshed along the crop produce which lowers the quality. Such produce fetches fewer prices in the market. E.g.: Leafy vegetables, grain crop.
4. Reduction in quality of livestock produce: Weeds impart an undesirable flavor to the milk (Ghaneri), impair quality of wool of sheep (Gokhuru, Aghada), and cause death of animals due to poisonous nature of seed (Dhatura).
5. Harbour insect-pests & disease pathogens: Weeds either give shelter to various insect pests & disease pathogens or serve as alternate hosts & thus helps in perpetuating the menace from pests & diseases. E.g.: Gall fly of paddy, midge fly of Jowar, leaf minor of soybean & Groundnut, rust of Wheat, tikka of Groundnut, Black rust of wheat ,Downey mildew (Saccharum spontaneum).
6. Check the flow of water in irrigation channels: Weeds block drainage & check the flow of water in irrigation canals & field channels thereby increasing the seepage losses as well as losses through over through over flowing, so reduce the irrigation efficiency.
7. Secretions are harmful: Heavy growth of certain weeds like quack grass (Agropyon repens) or lavala lowers the germination & reduce the growth of many crop plants due to presence of certain phytotoxins secreted by weeds.
8. Harmful to human beings and animals: Weeds cause irritation of skin allergy & poisoning to human beings, also death of castles.
9. Cause quicker wear & tear of farm implements: Being hardy & deep rooted; the tillage implements get worn out early & cannot work efficiently unless they are properly sharpened or mended.
10. Reduce value of the lands: Heavily infested lands with perennial weeds fetch less price as require heavy expenditure to brought under cultivation.
Benefits Or Advantages Derived From Weeds:
1. Weeds when ploughed under, add nutrients, organic matter.
2. Weeds check winds or water erosion by soil binding effect of their roots (undirkani).
3. Useful as fodder for castles (Hariyali) & vegetable by human beings (Ghol, Tandulja).
4. Have medicinal value, Leucas aspera isused aga9inst snake bite, oil of satyanashi seed is useful against skin diseases, nuts of lavala are used in making scents (Udabattis/Incense sticks).
5. Have economic importance e.g.: saccharum spp used for makingthatches.
6. Reclamation of alkali lands (Satyanashi).
7. Serve as ornamental plants (Ghaneri).
8. Used for fencing (Cactus, Nagphana).
9. Used as mulch to check the evaporation losses of water from soil.
10. Used as green manuring & composting.
11. Fix atmospheric ‘N’ (Blue green algae, Tarota, Unhali, etc.)
Dispersal Or Dissemination Or Spread Of Weeds
Agencies responsible for dissemination are:
1. Wind: Seeds may be very small & light, equipped with parachute like arrangement, plumes or fuzz. They blow by wind to along distance. E.g.: Seeds of Rui/Ruchki, Striga, Gajar Gawat.
2. Water: The irrigation canals, drainage channels, surface runoff, flood water of rivers & streams carry weed seeds.
3. Animals like wild & domestic: Weeds having hooks (Gokhuru), twisted awns, spines, etc. E.g.: Ghaneri, weeds of Graminae family.
4. Man: Man disperse the weeds indirectly through compost (partially decomposed), feeding castles with hay or fodder having weed plants, using uncleaned farm machinery. E.g.: Ghaneri, weeds of Graminae family.
5. Crop weed: During harvesting, they get mixed with produce. E.g.: Jungli dhan, Bharad in rice and phallaris in wheat.
Principles Of Weed Control
For successful control, one has to consider the following points:
1. Habits of weed plants:
A xerophytes weed (E.g. Alhagi camelorum) thriving under dry & arid conditions will die if fields are flooded with water. Similarly weeds which thrive under marsh or ill drained condition of soil can be controlled by improving drainage.
2. Life cycle of the weed: Annuals & biennials can be controlled effectively if the land is cultivated before seedling stage of weeds. Perennials require deep ploughing to dig out rhizones, bulbs, etc. vegetative part by which they propagate.
3. Susceptibilities: Some weeds are susceptible to certain chemicals while others are not. E.g.: Dicots are susceptible to 2, 4-D while monocots are not, hence 2,4-D is used to control broad leaved weeds in monocot crops.
4. Dormancy period: While controlling dormancy weeds, period is to be considered as they have long dormancy period.
5. Resistance to adverse conditions without losing viability: Some weed seeds have hard seed coats which enable them to remain for a long time without losing their viability, hence they should be controlled before seed formation.
6. Methods of reproduction: Weeds propagate either by seeds, vegetative parts or by both. Seeded weeds should be removed or smothered before seed formation. Vegetatively propagated weeds should be exposed to sun heat to dry & die like rhizome, bulbs, solons, etc. by deep ploughing. Frequent cultivation leads to destroy green leaves & thereby exhaust the food reserves & starve the plants may have to be restored too. In weeds propagated by both mechanical & chemical methods may have to be followed.
7. Dispersal of seeds: Weeds can be controlled or kept in check if the ways in which different weed seeds disseminate are known and counter measures are undertaken.
Weed Control Methods
Broadly classified in two groups:
A)Preventive Measures.
B) Curative or Control Measures which includes:
i. Mechanical
ii.Cropping or Cultural
iii.Biological &
iv.Chemical
A) Preventive Measures: In this, the weeds are prevented from its multiplication, introduction & nipped off the buds. It consists of:
1) Use clean seed,
2) Use well decomposed FYM/Compost,
3) Cut the weeds before seeding,
4) Remove weed growth or keep irrigation & drainage channels clean or free from seeds,
5) Avoid feeding of grain screenings, hay or fodder containing weed seeds without destroying their viability by grinding or cooking,
6) Avoid use of sand or soil from weed infested areas to clean or cultivated areas,
7) Avoid allowing castles to move from weed infested areas to clean or cultivated areas,
8) Clean all the farm implements & machinery properly after their use in infested areas & before using in clean areas,
9) Keep farm fences, roads & bunds clean or free from weeds.
10) Watch seedlings in nurseries carefully so that they do not get mixed with weed seedlings & get carried to the fields.
B) Curative Measures: These measures are followed to remove or to smother the weed growth & further multiplication. It includes:
i) Mechanical methods (Physical): It comprises:
1) Hand pulling;
2) Hand weeding;
3) Burning;
4) Flooding;
5) Hoeing;
6) Tillage;
7) Moving;
8) Smothering with non-living material (mulching). Burning of seed bed is called as ‘rabbing’.
ii) Cropping and competition methods (Cultural): “One who establish first/early, will suppress other.” Therefore, the cultural practices are so managed that the crop plants should establish early and grow faster ahead of the weeds.
It includes:
1) Crop roations: It checks the free growth of weed due to change of crops season to season.
2) Kind of crop: Groundnut covering crops like legumes will smother the weed growth. E.g.: sun hemp, groundnut.
3) Use of fertilizers: Application of optimum doses of fertilizers to crop will help to grow faster.
4) Date & rate of planting or sowing: Sowing of crops at proper time with optimum seed rate will help the crop to cover the ground & will make the weeds deprive of light.
iii) Biological methods: It includes the use of living organisms for suppressing or controlling the weeds. Plant, animal or micro organisms may be used for destruction of weeds. These are called as bioagents which feed on only the weeds and not on crop plants. E.g.: Prickly pear or Nagphana weed in South India was controlled by Conchineal insects. (Dactlopius tomentosus). In Australia (Hawaii Islands) several kinds of moths were used to control Lantana Camara which eats the flowers & fruits. This method is very efficient & economical provided right type of predators, parasites or pathogens which even under starvation conditions will not feed upon cultivated crops are found out & introduced.
iv) Chemical methods: This is very effective in certain cases and has a great scope provided the chemicals are cheap, efficient & easily available. The chemicals used for weed control & which suppress or destroy the growth of weeds, called as herbicide. These either help in killing the weeds or in inhibiting their growth.E.g.2, 4-D, Atrazine, Glyphosate, etc.
Types of herbicide:
i) Selective herbicides are those which kill only weeds without injuring crop plants.
ii) Non-selective herbicides are those which kill all kinds of vegetations i.e. weed and crop plant.
iii) Contact herbicides kill all the plant parts which may get covered by the chemical by directly killing the plant cells. These chemicals are effective against annuals particularly when they are young but not perennials.
iv) Translocated/Systemic herbicides are first absorbed in the foliage or through roots and are then translocated to other parts of the plant. Or Kill plants after their absorption by accelerating or retarding the metabolic activities of plants. These are more effective in destroying deep rooted perennials.
Soil sterilents: are non-selective herbicides and have to be applied into the soil. They make the soil sterile and incapable of supporting any plant growth. As such any weed seeds or weed seedlings present in the soil are killed.
Based on relative time of application to weed emergence the herbicides are classified as:
I) Pre-plant applied (Before planting of crop)
II) Pre-emergence (Before emergence of weeds)
III) Post-emergence (After emergence of weeds)
Acid equivalent (a.e.) refers to that part of the formulation that theoretically can be converted into the acid.
Active ingredient (a.i.) is that part of the chemical formulation which is directly responsible for the herbicidal effects.
Pre and post-emergence treatments to control weeds: Both the terms, Pre and post-emergence treatments are related with time of application of herbicides for control of weeds.
Pre-emergence treatment or application of herbicides: Application of herbicides after sowing of crop but before emergence of crop and weeds is called pre-emergence application. It is done from first to fourth day of sowing and only selective herbicides are used. Generally germinating weeds are killed by pre-emergence application and gives competitive advantage of crop. E.g.: Pre-emergence application of Atrazine @ 0.5 to 2.5 kg/ha in sugarcane, Jowar, Alachlor @ 1.5 to 2.5 kg ai/ha in Groundnut, Duiron @ 2.0 kg ai/ha or Oxadiazon @ 1.5 kg ai/ha in cotton.
Post-emergence application of herbicides: Application of herbicides after emergence of crop is called post-emergence application. It is generally resorted to when the crop has grown sufficiently to tolerate herbicides and to kill weeds that appear late in the crop. Generally, it is done about 30-40 days after sowing. For example, application of Stam F34 @ 2 kg/ha or MCR 1 kg/ha in paddy 3 weeks after transplanting, 2,4-D @ 0.4 kg/ha in Wheat after 4-8 leaf stage, Pendimethalin @ 0.75 to 2.0 kg ai/ha in rice after 3-5 DAT, Isoproturon @ 1.0 kg ai/ha 30 – 35 days after sowing of Wheat.
Soil Fertility And Productivity
Soil fertility: is the capacity/ability of the soil to supply the plant nutrients required by the crop plants in available and balanced forms. Or
It is the capacity of soil to produce crops of economic value to man and maintain the health of the soil for future use. Or
The soil is said to be fertile when it contains all the required nutrients in the right proportion for luxuriant plant growth.
Plants like animals and human beings require food for growth and development. This food is composed of certain chemical elements often referred to as plant nutrients or plant food elements. These nutrients are obtained from soil through roots.
Plants need 16 elements for their growth and completion of life cycle. In addition to these, 4 more elements viz. sodium, vanadium, cobalt and silicon are absorbed by some plants for special purposes.
Classification and source of nutrients:
Class Nutrient Source
Basic C, H, O Air and water
Macro N, P, K, Ca, Mg, S Soil
Micro Fe, Mn, Zn, Cu, B, Mo & CI Soil
Four more recognized nutrients are NA, Co, VA & SI.
Basic nutrients (C, H, and O) constitute 96% of total dry matter of plants. Macro (Major) nutrients (primary-N, P, K, and secondary-Ca, Mg, S) are required in large quantities while Micro nutrients (Trace elements-Fe, Zn, Cu, B, Mo, Cl, and Mn) are required in small quantities. These trace elements are very efficient and minute quantities produce optimum effect. On the other hand, even a slight deficiency or excess is harmful to plants.
Function of the plant:
Elements that provide basic structure to the plant – C, H, O.
Elements useful in energy storage, transfer and bonding – N, S & P. these are accessory structural elements which are more active and vital for living tissues.
Elements necessary for change balance – K, Ca & Mg, act as regulators and carrier.
Elements involved in enzyme activation and electron transports. Fe, Mg, Cu, Zn, B, Mo & Cl are catalysers and activators.
Criteria of Essentlailty: Armon and Stout (1939) proposed criteria of essentiality which was refined by Arnon (1954) as:
The plant must be unable to grow normally or complete its life cycle in the absence of the element.
The element is specific and cannot be replaced by another.
The element plays a direct role in metabolism and
The deficiency symptoms of the element can be corrected or prevented by application of that element only.
In general, an element is considered as essential, when plants can’t complete vegetative or reproductive stage of life cycle due to its deficiency when this deficiency can be corrected or prevented only by supplying this element and when the element is directly involved in the metabolism of the plant.
Nicholas (1961) proposed the term functional nutrient for any mineral nutrient that functions in plant metabolism whether or not its action is specific. E.g.: Na, Co, Va and Si.
Soil fertility denotes the capacity of the soil to produce crops of economic value and maintain the health of the soil for future use. Or
It is the capacity of soil to supply essential nutrients to normal plants in adequate amounts and in a balanced proportion.
Or
It is better to cultivate small piece of fertile land than large nutrient needs of the crop. Or The soil is said to be fertile when it contains all sixteen of the required nutrients in the right proportion for luxuriant plant growth.
Manures and Fertilizers
Plant requires food/nutrients/elements for its growth and development which are absorbed through soil. The nutrient supplying sources are manures and fertilizers. Application of manures and fertilizers to the soil is one of the important factors which help in increasing the crop yield and to maintain the soil fertility. N, P and K are the 3 major elements required for the crop growth.
Manure: It is a well decomposed refuse from the stable and barn yards including both animal excreta and straw or other litter. Or
The term manure implies to the any material with the exception of water which when added to the soil makes it productive and promotes plant growth.
Fertilizers: These are industrially manufactured chemicals containing plant nutrients. Or
It is an artificial product containing the plant nutrients which when added to soil makes it productive and promotes plant growth.
Difference between Manures and Fertilizers:
Sr No
Characteristics
Manures
Fertilizer
1
Origin
Plant or animal origin
Chemical synthesized or manufactured
2
Nature
Organic in nature
Inorganic in nature
3
Type
Natural product
artificial product
4
Conc. Of nutrients
less concentrated
More concentrated
5
Material
Supply organic matter
Supply inorganic matter
6
Nutrient availability
slowly available
May or may not be readily available
7
Nutrients
Supply all the primary nutrients including Micronutrient
Supply specific type of nutrients one, two or three. micro nutrients may or may not be present
8
Effect on Soil Health
Improves physical condition of soil
Do not improve the physical condition of soil
9
Effect on plant growth
No bad effect when applied in large quantities.
Adverse effect on plant whenever there is deficiency or excessive application
Classification Of Manures And Fertilizers
Manures and fertilizers may be:
1. Natural or
2. Artificial.
1. Natural Or Organic Manures: Natural manures are those which are bulky in nature and supply nutrients in small quantities and organic matter in large quantities.
These are two types:
1. Bulky organic and
2. Concentrated org. manures.
1. Bulky OM: These are those which contain small percentage of nutrients and are applied in large quantities. E.g.: Farm Yard Manure (FYM), compost, Night soil, sludge and sewage, sheep and goat manure (Folding), Poultry dropping, Green manures, etc.
2. Concentrated OM: These are those which are organic in nature and contain higher percentage major plant nutrients like N, P and K as compared to bulky OM. These are made from materials of animal and plant origin. The examples of manures of plant origin are oilseed cake which may be edible or non-edible. Edible oil seed cakes are Groundnut cake, Linseed cake, Sesamum cake, Safflower cake (decort). Non-edible oil seed cakes are castor cake, Neem cake, Safflower cake (undercoat). The examples of manures of animal origin are Bone meal, Fish meal, Meat meal and blood meal.
A. Bulky Organic Manures:
a) Farm Yard Manure (FYM): FYM is a mixture of cattle dung, urine, litter or bedding material, portion of fodder not consumed by cattle and other domestic wastes like ashes, etc. collected and dumped into a pit or a heap in the corner of the back yard. Or
FYM refers to the decomposed mixture of dung and urine of farm animals along with the litter (bedding material) and left over material from roughages or fodder fed the cattle.
Because of the varied nature of the material, the composition of the manure itself varies widely but on an average well rotted FYM contains 0.5% N, 0.2%, P2O5 and 0.5% K2O. It also influences by various factors.
Factors Influencing The Composition of FYM
1) Source of manure: Composition of manures varies with kind of animal producing it. Poultry droppings is the richest followed by sheep manure for nutrient contents. Dung contains phosphate while urine contains N and K2O. Amount of urine soaked in bedding material also decides the composition and vary with kind of animal.
2) Food of the animal: The richer the food in proteins, the richer will be the manure in ‘N’ which comes out in the dung and urine.
3) Age and condition of the animal: Young animals need more proteins to build up their body; hence manure is poorer in N content than old animals. Manure of sick animal is richer than healthy animals.
4) Function of the animals: Milch cantles utilize proteins for milk production; hence manure is poor in N, P & K content than draft purpose animals as they utilize more carbohydrates.
5) Nature & proportion of litter: The composition of litter varies with the kind of straw and hence will affect the quality of manure. Bajara stalks are rich in N, P & K followed by wheat & maize.
6) Preservation: Under ordinary storage, there are losses of N. Potash get lost due to leaching when the manure is too moist.
There are 3 methods of FYM preparation:
1. Heap,
2. Box and
3. Pit or Trench method.
Compost & Composting
Compost is the well rotted plant and animal residue. Composting means rotting of plant & animal remains applying in fields. It is largely a biological process in which micro-organism of both the types, aerobic and anaerobic, decompose organic matter and lower the Carbon: Nitrogen (C: N) ratio of refuse.
Compost making is the process of decomposing plant residues in a heap or pit rather than in the soil with a view to bring the plant nutrients in more readily available form. The essential requirements of decomposing are air, moisture, optimum temp. And a small quantity of ‘N’.
Types of Compost/Methods of Composting:
Based on the composting material used and the composition of the final product, composting methods are classified in two types:
1. Farm or Rural Compost
2. Town or Urban compost.
Green Manuring
It is a practice of ploughing in the green plant tissues grown in the field or adding green plants with tender twigs or leaves from outside and incorporating them into the soil for improving the physical structure as well as fertility of the soil. It can be defined as a practice of ploughing or turning into the soil, undecomposed green plant tissues for the purpose of improving the soil fertility.
The object of green manuring is to add an organic matter into the soil and thus, enrich it with ‘N’ which is most important and deficient nutrient.
Types of green manuring: There are two types of green manuring:
1. Green manuring in-situ: When green manure crops are grown in the field itself either as a pure crop or as intercrop with the main crop and buried in the same field, it is known as Green manuring In-situ. E.g.: Sannhemp, Dhaicha, Pillipesara, Shervi, Urd, Mung, Cowpea, Berseem, Senji, etc.
These crops are sown as:
i) Main crop,
ii) Inter row sown crop,
iii) On bare fallow, depending upon the soil and climatic conditions of the region.
2. Green leaf manuring: It refers to turning into the soil green leaves and tender green twigs collected from shrubs and tress grown on bunds, waste lands and nearby forest area. E.g.: Glyricidia, wild Dhaicha, Karanj.
Characteristics/desirable qualities of a good manuring:
1. Yield a large quantity of green material within a short period.
2. Be quick growing especially in the beginning, so as to suppress weeds.
3. Be succulent and have more leafy growth than woody growth, so that its decomposition will be rapid.
4. Preferably is a legume, so that atm. ‘N’ will be fixed.
5. Have deep and fibrous root system so that it will absorb nutrients from lower zone and add them to the surface soil and also improve soil structure.
6. Be able to grow even on poor soils.
Stage of green manuring: A green manuring crop may be turned in at the flowering stage or just before the flowering. The majority of the G.M. crops require 6 to 8 weeks after sowing at which there is maximum green matter production and most succulent.
Advantages of green manuring:
i) It adds organic matter to the soil and simulates activity of soil micro-organisms.
ii) It improves the structure of the soil thereby improving the WHC, decreasing run-off and erosion caused by rain.
iii) The G.M. takes nutrients from lower layers of the soil and adds to the upper layer in which it is incorporated.
iv) It is a leguminous crop, it fixes ‘N’ from the atmosphere and adds to the soil for being used by succeeding crop. Generally, about 2/3 of the N is derived from the atmosphere and the rest from the soil.
v) It increases the availability of certain plant nutrients like P2O5, Ca, Mg and Fe.
Disadvantages of green manuring:
i) Under rain fed conditions, the germination and growth of succeeding crop may be affected due to depletion of moisture for the growth and decomposition of G.M.
ii) G.M. crop inclusive of decomposition period occupies the field least 75-80 days which means a loss of one crop.
iii) Incidence of pests and diseases may increases if the G.M. is not kept free from them.
Application of phosphatic fertilizers to G.M. crops (leguminous) helps to increase the yield, for rapid growth of Rhizobia and increase the ‘P’ availability to succeeding crop.
Artificial Or Chemical Or Inorganic Fertilizers
These can be classified as:
1) Straight fertilizers: These are those which supply only one primary plant nutrient, viz. N, P or K. Depending upon the nutrient present in the fertilizer, these are classified as:
a) Nitrogenous fertilizers: These are those which contain and supply only the nitrogen. Or are those fertilizers that are sold for their ‘N’ content and manufactured on a commercial scale.
These are classified into 4 groups on the basis of the chemical form in which ‘N’ is combined with other elements in a fertilizer (Chemical form of ‘N’).
i) Nitrate form (NO3): Sodium nitrate (Chilean nitrate), Calcium nitrate, Potassium nitrate and Nitrate of Soda Potash.
ii) Ammonical form (NO3): Ammonium sulphate, Ammonium Chloride and Anhydrous ammonia.
iii) Nitrate & ammoniacal form: Ammonium Nitrate, Calcium Ammonium Nitrate & Ammonium sulphate nitrate.
iv) Amide form (Cn2 or NH2): Calcium cynamide, Urea and Sulphur coated urea.
b) Phosphatic fertilizers: These are those which contain and supply only the ‘P’. P content in fertilizers is expressed in oxidized form, phosphorus pent oxide (P2O5) while its content in soil and plant is expressed in elemental form as ‘P’. The conversion factors for elemental to oxidized form and vice versa are 2.29 and 0.43, respectively.
These can be divided into 3 groups based on their availability to crop and solubility.
i) Containing water soluble phosphoric acid: Fertilizers are available in the form of mono calcium phosphate or ammonium phosphate. E.g.: single super phosphate, double super phosphate and triple super phosphate.
ii) Containing citric acid soluble phosphoric acid: These fertilizers contain citrate soluble phosphoric acid or dicalcium phosphate. E.g.: Basic slag, Di-calcium phosphate.
iii) Containing phosphoric acid not soluble in water or citric acid: E.g.: Rock phosphate, raw bone meal, steamed bone meal.
c) Potassic fertilizers: These are those which contain and supply only the ‘K’. Potassium in the fertilizer is expressed as K2O (Potassium oxide). The conversion factor to express in elemental factor (K) is 0.83 and oxide form is 1.2.
These are grouped in two as:
a. Chloride form: - E.g. Muriate of potash or pot. Chloride.
b. Non chloride form: - E.g. Potassium Sulphate, Potassium Magnesium sulphate, Potassium nitrate.
2) Complex or Compound fertilizers: These are those which contain two or three primary plant nutrients of which two primary nutrients are in chemical combination. E.g.: Diammonium phosphate, Nitro phosphates, Ammonium phosphate, Potassium nitrate, Ammonium Sulphate phosphate, Ammonium Nitrate phosphate, Ammonium Potassium phosphate.
a. Fertilizer mixtures/Mixed fertilizers: These are physical mixtures of straight fertilizers containing two or three primary plant nutrients.
These are made by thoroughly mixing the ingredients either mechanically or manually. Fertilizer grade refers to the guaranteed minimum percentage of N, P2O5 and K2O contained in fertilizer materials. E.g.: 20:20:0, 28:28:0, 18:18:10, 14:25:14, 17:17:17, 14:28:14 and 18:8:9, etc.
b. Micro nutrient fertilizers: These are the nutrients which supply the nutrients required in smaller quantities. These are the chemicals which supply the elements required by the plant in very small quantity. E.g.: Copper Sulphate, Zinc Sulphate, Borax, Sodium Borate, Manganese Sulphate, Sodium Molybdate, Ammonium Molybdate, Ferrous Sulphate, etc.
c. Soil amendments: These are those which improve the soil by correcting its acidic or saline, or alkaline conditions and neutralizing the injurious effects that may result from improper use of fertilizer. E.g.: Lime, Gypsum, Sulphur, and Molasses. These are the substances that influence the plant growth favourably by producing the soil one or more of the following beneficial effects:
1. Changing the soil reactions i.e. making the soil less acidic (Lime) or less alkaline (Gypsum).
2. Changing the plant nutrients in the soil from unavailable forms.
4. Improving the physical condition of soil (Molasses).
5. Correcting the effects of injurious substance.
d. Bio-fertilizers/Microbial innoculents: It may be defined as preparation containing live or latent cells of the efficient strains of N fixing, phosphate solubilizing or cellulytic micro organisms.
These are used for application to seed, soil or decomposing areas to increase the no. of such certain microbial process to make the nutrients in available form to plants such as Rhizobium, Azotobacter, Azospirillum, Blue-green algae and Azolla.
Fertilizer Mixtures (FM)
When two or more fertilizers are mixed together to supply two or three major elements i.e. N, P2O5 and K2O is known as fertilizer mixture or Mixed fertilizer. Or
A mixture of two more straight fertilizer materials is referred to as fertilizer mixture. Sometimes, complex utilizes containing two plant nutrients are also used in formulating fertilizer mixtures. Complete fertilizer refers to the fertilizers containing 3 major plant nutrients, N, P2O5 and K2O.
Types of fertilizers: There are two types of fertilizer mixtures:
a. Open formula fertilizer mixtures: The formulae of such fertilizers in terms of kinds and quantity of the ingredients mixed are disclosed by the manufacturers.
b. Closed formula fertilizer mixtures: The ingredients of straight fertilizers used in such mixtures are not disclosed by the manufacturers.
Materials used in fertilizer mixtures: Different materials go in to production of mixed fertilizers. In accordance with their principle function in the mixture, the materials can be grouped into:
1. Suppliers of plant materials: These are the straight fertilizers added to supply the plant nutrients mentioned in the grade, thus, are the primary materials most essential for preparing mixed fertilizers.
2. Conditioners: These are the organic substances which prepare the fertilizer mixture in good drilling condition and reduce caking. E.g.: Tobacco stems, Peat, Groundnut hulls and paddy hulls (Husks), bone meal, oilcakes.
3. Neutralizers of residual acidity: The substances used to neutralize the residual effects are known as neutralizers. For example, if the ‘N’-ous fertilizers used are acididic in nature like Amm. Sulphate, Urea, a basic material like lime stone is added to counteract the acidity.
4. Filler: Filler is the make – weight material added to a fertilizer mixture. It is added to make up the differences between the weight of the added fertilizers required to supply the plant nutrients and the desired quantity of fertilizer mixture, such as sand, soil, ground coal ashes, sawdust and other waste products.
5. Secondary and micro – nutrients: Some times, secondary and micro – nutrient carrying fertilizers are added to correct its deficiency.
An expression indicating the % of plant nutrient in a fertilizer mixture is termed as fertilizer grade and the relative proportion of major plant nutrients in the mixed fertilizer taking ‘N’ as one, called as fertilizer ratio. For example, in a fertilizer mixture of 6:12:6 grades, the fertilizer ratio is 1:2:1.
The low analysis fertilizers contain less than 25% of primary nutrients and the high analysis fertilizers contain more than 25% of primary nutrients. On the other hand, the low analysis mixed fertilizers contain less than 14% sum of the primary nutrients and high analysis mixed fertilizers contain more than 14% sum of the primary nutrients.
Advantages:
1. The balanced fertilizer mixture suited to crop and soil can be supplied,
2. All the required nutrients can be supplied at one time by the application of fertilizers mixture and thus, time and labourers are saved.
3. Storage and handling costs are reduced.
4. Micro nutrients can be incorporated.
5. Mixtures have better physical condition and are easier for application.
6. Residual acidity can be neutralized by using neutralizers in mixture.
Disadvantages:
1. The cost of plant nutrients is higher than straight fertilizers.
2. All only one nutrient is required by the crop, the fertilizer mixtures are not useful and sometimes farmers may add nutrients in excess or in limited quantity.
Precautions To Be Taken While Preparing Fertilizer Mixtures
1. Do not mix the fertilizer containing ammonia like Amm. Sulphate with basically reactive fertilizers like lime, basic slag, Rock Phosphate and Calcium Cynamide as losses of ‘N’ may result through escape of gaseous ammonia.
2. Do not mix water soluble phosphatic fertilizer (Super Phosphate) with the fertilizer containing free lime (basic slag, Calcium Cynamide) as this coverts the portion of soluble phosphate into soluble phosphate.
3. Do not mix fertilizers which are easily soluble and hygroscopic like urea, Calcium Ammonium Nitrate with other fertilizers because they will form lumps. The fertilizer mixtures are made manually or in the factory, having the grades 6:12:0, 12:6:0, 9:9:0, 9:9:5, 15:5:5, 10:5:5, etc.
Formulation of FM: The quantity of fertilizers for fertilizer mixture can be calculated by
Q = M * T \ F
Where Q = Quantity of fertilizers to be calculated
M = Total quantity of mixture to be prepared.
T = Parts of nutrients in the fertilizer grade.
F= % of nutrients in the supplier fertilizer.
Unit value of fertilizers: One percent of N, P or K present in one tone of a fertilizer is treated as one unit. A unit is thus equal to 10kg.
The unit value of plant food in a fertilizer is the price of one tone of fertilizers divided by the percentage content of that particular nutrient.
Unit value = Price of 1 tonne fertilizers/ % of nutrient in the fertilizer
The fertilizer having a lower unit value will be cheaper than a fertilizer having a higher unit value. It is made use in determining the price of fertilizer mixtures containing N, P and K and in comparing the cost of 2 or 3 fertilizers providing same nutrient.
Methods Of Fertilizer Application
In order to get maximum benefit from manures and fertilizers, they should not only be applied in proper time and in right manner but any other aspects should also be given careful consideration. Different soils react differently with fertilizer application. Similarly, the N, P, K requirements of different crops are different and even for a single a crop the nutrient requirements are not the same at different stages of growth. The aspects that require consideration in fertilizer application are listed below:
1. Availability of nutrients in manures and fertilizers.
2. Nutrient requirements of crops at different stages of crop growth.
3. Time of application.
4. Methods of application, placement of fertilizers.
5. Foliar application.
6. Crop response to fertilizers application and interaction of N, P, and K.
7. Residual effect of manures and fertilizers.
8. Crop response to different nutrient carrier.
9. Unit cost of nutrients and economics of manuring.
Fertilizers are applied by different methods mainly for 3 purposes:
1. To make the nutrients easily available to crops,
2. To reduce fertilizer losses and
3. for ease of application.
The time and method of fertilizer application vary in relation to
1) The nature of fertilizer.
2) Soil type and
3) The differences in nutrient requirement and nature of field crops.
Application of fertilizers in solid form: It includes the methods like (See chart):
I) Broadcasting: Even and uniform spreading of manure or fertilizers by hand over the entire surface of field while cultivation or after the seed is sown in standing crop, termed as broad casting. Depending upon the time of fertilizer application, there are two types of broadcasting:
A) Broadcasting at planting and
B) Top dressing.
A) Broadcasting at planting: Broadcasting of manure and fertilizers is done at planting or sowing of the crops with the following objectives:
1) To distribute the fertilizer evenly and to incorporate it with part of, or throughout the plough layer and
2) To apply larger quantities that can be safely applied at the time of planting/sowing with a seed-cum-fertilizer driller.
It is adopted with the following condition:
1) When N-ous fertilizers like amm. Sulphate, Amm. Sulphate Nitrate, Concentrated organic manures, are to be applied to the soil deficient in N or where N is exhausted by previous crops like fodder, Jowar, F. maize.
2) When citrate soluble P-tic fertilizers like basic slag and dia-calcium phosphate, are to be applied to moderately acid to strongly acid soils.
3) When K-ssic fertilizers like Muriate of potash and potassium sulphate are to be applied in potash deficient soil.
B) Top dressing: Spreading or broadcasting of fertilizers in the standing crop (after emergence of crop) is known as top-dressing. Generally, NO3 – N fertilizers are top dressed to the closely spaced crops like wheat, paddy. E.g.: Sodium Nitrate, Amm. Nitrate and urea, so as to supply N in readily available from the growing plants. The term side dressing refers to the fertilizer placed beside the rows of a crop (widely spaced) like maize or cotton. Care must be taken in top dressing that the fertilizer is not applied when the leaves are wet or it may burn or scorch the leaves. The top dressing of P and K is ordinarily done only on pasture lands which occupy the land for several years.
In some countries, aero planes are used for fertilizer application in hill terrains where it is difficult to transport fertilizers and where large amount are to be applied because of severe deficiency and under following situations:
1. Where very small quantities of fertilizers are needed over large areas. E.g.: Micro nutrients.
2. When high analysis materials are applied.
3. When fertilizer application may be combined with insect control or some other air operation and
4. As a labour and time saving device.
II) Placement: In this, the fertilizers are placed in the soil irrespective of the position of seed, seedling or growing plant before or after sowing of the crops. It includes:
1. Plough sole placement: The fertilizer is placed in a continuous band on the bottom of the furrow during the process of ploughing. Each band is covered as the next furrow is turned. By this method, fertilizer is placed in moist soil where it can become more available to growing plants during dry seasons. It results in less fixation of P & K than that which occurs normally when fertilizers are broadcast over the entire soil surface.
2. Deep placement or sub-surface placement: In this method, fertilizers like Amm. Sulphate and Urea, is placed in the reduction zone as in paddy fields, where it remains in ammonia form and is available to the crop during the active vegetative period. It ensures better distribution in the root zone, and prevents any loss by surface runoff. It is followed in different ways, depending upon local cultivation practices such as:
i) Irrigated tracts: The fertilizer is applied under the plough furrow in the dry soil before flooding the land and making it ready for transplanting.
ii) Less water condition: Fertilizer is broadcasted before puddling which places it deep into the reduction zone.
iii) Sub – soil placement: This refers to the placement of fertilizers in the sub-soil with the help of heavy power machinery. It is followed in humid and sub-humid regions where many sub-soils are strongly acid, due to which the level of available plant nutrients is extremely low. P-tic and K-ssic fertilizers are applied by this method in these regions for better root development.
III) Localized placement: It refers to the application of fertilizers into the soil close to the seed or plant. It is usually employed when relatively small quantities of fertilizers are to be applied. It includes methods like:
Advantages:
i) The roots of the young plant are assured of an adequate supply of nutrients,
ii) Promotes a rapid early growth,
iii) Make early Intercultivation possible for better weed control,
iv) Reduces fixation of P & K.
1. Contact placement or combined drilling or drill placement: It refers to the drilling of seed and fertilizer together while sowing. It places the seed and small quantities of fertilizers in the same row. This is found useful in cereal crops, cotton and grasses but not for pulses and legumes. This may affect the germination of the seed, particularly in legumes due to excessive concentration of soluble salts.
2. Band placement: In this, fertilizer is placed in bands which may be continuous or discontinuous to the side of seedling, some distances away from it and either at level with the seed, above the seed level or below the seed level. There are two types of band placement: It includes hill and row placement.
a. Hill placement: When the plants are spaced 3 ft. or more on both sides, fertilizers are placed close to the plant in bands son one or both sides of the plants. The length and depth of the band and its distance from plant varies with the crop and the amount of fertilizer as in cotton.
b) Row placement: When the seeds or plants are sown close together in a row, the fertilizer is put in continuous band on one or both sides of the one or both sides of the row by hand or a seed drill. It is practiced for sugarcane, potato, maize, tobacco, cereals and vegetable crops.
Higher rates of fertilizers are possible with row placement than hill placement. For applying small amount of fertilizers, hill placement is usually most effective.
3. Pellet application: In this method, fertilizer (N-ous fertilizers) is applied in the form of pellets 2.5 – 5.0 cm. deep between the rows of paddy crop. Fertilizer is mixed with soil in the ratio of 1:10 and make into dough. Small pellets of a convenient size are then made and deposited in the soft mud of paddy fields. It increases the efficiency of N-ous fertilizers.
4. Side dressing: Fertilizers are spread in between the rows or around the plants. It includes i) application of N-ous fertilizers in between the rows by hand to broad row crops like maize, S.cane tobacco, cereals which is done to supply additional doses of N to the growing crop. ii) Application of mixed or straight fertilizer around the base of the fruit trees and done once, twice or thrice in a year depending upon age.
Application Of liquid fertilizers
It includes:
1. Starter solutions: Solutions of fertilizers, generally consisting of N-P2O5 – K2O in the ratio of 1:2:1 and 1:1:2 are applied to young vegetable plants at the time of transplanting. It helps in the rapid establishment of seedlings and quick early growth.
Advantages:
i) The nutrients reach the plant roots immediately and
ii) The solution is sufficiently diluted so that it does not inhibit growth.
Disadvantages:
i) Extra labour is necessary and
ii) Fixation of phosphate is greater.
2. Foliar application: It refers to the spraying of leaves of growing plants with suitable fertilizers solutions. These solutions may be prepared in a low concentration to supply any one plant nutrients. It is preferable to soil application when:
i) The soil conditions or a competitive crop makes nutrients from soil dressing unavailable, like late application of N to crops raised under Rainfed condition,
ii) An accurately time response to fertilizers is required. E.g.: change in the reason,
iii) Routine applications are made of insecticidal or pesticidal sprays to which nutrients the crop prevents application of fertilizer to the soil but permits its application to the leaves from a high clearance sprayer or from a helicopter.
Difficulties (disadvantages) associated with this method are:
i) Leaf burn on scorching may occur, if strong solutions used.
ii) Small quantities of nutrients can be applied in one single spray due to low concentrations.
iii) Several applications are needed for moderate to high fertilizer doses, and
iv) Costly method than soil application.
3. Direct application to the soil: With the help of special equipment, anhydrous ammonia (a liquid under high pressure up to 200 PSI or more) and N solutions are directly applied to the soil. It allows direct utilization of the cheapest N source. Plant injury or wastage of ammonia is very little if the material is applied 10cm below the seed. Otherwise, the N from ammonia will be lost. If requires moisture content at field capacity and good soil tilth.
4. Application through irrigation water: Straight and mixed fertilizers containing N, P & K easily soluble in water, are allowed to dissolve in the irrigation stream. The nutrients are thus carried in solutions. This saves the application cost and allows the utilization of relatively in expensive soluble fertilizers, like N-ous fertilizers
Soil
Soil: The word ‘soil’ is derived from a Latin word, “Solum”, meaning ‘floor’. Soil is a complex system made up of mineral matter, organic matter, and soil water and soil air. Therefore, it contains not only the solid and liquid phases but also the gaseous phase.
Soil is a thin layer of earth’s crust which serves as a natural medium for the growth of plants. Soil is the unconsolidated mineral material on the immediate surface of the earth that serves as a natural medium for the growth of land plants. Soil is the unconsolidated mineral matter that has been subjected to, and influenced by genetic and environmental factors, parent material, climate, organisms and topography all acting over a period of time. Soil is a natural body, synthesized in profile form from a variable mixture of broken and weathered minerals and decaying organic matter which covers the earth in a thin layer and which supplies when containing the proper amounts of air and water, mechanical support and in part, sustenance for plans.
Some definitions of the soil,
According to Joffe (1949),”The Soil is a natural body of minerals and organic constituents differentiate into horizons of variable depth, which differs from the materials below in morphology, physical make up, chemical properties and composition and biological characteristics.”
Soil is a dynamic natural body developed as a result of pedogenic processes during and after weathering of rocks, consisting of minerals and organic constituents, possessing definite chemical, physical, mineralogical and biological properties having variable depth over surface of the earth and providing medium for plant growth of land plants.
The soil is heterogeneous, polyphasic, particulate, disperse and porous system, in which the interfacial area per unit volume can be very large. The disperse nature of the soil and its consequent interfacial activity give rise to such phenomena as:
1. Absorption of water and chemical,
2. Inoic exchange,
3. Adhesion
4. Swelling and Shrinking,
5. Dispersion and Flocculation and
6. Capillary.
Functions of soil:
1. Soil provides anchorage to root enabling plants to stand erect.
2. It acts as a store house of water and nutrients for plant growth.
3. It acts as an abode of flora and fauna which suitably transform nutrients for uptake by plant roots.
4. It provides space for air and accretion which creates healthy environment for the biological activity of soil organisms.
Soil is natural body, differentiated into horizons of mineral and organic constituents, usually unconsolidated, of variable depth, which differs from the percent material below in morphology, physical properties and constitution, chemical properties and composition and biological characteristics.
Soil profile: The vertical exposure of soil with its various layers (horizons) Or
A vertical section through the soil is called as the soil profile.
The various distinguishable layer of soil that occurs are called horizons.
Soil- Components Of Soil Or Phases Of Soil
Minerals soils consist of 4 major components: Mineral materials, OM, water and air in various proportions. Approximately 50% of the total volume of the surface horizon of many soils is made up of inorganic Materials (mineral matter) and OM (5%) and the remaining volume is per space between the soil particles. Water and air occupy these pore spaces in various proportions. The proportion of air and water varies from one season to another. At optimum moisture for plant growth, the 50% of pore space possessed is divided roughly in half 25% of water space and 25% or air.
The soil may be described as the three phase system: Soil solid, Liquid and gaseous phase.
1. Solid phase: Soil material less than 2 mm size constitutes the soil sample. It is broadly composed of inorganic and organic constitutes. Soils having more than 20% of org. constitutes are arbitrarily designated organic soils. Where inorganic constituents dominate, they are called mineral soils. The majority of the soils of India are mineral soils. It accounts for nearly 50% of the total volume and 95% without of the solid phase is made up of inorganic or mineral matter. The remaining 5% weight comprises of OM which is mainly derived from dead parts of the vegetation an animals.In inorganic constituents consist of silicates, certain preparation of carbonates, soluble salts, an free oxides of iron, aluminium and silicon. The humus and humus like fractions of the solid phase constitute the soil organic matter. Soil is the habitat for enormous number of living organisms like roots of higher plants (Soil Macro flora), bacteria, fungi, actinomycetes and algae (Soil Micro flora). A gram of fertile soil contains billions of these micro-organisms. The live weight of the micro-organisms may be about 4000 kg/ha may constitute about 0.01 to 0.4% of the total soil mass. Soil also consists of protozoa and nematodes (Soil Micro Fauna).
2. Liquid phase: About 50% of the bulk volume of the soil body is generally occupied by voids or soil pores which may be completely or partially filled with water. A considerable part of the rain which falls on soil is absorbed by the soil and stored in it to be returned to the atmosphere by direct evaporation or by transpiration through plants. The soil acts as the reservoir for supplying water to plants for their growth. The soil water keeps salts in solution which act as plant nutrients. Thus, the liquid phase is an aqueous solution of salts, when water drains from soil pores are filled with air.
3. Gaseous phase: The air filled pores constitutes the gaseous phase of soil system and dependent on that of the liquid phase. The N and O2 contents of soil air are almost the atmospheric air but the concentration of CO2 is much higher (8 – 10 times more) which may be toxic to plant roots. This phase supplies O2and thereby prevents CO2 toxicity.
The 3 phases of the soil system have definite roles to play. The solid phase provides mechanical support for and nutrients to the plants. The liquid phase supplies water and along with it dissolved nutrients to plant roots. The gaseous phase satisfies the acration (O2) need of plants.
Soil- Classification Of Soils
Soils can be grouped into categories based on their present properties. The most general soil category is called order. All world soils are place into 10 orders.
1. Entisols: Those soils that have natal, if any, profile development are known as entisols. Soils in desert belong to this classification. The productivity of these soils varies with their location and properties. With controlled water supply and proper fertilization, these soils have good productivity and good for vegetables, groundnut, citrus, wheat, paddy, etc.
2. Inceptisols: These soils have better profile development than entisols but are less developed. The horizons are formed mostly from alteration of the parent materials with accumulation of clay. The productivity is limited due to poor drainage. Found in humid regions.
3. Histosols: These are organic soils (pleats and mucks) consisting of variable depths of accumulated plant remains in bogs, marshes and swamps that have developed under water saturated environment. Highly rich in organic matter i.e. Org. C ranges from 12 to 18% in soils with low to more than 50% clay content.
4. Aridisols: Soils found in arid or dry areas with light in colour, poor inorganic matter and are not subjected to leaching, used for cultivation with irrigation. Process a horizon of CaCO3 (lime), Calcium sulphate (Gypsum) or more soluble salts. These are desert soils.
5. Mellisols: Mostly these are grasslands having thick surface horizon of dark colour, dominated by divalent cations. Process normal granular or crub structure, do not harden on drying and with moderate to have fertilization soil are productive.
6. Vertisols: These have a high content of clays that swell when wetted (more than 30%). During the dry season, these soils on tract and give rise to deep cracks which disappear in the wet season or after irrigation. Found in sub humid or semi arid (Temperate to tropical) climates where temp. are moderate to high. Good for crop production with fine texture which are plastic and sticky when wet and hard when dry. Difficult to manage due to very little time for their proper preparation by tilling good for the production of cotton, millet, sorghum, wheat, paddy, etc.
7. Alfisols: Develop in humid and sub humid climates (500 mm to 1300 mm rainfall) with gray to brown surface horizons. Soils are slightly too moderately acid and quite productive with good texture. Soils are frequently under forest vegetation.
8. Spodosols: Soils belong to forests with low content of bases, having coarse texture (sandy). Found in humid climates where temperatures are low. The subsurface horizons have accumulation of org. matter and sesquioxide.
9. Ultisols: These are strongly acid, normally forest soils with low content of bases extensively weathered soils of tropical and subtropical climates, respond to good mgt. practices, have clay of 1:1 type and give good crop production with adequate fertilization.
10. Oxisols: These are most developing in tropical and subtropical climates. The subsurface horizons are high in clay and acid. The soils are productive with supplements of ‘P’ micro-nutrients.
Soil Groups Of India
1. Red soils: Derived from crystalline, metamorphic rocks, which consist of granites, gneisses and schist’s, red or reddish brown, either in situ or from the decomposed rock materials washed down to lower level by rain, light textured with porous and friable structure. They have neutral to acid reaction and are deficient in N, humus, P2O5 and lime.
Cover large parts of TN, Karnataka, N-E AP, eastern part of MP to Chota Nagpur and Orissa, noticed in Up, Bihar, WB and Rajasthan.
2. Laterites and laterite soils: Formed in situ condition under conditions of high rainfall with alternating wet and dry periods, to reddish yellow, low in N, P, K, lime and magnesia. Formed due to the process of laterization in which silica is removed while Fe and Al remain behind in the upper layers.
Soils are common on the low hills in eastern AP, K, Kerala, eastern MP, Orissa, Assam and Ratnagiri district of MS.
3. Black soils: Highly clayey, 35 to 60% even up to 80% in valleys or depressions dark colored, from deep cracks during dry seasons, characterized by swelling and low permeability, neutral to slightly alkaline, High CEC, high content of K, exchangeable Ca and Mg poor in org. matter, N, P. The clay is mainly montmorillonite type, hence soft on wetting and contract on drying. These are called as regures or black cotton soils which are divided into: Very deep (More than 90 cm depth), Deep (45 – 90 cm), moderately deep (22.5 to 45 cm), Shallow (7.5 to 22.5 cm) and very shallow (below 7.5 cm depth). Black colour is not due to org. matter but due to presence of titaniferrous magnetite compounds and/or clay complexes. Major areas of black soils are in MS, MP and parts of AP, Gujarat and TN.
4. Alluvial soils: Develop from water deposited sediments. Do not show any prominent profile development. Varies in nature and properties which depends on sediments from which they develop the percent material in the respective catchments area and the place of deposition in valleys. Mostly poor drained, grayish colour, acidic but develop into saline and alkali soils in dry regions.
Occur in all states along rivers, for example, Indo-gangeric plains, Brahmaputra valley, Coastal areas of Gujarat, Ms, K, Kerala, TN, AP, Orissa, WB and Goa.
Sub-divided into: Old, Recent, Lacustrine, Coastal and Deltaic alluviums.
5. Desert soils: Formed in arid regions, as a result of physical weathering, sandy. Both wind and water erosion is severe in such soils, well supplied with soluble salts. Low in N and org. matter has a high pH.
Soils form a major part of Rajasthan, Southern part of Haryana and Punjab, northern part of Gujarat and receive 50 cm to less than 10 cm rainfall with high evaporation
.
6. Saline and alkaline soils: Soils show white crustation of salts of Ca, Mg and Na on the surface, poor drained and infertile. Occur in semi-arid areas of Bihar, UP, Punjab, Rajasthan Coastal and Deccan Canal Tract of MS.
7. Peaty and marshy soils: Soils are black, clayey, highly acidic (pH3.5) and contain 10 to 40% org. matter, poorly drained, high ground water table. Found in Kerala, Coastal tracts of Orissa, Sunder ban area of WB, SE and Coast of TN and in parts of Bihar and UP.
Soil- Physical Properties Of soil
The physical properties of soils are dominant factors affecting the use of a soil which determine the availability of O2 in soils, the mobility of water into and though soils and case of root penetration and also the chemical and biological behavior of soil. These depend primarily on the amount, size, shape and arrangement of its inorganic particles, shape and arrangement of it inorganic particles, kind and amount of org. matter, the total volume of pore spaces and the way it is occupied by water and air at a particular time.
Those are: Texture, Structure, Density, Porosity, Consistency, Colour and Temperature.
Soil Textures: It refers to the relative proportions of soils separates i.e. sand, silt and clay in particular soil. It is permanent or static property of soil.
Natural soils are comprised of soil particles of varying sizes. The soil particle size groups are called as soil separates as stone (more than 20mm dia). Gravel (2 – 20 mm dia), Fine earth (less than 2mm dia) coarse sand (0.2 to 2 mm dia), fine sand (0.2 to 0.02 mm), silt (0.02 to 0.002 mm) and clay (less than 0.002 mm dia).
1. Sand: Sand particles are large with very little surface area exposed (0.1 m2/g specific area). These are fragments of quartz, insoluble; nutrients supplying ability are practically nil. Pre space are bigger (macro pores) which facilitates rapid movement of air and water. Sand does not absorb water; do not exhibit properties swelling and shrinkages, stickiness and plasticity. Unless coated with clay or silt, they do not exhibit properties as Cohesions, moisture and nutrient retention, etc. Soils having high percent of sand can be easily cultivated with little or light draft requirements, low water holding capacity, less fertile, dry out quickly. As sand grains are large and coarse, soils dominated by sand are called as coarse textured or light soils.
2. Silt: These particles are intermediate in size to sand and clay. Because of adhering film of clay, they exhibit some plasticity, cohesions adhesion and absorption and can hold more amount of water than sand but less than clay. Soils dominated by silts armid way in properties, workability and productivity between sandy and clayey soils. The average specific area of silt particles is 1 sp. m/g.
3. Clay: It ultra microscopic size and large surface area (10 to 1000 sq. per. g.). The clay particles are smooth and in a colloidal state. It greatly influences the physical and chemical properties of soil. Clay particles absorb and retain water, sweel on wetting and shrink on drying, exhibit properties like flocculation (grouping/clustering)., deflocculating, plasticity and stickiness. Soils with high clay are poor drained, require very heavy draft for cultivation, can be worked in narrow range of moisture regime. Clayey soils are called as heavy soils as they are difficult or heavy for cultivation.
Textural classes: All soils have all the three soil separates in varying proportions. Based on their proportions, the soils can be grouped into textural classes and are named according to the soil separates which is predominant in them as:
Group
Class
Ranges (%) of
Sand
Silt
Clay
Very coarse textured
Sand
85-100
0-10
0-10
Loamy sand
70-90
0-30
0-15
Coarse textured
Sandy loam
43-80
0-50
0-20
Loam
23-52
28-50
7-27
Silt Loam
0-50
50-88
0-20
Silt
0-20
88-100
0-12
Medium textured
Sandy % clay Loam
45-80
0-28
20-55
Fine textured
Clay loam
20-45
15-53
27-40
Silty clay loam
0-20
40-73
27-40
Fine textured
Sandy clay
40-65
0-20
35-45
Silty clay
Clay
0-20
0-40
40-60
0-40
40-60
40-60
Significance of soil texture:
It influences physical and chemical properties like water holding capacity, nutrient retention and fixation and its availability, drainage, strength, compressibility and thermal regime. Suitability of a soil to a particular crop depends on texture in addition to soil depth, depth of water table, salinity and alkalinity. Loamy soils (Silty) exhibit intermediate properties, so best for agricultural production because they retain more water and nutrients than sandy and have better drainage, aeration and tillage properties than clay soils.
Soil Property- Soil Structure
The primary particles – sand, silt and clay are held together in clusters or peds of various shapes and sizes. Individual soil particles are joined together into groups or clusters by cementing agents just as bricks with cement or lime mortar to make buildings or various sizes and shapes, called as soil aggregates or peds. Natural aggregates are called as peds and artificial/aggregates by cultivation are called as clods.
The arrangement of primary particles and their aggregates (secondary) into certain pattern in the soil mass, called as Soil Structure. Soil structure influences the soil environment through its effect on the amount and size of pore spaces, water holding capacity, availability of plant nutrients and growth of micro-organisms. The size, shape and arrangement of the soil aggregates give indication of the ability of the soil to:
1. Allow air and water movements through the soil.
2. Allow plant roots to move through soil and make use of soil and
3. Hold enough soil moisture in a form available for plants use.
Types of soil structure:
There are four types on the basis of shape and arrangements:
1. Plate like/Platy: Horizontally, layered, thin and flat like the plates with horizontal dimensions greater than the vertical ones.
2. Prism like: Aggregates are elongated like pillars or prism, often six sided, up to 15 cm dia. They have vertical axis greater that oriental and the length of elongated pillars varies, depending upon soil and may go up to 15 cm or more and commonly found in sub soil horizon of arid and semi-arid region soils. Further divided as: with flat tops, called as prismatic and with rounded tops, called as Columnar aggregates.
3. Blocky like: These are cubes like 3 dimensions of about same size. When the edges or size are sharp, called as Angular blocky and when rounded, called as Sub-angular blocky. These usually found in the sub-soil horizon.
4. Spheroidal like: The aggregates are rounded or like a sphere. All the axes are approximately of the same dimensions, with curved or irregular faces, not more than 1 cm dia.
Further divided into:
I) Crumb: The aggregates are small and are weakly held together and are porous like crumbs of breads, found in pasture soils or grassy lands.
II) Granular: Similar to crumb except that the aggregates are harder, less porous and the individual soil particles are more strongly held together than in the crumb structure. Commonly found in cultivated fields.
Classes of structure: Aggregates/peds classified on the basis of their sizes as: Very fine, Fine, Medium, Coarse (or thick) and Very coarse (or very thick).
Grades of structure: Depending upon the stability, distinctness, durability, strength of the ease with which they can be separated, the aggregates are classified onto the four grades as: Structure less, Weak, Moderate and Strong.
Soil Property- Density Of Soil
The density of the soil i.e. mass per unit volume can be expressed tn two ways: The density of the solid particles of the soil, called as particle density and the density of the whole soil including pore space, is called as bulk density. Particle density is also called as true specific gravity and bulk density is called as apparent specific gravity.
1. Particle density: It is the weight of the soil solids (g) without pores per unit volume (cc). It varies from 2.6 to 2.7 g/cc in most of the mineral soils with average of 2.65 g/cc. It is not affected by texture and structure of coil and it is static property.
2. Bulk density: It is the mass (weight) per unit volume of the soil inclusive of pore spaces in its natural structure.
It varies from1.3 to 1.7 g/cc in sandy soils and 1.1 to 1.4 g/cc in clay soils. However, it is affected by texture, structure, organic matter and depth of the soil. Surface soils have low bulk density than lower surfaces.
Soil porosity: Soil has spaces which are occupied by water and air. The amounts of water and air present in pore spaces vary and depend upon their relative amounts. The amount of pore space depends upon the arrangement of solid particles, organic matter content, granulation and aggregation (texture), depth of the oil, cultivation and cropping pattern of the soil.
The pore spaces are of two types: 1) Macro or non-capillary (more than 0.06 mm) and 2) Micro or capillary pores (less than 0.06 mm) having bigger and smaller sizes, respectively. Pore spaces between the aggregates of soil particles are macro spaces which are occupied by air and those between the individual particles of the aggregates are micro pores which hold the water. Macro pores allow rapid movement of air and water as water than micro pores. Proportion of macro and micro pores is important than total porosity.
Porosity of the oil can be calculated by formula:
Porosity = 100 – (Bulk density * 100)/ particle density = 100 ( 1 – BD/ PD.
Sandy soils have 30 – 40%, clayey 50 – 60% porosity.
Soil colour: Colour indicates, approximately, the organic matter content of soil. The soils have various shades of black, yellow, red and grey colors. It may vary with the depth or horizons. Factors responsible for colour are:
1. Parent material from which soils are formed. E.g.: Red sandstone impart red colour to the soil.
2. Organic matter content imparts brown to blackish colour to the soil.
3. Minerals present in soil. E.g.: titanium (darker), Iron compounds like hematite (red) and limonite (yellow), silica or lime (whitish or grayish).
4. Accumulation of alkali – salts. E.g.: White or black depending upon type of salts.
Soil colour is useful for classification, to indicate organic matter and fertility, aeration, drainage, salt accumulation.
Soil air: In the gaseous phase of soil, water and air compete for the same pore space and their volume fractions are so related that an increase of one generally decreases the other. The amount and composition of soil air are believed to affect plant growth. Field air capacity is the fractional volume of air in a soil at field capacity which depends on texture. E.g.: sandy (25% or more), Loamy (15-20%) and clayey (below 10%). The circulation of air in soil mass is known as soil serration which is influenced by temperature water and diffusion. Soil air greatly varies in composition or CO2 than N and O2 gases present in atmospheric air i.e. 0.2 to 0.3% in soil air and 0.33% in atmospheric air. This needs continuous exchange of gas to avoid accumulation of CO2 in the soil.
Soil temperature: It affects the crop growth and activity of micro organisms. Optimum soil temperature requirement for germination and plant growth varies with crops i.e. 9°C to 50°C. The functioning of micro-organisms in the soil is very active within a certain range of temperature (27-32 °C). The major source of heat is sun and heat generated by the chemical and biological activity of the soil is negligible. Temperature can be controlled by maintaining optimum moisture content, providing drainage, mulching, organic matter, cultivation practices.
Soil consistence: It refers to the degree of resistance of a soil material to deformation or rupture or crushing which depends upon the degree and kind of forces (adhesion, cohesion) which attract one molecule to another. Adhesion is the force between similar materials.The consistence of soil is influenced by nature of clay minerals, exchangeable bases and humus. Thus helps to decide the time and type of tillage operations required to bring the soil at good tilth. The consistency also depends on plasticity of soil which is the ability to the kolded into different shapes when a certain amount of force is applied and then to retain even when the forces is removed.
Soil strength: Soil strength or mechanical resistance indicates the resistance offered by the soil to root penetration. It depends on soil moisture i.e. increase with decrease in soil moisture content and vice-versa. Soil compaction and bulk density also affect the soil strength.Soil compaction and soil crushing are also other physical properties of soil. These reduce the bulk density. These are useful for proper agril. Implements for land preparation, germination of seed.
Soil organic matter: It is mainly derived from the dead parts of vegetation and animal i.e. plant and animal residues. It forms a very small but important portion (5%) of the solid phase of soil. Its composition varies with type of vegetation, nature of soil population, drainage, rainfall and temp. Condition and the land management practices. The role of organic matter in maintenance, development and improvement of soil is well known as it enhances microbial activity, improves physical condition and fertility of soil and thereby soil productivity, enhances buffering capacity, prevent loss of nutrients, improves water retention and holding capacity etc. organic matter of soil cn be increased by addition of residues, green manuring, crop rotation etc. It influences the C?N ratio of soil. It is affected by climate which decides the nature of vegetation.
Biological And Chemical Properties Of Soil
Biological properties of soil:
Soil is not a dead mass but an abode of millions of organisms, which includes crabs, snails, earthworms, mites, millipedes, centipedes. These feed on plant residues burrow the soil and help in aeration and percolation of water.
The soil organisms are of two types: Microflora and Micro fauna, Bactro Actinomycetes, Fungi and Algae relate to former and Protozoa, Nematodes relate to some of these have symbiosis with other organisms. They act on plant and animal residue and release the food material which in turn used by plants.
Chemical properties of soil:
These are pH of soil, cation exchange capacity; buffering capacity and soil colloids. These are having more significance in the crop production.
PH of the soil decides the soil reaction as acidic, neutral and alkaline. The crops in the tolerance to the soil reaction. PH also influences the availability of nutrients. These with less than 7 are acidic, 7 neutral and above 7 alkaline. Acidic and alkaline soils need reclaim for crop production by addition of soil amendments.
Agricultural Meteorology
Introduction to Meteorology
1.Aristotle [384-322B. C.] defined Meteorology as a study of lower atmosphere.
[Meteor- Lower atmosphere and logus- means science]
2. It is also defined as the science of atmosphere and its phenomena, especially those phenomena which we call collectively as weather and climate.
3. Meteorology can be defined as the Science of atmosphere which deals with the physics, chemistry and dynamics of atmosphere and also their direct and indirect effects upon the earth surface, oceans and thereby Life in general
Study of weather elements comes under Meteorology and this Science and with Animals Science also.
Climatology:-
It is defined as a scientific study of climate. It discovers, describes, & interprets the climate on the basis of causes processes that generate them or
Climatology is the science which studies average condition of weather or the state behavior of the atmosphere over a place or region for a long period of time.
Ecology:-
1. According to Taylor 1936. Ecology is the science of all relation of all organisms to all their environment.
2. According to 1957. Ecology concerned itself with the inter relationship of Living organisms and their environment.
3. In general ecology is a branch of biology that deals with the relation of living things to their surroundings.
Agricultural Meteorology and Its Levels
1. J.W. Smith (1916) has defined Agricultural Meteorology as “Meteorology in its relation to agriculture”
2. It can be defined as the science investigating Meteorology, climates and hydrologic condition, which are significant to agriculture.
3. In short Agril. Meteorology is the applied branch of meteorology, which deals with the relationship between climates, weather and life and growth of the cultivated plants and animals.
Levels of Study of Meteorology:
Study of meteorology is organized at three levels.
1. Micro scale:
A process operating within vegetation canopies near earth surface its size is in few cm and Life span is few seconds.
2. Mesoscale:
The systems are approximately 10km in size and a lifetime is of few hours [up to5 hrs] eg. Thunder storm.
3. Macro scale: It is divided into two scales.
A) Synoptic scale:
These systems have a diameter of few thousand km. and life time of about 5 days
Eg. Tropical storm, cyclones.
B) Planetary scale:
These systems have a diameter of 5000 to 10000km and persist for several weeks
Eg. Waves in the atmosphere circulation.
Importance And Scope Of Meteorology
Almost all social, industrial, agricultural, commercial, transports etc. Activities directly or indirectly are affected by weather and climate. The atmosphere affects and sustains human life, animal, micro- organisms, insects, pests, plants, tree’s forests and marine culture at all times during every stage of growth and development Meteorology has therefore, greatest scope on every human enterprise in the modern Life.
The fields of applications are given below to illustrate the scope of meteorology.
1. Safe Navigation:
For safe navigation on sea the knowledge of adverse weather i.e. large tidal waves, ocean waves, high speed wind, cyclonic storms etc is needed which is supplied in weather forecast from meteorology.
2. Safe aviation:
For transport through air, the pilots need the information about atmospheric conditions such as the electric lightening, high speed winds and their directions, thunder storms, foggy atmosphere etc. So pilots can go safely. For this purpose accurate forecasts are needed and are only possible from meteorology.
3. Industry:
Many industries for their raw material depend on agricultural produce and accordingly location of industry is decided, so it is necessary to consider the weather and climate e.g. sugar mill, distillery, jute mill etc.
4. Animal Production:
Beef, poultry and milk production also depend on weather and meteorology provides the information for successful animal production and animal husbandry.
5. Fisheries:
Fishermen need information of atmospheric and oceanic changes before they proceed on sea for fishing and this is possible from meteorological knowledge.
6. Irrigation and water resources:
Meteorological and hydrological information assists in planning the location size and storage capacities of dams to ensure water supply for irrigation and domestic needs. When and how much to irrigate is also decided from the meteorological information.
7. Land use planning:
The meteorological data supplemented with soil and topographic information help to plan the sites for the specific land use for drop production, forests, urban residence, industry etc.
8. Human Life:
Human being tries to acclimatize himself with the prevailing weather conditions, for this they manage for type of clothing, housing food habit etc.
8.1 Clothing:
Warm cloths during winter and thin cloth during summer are used.
8.2 Housing:
Direction of windows, doors for proper ventilation, roofing-plain in low rainfall region whereas. Slanting roof in the areas where rainfall is more and frequent in occurrence.
8.3 Food habits:
Heavy diet during winter season is recommended whereas during summer season more quantum of water consumption is needed.
9. Human health:
If any sudden change in the climatic conditions is experienced it results into equdemics of material fever. Asthma patent suffers more during cloudy conditions.
10. Commerce:
Trading of any item is made according to need of the people in relation to weather prevailing e.g. Gum shoes, umbrella and raincoats are generally traded in rainy season only, woolen cloths in winter season and white cotton cloths. Cold drinks etc. are in more demand in summer season.
Importance and Scope of Meteorology in Agriculture
Weather and climate is a resource and considered as basic input or resources in agricultural planning, every plant process related with growth development and yield of a crop is affected by weather.
Similarly every farm operation such as ploughing harrowing, land preparation, weeding, irrigation, manuring, spraying, dusting, harvesting, threshing, storage and transport of farm produce are affected by weather.
The scope of Agril Meteorology can be illustrated through the following few applications.
1. Characterization of agricultural climate:
For determining crop growing season, solar radiation, air temperature, precipitation, wind, humidity etc. are important climatic factors on which the growth, development and yield of a crop depends Agro-meteorology considers and assess the suitability of these parameters in a given region for maximum crop production and economical benefits.
2. Crop planning for stability in production:
To reduce risk of crop failure on climatic part, so as to get stabilized yields even under weather adversity, suitable crops/cropping patterns/contingent cropping planning can be selected by considering water requirements of crop, effective, rainfall and available soil moisture.
3. Crop management:
Management of crop involves various farm operations such as, sowing fertilizer application. Plat protection, irrigation scheduling, harvesting etc. can be carried out on the basis of specially tailored weather support. For this the use of operational forecasts, available from agro met advisories, is made
e.g. 1) Weeding harrowing, mulching etc are undertaken during dry spells forecasted.
2) Fertilizer application is advisable when rainfall is not heavy wind speed is<30 km/hr and soil moisture is between 30 to 80%
3) Spraying/dusting is undertaken when there is no rainfall, soil moisture is 90% and wind speed is<25km/hr.
4. Crop Monitoring:
To check crop health and growth performance of a crop, suitable meteorological tools such as crop growth models. Water balance technique or remote sensing etc. Can be used.
5. Crop modeling and yield –climate relationship:
Suitable crop models, devised for the purpose can provide information or predict te results about the growth and yield when the current and past weather data is used.
6. Research in crop –climate relationship:
Agro-meteorology can help to understand crop-climate relationship so as to resolve complexities of plant process in relation to its micro climate.
7. Climate extremities:
Climatic extremities such a frost floods, droughts, hail storms, high winds can be forecasted and crop can be protected.
8. Climate as a tool to diagnose soil moisture stress:
Soil moisture can be exactly determined from climatic water balance method, Which is used to diagnose the soil moisture stress, drought and necessary protective measures such as irrigation, mulching application of antitranspirant, defoliation, thinning etc. can be undertaken.
9. Livestock production:
Livestock production is a part of agriculture. The set of favorable and unfavorable weather conditions for growth, development and production of livestock is livestock is studied in Agril. Meteorology. Thus to optimize milk production poultry production, the climatic normal are worked out and on the suitable breeds can be evolved or otherwise can provide the congenial conditions for the existing breeds.
10. Soil formation:
Soil formation process depend on climatic factors like temperature, precipitation, humidity, wind etc, thus climate is a major factor in soil formation and development.
Weather and climate And Its Difference
Weather:
Weather can be defined as the physical condition or state of the atmosphere at a particular time and place.
Climate:
Climate is defined as generalized or average condition of weather of a place or region.
Or
Climate:
It is a composite or generalized of the variety of day to day weather conditions.
Difference between weather and climate
Sr No
Weather
Climate
1
Instantaneous physical state of atmosphere at particular place.
Normal physical state or generated condition of atmosphere or long term average condition of a place.
2
Weather changes refer to specific instant of time( day or week)
It is generalized over a longer span of time and for a longer area.
3
It is expressed in terms of numerical values of meteorological elements.
It is expressed in terms of time averages and area averages of meteorological elements.
4
Weather is measured in observatory. So the observatory must at a place for which weather is to be described.
This is derived information on regional basis. So scripts of observatories extending over a region are necessary.
5
No statistical treatment is applied to the meteorological elements. They are used as observed and hence always changing.
Application of statistical method over a longer period I done. It is more or less stable with few random changes.
6
it provides meteorological information.
It constitutes geographical information in respect of weather.
7
Weather of two places having same numerical value must be same.
Climate of the two places having the same averages of weather can not be same, because their distribution over the years may be different.
8
Weather can be categorized as fair, unfair, excellent etc.
Climate is classified as desert climate, marine climate, tropical climate etc.
9
Weather decides the success or failure of a crop in a particular season.
Climate decides the type of crop suitable for a region, while introducing new crops climate is considered.
10
Adverse weather results into crop failure or loss and warrants short term contingent planning.
Climate is considered in long terms agricultural planning.
Climatic Controls
The value of weather elements are modified by the interference of the factors of determining causes like latitude, altitude, etc. Such factors are called as climatic factors of climatic controls.
1 Latitude:
The most important influence of latitude is on temperature of a place Temperature tends to decrease with increase with increase in latitude. Places far away from the equator are colder than those near it. This is because the angle of the Sun’s rays decreases as we go to higher latitudes and also the rays have to pass through a greater distance of the atmosphere before they strike the earth’s surface. They have therefore less heating effect than the rays falling on the equatorial region.
2 Altitude: Pressure and temperature generally decreases with increase altitude, and the capacity of the air to hold moisture also decreases.
3 Topography:
Wind velocity primarily changes with change in topography which may result in Change in temperature
4. Mountains:
High mountain chains fact as a barrier to free flow of winds and divide one type of climatic zone from another. For example moist monsoon current of the Indian sub-continent is not allowed by the Himalayas to crossing into our country in winter.
5. Land and sea distribution:
Distribution of land and sea has a profound effect on climate. Places near the sea have moderate climate. On the other hand places for away from the sea are very hot in summer and very cold in winter. So they are said to have an extreme climate.
6. Oscan currents:
Ocean currents have a considerable influence on the climate of the coastal regions and Islands near which they flow. The warm currents tend to raise the temperature of the place while the cold currents make a place colder.
Earth’s Atmosphere
Meaning:
The dynamic layer surrounding the earth above its surface containing various gases, moisture, aerosols etc. is called atmosphere.
Definitions:
1. Atmosphere can be defined as the gaseous envelope surrounding the earth.
2. Atmosphere can be defined as a grand body from the earth surface to the outer space and composed of number of gases.
The estimated mass of the atmosphere is 5.6 x 1014 metric tones. It extends over about 400 km height and meteorological events and effects occur in it. The thickness of gaseous envelope is equal to 1% of the earth’s mean radius.
Usefulness of the atmosphere:
1. It fulfils the biological oxygen demand (BOD) of the animal life.
2. It supplies the necessary precipitation or moisture.
3. It protects the biological life on the planet from harmful extraterrestrial radiations like UV, by absorbing it though ozone.
4. It maintains the warmth of the plannet through its green house effect, avoiding the temperature to fall to too extreme limits.(The earth’s temperature in the absence of atmosphere would have been +950C (day),and -1450C (Night)
5. It provides the necessary CO2 which is basic input required to run photosynthesis process in plants to build biomass.
6. It provides the necessary medium for the transport of pollens. Seeds spores and insets.
7. Many physical chemical and hydrological processes responsible for weather and climate occur in atmosphere only.
8. Atmosphere is a big reservoir of nitrogen. Some plants and microbes can fix this nitrogen for plant growth eg, Azolla pinara Azotobacter.
Composition of the atmosphere:
The various constituents of the atmosphere can be divided into following three categories.
Structure of Atmosphere,
1
GASES
Moisture
Solid impurities or Aerosols
1.
Nitrogen(N2)
Water Vapour
1
Dust particles
2.
Oxygen(O2)
2.
Carbon particles
3.
Argon (Ar)
3
Salt particles
4.
Carbon dioxide (CO2)
4
Water droplets and ice crystals.
5.
Ozone (O3)
5.
Spores
6.
Sulphur dioxide (NO2)
6.
Pollen grains
7.
Nitrogen dioxide (NO2)
8.
Ammonia (NH3)
8.
Smoke
9.
Carbon monoxide
(CO2)
10
Neon (Ne)
11
Helium (He)
12
Hydrogen(H)
13
Krypton(K1)
14
Xerox(Xe)
15
Melhane)(CH4)
16
Nitrous oxide(N2O)
17
Radon(Rn)
Aerosols
There exists different solid partials like dust, organic particles like carbon , inorganic particles like salt and also some liquid particles(Water droplets and crystals) which remain suspended in the atmosphere. There particles are dispersed in the atmosphere and are dispersed in the atmosphere and are known as aerosols.
Non Variable and Variable Components
1. Non-variable components:
Some gases of the atmosphere remain constant at surface of globe up to the height of 80 to 88 km. This is due to transportation of gases on continental* level, diffusion of gases, turbulent mixing and convection.
These gases are called non-variable components.
They are Non-variable components (permanent constituents)
Sr.No
Constituents
Symbol
Percentage by volume
1
Nitrogen
N2
78.084
2.
Oxygen
O2
20-946
3
Argon
Ar
0.934
4
Carbon dioxide
CO2
0.032
5
Neon
Ne
18.18x10-4
6
Helium
He
5.24x10-4
7
Crypt on
Kr
1.14x10-4
8.
Xenon
Xe
0.087x10-4
9.
Hydrogen
H2
0.5x10-4
10.
Methane
CH4
1.5x10-4
11.
Nitrous oxide
N2O
0.5 x 10-4
12
Radon
Rn
6 x 10-18
1. Variable components:
Some gases or components of the atmosphere ch anges with change with change in time, palce, season etc, and these components are called as variable component they are-
Variable components or constituents:
S.N.
Constituents
Symbol
Percentage by volume
1
Water vapour
H2O
<4
2.
Ozone
O3
<0.07x10-4
3.
Sulphur dioxide
SO2
<1x10-4
4.
Nitrogen dioxide
N02
<0.02x10-4
5.
Ammonia
NH3
1 race
6.
Carbon monoxide
CO
~0.2x10-4
7.
Dust (Salt2 Soil)
<10-3
8.
Water (liquid & solid)
Compositional layering of the Atmosphere
The atmosphere can be divided into two spheres on the basis of its chemical composition occurring with height i.e. (1) Homosphere. (2) Hereto sphere.
Homosphere:
In the lower region up to the height of 88 km the various gases are thoroughly mixed and are homogenous by the process of turbulent mixing, and diffusion. This sphere is called as Homosphere. Herein the presence of gases is governed by the diffusion and the composition remains normally.
Hydrosphere:
In hydrosphere gaseous composition changes and various gases form separate compositional layering individually.
Satellite data have shown the presence of different chemosphere in follows:
1
Nitrogen and oxygen
From 88 to 115 km
2
Automatic oxygen layer
From 115 to 965 km
3
Helium layer
From 965 to 2400 km
4
Hydrogen layer
From 2400 to 10,000 km
The distribution of the gases is governed by the earth’s gravitational field. Thus heavier gases sink downward while the lighter gases like hydrogen remain at higher altitude.
Physical Structure Of Atmosphere
(Stratification of atmosphere or layering of atmosphere)
On the basis of the vertical temperature difference, the atmosphere can be divided into four horizontal layers or shells, namely.
A) Lower Atmosphere: 1. Troposphere and 2. Stratosphere
B) Upper Atmosphere: 1. Mesosphere and 2. Thermosphere.
A) Lower Atmosphere:
1. Troposphere:
The altitude of the troposphere changes according to latitude. It has an elevation of about 16 km at the equator and only 8 km at the poles. Its average altitude is about 11 km. It contains near about 75% of the gaseous mass of the total atmosphere, water vapour and aerosols. It is the realm of clouds, storm and convective motion, The outstanding characteristic of the troposphere is the filmy uniform degree in temperature with increase in altitude until minimum temperature of -50% 0C-------600C is reached. The isothermal layer marking the end of temperature decrease is called tropopause and it separates troposphere and stratosphere. Through out the troposphere there is a general decrease of temperature with increase in height at a minimum rate of about 6.50C/km or 3.60F/1000 ft.0C
2. Stratosphere:
This is the second atmospheric layer above trop pause which extends upwards about 50 km. The stratosphere contains much of the total atmospheric ozone. The density of ozone is maximum at 22 to 24\5 km height approximately. The ozone at the upper layer of this sphere absorbs the ultraviolet rays from the Sun and temperature may exceed 00C. In stratosphere the temperature increases with increase in height.
B) Upper Atmosphere:
1. Mesosphere:
This is the third layer of atmosphere. A thin isothermal layer called a stratopause is the boundary layer, which separates stratosphere and mesosphere. Above the warm stratopause, temperature decreases with increase in height to a minimum of about-900C at about 80 km height Pressure in this layer is very low and decreases from 1 Mb at about 50 km to about 0.01 mb at 80 km nearly. The thin isothermal layer, which separates mesosphere from thermosphere, is called mesopause.
2. Thermosphere:
Outermost shell is known as thermosphere. It lies above 80 km height . In this sphere the atmospheric densities are extremely low. In this sphere temperature increases with increase in height due to absorption of ultraviolet radiation from the Sun. probably it reaches to 9500C at 350 km to 17000 C at an underfined upper limit but these temperatures are essentially theoretical. Such temperatures are not felt by the hands exposed by astronaut or the artificial satellite because of rarefied air.
Solar Radiation And Its Terms
Agriculture is the exploitation of solar energy under adequate supply of nutrients and water by maintaining plant growth. So it is but natural that any efforts of thoroughly understanding of solar radiation will be immense use for its fullest exploitation by the crop plants in terms of their growth and yield.
The sun is the primary source of energy. Supplying about 99.9% out of total energy available at the earth surface. The temperature of the Sun is 6000 K and gives out energy about 5.6 x10 27 cal per minute. The Sun radiates its energy in the form of wave lengths from 0.15 to 4.0 u and are generally called as short wave lengths. On contrary after absorption of solar energy, earth emits its energy between 4 to 100 u and is categorized as long wave length.
There are three methods of transfer of heat or energy that means there are three different ways by which heat can flow from one point to another are:
1. Conduction
2. Convection
3. Radiation.
For conduction and convection of heat, material medium is necessary. But for radiation material medium is not necessary, because radiation takes place in the form of Electro magnetic waves.
The ultimate source of all the energy for physical and biological processes occurring on the earth is radiation received from the sun that is why it is commonly called solar radiation.
Some Terms (Definitions):
1. Radiation:
The transfer of heat energy in the form of electro magnetic waves with the speed of light is known as radiation (Light speed is 3x105 km/second).
2. Solar insulation:
The heat energy received from the Sun is known as solar insulation.
3. Radiant flux density:
It is defined as the amount of energy received on a unit surface in a unit time. ( In Meteorology we commonly use cal cm -2 min or largely min -1 as the unit of radiant flux density)
4. Emissive:
It is defined as the ratio of the emittance of a given surface at a specified wave length and temperature to the emittance of an ideal black body at the same wave length and temperature.
5. Absorptive:
It is defined as the ratio of the amount of radiant energy absorbed to the total amount incident upon the substance.
6. Reflectivity:
Is defined as the ratio of the radiant energy reflected to the total that is incident upon the surface.
7. Transmmissivity:
Is defined as the ratio of the transmitted radiation to the total radiation incident upon the medium.
8. Short wave radiation (SW):
Radiation with wave length range 0.15 to 0.76 u is known as short wave radiation.
9. Long wave radiation:
Radiation with wave length range 0.76 to 100 u is defined as long wave radiation.
Laws Of Radiation
The radiation reaching to the earth surface from the sun, atmosphere and from earth to atmosphere, space follows certain physical laws known as radiation laws. They are
Plank’s Law:
The Electro magnetic radiation consists of a stream or a flow of particles or quanta. Each quantum having energy content
E=hv. Where, h=Plank’s constant (6.625x1027 ergs sec-1)
V=frequency of Electro-magnetic length.
Greater the frequency (i.e. shorter the wave length) greater is the energy content of the quantum.
Stefan Boltzman’s Law:
The intensity of radiation emitted by a radiating body is proportional to the fourth power of its absolve temperature.
E=ST
Where E=Emissive of the body
S=Stepen’s constant (5. 67x10-8W m-2.K-4)
T=surface temp of the body in absolute 0K
3. Weins displacement Law:
The wave length of maximum intensity of emission is inversely proportional to the absolute temp, o f that body.
µ Max (um) =2897 T
For example, the temp. of earth surface is 2870K then its peak emission will be close to 10 µ similarly for the sun having temp, of 6000 0K it will peak at 0.5π
Kirchoffs Law:
Kirchoffs Law state that the absorptivity of a material for a radiation of a specific wave length is equal to its emissivity for the same wave length at same temperature.
Solar Constant
The solar constant is a measure of the rate at which solar wave radiation is received at the rop of the atmosphere on a unit surface unit time.
It is customary to express the solar constant in terms of cal. cm2 min and a value of 1.94 or 1.95 cal cm2 /min has been generally accepted Recent measurements suggest that it might be slightly higher i.e. 2.0 cal/cm2/min and that there is some slight variability mainly because of fluctuations in the ultraviolet rays.
Albedo
The term albino is usually defined as the fraction or percent of the reflected solar radiation from the surface to incoming solar radiation.
Thus, it is usually refers to the reflectivity of a particular band or portion of the spectrum.The albedo of the whole earth and atmospheric system approximates 35%
Albino is also defined as the ratio of reflected radiations to the total incident radiation.
Green House Effect
Out of the total solar radiation about 47% is absorbed at the earth surface. As a result the earth becomes hot and starts re-radiating long wave radiation. The exchange between the sky and the terrestrial radiation is largest governed by the atmospheric gases. The important principle is that the short wave lengths of the radiation’s from the sun can penetrate the atmosphere without being fully absorbed. These short radiation’s fall on ground, they heat it , and ground starts no- radiating long wages, The long waves emitted by the earth are absorbed in the atmosphere by water waves emitted by the earth are absorbed in the atmosphere by water vapour, CO2 and Ozone. On absorption of earth radiations these gases become warmer and in turn they again radiate the heat in still longer waves towards the earth This also increases the earth’s warmth.
The gases namely water vapour, CO2 and Ozone allows the solar radiations categorized as solar short waves to pass through the atmosphere towards the earth and not allow to escape the long waves radiations from the earth is known as green house effect.
This heat retaining behavior is similar to the roofed glass or green house used for experiment.
The atmospheric green house effect keeps the earth warm and does not allow its temperature to fall. The mean temp, of the earth is 150C since long and is maintained by green house effect.
Radiation Balance Or Net Radiation
The net radiation is the difference between the total downward and upward radiation fluxes and is a measure of the energy available at the ground surface. The balance of energy after gain and loss of both short wave and long wave radiation fluxes is known as net radiation.
Net radiation represents the amount of energy, which is used for various kinds of activities. It is dispensed as sensible heat, latent heat and also in physiological processes such as photosynthesis and respiration.
The importance of this parameter is that it is the fundamental quantity of energy available at the earth’s surface to drive he processes of evaporation, air and soil heat fluxes as well as other smaller energy consuming processes like photosynthesis etc.
If we consider the extra terrestrial radiation reaching annually (338wm-2)as 100%; Then out of this-
The net radiation reaching (SW) =100-28+25)-47% the earth surface. =114%
Long wave radiation reaching at earth surface =+96%
Therefore, Net long wave radiation =-114+96 = -18%
Net all wave radiation at earth surface =+47-18 = 29%
This surplus energy is used at the earth surface for
a) Sensible heat (QH) =4%
b) Latent heat (Eva)(QE)=25%
-----------
29%
Factors Affecting Solar Radiations
The amount of insulation received at particular place and time depends on the following factors:
1. Distance from the sun.
2. Duration of daily sunlight period.
3. Solar elevation or inclinations of the solar rays to the horizon.
4. Transparency of the atmosphere towards heat radiation and
5. Output of solar radiation.
The first three of these reasons are intimately connected with revolution of earth, It is to be noted here that the earth revolves about the sun in elliptic orbit and makes one complete revolution in 365 days, simultaneously it spins about itself and complete one rotation in 24 hrs.
The average distance of the earth from the sun is 149.5 million km).
The duration f daylight also varies with the latitude and season. Longer the day light duration, greater is the insulation received, In the solar region the duration of day light is 24 hrs during summer and minimum of zero in winter season.
Significance Of Radiation In Agriculture
The importance of the radiation in crop production is as follow:
1. It provides the necessary energy for all the phenomena concerning biomass production.
2. Photo synthetically Active Radiations (PAR) are the real source of energy for photosynthesis process. Plants are the efficient biological converters of solar energy into biomass. Radiation defines the yield of crop in particular region.
3. It laso provides the energy for the physical processes taking place in plants, soil and atmosphere.
4. It conditions the distribution of temperature and hence crop distribution on the earth surface.
Atmospheric Temperature
Definition:
The degree of hotness is known as temperature increases.
Temperature is a fundamental elopement of climate from many points of view, the most important in controlling the distribution of life on the earth. Most of the weather elements are dependent on it, directly or indirectly. Air of atmosphere receives the heat energy from the sun and its temperature increases. Due to different amount of heat energy receipt at different places, the air temperature at different places also vary. The variation in air temperature basically results into air motion, so as to equalize the energy content of the different regions of the earth. Thus temperature of air can be regarded as the basic cause for weather changes.
Qualification of Atmospheric Temperature:
Atmospheric temperature is continuously changing; it is never steady or constant for a long time. Therefore quantification of atmospheric temperature is very important aspect. The atmospheric temperature can be quantified in the following ways.
1. Maximum temperature:
It is the highest temperature attained by the atmosphere in diurnal variation.
2. Minimum temperature:
It is the lowest temperature attained by the at by the atmosphere in diurnal variation.
3. Average temperature:
It represents the average temperature condition of the atmosphere during 24 hours of the day.
Temperature Variation
Air temperature at any location is changes during a day, week, month, year or for any period. On this basis it is classified as-
A Periodic variation.
1. Annual temperature variation or Annual temperature cycle.
2. Diurnal temperature variation or Daily temperature cycle.
B. Horizontal variation
C. Vertical Variation.
A) Periodic Temperature Variation:
The temperature continuously changes during a day, week, month, year or any period and this change is called periodic temperature variation.Periodic temperature variations are -
1. Annual temperature variation or Annual temperature cycle:
The annual temperature Variation gives rise to seasons i.e. summer and winter. The annual temperature range varies greatly from place to place. It reflects the daily increase in insulation from mid-winter to mid-summer and decrease in the same from mid-summer to mid-winter summer and decrease in the same from mid-summer to mid-winter usually there is a temperature lag of 30 to 40 days after the period of maximum and minimum insulation
In the Northern hemisphere winter minimum occurs in January and summer maximum in July and vice versa in the southern hemisphere. The smaller range occurs near equator and largest in high latitudes. The difference between the highest and lowest temperature for a given period is known as temperature range. In the northern hemisphere it is summer from 21st of March to 22nd of September and winter from 23rd September to 20th March and vice-versa in southern hemisphere.
2. Diurnal Temperature Variation or Daily Temperature Cycle.
The Diurnal Temperature Variation give rise to daily maximum and Minimum temperatures.
From the sun-rise, sun energy continuously supplied and the Temperature continuously rises, recording maximum at about 2.00 to 4.00.P. m. though the maximum amount of solar radiation is received at the solar None (i.e. 12.00 hrs). This delay in occurrence of maximum temperature is Caused by gradual heating of the air by convective heat transfer from the Ground which is known as thermal lag or thermal inertia.
Similarly minimum air temperature occurs shortly offer sunrise due to lag in transfer of heat form the surface to the air / space.
B Horizontal Temperature Variation:
The rate of change of change of temperature with a horizontal distance is known as Temperature Gradient.
Maximum solar energy is received in equatorial region and therefore and Therefore highest temperatures are observed in equatorial region. As the latitude Increases the solar energy received on the earth correspondingly decreases and so also temperature decreases with increase in latitude being lowest on the pole.
The Sum crosses the equator twice in a year therefore two maxima And two minima are observed in annual cycle. Outside this zone only one Maxima and one minima is observed.
Isotherm:
Isotherm is defined as the line on the weather map joining the places of equal temperature.
C.Vertical Tempe ration Variation:
Vertical temperature variation does not show uniform behavior and The atmosphere can be divided into four spheres.
1. Troposphere - Temperature decreases from 150 C at earth surface up to - 60 0C at 11 km height.
2. Stratosphere - Temperature increases from -600C to 00C at 50km Height.
3. Mesosphere - Temperature fall and reaches about -900C at 80 km Height.
4. Thermosphere- Temp increases. Due to absorption of solar radiation by
Atomic oxygen, up to 9500C at 350 km height and 17000C at undefined upper Limit.
Factors Affecting The Air Temperature
The distribution of temperature over the earth surface depends on following factors:
1. Latitude:
Highest temperatures are generally at the equator and the lowest at the poles. The temperature decreases with the increase of latitude.
2. Altitude:
Temperature decreases with height in troposphere.
3. Season:
Coldest temperatures are in winter and highest temperatures are in summer seasons.
4. Distribution of land and water:
Water bodies are great moderators of temperature. Because of high Specific heat of water, so on the oceans, the regularity in temperature is more as compared to continents.
5. Topogrtaphy:
Mountain ranges affect the temperature by acting as obstacles to the Flow of cold air cold air near the surface and they often set conditions of warm winds.
6. Ocean currents:
Hot and cold ocean currents affect temperature e.g. Gulag Stream (Warm) in North Atlantic, Benguela current (cold) along West coast of South Africa, Peru Current (cold) along West Coast of South America.
7. Winds:
Various types of wind affect temperature.
8. Clouds and rains:
Clouds by obstructing the heat from the Sun and rains by cooling the Atmosphere, affect the temperature.
9. Color of the soil:
Black color of soils absorbs more radiations and other types reflect them.
10. Slope of the soil:
Black color of soils absorbs more radiations and other types reflect them.
11. Forest and vegetation:
Due to Evapotranspiration and interception of sun – rays, temperatures are moderated.
Soil Temperature And Its Importance
The Soil mantle of the earth is indispensable for the maintenance of plant life, affording mechanical support and supplying nutrients and water.
Soil constitutes a major storage for heat acting as a sink of energy during the day and source to the surface at night. In annual terms the soil stores energy during the warm season and releases it to air during the cold portions of the year.
Importance of Soil Temperature:
1. In affects plant growth directly, that is all crops practically slow down their growth below the soil temperature of about 90C and above the soil temperature of above 50 0C.
2. For germination of different seeds requires different ranges of soil temperature e.g. maize begins to germinate at soil temp of 7 to 100C.
3. Most of the soil organisms function best at an optimum soil temperature of 25 to 350C
4. The optimum soil temperature for nitrification is about 320C.
5. It also influences soil moisture content, aeration and availability of plant nutrients.
Variations of Soil Temperature
There are two types of Soil Temperature:
1. Daily and Seasonal Variation of Soil Temperature.
a) There variations occur at the surface of the soil.
b) At 5 cm depth the change exceeds 10 0C At 20 cm the change is less and at 80 cm diurnal changes are practically nil
c) On cooler days the changes are smaller due to increased best capacity as the soils become wetter on these days.
d) On a clear sunny day a bare soil surface is hotter than the air temperature.
e) The time of the peak temperature of the soil reaches earlier than the air temperature due to the lag of the air temperature.
f) At around 20 cm in the soil the temperature in the ground reaches peak after the surface reaches its maximum due to more tune the heat takes to penetrate the soil. The rate of penetration of heat wave within the soil takes around 3 hours to reach 10 cm depth.
g) The cooling period of the daily cycle of the soil surface temperature is almost double than the warning period.
h) Undesirable daily temperature variations can be minimized by scheduling irrigation.
Seasonal variations of Soil Temperature:
a) Seasonal variations occur much deeper into the soil.
b) When the plant canopy is fully developed the seasonal variations are smaller.
c) In winter, the depth to which the soil freezes depends on the duration and severances of the winter.
d) In summer the soil temperature variations are much more than winter in trophies and sub trophies.
Thermal Properties Of Soils
1. Specific heat (Mass specific heat):
It is the amount of heat required to raise the temperature of one gram of substance by 1 0C. The values for most minerals present in the soil are between 0.18 to 0.20 cal/gm.
2. Heat capacity (volume specific heat):
It is the amount of heat required to raise the temperature of one cubic centimeter substance by 1 0C .Most soils have a heat capacity in the range of 0.3 to 0.6 cal/Cm3.
3. Thermal conductivity:
It is defined as the quantity of heat transmitted through unit length of substance per unit cross section, per unit temperature gradient per unit time.
Thermal conductivity is the ability of the substance to transfer heat from molecule to molecule to molecule. For this reason it is sometimes called inolcular conductivity. It varies with porosity, moisture content and organic matter content of soil. It is expressed in Jm-1 s-1 K-1
4. Thermal diffusivity:
Thermal diffusivity is the ratio of the thermal conductivity to volume specific heat.
Thermal diffusivity = Thermal conductivity/ Volume specific heat
Daily And Seasonal Patterns Of Soil Temperature
The range of soil temperature in summer and winter decreases with increasing depth. At 40 cm depth the change is very minor and at 81 cm no diurnal change occurs.
In summer soil temperature decreases with depth during the day time.Temperature gradients direct heat into the soil. At night hours the temperature is highest between 20 and 40 cm, and from that level heat is directed both upward and downward.
In winter the 81 cm depth is warmer and the diurnal change is still very minor at 40 cm depth. Heat is transferred upward from those levels though out the day and night, because of the low radiation intensity in winter. The daily range of surface temperature is very small; however the range is still greater at the surface than any below level. Only during the hours near noon does heat penetrate into the soil from the surface.
Soil Temperature Profiles
The heat is continuously moving in to or out of the soil and thermal energy is being continuously redistributed in the soil. Heat will not flow under isothermal condition.
The pattern of soil temperature profiles changes rapidly during & normal day. The soil surface is the coldest level in the early morning and the warmest in the early afternoon.
At midday heat is directed downward through the upper one metro soil. The profiles show that the heat exists from middle of the layer after sunset but some heat flow continuously downward throughout the night. During most of the day temperature profile indicate downward heat flux. This is summer there is a net daily gain or storage of heat in the soil.
Factors Affecting The Soil Temperature And Its Control
1. Solar radiation:
The amount of heat from the Sun that reaches the earth is 2.0 cal/cm2 min -1 the amount of radiation received by the soil depends on angles with which the soil faces the Sun.
2. Condensation:
Whenever water vapour from soil depths or atmosphere condenses in the soil, its heat increases noticeably.
3. Evaporation:
The greater the rate of evaporation, the more the soil is cooled.
4. Rainfall:
Rainfall cools down the soil.
5. Vegetation:
A bare soil quickly absorbs heat and becomes very hot during the summer and become very cold during the winter. Vegetation acts as a insulating agent. It does not allow the soil to become either too hot during the summer and two cold during the winter.
6. Colour of the soil:
Black colored soils absorbs more heat than light closured soils Hence black color soils are warmer than light colored soils.
7. Moisture content:
A soil with higher moisture content is cooler than dry soil.
8. Tillage:
The cultivated soil has greater temperature amplitude as compared to the uncultivated soil.
9. Soil texture:
Soil textures affect the thermal conductivity of soil. Thermal conductivity decreases with reduction in particle size.
10. Organic matter content:
Organic matter reduces the heat capacity and thermal conductivity of soil, increases its water holding capacity and has a dark color, which increases its heat absorbability.
11. Slope of land:
Solar radiation that reaches the land surface at an angle is scattered over a wider area than the same amount of solar radiation reaching the surface of the land at right angles. Therefore, the amount of solar radiation reaching per unit area of the land surface decreases as the slope of the land is increases.
Soil temperature can be controlled by:
1. Regulating soil moisture.
2. Proper soil management practices so a to have good drainage.
3. Application /use of mulching.
4. Sufficient addition of organic matter.
Air Pressure
Definition:
Atmospheric pressure can be defined as the weight exerted by air column on units surface of the earth.
Units of pressure:
1. Height of mercury column measured in inches, cm, and mm
2. Bar, bar is a force equal to 106 dynes/cm2
3. SI (standard International) unit or pressure is Pascal
1. Pascal = force of 1 Newton/m2
= 1 N m2
Standard atmospheric pressure:
The standard atmospheric pressure is given at mean sea level at 450K latitude and at temperature of 2730K
Standard Atmospheric = 29.92 inches or 76 cm or 760 mm
Pressure = 1013.25 mb
= 101.325 kilo Pascal (Kpa)
= 14.7 lbs/inch2
1.014 x 106 dynes/cm2
Isobar:
Any line joining the places of equal atmospheric pressure on the weather map is known as isobar. Where isobars are closely spaced, a rapid of steep change in reassure is indicated. When isobars are widely speeding, a slow change in pressure is indicated. Two isobars are never cross each other. Isobars are plotted on the map to show the distribution of pressure. The isobars are drawn at pressure intervals of 2, 3,4 or 5 mb.
Pressure gradient:
The rate of change of atmospheric pressure per unit horizontal distance between two points at the same elevation is known as pressure gradient or isobaric slope. This change tak3es place and is measured in the direction perpendicular to the isobars preferably from high to low pressures. This exerts a force on air particles and is important in determining the strength of wind. The pressure gradient is expressed in decrease in pressure per unit horizontal distance as mb/100 meters.
Variation in Atmospheric Pressure
1) Variation with height or vertical variation:
The pressure depends on the density or mass of the air. The density of air depends on its temperature. Its composition and force of gravity. I t is observed that the density of air decreases with increase in height so the pressure also decreases with increase in eight.
The pressure at sea level is 1013.25 mb at 50 km height it becomes 0.93 mb and 80 km it is only 0.03 mb. This indicates how rapidly the atmospheric gas becomes thinner to decrease density and so the pressure. The pressure decreases on an average at the rate of about 34 mb per every 300 meters height.
2) Horizontal variation of pressure:
The horizontal variation of atmospheric pressure depends on temperature, extent of water vapor, latitude and land and water relationship.
i)The equatorial low pressure belt :
Along the equator lies a belt of low pressure known as the equatorial low or doldrums or calm. This low pressure belt lies between 50 North and 50 South latitudes.
ii) Sub – tropical high pressure belt:
The high pressure belt are found between 24 – 300C latitudes in both the hemispheres.
iii) Low pressure belts near 600 latitudes:
The airs from this area get thrown outwards on account of the rotation of the earth and this is how the low pressure belts are created.
iv) Polar high pressure belts:
The temperature is extremely low in the Polar Regions. The air being cold and heavy throughout the year a high pressure belt is created in both Polar Regions.
3. Diurnal variation:
At a given station the pressure show the two high and two lows. On normal pressure day two maxima i.e. one at 10 a.m. and another at 10 p.m. and two minimasi.e. one at 4 a.m. and another at 4 p.m. are observed. Thus there is double oscillation caused by alternate heating and cooling of atmosphere.
Factors affecting atmospheric pressure:
1. Temperature of air
2. Altitude
3. Water vapour in air
4. Revolution and gravitation of the earth.
Wind And Its Importance
Definition:
The air that moves parallel to any part of the earth surface is called wind or The air moving horizontally on the surface of the earth is known as wind.
Air Current:
Vertically or nearly vertical movements of air resulting from convection ,turbulence or any other cause is known as air current.
Importance or Role or Effects Of Wind In Agriculture:
1. Wind increases the transpiration and intake of CO2
2. The turbulence created by wind increase CO2 supply and the increase in photosynthesis.
3. When wind is hot, desiccation of the plants takes place, because humid air in the inter cellular places is replaced by dry air.
4. The hot and dry wind makes the cells expanding and early maturity, it results in the dwarfing of plants.
5. Under the influence of strong wind the shoots are pressurized and get deformed.
6. Strong winds produces loading of crops.
7. The coastal area affected by strong wind bring salt and make the soil unsuitable for growing plants.
8. Strong winds affect the plants life both mechanically and physiologically.
Wind Direction and Wind Speed
A wind is named according to the direction from which it blows e.g. a wind coming from west is called west wind.
The direction from which wind blows is termed as windward direction and that to which it blows is termed as leeward direction.
Classification of Wind
Vertical current
Horizontal
Periodic
Regular
Local
1. Divergence
1.Monsoon Winds
1. Planetary Earth’s general circulation
1.Land and sea breeze
2. Convergence
2. Mountain and valley breeze
3. Eddies
3. Foehn/Chinnook winds
4. Convection
4. Tomadoes
Earth’s general circulation system (Surface wind)
The earth’s surface wind system or earth’s general circulation of wind can be represented by a simple model shown in fig. In this model, the earth surface been considered uniform, means either all and or all water and the effects of local systems have been ignored, therefore the actual wind system is much more complicated than the described in the model.
It is to be noted that unequal heating of the earth’s surface generate pressure gradient which give rise to wind. There are three latitudinal circulations and there are also important longitudinal variations around each hemisphere.
1. Trade winds:
The condition of greatest heating and expansion at the equator causes rising of air and creating low pressure belt (50 N to 50S latitude) known as doldrums or equatorial low or calm. The rising of air from equator causes increase in pressure at 350 N 350S which is known as sub-tropical high or Horse latitude belt. The winds therefore flow from horse latitude belt. The winds therefore flow from horse latitude to the equatorial region called “Trade winds” While moving these winds, they are deflected by corollas force to the right in the and nor them hemisphere and to left in southern hemisphere and become North – East trades and south –East Trades in northern and southern hemispheres respectively.
The blow of air from equator and accumulation of air over 25-35 0 latitudes giving rise to high pressure belt region of descending air is known as Hadley cell.
2. Westerlies wind:
There situated at about 600 – 650 latitudes a low pressure area in both the hemisphere is known as sub-polar low or polar front. The winds that flow from sub-tropical high pressure area (Located at 250 - 350 latitude in both the hemisphere ) to the low pressure area, situated at about 600 - 650 latitude in both the hemisphere, are known as Westerlies or prevailing wisterias ( anti trade winds) In the upper atmosphere the reverse air movement takes place. This circulation is known as feral cell. These winds instead flowing in straight line are deflected due to corollas force. In northern hemisphere their direction is North – West and in southern hemisphere it is South-West.
3. Polar winds or Polar Easterlies winds :
Near the poles due to shrinkage of air and due to cooling, there exists permanent high pressure on the poles. Therefore winds flow from the polar high to sub-polar low pressure area at about 60-650 latitude. The wind flow in North-East direction in northern hemisphere and in south-East direction in southern hemisphere. These winds consist of clod air. The air circulation is known as polar cell.
Local Winds:
These winds are generated due to local condition and hence influence over very small area, therefore such winds are called local wind.
1. Land and sea breeze :
An interchange of air between the sea and coastal land due to unequal heating and cooling is known as land and sea breezes. They are local in nature. During day time the coastal land and sea breezes.. They are local in nature. During day time the coastal land as heated very fast as compared to sea water causing low pressure over the land. Therefore the surface air blows from sea to land and this is known as sea breeze. While during night time, the land cools faster than the sea, causing high pressure area over land as compared to sea. Therefore air blows from land to sea and this is known as land breeze.
2. Mountain and valley breeze:
An interchange of air between the mountain and valley due to unequal heating and cooling of the two places is known as mountain and valley breeze. During daytime, the valley breeze. During daytime, the valley floors become more heated; the air over it expands and rises. This rising air slides up the mountain slope and is known as valley breeze. During night reverse process takes place. Due to cooling of the air in the valley contracts and consequently augmented by air from the neighboring hills and mountains. The air on the mountain slopes also cools and slides down into the valley which is known as mountain breeze.
3. Ketabatic winds:
A mass of cold air over an elevated plateau during the winter tends to become more dense through radioactive cooling and then will drain down the slopes into the valleys below. The resulting down slope, drainage type winds are called Ketabatic winds. Most are relatively gentle breezes, not exceeding 4 to 5 m/s occasionally how ever, the cold dense air may be set in motion by a migrating cyclone or anticyclone and the Ketabatic winds may then attain destructive violence.
Foehn Winds
The Foehn winds is a down slope flow of air that occurs in manyu mountainous areas but is it not caused by the drainage of dense air, It occurs when the prevailing winds in warm, moist air are directed against a mountain. The forced ascent on the windward side, as illustrated in fig given below, usually causes cloud to form, Frequently, precipitation will also occur. During most of this ascent the air is cooled at the moist mountain top, much of the moisture may have been removed. This means that the air at the top has absorbed the latent heat released by the condensation of the moisture it contained. As the air descends the lee slopes, it is warmed at the dry adiabatic rate (100C/km). When it arrives at the bottom of the mountain, the air is warmer than at the same elevation on the windward side, having been heated by the latent heat of condensation. It is also drier because it has lost some of its moisture through condensation and/or precipitation on the windward mountain slope.
The Indians on the lee slopes of the Rockies referred to the wind as snow eater,” encase of the starting way in which large amount of snow could be melted and evaporated by the warmth and dryness of the air.s
Monsoon Wind
An interchange of air between the land and oceans due to unequal heating and cooling of continents and oceans is known as monsoon winds.
It has an annual period of occurrence. During summer, the land is heated Very much as compared to the oceans which cause which oceans low pressure Over the land and the winds blow from the oceans to the continents. During winter, land cools down faster than the oceans causing high Pressure over continents and low pressure over the oceans and the wind Blows from continents to oceans. The Indian monsoon is the best known Example of this alternating circulation system. There are two types of Monsoons over India i.e. south – west monsoon and North- East monsoon.
1.South – West Monsoon:
India is positional situated in North – East trade winds and should have N- E winds throughout the year, but a low pressure through lies along the Ganges and upper India, due to which S.- W winds predominate. During April to September a low pressure center is formed over N – W India. The s-W trade winds of the Indian ocean blow to the equator and then turning to the right under carioles force and move on a S – W winds Around the low pressure center over India. [This monsoon blows from the African coast (150E)]. The moisture laden air while rising the mountain of Asia cools, condense and precipitate. As a result the pressure is lowered to increase the pressure gradient.
2. North – East Monsoon:
Complete reversal of the S – W monsoon winds takes place as the high pressure centre is located in eastern Asian (1035 mb) and low in about 1010 mb. During this time from North to South the cold season is established. This monsoon is active during October and November. The winds flow in North- East direction. This wind is generally dry but gives rains to AP, TN states. Monsoon winds also exist over west Africa, Brazil, eastern USA, Australia. Philippines etc.
Forces Acting to Produce Wind
Wind is motion of air in response to unbalanced forces acting in horizontal direction. The different forces involved in the flow of the wind are described below:-
1. Horizontal pressure gradient (PG) force:
The rate of change in atmospheric pressure between two points at the Same elevation is called the pressure gradient or isobaric slope. It is proportional to the difference in pressure and is the immediate Cause of horizontal air movement. The direction of air flow is from high to Low pressure and the speed of flow is directly related to the pressure Gradient. The pressure gradient is said tube steep when the rate of change Is great and the gradient the more rapid will be the flow of air. The direction of the pressure gradient is perpendicular to the isobars and pointing towards low pressure.
PG = 1/P* dp/dn
Where P= air density
Dp/dn = rate of change in pressure with distance.
2. The earth’s rotational deflective force [Coriolis force]:
This force comes into play due to rotation of the earth on it axis. It has most potent influences upon wind direction. The Coriolis force effect Causes all winds in the nor them hemisphere to move or deflect toward the Right and those of the sot herm hemisphere to move to the left with respect to the rotating earth. At the equator the effect has a value of zero (Sin 90=1).and it increases regularly towards the poles (and becomes Sin 90=1). The Coriolis effect changes wind direction but does not change wind speed.
3. Centrifugal force :
This force tends to throw the air particles outward from the centre of small circle path on which the particle is moving. The centrifugal force works against the gravitational attraction directed forwards the earth centre.
4. Frictional force:
The roughness of the surface provides frictional resistance to the air motion. It is the retarding effect of trees, buildings and other irregularities in the topography; It is always opposed to the direction of the air motion and therefore fends to decrease the wind speed. Friction causes a movement of air across the isobars towards low pressure.
5. Geotropic winds:
When a wind flows in a straight line with no acceleration or frictional force on it, the only forces acting are the carioles and pressure gradient foresee. The wind that blows under these conditions is called as geotropic wind.
Cyclone and Anticyclone
It is the atmospheric disturbance in which the air pressure decreases at a particular location (Low pressure at centre) and there is a wind movement towards centre.
A system of close isobars with the lowest pressure at the centre is called as cyclone.
The pressure gradient force and carioles force cause air, flow in cycle to be spurning convergent system. In the northern hemisphere the direction of rotation of cyclone is antilock wise while in the southern hemisphere it is clockwise. Cyclones are also known as Lows or press ions. The velocity of wind in cyclone is more than 34 knots.
Anticyclone:
When there is a area of high pressure at centre, the flow of air starts from centre to outer side.
A system of closed isobars with highest pressure at centre is known as anticyclone.
The air flow has spiraling divergent system so that it moves obliquely across isobars away form centre. The direction of rotation of antic clones in the northern hemisphere is clock wise while in southern hemisphere it is antilock wise. These are known as “Hights.”
Atmospheric Humidity
Humidity:
Water vapor present in the atmosphere is known as humidity.
Vapour pressure:
When water vapour mixes with other gases of atmosphere, it exerts a pressure in all directions as do the other gases. This partial pressure exerted by vapour is known as the vapour pressure.
Saturated vapour pressure :
When air contains all the moisture that it can hold to its maximum limit, it is called saturated air and the vapour pressure exerted by this air is called saturated vapour pressure.
Relative humidity (RH) :
Relative humidity represents the amount of water vapour actually present in air compared with the maximum amount of vapour can be held b same air at a given temperature.
RH= Actual quality of water vapour present in a given volume of air x 100
Maximum amount of water vapour the same volume of air can hold
Absolute humidity (AH):
Absolute humidity is defined as the ratio of actual mass of water vapour present to the total volume of moist air in which it is contained.
It is measured in grams per cubic meter of air or in terms of partial pressure of water vapour in air in mbor mm of mercury.
AH = Weight of water vapour
Volume of air
Specific humidity:
Specific humidity is defined as the ratio of mass of water vapour to the given mass of air containing the moisture.
Thus it will be measure in grams of water vapour per kilogram of air.
Mixing ration:
It is the ration of the mass of water vapour to the mass of dry air
Maximum ration = MV/Ma
Where
MV = Mass of water vapour
Ma = Mass of dry air
Psychometric: Measurement of humidity with different instruments is called psychometric.
Variation In Relative Humidity
Diurnal variation in RH
The diurnal variation in relative humidity is approximately inverse to that of temperature about sunrise the RH is maximum and between 14 to 15 hrs minimum RH is observed.
Annual variation in RH: The annual variation of relative humidity is largely depends upon the locality.
At regions where the rainy season is in summer and winter is dry, the maximum relative humidity occurs in summer and minimum in winter and at other regions maximum RH occurs in winter.
Over ocean RH reaches maximum in summer.
Variation of RH with latitude and altitude:
RH shows maximum at equation or about 80%. Therefore it decreases to 70% in the regions of high pressure belts in 30-350 and afterwards increases again to 80 to 90% in the polar region.
The vertical variation of RH is not governed by any exact law. In or near the clouds it is 100% but below or above it is different. The moist air masses carried out by advection at altitudes also change relative humidity.
Clouds, It's Types and Their Classification
Cloud:
Cloud can be defined as a mass of tiny water droplets ice crystals OR both condensed on hygroscopic nuclei and suspending in the atmosphere.
Clouds and fogs are composed of water droplets or ice crystals or both of the order of size 20 to 60 microns (0.008-0.024 millimeter).
Isoneph:
Lime joining places of equal clouds cover on a map is known as isoneph.
Principles of cloud classification :
The great variety of cloud forms necessitates a classification of weather reporting. The internationally adopted system is based upon (a) The general shape; structure and vertical extend of the clouds and (b) their altitude.
Types of clouds: There are four basic types of clouds:
1. Clrrus (CI):
Meaning “cur” and is recognized by its veil, like fibrous or featery form. It is the highest type of cloud, ranging from approximately 7-12 km in altitude. (20,000 to 35,000 feet).
2. Cumulus (Cu):
Meaning “heap”, is the wooly, bundly cloud with rounded top and flat base. It is the most common in the summer season and in latitudes where high temperature prevail and it always results from convection Its height is variable and depends on relative humidity of the air.
3. Stratus (St):
It is a sheet type cloud without any form to distinguish it. It is usually lower than cumulus.
4. Nimbus (Nb):
It is any dark and ragged cloud and from which precipitation occurs.
Classification Of Clouds
Clouds have been classified according to their height and appearance by world Meteorological organization (WHO) into 10 categories.
Cloud family and Height
Name of cloud and abbreviation
Composition
Possible weather change
Description and appearance
1
2
3
4
5
Family A High clouds 7 to 12 km
1 Cirrus (Ci)
Ice crystals
May Indicate storm showery weather
It is wispy and feathery, sun shines without shadow. It does not produce precipitations
2. Cirrocumulus (CC)
Ice crystals
Possible storm
Meekerel sky, often fore renners of cyclone, look like sippled sand
3. Cirrostratus(Cs)
Ice crystals
Possible storm
Meekeral sky, often fore runners of cyclone, look like sippled sand.
Family B middle clods 3 3-7 km
4. Altocumulus (As)
Ice & water
Steady rain or snow
Looks like wool peak, sheep bulk clouds.
5. Atmostratus (As)
Water and ice
Impending rain or snow
Fibrous veil or sheet, grey or bluish, produce coronos, usually ct.st shadow.
Family C low clouds from ground to km
6. Stratocumulus (Se)
Water
Rain possible
Long parallel rolls, pushed together or broken masses which look soft and grey but with darker parts, air is smooth above but strong updrafts occur below.
7. straus (St)
Water
May produce drizzle
A low uniform layer, resembling fog, but resting not on the ground, chief winter cloud.
8.Nimbostrauts
Water or Ice
Impending rain or snow
Fibrous veil or sheet, grey, grey or bluish produce coronas, usually
Family D clouds with vertical development from 0.5 to 16 km
9.Cumu-lus (Cu)
Water
Fair weather
Looks like wool pack, dark below due to shadow, may develop into cumulous –Nimbus flat base.
10, Cumulous –Nimbus (Cb)
Ice in upper level and water in lower level.
Violet winds rain, all possible thunderstorm hail lighting possible
Thunder head, towering anvil top, violet up and down drafts, aviators avoid them, develop from cumulus, chief precipitation makers.
10 cumulo-Nimbus(Cb)
Ice in upper level and water in lower level
Violet winds rain, all possible thunderstorm hail lighting possible
Thunder head, towering anvil top, violet up and down drafts, aviators avoid them, develop from cumulus chief precipitation makers.
Clouds, It's Types and Their Classification
Cloud:
Cloud can be defined as a mass of tiny water droplets ice crystals OR both condensed on hygroscopic nuclei and suspending in the atmosphere.
Clouds and fogs are composed of water droplets or ice crystals or both of the order of size 20 to 60 microns (0.008-0.024 millimeter).
Isoneph:
Lime joining places of equal clouds cover on a map is known as isoneph.
Principles of cloud classification :
The great variety of cloud forms necessitates a classification of weather reporting. The internationally adopted system is based upon (a) The general shape; structure and vertical extend of the clouds and (b) their altitude.
Types of clouds: There are four basic types of clouds:
1. Clrrus (CI):
Meaning “cur” and is recognized by its veil, like fibrous or featery form. It is the highest type of cloud, ranging from approximately 7-12 km in altitude. (20,000 to 35,000 feet).
2. Cumulus (Cu):
Meaning “heap”, is the wooly, bundly cloud with rounded top and flat base. It is the most common in the summer season and in latitudes where high temperature prevail and it always results from convection Its height is variable and depends on relative humidity of the air.
3. Stratus (St):
It is a sheet type cloud without any form to distinguish it. It is usually lower than cumulus.
4. Nimbus (Nb):
It is any dark and ragged cloud and from which precipitation occurs.
Classification Of Clouds
Clouds have been classified according to their height and appearance by world Meteorological organization (WHO) into 10 categories.
Cloud family and Height
Name of cloud and abbreviation
Composition
Possible weather change
Description and appearance
1
2
3
4
5
Family A High clouds 7 to 12 km
1 Cirrus (Ci)
Ice crystals
May Indicate storm showery weather
It is wispy and feathery, sun shines without shadow. It does not produce precipitations
2. Cirrocumulus (CC)
Ice crystals
Possible storm
Meekerel sky, often fore renners of cyclone, look like sippled sand
3. Cirrostratus(Cs)
Ice crystals
Possible storm
Meekeral sky, often fore runners of cyclone, look like sippled sand.
Family B middle clods 3 3-7 km
4. Altocumulus (As)
Ice & water
Steady rain or snow
Looks like wool peak, sheep bulk clouds.
5. Atmostratus (As)
Water and ice
Impending rain or snow
Fibrous veil or sheet, grey or bluish, produce coronos, usually ct.st shadow.
Family C low clouds from ground to km
6. Stratocumulus (Se)
Water
Rain possible
Long parallel rolls, pushed together or broken masses which look soft and grey but with darker parts, air is smooth above but strong updrafts occur below.
7. straus (St)
Water
May produce drizzle
A low uniform layer, resembling fog, but resting not on the ground, chief winter cloud.
8.Nimbostrauts
Water or Ice
Impending rain or snow
Fibrous veil or sheet, grey, grey or bluish produce coronas, usually
Family D clouds with vertical development from 0.5 to 16 km
9.Cumu-lus (Cu)
Water
Fair weather
Looks like wool pack, dark below due to shadow, may develop into cumulous –Nimbus flat base.
10, Cumulous –Nimbus (Cb)
Ice in upper level and water in lower level.
Violet winds rain, all possible thunderstorm hail lighting possible
Thunder head, towering anvil top, violet up and down drafts, aviators avoid them, develop from cumulus, chief precipitation makers.
10 cumulo-Nimbus(Cb)
Ice in upper level and water in lower level
Violet winds rain, all possible thunderstorm hail lighting possible
Thunder head, towering anvil top, violet up and down drafts, aviators avoid them, develop from cumulus chief precipitation makers.
Hydrological cycle
Water is essentially required for different life forms such as plants animals. Birds etc. For cell building and other purposes. The main source for the water is ocean. The water from the oceans is evaporated, clouds are formed and carried away by wind and they precipitate. The water received from precipitation is lost to the ocean back by different processes such as run- off evaporation from soil, lakes and ponds, streams, etc evapotranspiration from plants the water which is absorbed in the ground is also lost by direct or indirect way to the ocean, for example, some water which is absorbed in ground is utilized by plants and then evaporated, the ground waer which is absorbed in ground is utilized by plants and then evaporated. The ground water flows to the streams and the stretch finally lost in the oceans etc. Thus, we find that there is a constant circulation of water from oceans to the air and back again to the oceans. This process has not end beginning and therefore it is termed as hydrological cycle or water cycle. The hydrological cycle can be briefed by the following equation.
P = ET + DST + S
The total amount of water present on the earth surface remains constant but undergoes continuous transformation from water vapour to liquid. This equation is also called as water balance equation. Where P is the water received by precipitation, ET is loss by evapotranspiration, dst is the gain on loss by storage in the soil and S is the surplus run-off of water, from this mathematical relation, we can find out the value of other elements.
Precipitation and Forms of Precipitation
It can be defined as earthward falling of water drops or ice particles that have formed by rapid condensation in the atmosphere.
Forms Of Precipitation
A. Liquid form
B. Solid form
C. Mixed form
1. Rain
1. Snow
1. Sleet
2. Drizzle
2. Hail
2 Hail
3.Shower
A. Liquid Form
1. Rain:
Rain is defined as precipitation of drops of liquid water. The clouds consists of minutes of minutes droplets of water of about 0.02 mm diameter. When these minute water droplets in clouds combine and form large drops that become so large that they can not remain suspended in the air and they fall down as rain. The droplets are formed by repaid condensation. The rain drops have diameters ranging from 0.05 to 0.06 cm (0.5 to 0,6 mm) The line joining the places of equal rainfall called Isohyets.
Types of Rain:
I) Convectional rains:
Due to heating, the air near the ground becomes hot and light and starts upward movement (This is known as convection.) as air moves upward it cools at the DALR (9.80C/km) and becomes saturated(having RH 100%) and dew point is reached where the condensation. begins . This level or height is known as condensation level. Above condensation level air cools at SALR (5 0C/km) clouds are formed. Then further condensation results into precipitation. These rains are known convectional rains.
II) Ographic or relief rains:
When the moist air coming from sea encounters mountain or relief barrier, it can not move horizontally and has to overcome mountain. When this air rises upward, coolsdown, cloud is formed and condensation starts and giving precipitation. These rains are known as or orographic rains thus high rains are possible on the windward side of the mountain. After crossing the mountain divide, when air descends downward, the air is compressed and it warmed up at DALR. This warm air does not give any precipitation on the leeward region. This is known as rain shadow region.
III) Cyckibuc/Frontal and Convergent rains:
Frontal precipitation is produced when two opposing air currents with different temperature meet, vertical lifting takes place which gives rise to condensation and precipitation. When the humus and warm air mass meets the cold air mass, the colder air being denser tends to push below the warmer air and replace it. The boundary zones along which two air masses meet are called as fronts. When the mixing of warm and moist air with cold air mass takes place, the temperature of the warm and air falls down, saturation occurs and may give precipitation and it also responsible for cyclone formation and rains received from cyclones are called cyclonic reins.
Thunder Storms:
It is the atmospheric disturbance which is always accompanied by thunder and lightening and sometimes by hail. It is a local storm covering comparatively small area and often causing damage. Its chief
Characteristics are an immense cumulo-nimbus cloud accompanied by copious precipitation, a marked drop in temperature and a more or less destructive out rushing squall wind which precedes the rainfall. Thunder storms occur in every part of the world and their frequency decreases with increase in latitude.
Storms are of two types:
1) Frontal or general thunderstorm:
This occurs over wide areas in connection with passing of a cyclonic disturbance.
2) Local thunder storm:
This forms as a result of strong local convection.
3) Drizzle:
It is more or less uniform precipitation of very small and numerous raindrops which are carried away even by light wind. The drizzle drop is less than 0.5 mm in size, and precipitate at the rate usually less than 1 mm per hour.
4) Shower:
Precipitation lasting for a short time with relatively clear intervals is called shower. This occurs from the passing clouds.
B) Solid Form:
1. Snow:
Snow is defined as precipitation of water in the solid form of small Or large ice crystals. It occurs only when the condensing medium has a temperature below freezing temperature, snow is generally in the form of individual crystals or in flakes that are aggregates of many crystals. Snow flakes are formed in high clouds. Snow is measured with snow gauge.
2. Hail:
Hail is a precipitation of solid ice. On a warm sunny day, a strong Connective column may cause the formation of pellets having spherical Shape and concentric layers of ice. Such a formation is known as hail.
C. Mixed Form:
1. Sleet
Simultaneous precipitation of the mixture of rain and snow is called as sleet.
2. Hailstorm:
Rainfall associated with hail stones is called hailstorm.
Mechanism or process of Rain formation or Process of Precipitation:
There are two methods by which rain drop is formed.
1. Bergeron mechanism:
There are two methods by which rain drop is formed.
1. Bergeron mechanism:
The cloud having cold temperature is cold temperature is cold cloud. In these clouds Ice particles are formed due to very low temperature (-150C to -250C). These ice particles are grow rapidly by deposition of water vapors (sublimation) developing in to hexagonal shaped ice crystals. These ice crystals on collision form snow pellets and melt into water droplets when falling on ground through warm atmosphere. This mechanism is suggested by Swedish Meteorologist Bergeron in 1933. Artificial rain making is based on these mechanisms.
2. Collission and coalescence mechanism:
The cloud having slightly higher temperature is not cloud. In these Clouds fine water droplets exist instead of ice particles. This fine water Droplets colloid and coalesce (combine) and grow into the larger size and fall on earth as rain drop.
Drought and Its Classification
Definition:
Drought is a period of inadequate or no rain fall over extended time creation soil moisture deficit and hydrological imbalances.
Classification of Drought:
Drought on different basis is generally classified into three categories.
A) Based on source of
Water availability
B) Time of occurrence
1.Meteorological
Drought
Slight drought
Moderate drought
Severe drought
1. permanent drought
2. Hydrological drought
2.Seasonal drought
3. Agricultural drought.
3.Contigent drought
Drought classification
A. On the basis of source of water availability:
Drought is classified into three types on the basis of water availability.
1. Meteorological drought:
The meteorological droughts mainly indicate deficit rain of different quantum. The IMP classified this drought as follows from the rainfall departure.
Slight drought : When rainfall is 11 to 25% less from the normal rainfall.
Moderate drought : When rainfall is 26 to 50% less than the normal rainfall.
Severe drought : When rainfall is more than 50% less than the normal rainfall
2. Hydrological drought:
It is defined as the situation of deficit rainfall when the hydrological sources like streams, rivers, lakes, wells dry up and ground water level depletes. This affects industry and power generation.
3. Agricultural drought:
This is the situation resulted from inadequate rainfall, when soil moisture falls to short to meet the water demands of the crop during growth. Thus affects crop may wilt due to soil moisture stress resulting into reduction of yield.
B. On the basis of time of occurrence:
Drought differs in time and period of their occurrence and on this basis Thormathwite delineated following three areas.
1. Permanent drought area:
This is the area generally of permanent dry, arid p desert regions. Crop production due to inadequate rainfall is not possible without irrigation. In the these areas vegetation like cactus. Thorny shrubs, xerophytes etc. are generally observed.
2. Seasonal drought:
It occurs in the regions with clearly defined as rainy (wet) and dry climates. Seasonal drought may occur due to large scale seasonal circulation. This happens in monsoon areas.
3. Contingent drought:
This results due to irregular and variability in rainfall, especially in humid and sub humid regions. The occurrence of such droughts may coincide with grand growth periods of the crops when the water needs are critical and greatest resulting into severity of the effects i.e. yield reduction.
C. on the basis of medium:
On the basis of medium in which drought occurs. Mexico (1929) has divided the drought into two types.
1. Soil drought:
It is the condition when soil moisture depletes and falls short to meet potential Evapotranspiration of the crop.
2. Atmospheric drought:
This results from low humidity, dry and hot winds and causes desiccation of plants. This may occur even when the rainfall and moisture supply is adequate.
Strategy to mitigate drought OR How to overcome the drought:
1. Preventing and recycling of excess runoff
2. Deep tillage to absorb and hold maximum moisture.
3. Timely weed management to control water loss by ET.
4. Planning for suitable cropping system.
5. Selection of short duration and drought tolerant crops.
6. Contingency crop planning for abnormal weather situation.
7. Management of various inputs to suit the climate.
8. Conserving the soil moisture by agronomic practices like mulching use of antitranspirant on the crops to reduce ET.
9. To apply irrigation.
10. Reduction of plant population to reduce ET.
11. Timing of foliage to reduce ET.
Drought year:
The year is considered “drought year “when less than 75% of the normal rainfall is received. Drought prone area: It is defined as one in which the profanity of a “drought year “is 20 to 40.
Chronic drought prone area:
Is defined as one in which the probability of “drought year” is greater than 40%.
Weather Forecasting And Its Classification
Weather forecast:
Means any advance information about the probable weather in future, which is obtained by evaluating the present and past meteorological conditions of the atmosphere is called weather forecast.
Agricultural weather forecast:
Forecasting of weather elements viz sunshine hours, occurrence of dew, relative humidity, rainfall, temperature, winds etc. Which are important in agriculture and for farming operations is known as agricultural forecast.
In weather forecasting the advance information of weather elements like distribution of rain fall, warming for heavy rain fall, temperature change important special hazardous weather like if thunderstorm hailstorm, show or frost, sky cover, winds, humidity, dew drought, evaporation rate etc is provided.
Classification weather forecasting:
Weather forecasting on the basis of their validity periods or time scale is classified as follows :
1. Now casting:
It is based on synoptic situation prevailing at the time of forecasting and is valid up to 3 days on 72 hrs and is issued twice a day.
2. Short range forecast (SRF):
It is based on synoptic situation prevailing at the time of forecasting and is valid up to 3 days or 72 hrs. and are issued twice a day.
3. Medium range forecast (MRF):
Forecasting of meteorological elements over different agro climatic zones for periods ranging from3-10 days is known as medium range forecast.
4. Long range forecast (LRF):
The forecast valid for more than 10 days (i.e. a month or a season is knows as long range forecast.
Importance or Significance of Weather Forecast in agriculture
1. The forecast of the weather events helps for suitable planning of farm.
2. It helps in to undertake or withheld the sowing operation
3. It helps in following farm operation:
I) To irrigate the crop or not
II) When to apply fertilizer or not.
III) Whether to start complete harvesting or to withhold it.
4. It also helps in to take measures to fight frost.
5. It helps in transportation and storage of food grains.
6. Helps in management of cultural operations like plugging harrowing hoeing etc.
7. It helps in measures to protect livestock.
Crop Models And Its Techniques
Agrometeoorological forecasting is also concerned with the assessment of current and expected crop performance. It utilizes the past and the present weather data and crop data to predict the crop performance in the future. These forecasts may be about the occurrence of some phonological events viz. Emergence, flowering, fruiting, maturity and harvesting etc or may be about the possible crop production. Of the agro meteorological forecasts in use. Probably the most important economically are the forecasts of crop yield. The impact of weather and climate on crop growth and yield can be represented by crop weather models.
A model in general is an equation or set of equations which represents the behavior of a system. There are many types of the models as follows.
1. Statistical empirical model: Actual mechanism of processes is not disclosed.
2. Mechanistic model: mechanism of the processes involved id discussed e.g. photosynthesis based model.
3. Static model: Time is not a factor.
4. Dynamic model:These models predict changes in crop status with time.
5. Deterministic model: In which a definite output is given e.g. NPK doses are applied and the definite yields are given out.
6. Stochastic model: The models are based on the probability of occurrence of some event or external variable. Probabilities are given out.
The statistical techniques used in designing the models are as follows:
1. Simple regression analysis
2. Simple correlation technique.
3. Curvilinear correlations techniques
4. Multiple regression analysis
5. Stepwise regression analysis
6. Fishers orthogonal polynomial techniques
7. Mallow’s Cp techniques.
8. Marko cham model.
Bar (1979) has tried to classify the basic types of crop weather models as follows:
1. Crop growth simulation models
2. Crop weather analysis models
3. Empirical statistical model
Part 4
Rainfed Agriculture
Dry Land Farming
Indian agriculture is traditionally a system of Rainfed agriculture. Out of 143 million hectares of net cropped area, about 72% is Rainfed production about 45% of food grains and 75 - 80% of pulses and oil - seeds and a number of important industrial crops. Considering the present rate of development of irrigation facilities and also water potentiality of the country, express estimate that at any point of time 50% of cropped area in India will remain under Rainfed farming system.
Such vast areas as of now consume hardly 25% of total fertilizer consumption of the country. Due to poor level of management, crop productivity is also very low resulting in socio - economic backwardness of the people.
Dry lands: Areas which receive an annual rainfall of 750 mm or less and there is no irrigation facility for raising crops.
Dry land Agriculture: Scientific management of soil and crops under dry lands with out irrigation is called dry land agriculture.
Dry land crops: It refers to all such crops which are drought resistant and can complete their life cycle without irrigation in areas receives an annual rainfall less than 750 mm.
Drought: It is an condition of insufficient moisture supply to the plants under which they fail to develop and mature properly. If may be caused by soil, atmosphere or both.
Dry farming : In the country with low and precarious rainfall two types agricultures are usually met, one crop production on aerable farming land other animal husbandry, including management of grazing areas.
Definiuons:
The different definitions of dry farming given by various express are described below.
1. Dry farming is an improved system of cultivation in which maximum amount of moisture is conserved in low and untimely rainfall for the production of optimum Quantities of crop on economic and sustames basis.
2. Dry farming in short, is a programme of soil and water management designed to conserve the maximum quantity of water on a particular piece of land.
By Anand
3. Dry farming is the profitable production of useful crops without irrigation on land that receive annually a rainfall of 500 mm or less.
By Anonymous
4. In a more specific way dry farming may be defined as an efficient system of soil and crop management in the regions of low land and uneven distributed rainfall.
By Anonymous
Dry land Vs Rainfed farming.
Constituents
Dryland farming
Rainfed farming
1. Rainfall (mm)
< 750
>75
2. Moisture
Shortage
Enough / Sufficient
3. Growing season
<200
>200
4. Growing regions
Arid and Semiarid & up lands of sub humid & humid regions.
Humid and slub humid regions.
5. Cropping system
Single crop or
intercropping
Intercropping or double cropping.
6. Constraints
Wind and water erosion
Water errosion.
Rainfed Farming
Growing of crops on natural preciption without irrigation.
Dry farming areas : Dry farming areas (as per the IV five year plan) are those areas receiving an annual rainfall ranging from 375 to 1125 mm and very limited irrigation facilities. Areas which receive less than 375 mm of average rainfall are considered as absolutely arid or desert areas, which require special treatment. As many as 128 districts in the country falls under category of dry farming areas as defined above. Out of these 25 dists from the states of Rajasthan, Sourashtra and rainshado region of Maharashtra and Karnataka belong to very high intensity dryfarming areas (i.e. rainfall ranges from 375 to 750 mm and irrigated area belong 10% of the cropped area.)
As the Encylopedia Britanmputs Dry land farming consists of making the best use of limited water supply by storing in the soil and much of the rainfall as possible and by going suitable crop plants those make the best use of this moisture.
The major physiographic regions observed in India namely
i) Mountain region
ii) Indogangatic alluvial plains
iii) Peninsular or Deccan plateau &
iv) Coastal plains.
National Agricultural Research Project (NARP) launched in 1979 by ICAR with soft loan support from International Development Agency (IDA) of World Bank. Where in state Agricultural Universities were advised to divide each zone / state into subzons (NARP). Accordingly 120 sub zone map based primarily on rainfall, existing cropping pattern and administrative units was prepared.
Although the agro climatic regional approach considers an agro - climatic zone having a greater degree of commonality of the relevant basic fetures of soils, topography, climate and water resources. Yet in practice this approach neighter gave adequate consideration to soils and environmental conditions nor had a uniform criterion. Moreover, the use of state as a unit for sub - division may not be reconciled with, as it resulted is the creation of many sub - divisions having similar agro - climation characteristics, occurring in different states.
Since the agro - climatic regional planning a approach was intended take an integrated view of agricultural economy in relation to resource bas and linkage with other sectors, further development should be specific agro - ecoregions and considered to generate an agro ecological region my of the country giving due recognition to climatic conditions, length growing period, land form & soils.
Soil And Climatic Studies In Rainfed Agriculture
i) Soils
: -
Out of total cultivable land in M.S. 87 per cent area comes ur rained. Soils of drought prone areas of M.S. area derived from the be igneous rock Basalt commonly known as Deccan trap. The colours of soil vary from reddish brown to dark gray black and are called verti. The soils exhibit a definite to posegence of ridge medium dear 122 - 90 cm depth) soils on sloped land deep soils (more than 90 cm meen) end of watershed. The distribution of very shallow, shallow, medium deep and deep soils in drought prone areas of M.S. is about 10,20,45 and 25% respectively. They usually under lined partially decomposed rock locally known as murrum which overlies parent material. On account of more or less complete absence of leaching the soils are base saturated. The exchangeable calcium is predominant cation. The free lime is reserve is fairly high (3 to 10%) and at places excessive quantities of time nodules accumulate. The problematic soils viz. saline, saline sodic land sodic soils do occur in patches in low lying areas.
As regards the fertility status, the soils are generally low in organic carbon (0.35 to 0.5%) total nitrogen (0.03 to 0.05%) low to medium available phosphate (10 to 30 kg p2O5/ha) and high available potash (300 to 750 kg K2O/ha). Usually micro-nutrient deficiencies are not observed in dry land crops. However in eroded soils, crop like groundnut have shown some response to boron application. Cereal crops give fairly good response to nitrogenous fertilizers while oilseeds and legumes give good response to phosphatic fertilizers.
Soils exhibit adverse physical characters because of high clay content (35 to 65%) of type clay mineral. The soils exhibit high volume expansion when moist and shrink when dry. The infiltration rate of soils is moderately slow (0.5 to 0.9 cm/ha). During the process of shrinkage, wide land deep cracks are developed even up to Murrum strata in medium deep soils. The crack development accelerates the soil moisture loss from the deeper layers (phases). Further soils exhibit varying degree of erosion depending on the slope, tillage operations and cropping season. The soils classed as moderate to high erodible. Hence soil and water conservation is a pre - requisite for successful cropping. Limited soil depth puts limitations on availability of water and nutrients for cropping intensity. Usually soils having less than 45 cm depth are useful for Kharif crops as they are unretentive of soil moisture. Inter mittant wetting due to frequent rainfall during June to Aug helps to mature crops on such soils. Soils having depth more than 45 cm have high moisture storage and retentive capacity. Under dry land to bring the soil moisture in the available range (i.e. above PWP) the rainfall required is quite high since the precipitation in the early part of monsoon is quite inadequate the medium deep soils (beyond 45 cm deep) usually do not have adequate moisture for sowing. It is only due to receipt of about 200 mm of rains during September the medium deep and deep soils are adequately moistened for Rabi cropping. Hence Rabi cropping is predominant and medium deep and despoils one grown with Rabi crops.
The moisture storage capacity of soil mainly depends on clay content and soil depth. However, city content is generally above 45 percent in medium deep and deep soil the moisture deptetion of soil depends on the moisture held in the soil at different tensions. The soil moisture is always below the moisture at 15 bar (PWD) which ultimately results in faiture of crops in dry land agriculture.
ii) Climate: Wether, which is part of climate, plays an important role in crop planning in dry farming area. Out of the several elements of weather, rainfall has key position in success of dryfarming.
In dry land areas, South West Monsoon brings the bulk of rainfall. The South West Monsoon is followed by North East Monsoon which supplements to South West Monsoon are the main source of rainfall. There are four types of rainfall characterized by the nature in different parts of India. Generally, the rainfall is scanty, erratic and ill distributed. The draught prone area in Maharashtra State Covers about 1/3 of the total area of the state. The climate in this is usually hot and PE (Potential Evaporation) is for in excess of the precipitation is classified as semiarid e.g. Annual precipitation at Solapur is about 7/22 mm. but PE is about 1300 mm annually resulting in deficient 60%.
iii) Rainfall features :- The annual Average rainfall varies from 400 mm to 700 mm. Year to year fluctuations are so much that there is no guaranteed of fixed quantity of rainfall. Uncertain and ill distributions of rainfall are two qualities which makes the Rainfed farming difficult. Rainfall starts in lated June to Early July.
There is depression during late July and early August Again there is good rainfall in late August and September. The rainfall totally recedes but mid October. The probability of rainfall is more than half of the normal fairly good (P = 0.58) during September.
iv) Dry spells: - It is another rainfall feature. Breaks in monsoon a normally experienced (observed) during rate July and August. They month extend by 2 week to 13 weeks at a stretch. A break is defined as period receiving less than 15 mm rainfall in consecutive weeks. The normal rainfall during the week being more than 50 mm. A duration of break month than 4 week and frequently more than 3 times usually results in fatures than 4 weeks and frequently more than 3 times usually results in faitures crops.
Variation in the rainfall with in the district is also observed. In Solapur, particularly variation in annual precipitation is noticed from 500 mm in western part to about 700 mm in eastern parts.
v) Water availability period: - Water availability depends on rainfall and PE. Humid (when rainfall exceeds PE) and moist (when rainfall is less than PE but exceeds PET) period together provides congenial weather for active crop growth.
vi) Wind velocity: - Wind velocity is generally hitch during July and August. If wind velocity exceeds 18 - 20 km./hr. Such period coincided with dry spell. Hence Evapotranspiration is at high degree. If velocity is low the lowest evaporation rates are observed during November and December.
vi) Bright sunshine hours: - Bright sunshine is usually experienced during months of Jan. and Feb. At Solapur it is about 8 to 9 hours. During April and May the sky is usually have with more dust particles, lowest bright sunshine is noticed during Aug. (4 to 5 hours). This indicates the cloudy weather but no rainfall.
vii) Humidity: - Humidity is high during July and Sept. During Feb. to May it is low. During dry spell, less relative humidity is noticed. Evaporation demands are also accelerated with high temperature and low humidity.
viii) Temperature: - a Maximum temperature exceeds 410 C during late April and early May. Minimum temp. is noticed during December. Lowest weekly minimum temperature is about 14 to 150C. Generally climate is semi and with mild winter and hot summer. Crop like wheat and gram requiring longer cool period hence do poor while prolonged cold weather however, Jowar suffers considerably.
Why crop failures are common, yields are not static under Rainfed farming because.....
1. Inadequate and uneven distribution of rainfall.
2. Late on set and early cessation of rainfall.
3. Prolonged dry spells during the crop growth period.
4. Low moistone retension capacity of soils.
5. Low fertility of soils, low humidity, higher temperatures, higher wind velocity.
Different Soil Types And Their Characters In M.S
Particulars
Soil type
Shallow
Medium
Deep
A) Area of state
10%
65 to 66%
25%
1. Parent material
Trap basalt
Trap basalt
Trap basalt
2. Topography
Undulating
Undulating
Flat
3. Depth (Cm)
Up to 22.5
45 to 90
Above 90
4. Texture
Clay
Clay loam
Clay
5. Colour
Light black
Grayish black
Black
6. pH
7.5 to 8.0
5.0 to 8.5
8.0 to 8.5
7. T.S.S. %
0.2
0.2
0.2 to 0.3
8. Lime (CaCO3)%
0.5 to 5.0
1.0 to 10.0
2.5 to 15.0
9. Nitrogen kg /ha
Trace
80 to 120
100 to 200
10. C/N ratio
8 to 10
10 to 12
18 to 40
11. Available P2O5 kg/ha
8 to 10
15 to 30
18 to 40
12. Available K20 kg/ha
60
250 to 500
250 to 850
13. Base situation
10 to 15 mg/100
30 to 60
70 to 80
capacity
per gram
14. Sodium Saturation %
Trace
10
10
Agro Climatic Zones Of India In General
Introductions: - The important rational planning for effective land use to promote efficient is well recognized. The ever increasing need for food to support growing population @2.1% (1860 millions) in the country demand a systematic appraisal of our soil and climatic resources to recast effective land use plan. Since the soils and climatic conditions of a region largely determine the cropping pattern and crop yields. Reliable information on agro ecological regions homogeneity in soil site conditions is the basic to maximize agricultural production on sustainable basis. This kind of systematic approach may help the country in planning and optimizing land use and preserving soils, environment.
India exhibits a variety of land scopes and climatic conditions those are reflected in the evolution of different soils and vegetation. These also exists a significant relationship among the soils, land form climate and vegetation. The object of present study is to delianate such regions as uniform as possible introspect of physiographic, climate, length of growing period (LPG) and soils for macro level and land use planning and effective transfer of agro - technology.
Agro Climatic Zones: - Agro climatic zone is a land unit in Irens of mator climate and growing period which is climatmenally suitable for a certain image of crops and cultivars (FAO 1983). An ecological region is characterized by district ecological responses to macro - climatic as expressed in vegetation and reflected fauna and equatic systems. Therefore an agro-ecological region is the land unit on the earth surface covered out of agro - climatic region, which it is super imposed on land form and the kinds of soils and soil conditions those act as modifiers of climate and LGP (Length of growing period).
With in a broad agro climatic region local conditions may result in several agro - ecosystems, each with it's own environmental conditions. However, similar agro ecosystems may develop on comparable soil, and landscape positions. Thus a small variation in climate may not result in different ecosystems, but a pronounced difference is seen when expressed in vegetation and reflected in soils.
India has been divided into 24 agro - climatic zone by Krishnan and Mukhtar Sing, in 1972 by using "Thornthwait indices".
The planning commission, as a result of mid. term appairasal of planning targets of VII plan (1985 - 90) divided the country into 15 broad agro - climatic zones based on physiographic and climate. The emphasis was given on the development of resources and their optimum utilization in a suitable manner with in the frame work of resource constraints and potentials of each region. (Khanna 1989).
Agro climatic zones of India :- (Planning commission 1989)
1
Western Himalayan Region
Ladakh, Kashmir, Punjab, Jammu etc.brown soils & silty loam, steep slopes.
2
Eastern Himalayan Region
Arunachal Pradesh, Sikkim and Darjeeling. Manipur etc. High rainfall and high forest covers heavy soil erosion, Floods.
3
Lower Gangatic plants Regions
West Bengal Soils mostly alluvial & are prone to floods.
4
Middle Gangatic plans Region
Bihar, Uttar Pradesh, High rainfall 39% irrigation, cropping intensity 142%
5
Upper Gangatic Plains Region
North region of U.P. (32 dists) irrigated by canal & tube wells good ground water
6
Trans Gangatic plains Region
Punjab Haryana Union territory of Delhi, Highest sown area irrigated high
7
Eastern Plateaus & Hills Region
Chota Nagpur, Garhjat hills, M.P, W. Banghelkhand plateau, Orissa, soils Shallow to medium sloppy, undulating Irrigation tank & tube wells.
8
Central Plateau & hills Region
M. Pradesh
9
Western Plateau & hills Region
Sahyadry, M.S. M.P. Rainfall 904 mm Sown area 65% forest 11% irrigation 12.4%
10
Southern Plateau & Hills Region
T. Nadu, Andhra Pradesh, Karnataka, Typically semi and zone, Dry land Farming 81% Cropping Intensity 11%
11
East coast plains & hills Region
Tamil Nadu, Andhra Pradesh Orissa, Soils, alluvial, coastal sand, Irrigation
12
West coast plains & Hills Region
Sourashtra, Maharashtra, Goa, Karnataka, T. Nadu, Variety of cropping Pattern, rainfall & soil types.
13
Gujarat plains & Hills Region
Gujarat (19 dists) Low rainfall arid zone. Irrigation 32% well and tube wells.
14
Western Dry Region
Rajasthan (9 dists) Hot. Sandy desert rainfall erratic, high evaporation. Scanty vegetation, femine draughts.
15
The Island Region
Eastern Andaman, Nikobar, Western Laksh dweep. Typical equatorial, rainfall 3000 mm (9 months) forest zone undulating
Rainfall, Its Distribution And Its Effectiveness In Rainfed Agriculture
Distribution of Rainfall: - The amount of rainfall received at periodic intervals like weeks, months, seasons etc. indicate distribution. In addition distribution of rainfall can be known by the length of dry spell, wet spells land rainy days. Distribution of rainfall is more important than total rainfall.
Rainfall pattern at three locations:-
Sr. No.
Index
Hyderabad
Solapur
Dhule
1
Annual rainfall (mm)
764
742
625
2
Seasonal rainfall (mm)
580
556
450
3
Coefficient of variation%
4
PE (mm)
1757
1802
1502
5
Growing season
130
148
125
6
Soil
Vertisols
Vertisols
Medium deep
From the above data the growing season is slightly less at Hyderabad as compared to Solapur, However rainy season crops are more successful at Hyderabad and annual yields range 50 to 70 q/ha. While at Solapur and Dhule rainy season crops are risky and annual yields range from 10 to 12 q/ha. Low yields at Solapur and Dhule are mainly due to discontinuous rains or long breaks in rainfall during crop growth period.
Rainfall distribution is based on:
1. Weekly or monthly rainfall will give distribution of rainfall in weeks during a crop season.
2. Wet and dry spells - A wet spell is a number of continuous days of rainfall. A dry spell is a number od continuous rainless days.
3. Rainy days: If the rainfall received is more than 2.5 mm on any day. This particular day is called rainy day.
4. Periodicity of rainfall.
5. Onset of monsoon.
6. Recurrence of rainfall events.
7. Dependability of rainfall
8. Certificient of variation. If C.V. is more variation in rainfall is more and vice - a - versa.
9. Length of the growing season (LGS): If LGS is less a short duration crop should be selected. L.G.S. depends on duration of rainy season and moisture retention.
Rainfall being a single most important factor for success of crops in the dry farming areas. It is generally known that India receives its annual rainfall by the particular phenomenon called monsoon which consists of series of cyclones those arise in the Indian Ocean. These travel in the North East direction and enter the peninsular India along the Western coast. These cyclones occur from June to Sept. is known as south West monsoon. This is followed by second third and fourth rainy season during periods from Oct. to Nov., Dec. To Feb. and March to May respectively. South West Monsoon is the most important as it covers major parts of India and brings bulk of the total annual rainfall.
The North East of Returning monsoon: By the end of Sept. South West Monsoon ceases to penetrate North West India but continues a full month longer in Bengal. On account of south East North easterly winds being to flow on the Eastern coast. Some times some of these cyclones penetrate In land and give supplementary rainfall to dry region of the plateau of the peninsular India. This is known as returning monsoon.
Precipitation And Its Factors
Precipitation is reaching of atmospheric humidity either as rain or snow to the ground. OR Precipitation can be defined as earth word falling of water drops of ice particles that have formed by rapid condensation in the atmosphere and are too large to remain suspended in the atmosphere.
Factors influencing precipitation:-
1. Only blowing of winds coming even over the sea is not enough to produce precipitation.
2. Horizontal movement is not conductive to precipitation.
3. The rain bearing clouds, hills, mountains, slanting slopes of the river ralleys lake dynamic cooling of the clouds.
4. Water vapour in atmosphere and moat conditions which promote greater precipitation.
5. Regiour covered with thick forest contributes more water vapour by transportation and thus provide favorable condition for preciption.
6. The prevalence of dry winds, higher temperature absence of barriers and cutting of monsoon currents these are unfavorable for precipitation.
7. Long & short breaks in the monsoon caused due to prevalence of dry winds slowing over land or desert plains from North East.
8. On the other hand geographical position, physical configuration and meteorological conditions are responsible for precipitation.
Type Of Rainfall In Dry Areas
1. First type rainfall: Rainfall receives from south west Monsoon. Rainfall receives up to 60% in the first three months viz. June - July - August - Rontak Jodhpur Jalgaon.
2. Second type rainfall: Rainfall receives from south - West Monsoon (40 to 55%) and supplemented with North East Monsoon (40 to 50%) Pune. Wal A Nagar Raichur - Maximum rainfall receives in July & Sept.
3. Third type rainfall: Rainfall receives from North East Monsoon (60%) Solapur Bijapur a Karnataka.
4. Four type rainfall: Rainfall receives uniformly (Well distributed) from Both Monsoon currents, places of rainfall - Chennai. Total rainfall received in 5 to 6 months.
Decennial rainfall: The mean total rainfall received during past 10 years:
Winds coming over land surface from the North - East are dry and cold and man cause of breaks in the monsoon or they tend to decrease the rainful of a tract by diluting the moisture laden masses of the atmosphere. Indian be divided into three zones of the basis of rainfall.
A) Heavy rainfall zone: above 1250 mm.
B) Moa crate rainfall zone: 750 to 1250 mm.
C) We rainfall zone: Less than 750 mm annual rainfall.
The average rainfall of Solapur varies from 500 to 720 mm and had bimodal stribution. The first peak is usually experienced during June and Second during Sept. Rainfall during Sept. is more assured and is in the rage of 150 to 200 mm. Even though Monsoon sets in by the end of June, July and August are characterized by dry spells of varying duration (2 to 8 weeks at stretch) and frequencies 1 to 5. Usually dry speels of more that 4 weeks duration or 3 dry spells of 2 week duration result in failure off Kharif crops. Such occasions are observed twice in fire years. Usually high wind velocity (18 to 20 km / hr)
At Solapur under dry land areas year to year fluctuatins are so much that there is no guarantee of a fixed quantity of rainfall. Generally rainfall starts in late June to early July. There is depression during late July to early August. Again there is good amount of rainfall in last Aug. and Sept. The rainfall totally recedes by mid October. This is the usual pattern of rainfall in draught prone areas. The probability of rainfall is more than half the normal is fairly good. (P = 0.58) during September.
Techniques Of Soil And Water Conservation In Rainfed Agriculture
Soil and water are most essential for the growth and sustenance of plant life. Soil is important as it provides, foothold for plants and majority of nutrients needed by them. Water is essential as it forms larger part of the living matter and acts as a nutrient carrier.
Though, both soil and water a sources are available in plenty, they are not distributed equally in quality and quantity in every part of the world and are not inexhaustible. Their abuse would mean a great loss resulting in poverty. It takes centuries to form one inch layer of soil, but it does not take long to lose it by erosion. Research work carried out in Maharashtra State which has an undulating topography, has shown that loss of soil from unprotected land is as much as 125 tons per hectare every year and may be as high as 300 tons in a single year. The weight of one hectare of soil 2.5 cm. deep is about 325 tons.
Similarly, rain water which can sustain a good crop, if not conserved properly will not only cause scarcity and famine, but also wash way the soil which is a valuable national asset. There are many examples which show how once fertile plains and valleys have become deserts or barren lands due to neglect by mankind. It is, therefore, the prime responsibility of each generation to conserve soil which is the main capital of the farmer as well as the nation, at all costs and pass it on in good condition from one generation to another, so that the posterity will not blame them.
Soil and water conservation cannot be achieved only by individual efforts. The problem is too big, involving collective efforts on the part of farmers, technicians and Government. Recognizing the seriousness of erosion problem, the Central Government established the Central Board of Soil Conservation to assist the States and River valley Projects. It has established soil conservation research stations at Dehradun, Kotah, Ootacamand, Bellary, Vasad and Jodhpur, arranges for training of technical personnel and also served as clearing house for soil conservation information.
On account of chronic scarcity conditions prevailing over 3 major portions of the Deccan tract. Soil and water conservation research was started in 1924 and soil conservation work was taken up on a large scale in Maharashtra from 1943 - 44 onwards. At present Maharashtra contributes nearly 50 p.c., of the total progress in respect of soil conservation measures in the country.
Erosion- Factors Affecting Soil Erosion
The factors that influence erosion are:
1. The amount and intensity of rainfall and wind velocity.
2. Topography with special reference to slope of land.
3. Physical and chemical properties of soil.
4. Ground cover its nature and extent.
Soil erosion is the wearing away detachment and transportation of soil from one place and its deposition at another place by moving water blowing wind or any other cause.
1. The amount and intensity of rainfall and wind velocity: Rainfall is the most forceful factor causing erosion through splash and excessive run off.
Rain drop erosion is splash, which results from the impact of water drops, directly on soil. Although the impact of rain drops on water in shallow streams may not splash soil, it does cause turbulence, providing a greater sediment carrying capacity. Large drop may increase the sediment carrying capacity of run off as much as 12 times.
If rain falls gently, it will enter the soil where it strikes and some will slowly run off, but if it occurs in torrents, as usually the monsoon rains doe, there is not enough time for the water to soak through the soil and it runs off causing erosion. Run off that causes erosion, therefore, depends upon intensity, duration, amount and frequency of rainfall. It is observed that rains in excess of 5 cm. per day always caused run off whereas those below 1.25 cm. usually do not.
(The results of soil and runoff losses from air dry deep black and later tic soils with 2 p.e., slope under a rainfall simulator with a constant rainfall immensity of 8.75 cm. per hour indicate that soil loss per 2.5 cm. of siuautated ram) in case of latertic soil is 0.25 tons per hectare. Thus the soil loss in case of deep black soil which is heavier than latertic soil is ten times more.
2. Topography will special reference to slope of lands: Slope accelerates erosion as it increases the velocity of flowing water. Small differences in slope make big difference in damage. According to the laws of hydraulics, a four - time increase in slope doubles the velocity of flowing water. This doubled velocity can increase the erosive power four times and the carrying capacity by 32 times. In one of the experiments in United States of America, it was observed that the loss of soil per hectare due to erosion in a maize plot was 12 tons when the slope was 5 p.c., but it was as high as 44.5 tons under 9 p.c., slope.
3. Physical and chemical properties of soil: Some soils erode more readily than other under the same conditions. The crodibility of the soil is influenced by its texture, structure, and organic matter, nature of day and the amount and kind of salts present. There is less erosion in sandy soil because water is absorbed readily due to high permeability. More organic manure in the soil improves granular structure and water holding capacity. As organic matter decreases, the crodibility of soil increases. Fine textured and alkaline soils are more crodible.
In general, soil detachability increases as the size of the particle increases but soil transportability increases with the decrease in particle size. Clay particles are more difficult to detach than sand, but are easily transported on a level land and much more rapidly on slopes.
4. Ground cover, its nature and extent: The presence of vegetation ground cover retards erosion. Forests and grasses are more effective in providing cover than cultivated crops. Vegetation intercepts the erosive beating action of falling raindrops retards the amount and velocity of surface fun off, permits more water flow into the soil and creates more storage capacity in the soil. It is the lack of vegetation that creates erosion permitting condition.
Normal And Man Made Erosion
Weathering of parent rock and erosion are natural processes by agencies like water and wind. This type of erosion occurring in nature is normal or geological erosion. If both the processes are equal i.e., erosion removing as much top soil as the weatchring processes from it, there is not much harm done, but it is generally not so. In order to provide food and shelter, man has cut down forests indiscriminately, allowed grazing of grasses excessively and ploughed the land and exposed it to nature with the result that erosion of soil has been faster than it was formed.
This is man - made erosion and is a result of bad land management. The worst form of cultivation is shifting cultivation. The practice is common with tribal communtics. They fell the forest and burn all vegetation and cultivate the cleared areas for 2 to 3 years and then abandon them for some years. This accelerates erosion and many good hill slopes have been denuded of vegetation and top soil, making tem barren.
Damage Caused By Erosion
Erosion does not only cause considerable damage to good fertile and but is also detrimental in many other ways which are discussed below:
1. Washing away of fine soil: The top 18 cm. of soil is most important from the point of plant growth. Eighty p.c. roots of the plants are found in the surface soil and they absorb their nutrition and water from that zone. If the top soil is washed away by erosion, the water holding capacity of the soil is decreased and productivity goes down.
2. Deposition of coarse material in low lying areas: Low lying areas are exposed to the danger of deposition of coarser particles which are washed from higher hilly areas. This makes the soil less productive. It is also a common experience that during floods good fertile soils on the river banks are corded and covered with layers of sand with the result that they become infertile.
3. Silting of tanks: Tanks get filled every year during monsoon season by water from catchments area. This water also brings with it large quantities of silt and day. If proper antierosion measures are not taken in catchments area, reservoirs get silted and their storage capacity is considerably reduced.
4. Lowering of the underground water table: If surface run off is allowed to go on unchecked, the quantity of water that should infiltrate into the soil is very much decreased. Water table in wells goes down as underground water is not replenished and irrigation cost goes up.
Water Conservation
Along with soil water is another important factor essential for all life and production of food. The main source of water is precipitation. In India precipitation is not property distributed throughout the year. It is received within a few months of rainy season and that too in a critic manner. It may rain 50 to 125 mm. in one day causing flood and damage to crops and then there may be a dry spell for some days when crops may begin to will. Hence proper conservation of water as well as collecting surplus water in tanks and reservoirs of letting it out into the rivers assume great importance. To understand water conservation it is necessary to study the hydrologic cycle.
Hydrologic Cycle
Water moves in a continuous cycle from ocean to clouds to earth and back to ocean. The water in the ocean is converted into vapour by the heat of the sun and this vapour moves in the form of clouds over the land and condenses into rain. Some rainwater enters the soil while the rest flows into streams and rivers and is either stored in tanks and reservoirs or allowed to go back to sea. Of the water that enters the soil some is stored for use by the plant some gets evaporated from the surface of the soil and some moves down to replenish the water table. This becomes the source of water for wells and springs. This cyclic movement of water is known as the hydrologic cycle. The water that is held by the soil in available form is essential for plant growth. It is not yet possible for the man to control rainfall but its infiltration and run off can be regulated to a great extent by improved management practices. Efforts should be made to store rain water either in the soil or in the reservoirs when it is in plenty and carry over to periods when rain water is not available. The former is known as conservation of water in soil, while the latter, conservation in reservoirs.
Loss of Water From Soil
Water is lost from soil in four ways:
1. Surface run off.
2. Downward movement of drainage.
3. Evaporation from soil surface.
4. Transpiration through leaves of plants.
Out of this loss of water through run off is the largest and is also the most damaging as it causes erosion main factor in conserving moisture relates to increasing infiltration and storage capacity of soil and reducing run off and evaporation. Uncontrolled water is the main cause of soil erosion. Almost all methods that deal with soil conservation are in principle the methods to control and conserve water. Soil and water conservation are, therefore, dealt together, Sufficient studies on all phases of hydrologic cycle such as evaporation, precipitation, run off, infiltration and deep percolation which occur simultaneously have not been carried out in India as yet, though 2 beginning has been made at many agricultural research stations.
Soil And Water Conservation Methods
The loss of soil and water under natural vegetation is the lowest. But lands must be cultivated and grown with crops to produce food. This can be done without much harm to the soil if proper soil and water conservation methods are followed. Such methods aim at encouraging water to infiltrate into the soil, reduce its velocity and check run off losses.
The most common soil and water conservation methods are
A) Management practice viz.
a) Strip cropping,
b) Mulching,
c) Crop rotation,
d) Contour cultivation,
e) Planting of grasses for stabilizing bunds,
f) Planting of trees and a forestation,
g) Cashew nut plantation, and
B) Mechanical practices such as
a) Bunding,
b) Terracing,
c) Gully or nala control,
d) Control of stream and river banks.
Soil And Water Conservation Methods - Management Practices
a) Strip cropping: This consists of growing erosion permitting crops and erosion resisting crops in alternate strips. The erosion permitting crops are cotton, jawar, bajara, etc. which allow the run off water to flow freely within the rows. The erosions resisting crops are mostly legumes like groundnut, much (Phaseolus aconitiolius), hulgn (Dolichos biflorus), Sow bear (Glycine max) which spread and cover the soil and do not allow run off water to carry much soil with it the soil which flows from the strips growing erosion permiuming crops is caught by the alternating springs.
In selecting a suitable legume crop it should be seen that the maximum canopy and root development of the crop coincide with the period of high intensity of rainfall.
b) Mulching : A mulch is natural or artificially applied layer of plant residues or other material on the surface of the soil with the object of moisture conservation, temperature control, prevention of surface compaction or crust formation, reduction of run off and erosion, improvement in soil structure and weed control. Artificial mulches of different kinds such as Jowar or bajara stubbles, stubbles, paddy straw or husk, sawdust etc., increase absorption of water and minimize evaporation. They also control run off and soil losses.
c) Rotation of crops: Rotation means growing a set of crops in a regular succession over the same field within a specified period of time. Continuous growing of Jowar or bajara crop causes more erosion, but if followed by a legume crop viz., hulga, matki or gram which covers the soil is causes less erosion. Rotation also helps in removal of plant nutrients in a uniform way from future depth of soil and in maintaining the fertility of the soil in dry farming region of Maharashtra adoption of gram Jowar rotation not only helps in conservation of moisture but also in increasing the crop yields the beneficial effect of rotation can be seen from the following table.
d) Contour cultivation: Tillage operations viz., ploughing, harrowing, sowing and Interculture should be done across the slope of land. This will help in creating obstructions to the flow of water at every furrow, which acts like a small bund and results in uniform distribution of water. This helps more initration of water less run off and erosion, and gives higher crop yield. Any cultivation done along the slope will accelerate golly formation, more run off and erosion and consequently permanent damage to land.
e) Planting of grasses for stabilizing bunds: Grasses prevent soil erosion and improve soil structure. The entire soil mass is penetrated by countless roots and soil aggregates and particles are enmeshed by the root system. Grasses should be grown on bunds which are not suitable for cultivation, both for checking erosion and providing pasture for cattle. Several grasses as well as legumes were tried on bunds at the Agricultural Research Station; Solapur which receives about 600 mm. of rainfall to see which of them will withstand drought conditions, give maximum root growth and canopy coverage, and stabilize bunds effectively. It was observed that anjan planted with spacing of 15 x 15 cm., produced the highest quantity of roots, followed by marvel - 8, Rhodes, thin Napier, blue panic, and kusal .Legumes do not have many roots but produce better canopy within a short period, while grasses are under the process of establishment. Planting of legumes mixed with grasses is, therefore, advantageous in preventing soil erosion in initial stages.
f) Planting of trees and afforestation: Forests conserve soil and water quite effectively. They not only obstruct the flow of water, but the falling leaves provide organic matter which increases the water holding capacity of the soil. If tree planting is done in the planned manner in open areas, it will serve as good wind break and if done along the banks of streams and rivers, it will regulate their flow. Farm forestry is another important aspect in soil and water conservation. The danger caused by deforestation has been only recently appreciated and a big plantation programme of hybrid eucalyptus, teak, casurina has been taken up by the Forest Departments in reserve forests, catchments areas of irrigation projects and on Government waste lands Vanamahotsava is also observed every year in the early part of monsoon and millions of trees are planted by the public with the help of the maff of the Agricultural and Forest Departments local bodies like Zillah Paris had, Panchayat Samitis and Gram Panchayat What is however important is to pay proper attention planted.
g) Cashew ant plantation : In coastal districts of Maharashtra which receive more than, 1,250 mm. rainfall a new programme of cahsewnut plantation has been undertaken from 1963 - 64 on hills having slope between 10 and 20 p.c.The sea breeze is conducive to the growth of cahsewnut plants and they do not require much aftercare once they establish in the soil. Staggered trenches of 300 x 30 x 30 cm. size are dug on contours at a distance of 6m. Cashew plants are raised in polythene bagsin nurseries and two months olds a plings are planted on the lower side of the trench with plant to plant distance of 6m.
Soil And Water Conservation Methods - Mechanical Practices
The above measures control erosion by good management practices. Bunding, terracing, gully or nala control, and construction of tanks and bandharas are mechanical measures requiring engineering techniques and structures. They reduce run off and impound water for longer time to help infiltration into the soil. Their construction and design will depend upon rainfall, soil slope and such other factors. These measures are costly but if properly maintamed will improve the land over a long period of time.
Bunding:
i) Block bunding: Bunding for control of soil erosion and conservation of surface run off was known to farmers for centuries. It was not uncommon to find Tals i.e., big bunds across large blocks of sloping lands. These bunds are constructed of earth or stone or both, at a great cost, to impound water and arrest soil washed from the fields lying above. They are high and broad enough to withstand the force of water from the catchments. Water is let out at the end of the monsoon and land which has received fertile silt is sown with crops. Such type of big bloods bunds are not constructed now as contour bunding has been taken up on catchments basis.
ii) Contour bunding: It consists of construction of a series of earthen bunds of suitable sizes along contours at a lateral distance of every 60 mm or a fall of 1 to 1.5 m. The shope of land is thus broken into smaller and more level compartments which hold soil as well as rain water. It has been estimated that about 75 million hectares of land i.e. about one fourth of the common land surfaces suffering from soil erosion. In Maharashtra State, the problem is more acute and it is estimated that out of 186 lakh hectares about 144 lakh hectares require bunding. The planning Commission has, therefore laid great stress on contour bunding programme, because bunding alone has been found to increase crop yield by 20 to 30 p.c.
The size, cross- section and interbund spacing depend upon the nature of rainfall, soil and slope of the area. In order to improve the technique of bunding, studies have been carried out in respect of spacing of bunds, shrinkage of bund sections and hydraulic gradients and kind and location of outlets etc. in different soil and rainfall conditions of Maharashtra State. On the basis of such studies it has been observed that the spacing between bunds should not be allowed to exceed 1.5m. Vertical drop or 67.5 m. lateral spacing. The following table21 is a fair guide.
iii) Graded bunding: In high rainfall areas, while conservation of soil is important, drainage of surplus water has to be attended to, for avoiding waterlogged condition of soil. The bunds are therefore, slightly graded longitudinally about 7.5 cm. per running 33 m. to prevent safe disposal of water into the nala. The cross sections into for safe removal of excess run off water it is essential to provide suitable waste water or outlet structures at proper places so that no damage is done to bunds in case heavy precipitation is received on any single day. Normally stone outlets are provided low rainfalls are as. Channel weirsor pipe outlets may also be provided. Grass outlets have been found to be effective and cheaper in heavy soil. The crest wall should be 30 cm. above the contour level and its length should be so designed as to discharge the surplus water from the maximum intensity of rainfall with are asonable period. 1,250 mm. Terrace bunds consist of comparatively narrow embankments constructed at intervals across the shope and the vertical spacing between bunds may vary from 1to 2 m., depending upon the slope, type of soil, rainfall etc. Bench terracing is done when gradient is stceper than 10 p.c. as in hilly ranges of Himalayas, Sahyadry etc. and consists of a series of step like platforms along contours. These terraces are like table tops sloping outwards and are provided with stone wateweirs to drain away surplus water. Angular and big boulders should be used for terrace outlets because round and small boulders will slip and get dislodged under the gushing water.
Gully or nala control: Gully or nala control is very essential to prevent its extension and further destruction of cultivated lands and grasslands. The sloping sides are planted with grass and trees. Suitable temporary and permanent structures such as check dams, overflow dams, drop structures are also provided. Small gullies can be stabilized by converting them into paddy fields. So far 17,034 nalas have been controlled and the target for sixth plan (1980 - 85) period is 2005.
Control of stream and river banks: Vulnerable sharp bends nalas by the sides of the rods and river bends near village sites cause considerable damage to property. These should be protected by providing spurs, jetties, rivets and retaining walls. Adjoining areas should be stabilized under permanent vegetation. Spurs are constructed at an angle to reduce the velocity of water and there by enabling the flood water to flow away but deposit coarse sand which will cause obstruction to successive water currents from cutting into the bank and thus straightening their course.
Runoff, And Their Types
Definition:” It is that portion of rainfall, which makes its way towards streams, rivers etc. After satisfying the initial losses etc. is called as runoff.
Types of Runoff:
1. Surface runoff.
2. Sub - surface runoff, and
3. Base flow.
1. Surface Runoff: It is that portion of rainfall which enters the stream immediately after the rainfall. It occurs. When all losses are satisfied and if rain is still continued, with the rate greater than in filtration rate; at this stage the excess water makes a head over the ground surface (surface detention) which tends to move from one place to another, known as overland flow. As soon as the overland flow joins to the streams, channels or oceans, termed as surface runoff.
2. Sub - surface Runoff: That part of rainfall, which first leaches into the soil and moves laterally without joining the water - table to the Streams Rivers or oceans is known as sub - surface runoff. Sometimes sub - surface runoff is also aerated under service ninoff due to reason that it takes very title time to reach the river or channel in comparision to ground water. The sub - surface runoff is usually referred as interflow.
3. Base flow: It is delays flow, defined as that part of rainfall which after talling on the ground surface in fill rated into the soil and meets so the water table and flow to the streams oceans etc. The movement of water in this type of runoff is very slow that is why it is also referred as delayed runoff. It takes a long time to join the rivers or oceans. Some times base flow is also known as ground water flow.
Thus,
Total Runoff = Surface runoff + Base flow (Including sub - surface runoff)
Factors Affecting Runoff
The runoff rate and its volume from an area, mainly in influenced by following tow factors:
a) Climatic factors and
b) Physiographic factors
Factors Affecting Runoff - Climatic Factors:
The climatic factors of the watershed affecting the runoff are mainly associated with the characteristics of precipitation, which include.
1. Type of precipitation
2. Rainfall intensity
3. Forms of precipitation
4. Duration of rainfall
5. Rainfall distribution
6. Direction of prevailing wind and
7. Other climatic factors.
1. Type of precipitation: Types of precipitation have a great effect on the runoff. For example a precipitation which occurs in form of rainfall, starts immediately in from of surface flow over the land surface, depending upon its intensity as well as magnitude, while a precipitation which takes place in form of snow or hails the flow of water on ground surface will not take place immediately, but after melting of the same. During the time interval of their melting the melted water infiltrates into the soil and results a very little surface runoff generation.
2. Rainfall intensity: The intensity of rainfall has a dominating effect on runoff yield. If rainfall intensity is greater than infiltration rate of the soil the surface runoff takes place very shortly while in case of low intensity rainfall, where is found a reverse trend of the same. Thus high intensities rainfall yield higher runoff and vice-versa.
3. Duration of rainfall : Rainfall duration is directly related to the volume of runoff due to the fact, that infiltration rate of the soil goeson decreasing with the duration of rainfall till it attains constant rate. As a result of this even a mild intensity rainfall lasting for longer duration may yield a coverderable amount of runoff.
4. Rainfall distribution: Runoff them a water sheed depends very much on the distribution of rainfall. The rainfall distribution for this purpose can but expressed by a team "distribution coefficient which may be defined as the ratio of maximum rainfall at a point to the mean rainfall of the watershed. For a given total rainfall, if all other conditions are the same, the greater the value of distribution coefficient, greater will be the peak runoff and vice - versa. However, for the same distribution coefficient, the peak runoff would be resulted from the storm, falling on the lower part of the basin i.e. near the outlet.
5. Direction of prevailing wind: The direction of prevailing wind, affected greatly the runoff flow. If the direction of prevailing wind is same as the drainage system then it has great influence on the resulting peak flow and also on the duration of surface flow, to reach at the outlet. A storm moving in the direction of stream slope produces a higher peak in shorter period of time than a storm moving in opposite direction.
6. Other climatic factors: The other climatic factors, such as temperature wind velocity, relative humidity, annual rainfall etc. affect the water losses from the watershed area to a great extent and thus the runoff is also affecter accordingly. If the losses are more the runoff will be less and vice -versa.
Current Category » Rainfed Agriculture
Factors Affecting Runoff - Physiographic Factors
Physiographic Factors:
Physiographic factors of watershed consist of both, the watershed as with as channel characteristics. The different characteristics of watershed and channel, which affect the runoff, are listed below.
1. Size of watershed
2. Shape of watershed
3. Slope of watershed
4. Orientation of watershed
5. Land use
6. Soil moisture
7. Soil type
8. Topographic characteristics, and
9. Drainage Density.
1. Size of watershed: Regarding the size of watershed, if all other factor including depth and intensity of rainfall are being same them two watershed irrespective of their size, will produce about the same amount of runoff .However a large watershed takes longer time for raining the runoff to the outlet as result the peak flow expressed are depth is being smaller and vise versa.
2. Shape of watershed:The shape of watershed has a great effect of runoff. The watershed shape is generally expressed by the terms "from factor and "compactness coefficient".
3. Shope of watershed: The shope of the watershed has an important roel over runoff but its effect is complex. It controls the time of overland flow and time of concentration of rainfall in the drainage channel which provide accumulative effect on resulting peak runoff. For example in case of a sloppy watershed. The time to reach the flow at outlet is less, because of greater runoff velocity which results into formation of peak runoff very soon and vice -versa.
4. Orientation of watershed: This factor affects the evaporation and transpiration losses from the area by making influence on the amount of heat to the received from the sun. The north or south orientation of watershed, affects the time of melting of collected snow. In a mountainous watershed the part of wind ward side of the mountain receives high intensity of rainfall resulting into more runoff yield while the part of watershed typing towards leeward side has reverse find of the same.
5. Land use: The land use pattern and land management practices used have great effect on the runoff yield. For example an area which is under forest cover, where a thick layer of much of leaves and grasses etc. has peen accumulated there formed a little surface runoff due to the fact that more rain water is absorbed by the soil. While in a barren field where not any type of cover is available a reverse trend is obtained.
6. Soil Moisture: The magnitude of runoff yield depends on the amount of moisture present in the soil at the time of rainfall. If rain occurs over the soil which has more moisture the infiltration rate becomes very less which results in more runoff yield. Similarly if the rain occurs after a long dry spell of time when the soil is dry, causing to absorb huge amount of rain water. In on the other hand, if the rain occurs in a close succession as in the rainy season; runoff yield has reverse effect.
7. Soil Type: In the watershed surface runoff is greatly influenced by the soil type as loose of water from the soil is very much dependent on inflientation rate which varies with the types of soil.
8. Topographic Characteristics: Topographic characteristics include mores topographical features of watershed which create their effect on runoff it is mainly undulating nature of the reason that runoff water gets additional power to flow due to slope of the surface and altitude time to infiltrate the water into solid.
Regarding channel characteristics to describe their effect on runoff the channel cross-section, roughness storage and channel density are mainly considered. These also have significant effect on runoff.
9. Drainage Density: The rain age density is defined as the nation of the trial channel length in the watershed to two total watershed areas it is expressed at.
(Tranned length (Total))
Drainage density = ------------------------------
Watered area
I
D.D. = --
A
A watershed having greater D.D. and incites formation of peak rain off very shortly to that of lesser D.D. watershed.
Different Agronomical Practices for Soil and Water Conservation
Conservation In Rainfed Areas
Soil conservation is a preservation technique, in which deterioration of soil and its losses are conserved by using it within its capabilities and applying conservation techniques for protection as well as improvement of soil. In hilly regions. Where land topography has steep slope and is subjected to erosion problem the vegetation cannot get established. Lack of the vegetative cover on sloppy soil surface accelerates the erosion and a large amount of soil is transported into the stream through runoff. In addition, the uncovered sloppy land also a cause extensive damage to the cultivable land at foothill through exporsition of sedimentson them.Sediment disposition covers the top fertilesoil layerand thus makes them unsuitable for cultivation.
Under this circumstance it becomes very necessary to treat such areas by adopting appropriate agronomical measures, so that they can be reclothed with negetations. The vegetation helps in reducing the surface runoff and soil cravsion both. The agronomical measures include contouring strip cropping and niluge practices to control they soil erosion. The use of these measures is entirely dependent upon the soil types land shope and rainfall characteristics.
In soil and water conservation programmes, the agronomical practices are counted as second line of defense the first being mechanical or engineering measures which are employed to arrest the soil erosion immediately. The role of agronomic measure is more economical long-lasting and effective. Always it is advisable to used but when its use is either inadequate or not sulpewant to achieve the goal of erosion control then use of mechanical measures to control erosion is recommended.
The agronomical measures are referred by the practices of growing vegetables on mild sloppy lanks to cover them and to control the erosion from there in living vegetation above the soil surface dissipates the crove power of agents either they are water or wind In case of water erosion it affects by several ways such as by enhancing infiltration rate and relucing together and thereby reducing runoff velocity to scour the soil particles screening the eroded particles to reach them into the channels or reservoirs; by dissipating the kinetic energy of falling raindrops and thus reducing the splash erosion. The effect of vegetation on wind erosion is also significant as it directly makes a hinderance in blowing path and thus deflecting the wind current at some distance away towards down stream side. The wind - strip cropping is a well known agronomical practice comployed for controlling the wind erosion in wind erosion susceptible areas.
The role of agronomical measures in achieve of soil & water conservation, has immense importance, perhaps much more than the others. It can be explained by considering the Universal Soil Loss Equation (A = R K L S C P) in which agronomical practices reflect the factor of crop management (C). The other factors such as R & K are the natural factor; we do not have any control on them. The L S and P factors may have value as I under worst conditions; although these can be reduced maximum up to 0.5 by applying an ideal soil and water conservation measures. The factor 'C' which is crop management factor has value as I for worst conditions, but it can be reduced up to 0.02. At this small value of C, the soil loss can be minimized up to one - fifteenth which is about 10.25 times more than the other factors. Looking this important effect of agronomical measures on soil loss, its scope is assumed to be more dominating in soil and water conservation programmes.
1. Contouring
2. Trip Cropping
3. Tillage Practices
These are the important agronomical practices employed for controlling the soil erosion from sloppy areas. Basically these measures create an obstruction in flow path of surface runoff by making the land surfaces rough due to channels ridges etc. formed under them. Each of these measures also have a direct relation with the infiltration rate and thereby presence of moisture in the soil profile. Infiltration rate is an effective factor in reducing the surface runoff and soil loss.
Different Agronomical Practices For Moisture Conservation In Rainfed Areas - Contour Cultivation
Contour cultivation refers to all the tillage practices or mechanical treatments like planting tillage and Interculture performed nearly on the contour of the area applied across the land slope. In low rainfall regions the primary purpose of contour cultivation is to conserve the rain water into the soil as much as possible. While in humid regions its basic purpose is to reduce the soil erosion / or soil loss by retarding the overland flow. In this farming system the furrows between the ridges made on the contours hold the runoff water and stored them into the soil in this way they reduce the runoff and soil erosion both.
Prior to start the contour farming on straight hilly land which is not engaged under bounds or lerrces a contour guide line should be established which should run across the field approximately at a constant level. At agricultural operators should be done with reference to the guide line established. In a relatively small field of conform shope, only one guide line is sufficient but in large area having long and uneven shope several guide lines may be required.
For locating the first contour line on a sloppy land it should be started from the highest point of the field and then preceded down the general slope. The contour lines are located at distance of 25 to 33 meters. Depending upon steepness of the land. On a long and gentle slope the first contour line is generally fixed at about 50 meters apart from the top of the hill. When contouring is done on steep shope and the area falls under high rainfall then there is probability to arise a scope for gulling problem. This may be overcome by applying contour farming practices along with strip cropping bunding or lerracing like practices.
Limitation of Contour Farming: Contour farming gives a better result in the field of relatively uniform slope. It is impracticable on the fields having irregular topographical features. Similarly the use of grassed waterways in conjunction with contour farming system is essential to reduce development of the gully.
When and Where to use Contour Cultivation: Contour cultivation is most efficient for reducing the runoff and soil erosion from gentle land slopes. Intense rain storms on steeper slopes cause water to accumulate behind the ridges until it breaks overuses downhill and crodes rills and gullies.
Table 10.1 Slope - Length Limits for contour farming:
Land slope (%)
Maximum slope length
1 - 2
120
3 - 5
90
6 - 8
60
9 - 12
35
13 - 16
25
17 - 20
18
20 - 25
15
Longer slopes until more crosion occurs in the gullies on contoured land than in the nills found between crop rows on the non - contoured land. There is some limit of land slope and its length on which contour cultivation is successful for controlling the soil crosion. Wischmeir and Smith (1978) have reported the values of kind slope and slope length for better contour farming which is cited in table. 10.1
The limits of slope - length change with the soil characteristics type of crops grown and rainfall of the area. The length of slope is used as greater on more permeable soils for more protective covers crops such as small grain crops and for less intense rainfall. Apart from the above the experience also reveated that with no - till and other reduced tillage systems that make the soil surface very well protected with crop residues allow the field length far in excess of those given in Table 10.1 can also be used safely for contour cultivation provided that the soil must be adequately protected with the crop residues every year
Strip Cropping
Strip cropping is also a kind of agronomical practice in which ordinary crops are planted / grown in form of relatively narrow strips across the land slope. These strips are so arranged that the strip crops should always be separated by strips of close growing and erosion resistance crops.
Strip cropping used as a technique for erosion control is a most effective method in certain soils and topography. This method becomes more effective for erosion control, which it is followed with crop rotations in the area where terraces are not practically feasible due to the fact that the length of slope is divided into different small segments. The strip crops check the surface runoff and force them to infiltrate into the soil, thereby facilitates to the conservation of rain water. Strip cropping is more intensive practice for conserving the rain water than contouring (i.e. about twice as effective as contouring) but it does not involve greater effect on soil erosion as terracing and bunding. Generally the use of strip cropping practice for soil conservation is decided in those areas where length of slope is not too longer.
Strip - cropping to control soil erosion caused by runoff derives its effectiveness mainly from following two factors:
a) Reducing the runoff flowing through the close - growing sod strips.
b) Increasing the infiltration rate of the soil under cover condition.
The reduction of runoff velocity between the row strips is achieved by making an observation in the flow path. The observations created by row crotion are also responsible to dissipate the kinetic energy of flow checking the flow of surface water. From field studies it has been observed that the strip cropping on the contour plays a key role in conserving the soil and water, when combined with terracing. The width of these strips depends on the topographical features of the area.
Field Strip Cropping: It is modified form of contour strip cropping in which crop strips are laid parallel across the land slope but not always exactly on the contour may be changed. This type of strip cropping is frequently used only where the topography is either too imegular or undulating as it makes accurate layout of contour strip cropping, impractical. The depressed areas should be avoided from field strip cropping they may be left for establishing the grassed water ways.
Buffer Strip Cropping: In buffer strip cropping the strips of grasses or legume crops are laid between contour strip crops in regular rotation. The width of these strips may or may not be even. The buffer strips are usually 2 to 4 m wide and are placed at 10 to 20 m meters. They can also be placed on critical stops of the field (The main purpose of buffer strip cropping is to provide a protection to the land from soil croson.)
Wind Strip Cropping: In wind strip cropping system the strip crops of uniform width are laid at right angles to the direction of preventing winds without regard of the contour. The main objective of this system is to control the wind crosion father than water crosion. This cropping is recommended for level or nearly level topography where wind crosion is more effective.
A guideline for deciding the width of wind strip - cropping can be have from the values given in table 10.2
Table 10.2 Recommended strip widths for wind strip
Cropping (FAO 1965)
Soill Types
Strip width (m)
Sandy soil
6.0
Loamy sand
7.0
Sandy loam
30.0
Loam
75.0
Silt loam
85.0
Clay loam
105.0
Layout of Contour Strip Cropping: In layout of a field for contour strip cropping the first step is to decide the width of strips at narrower points let the minimum width is assumed to be as 25 m. The next step is to establish a point for locating the contour line that will form the lower boundary of first strip. This point is located at 25 m apart from the top boundary of field by measuring along the steepest part of the stop. Now a contour line is drawn passing through this point up to the field boundary. This procedure is repeated until the entire field is laid out.
Width of Strips: It varies with the degree and length of land slope allowable soil loss soil types arrangements of crops grown in rotation and size of farm equipments used in tem aced fields the width of strip is adjusted according to the terrace interval but in untraced areas narrow width than the standard terrace interval is frequently used. In general steeper the slope narrower will be the strips of cultivated and dense growing crops both. An approximate range of trip widths based on average land slope and soil types is given in table 10.3
Table 10.3 Approximate range of strip width
Sr.No.
Percent Trand note
Width of strips (m)
(average)
Good soil
Fair soil
Poor soil
1
2
51
42
33
2
5
42
33
25
3
8
33
25
17
4
11
25
17
17
A buffer strip is more or less in a permanent contour strip usually varies in width which is normally kept between 3 to 5 m.
Crop Rotation: Crop rotations can be more effective for controlling soil crosion accompanied with strip cropping system. It can be used on the same piece of land by growing tilled crops; small grain crops hay crops or grasses either under a strip cropping system or a separate field system. In areas where perennial grasses and legumes are not feasible to grow, the row crops of small grain and annual legume crops can also be grown in strips. It is a general rule that no two cultivated strips should have the same planting or harvesting dates. The sequence of crops should be in such a manner that there could be form a dense - fibrous root system to hold the soil and retard the erosion, until the roots are croken down by tillage operations. All these activities of crop rotation also increase the organic matter in the soil thereby the physical condition of the soil become improved ultimately soil absorbs more water and also increases the capability of soil to resist the erosion.
Under use of crop rotation practices for controlling soil crosion, the simplest way to combine different crops in roa form and grow them in consecutive rotations. The frequency with which row crops should be grown depends upon the severity of crosion, taking place in the area. For example where crosion rate is very low the row crops can be grown at every alternate year but on the contrast in high erodible areas or where soil erosion is being more there may be practiced only once in five or even seven years cycle.
For erosion control by growing the crops in notation system probably the most suitable crops are legumes and grasses. The main benefits credited by these crops are mentioned as under:
* Reduction of soil erosion resulting from high degree of good ground cover.
* Help to maintain or improve the status of organic content in the soil thereby contributing the soil fertility and enable to develop more stable aggregates in the soil.
* Increase in soil nitrogen resulting from nitrogen fixation associated with legume crops.
Different crops and management practices used for growing them have different effects on soil structure. The crop affect the soil structure by the activities of their root system and the amount of organic residue contents added from the roots and top of the plants. The organic contents help in arranging and stabilizing the soil particles into granules or aggregates form. This in rum to provide greater pores in the soil mass causing rapid water take in the soil. Apart from above the soil aggregates are also developed by tillage operations wetting and drying of soil freeing and thawing of soil activities of micro organism and small animal like earth worm.
Interilled crops including vegetables and grain crops usually do not have effective root systems for improving the soil structure However most of the grain crops return a considerable amount of organic matter to the soil provided that the resides after grain movable should be covered into the soil by ploughing operations. The vegetable crops rectums very little organic matter to the soil. The dense root system of grass does much to create soil structure and also helps in binding the soil aggregates together.
Tillage Practices
Tillage is defined as mechanical manipulation of soil to provide a favorable environment for good germination of seeds and crop growth to control the wees to maintain infiltration capacity and soil aeration. A well planned tillage practice provides a favorable environment, suitable for better seed germination and effective plant growth. In addition, it also protects and maintains a strong soil structure to fight against erosion.
Tillage for Soil Conservation: Tillage is an important and primary tool for conservation of the land. As per definition, its primary purpose is to provide a favorable soil environment for the plant growth which is indirectly related to the soil conservation. The effect of tillage on soil erosion is the function of its several effects on soil such as aggregation surface sealing infiltration and resistant to crosion destruction of soi8l structure either by excessive tillage or tillage operations at improper soil moisture condition tends to increase the soil erodibility, causing significant soil loss. To achieve a best result for soil conservation the following points should be considered for tillage operations.
1. Till no more than necessary
2. Till only when soil moisture is in the favorable limit and
3. Vary the depth of ploughing.
Types of Soil Conservation Tillage Practices: There are a number of modified tillage practices have been developed; each of them related to the specified objectives for providing a better soil and water - plant relations. Reducing the runoff as well as soil crosion by enhancing infiltration capacity of the soil. The important types of soil conservation tillage practices are described below:
Mulch Tillage: It is performed either by making the soil surface cloddy or mulched with the help of crop residues. Mulch tillage is happened to be an effective measure to minimize soil erosion and to conserve the moisture when it is combined with strip cropping system. This type of tillage is also practiced to utilize the crop residues as mulch and also performing farming operations simultaneously. It can be defined as a method which permits the crops to grow where all or most of the residues from previous crops are left on the soil surface. The use of mulch tillage is based on the following profits.
1. The mulch intercepts the falling raindrops over the land surface and thus dissipating their kinetic energy which result in reduction or climination of their dispersing action on the oil structure.
2. The match ultge increases the infilte capacity.
3. The obstacles caused by leave stems and roots over the field reduce the velocity of surface flow and thus controlling the sheet crosion.
4. It maintains the soil relatively cool and moist which are essential for good plant growth and
5. Increases the crop yield by developing several conducive effects on soil.
Mulching:
It is defined as the application of any plant residues or other materials ot cover the top soil surface for.
* conserving the soil moisture.
* reducing the runoff and thereby to control soil erosion.
* checking weed growth
* protecting from winter climate.
* improving the soil temperature.
* modifying the micro - environment of soil to meet the needs of seeds for their good germination and better growth of seedlings.
The mulching is known to attribute the suppression of the weed growth conservation of moisture by checking evaporation and runoff to protect the soil against erosion (mainly from wind) to increase infiltration of water to fluctuate the soil temperature to enhance mineral nutrient availability to enhance nitrification to add nutrients and organic matters derived from decomposing of residues or other materials used as mulch to preserve or improve the soil structure. Mulching also improves the soil aeration creates better biological activates and thus to make a consequent beneficial effect on the soil fertility.
Mulching Materials:
The followings are used as mulching materials:
* Cut grasses or foliage
* Straw materials.
* Wood chips
* Saw dusts
* Papers
* Sand stones
* Glass woods
* Metal foils
* Cetto phanes
* Stones
* Plastics
Types of Mulches:
The mulches may be following types
a) Natural and
b) Synthetic
c) Petroleum
d) Conventional
e) Inorganic and
f) Organic
The natural mulches are borned by nature itself no man's effort is required.
Synthetic Mulches: Includes organic and inorganic liquids that are sprayed on the soil surface to form a thin film for controlling the various atmospheric happenings taking place over the top soil surface. The different synthetic mulching materials are as under.
* Rasins
* Asphalt emulsions
* Latex and out back asphalt
* Canvas
* Plastic and paper products
* Polythene and polyvinyl chloride (PVC).
* Bitumen emulsions.
The plastic mulches are very useful for nurseries in semi - arid and arid regions but their demerit is to have more cost and difficult to apply on large scales. The plastic mulching is also not suitable for the taller vegetations. In nurseries the dark colored plastic mulches make the soil surface very warm during the day hours because black body absorbs greater heat from the sunlight. This type of characteristic results in lower diurnal and higher nocturnal temperature.
Petroleum Mulch: The petroleum mulches are easier to apply and also less expensive. These mulches are available inform of emulsions of asphalt in water that can be sprayed on the soil surface at ambient temperature to form a thin film in continuous form that clings to the soil but not penetrate deeply. A thin film of petrol cum substance made so is termed as mulch film. The mulch film promotes uniform and rapid seed germination and also plays a significant role for vigorous growth of seedlings. An ideal surface film is also stable against erosion sufficiently porous to allow water in the soil yet insoluble in water and resistant enough to the forces of weather causing it to last as long is necessary for permanent vegetations to cyme established.
Conventional Mulch: The mulches such as hay or straw are more effective than the petroleum mulches. These mulches not only conserve the moisture and reduce the fluctuation of soil temperature but also protect the soil from rain drop impacts and hold the excess surface water in contact with the soil so as to increase the infiltration rate and thereby reducing the runoff and soil erosion. In skit on during day hours these mulches also absourth as resulting the surface of the mulch becomes hot and the soil on the other hand, during night hours, the mulch cools down and permitting the soil to remain warm. The papers mulches are also counted under conventional mulch are reported to give a remarkable result. Paper mulches are observed to increase the soil temperature especially of the surface soil layers. There are several evidence to show that paper mulching proves bettle performance in improvement of soil condition besides promoting the carthwarn activity. List at the same time the toxic elements of chemicals are coached out of the paper which has to be guarded against. The treated papers such as pitamanised have toxic effect on the plants.
Inorganic Mulches:
Soil mulch: It is an important mulch for the conditions of arid and semi - arid regions. Its application during summer and rainy seasons should be avoided. The soil mulch is also effective to reduce the evaporation particularly where the soil is saturated as a lower depth below the top surface or the moisture content is in excess of field capacity but hot in contact with a continuous water - table. Sometimes, the soil mulches are not effective under ordinary conditions as large amount of moisture evaporation establishes a protective dry layer of the soil which if worked will cause excessive so moisture loss.
In soil mulching a loose and dried soil layer of 5 to 8 cm thick is established on the soil surface. For this purpose the land surface is ploughed for the depth as specified above and left over for sometime to get dry of the ploughed soil; after that by planking operation the tilled soils are planed in this way a layer of dry soil in loose condition is prepared over the land surface which acts as soil mulch. The soil mulch prepared so obstructs the capillary loss of water from the lower layers due to following reasons.
* Lack of close contact with moist soil lying below.
* Increase in non - capillary pore space.
* Resistance to wetting.
These effects are said to be more apparent under isothermal conditions in regards of soil and temperature. Soil mulching has beneficial effect on soil aeration also.
The formation of crust on top soil surface is also counted as soil mulching it results in clogging of the soil pores which effectively seals the lower horizons from contact with the atmosphere and also prevents the diffusion of O2 and CO2.
The soil mulching becomes more effective when it is composed of crumbs and clods of proper size which are not liable to be broken down in form of surface crust by the impact of subsequent rains. In sundy areas the soil mulch should be prepared immediately after runs and renewed after subsequent rains when they get infiltrated downward and rap the maximum amount of moisture.
The general function of mulch is to raise the soil temperature during winter season and to lower the same during summer season by allowing low heat conduction through the same during summer season by allowing low heat conduction through the mulched layer and thus to maintain the soil temperature at a uniform level. In many cases the soil mulching also plays an important role to diminish the weeds growth from the soil.
Store Mulching:It involves the spreading of stone pieces on the ground surface to conserve the moisture and also to reduce the wind crosion. It is a very old practice followed in arid zones. Soil under the stones tends to be in moist condition but the temperature of that soil is slightly higher. The soils lying below the stones Harbour small animals and involve a high nitrification. The stone mulching is also used for tapir the dews particularly in those locations where significant dew fall takes place. Central Arid Zone Research Institute Jodhpur has reported the use of rubble much which is simply combination of mall fragments of stones and bricks provides better result on moisture conservation compared to the stone mulching synthetic mulching and mulching made by straw materials.
Organic Mulches: The tree bunches twigs leaves leaf litter grasses weeds etc. and used as organic mulch to cover the soil surface. The organic mulches are found superior than the artificial mulches in respect of conservation of moistures reduction in evaporation and runoff. By this mulch the control of evaporation is more effective particularly when rainfall takes place at frequent intervals but not found much effective when the rains are few and scattered in other words the infrequent rains and small showers may not be saved at all but for large rains which result we surface for several days with excess surface water for deep percolation these mulches may have their efficiency considerably more. Further more the light mulches are almost ineffective for controlling the evaporation because moisture conserving efficiency of mulch is inversely related to their capacity to absorb water or to extract it from the soil by capillary action. Resistant mulches do not decary sonly but last for a long time as a result they are more effective for conserving the soil moisture.
Benefits of Organic Mulches:
The various advantages are listed as under:
1. Very effective in reducing the soil erosion heatuse they promote interception loss and infiltration of rain water.
2. They obstruct the import of rain drops over the ground surface and thus dissipate the corrosive power of rainfall.
3. Very effective in preserving and impacting the soil structures by criminality the crusting of soil surface and sealing of pores by runoff.
4. Organic mulches also chance the dew fall by insulating the soil the really and electrically from the atmosphere.
5. The ascorbic molehes under the condition of bighorn temperature keep the sad temperature below the highest temperature.
Crop Residue Management- Use Of Mulches And Antitranspirants In Rainfed Agriculture
A Residue management: Consists of incorporating the crop residue like straw Stover, leaves, stubbles saw dust wood chips in soil at adequate level so as to develop and improve the physical and chemical properties of the soil.
Importance of crop residue management in Rainfed. Agril:
1. Crop residue management helps in controlling loss of water through runoff.
2. It increases infiltration and decreases evaporation of water.
3. It controls weeds, soil temperature through radition shilding.
4. It adds soil nutrients through organic matter.
5. It improves mineral solubility soil structure, soil biological regimes through organic matter addition.
Mulch, Their Types And Disadvantages
Mulch: Any material used (spread) at surface or vertically in soil to assist soil and water conservation and soil productivity is called much.
To achieve optimum advantage from the mulch the mulch should be applied immediately after germinationofcrop@5 ton/ ha (organic mulch). The practice of applying mulches to soil is possibly as old as agriculture itself. Mulches are used for various reasons but water conservation and erosion control are the most important objects in agriculture in dry regions. Mulches when property managed definitely aid wind and water erosion control. Other reason for high mulching is followed includes soil temperature modification soil conservation nutrient addition, improvement in soil structure weed control and crop quality control.
Disadvantages Or Limitations:-
1. Mulch is not been found effective other than Rabi Jawar.
2. In excess rainfall years mulch may not be effective.
3. Residue production in dry land is inadequate to result in sustainable water conservation.
Types of mulches: Materials used for mulches are crop residues levees clippings, bark manure, paper, plastic films, petroleum products, gravels etc.
1. Plastic films: Plastic fnms are more widely used as mulch. They help in maintaining higher water content in soil resulted from reduced evaporation, induced infiltration, reduced transpiration from weeds or combination of all these factors. They are relatively expensive expensive and difficult to manage under large scale field conditions for low value crops. (Polythene, polyvinyl).
2. Petrolium products: These are less expensive than plastic films and more readily applicable materials e.g. petroleum and asphalt sprays, resins etc.
3. Crop residues or stubble mulch: - Crop residues and other plant waste products (Straw, cloves, leaves, corn, and sawdust) are widely used as mulch. These materials are cheep and often readily available. The permit water to enter in the soil easily, when maintain at adequate level. These materials result in increased water content and reduced evaporation. Amongst the mulches tried light and thin stem material like dry grass was most effective as it provide good canopy, followed by gram stalks and wheat. Jawar stubbles were not as effective as other because of it is heavy weight and less canopy (cover). Use of mulch @ 5 tons / ha is found to be most effective in dry farming area. The mulch should be applied immediately after crop emergence to get optimum advantage. When these mulches are used the other crop operations like interculturing are not physible hence saving in cost of cultivation.
The effectiveness of various other materials as a mulch has been investigated. These materials have favourably influenced soil water content and evaporation but their use does not appear practically under large scale conditions e.g. gravels stones, granular materials, manure etc.
4. Vertical mulch: - Rainfall in dry farming area is with high intensity; due to moderately slow rate of infiltration the runoff is heavy. The water thus running as runoff could be stored in profile itself. In the recent past new technique has been evolved to tap such water.
Vertical mulch is a technique which consists of digging suitable trenches across the slope and thus making more surface are a available for water absorption. The open treaches are likely get silted in short period. This however can be prevented by inserting organic form waste material like straw stubbles or stalks which is called filter. The filter should be resistant to decomposition and provide service for 3 - 4 years. Such trenches at suitable intervals provide portion of low density which helps to intake water at higher rates. Water thus percolates in a trench and gets distributed in the profile. The width of trench should be adjusted in such a lastion that least area temains uncultivable. If trench could be accommodated between crop rows, there is practically no area wasted for trenches. Width of 20 cm is ideally suited for these propose. Depth of trench in black clay soil should be up to merum level and distances between two trenches may be about 4 m.
5. Soil or Dust mulch: If the surface of the soil is loosened, it acts as mulch for reducing evaporation. This loose surface of soil is called soil mulch or dust mulch. Interculturing creates soil mulch in growing crops and helps in closing deep cracks in Vertisols.
Effect of mulches on soil and plants:-
1. Soil water: - When soil surface is covered with mulch helps to prevent weed growth, reduce evaporation and increase infiltration of rain water during growing season. The water infiltrated in soil can be utilized by crops there by crop yields are increased. Mulches obstruct the solar radition reaching to soil. 2. Soil structure: - Crop residues when applied at adequate level increase infiltration rate. Decomposition of these residues results in improving soil aggregation and suability. Mulch slows (reduce) velocity of runoff.
3. Soil erosion: - Soils from dry region are nightly susceptible to water erosion and wind erosion because rainfall occurrence is frequent during intense storms and surface is adequately protected by vegetation effectively retard runoff. Therefore to reduce erosions by wind and water is an important reason for using mulches in dry regions.
4. Soil temperature: - Mulches results in greater water content and lower the evaporation. However effects on soil temperature are highly variable. White mulches decrease soil temperature while clear plastic mulches increase soil temperature.
5. Crop plants: - The effects of mulches on plants are operative through the effects of mulches on soil water, soil temperature structure and erosion. Reduced evaporation is major reason for the growth of the plants and there by high crop production due to mulch.
Antitranspirants
Antitranspirants are the materials or chemicals which decrease the water loss from plant leaves by reducing the size and number of stomata. Nearly 99 per cent of the water absorbed by the plant is lost in transpiration. Antiranspirants and is any natural applied to transpiring plant surfaces for reducing water loss from the plant. There are of four types.
1. Stomatal closing type: Most of the Tran spirants occur through the stomata on the leaf surface. Some fungicides like phenyl mercuric acetate (PMA) and herbicides like Atrazine in low concentration serve as antitranspirants by inducing stomatal closing. These might reduce the photosynthesis. PMA was found to decrease transpiration than photosynthesis.
2. Film forming type: Plastic and waxy material which form a thin film on the leaf surface and result into physical barrier. For example ethyl alcohol. It reduces photosynthesis eg. Tag 9; S - 789 foliate.
3. Reflectance type: They are white materials which form a coating on the leaves and increase the leaf reflectance (albedo). By reflecting the radiation, vapour pressure gradient and thus reduce transpiration. Application of 5 percent kaolin spray reduces transpiration losses. eg. Diatomaceous earth product (Celite), hydrated lime, calcium carbonate, magnesium carbonate, zincs sulphate etc.
4. Growth retardant: These chemicals reduce shoot growth and increase root growth and thus enable the plants to resist drought. They may also induce stomatal closure. Cycocel is useful for improving water status of the plant.
Antitranspiratnts are also useful for reducing transplantation shock of nursery plants (Horticultural plants) Examples / Different antitranspirants:
1. Metabolic inhibiter like phenyl mercuric acetate, some alkanyl succinic acids.
2. Growth retardant such as A.B.A. Cycocel.
3. Herbicides, fungicides
4. Salicylic acid.
5. Colourless plastics, silicon oil, wax or plastic.
6. White reflecting materials (e.g. Kaolin) emulsions or white wash.
Good features of contranspirant
1. Non toxicity
2. Non permanent damage to stomata mechanism.
3. Specific effects on gard cells and not to other cells.
4. Effect on stomata should persist at least for one week.
5. Chemical or material should be cheap and readily available.
Role of antitranspirants in annual field crops:
In general field crops are highly dependent or current photosynthesis for growth and final yield. Therefore it is unlikely that currently available antitranspirant would increase yield of an annual crop unless crop suffers stressed from inadequate water and or a very high evaporative demand, particularly during a moisture sensitive stage of development.
Fuahring (1973) sprayed stomata inhibiting or film forming anti - Tran spirants on field grown sorghum under limited irrigation conditions, he found that grain yield increases 5 to 17% and application of antitranspirant just before the boot stage was more effective than later sprays.
Water Losses And Their Control In Rainfed Agriculture
A. Use of Mulching:-
1. Mulching like grass, weeds & crop residues applied to the crop@ 5t / ha, reduce the maximum temp, of soil at 10 cm depth by 1 to 70C during monsoon season (July to Sept) by 4 to 100 C during summer season (April to June).
2. Mulches improved soil environment by way of increased moisture availability, reduction in soil temp. To optimum levels & thus higher water use & water use efficiency.
B. Tillage: - Affect soil - water relationships, aeration status, thermal characteristics & the mechanical impedance to the root penetration. Soil acts as mulch & restricts the upward movement of water to the evaporating site by reducing diffusivity gradients.
C. Use of Antitranspirants: - Define as the materials which decrease water loss from the plant leave by reducing the size or number of stomatal opening decreasing thereby the rate of diffusion of water vapour.
Two imp. Points in use of Antitranspirants:-
1. The application or an antitranspirants should restrict the water loss from the leaf surface without reducing photosynthesis, as carbon dioxide diffuse through stomata & is necessary for photosynthesis.
2. Transpiration causes cooling of the leaf surface & the use of antitranspirants should not completely stop transpiration & thus raise the leaf temperature.
Antitranspirants effective in Two ways:-
1. Through films that coat the leaf surface.
2. Chemicals that close the stomata
Examples of antitranspirants:-
1) Phenyl mercuric acetate Inhabits stomatal
2) Alkanyl succinic acids opening
3) Waxy or plastic emulsions - Film forming antitranspirants
4) White wash or kaolinite - Acts directly on wet cell walls & lower leaf temperatures & reduces vapor pressure gradient.
Effect on Photosynthesis of Antitranspirants:-
Antitranspirant result in size & no. of stomata’s of the leaves, however, a supply of carbon - dioxide diffusion into the stomatal cavity is necessary for the occurrence of photosynthesis & it the reduction in opening results in restriction of actual photosynthesis & the yield reduction will be there.
Example of Anti -Tran spirants
Growth retardants
Hydroxylamine hydrochloride
Abscisic acid
Phenyl mercuric acetate (PMA )
a-NAA
Silicon
Phosphon
Cetyl alcohol
Daminozide
Stearic acid
DAMS, TIBA, MH& CMH
Chlormeunat chloride
Methyl ester
Alacholor
Alkenyl succinic adid, 2, 4 - dinitrohenol.
Desiccarts or defoliants
Crop - ripens such as
2, 4 - D
Picloram
Paraquat
Ammonium isobutylate
H2SO4
Ccc, carbanyl urea,
Na - chlorate
Bromacil, Endothal
Diquat
Bacitracin
Minimum Tillage Or No Tillage (Zero tillage) Concept In Rainfed Farming
Tillage may be defined as the practice of modifying the state of soil in order to provide conditions favorable for plant growth.
Tillage can also been defined as the mechanical manipulation of soil with certain implement or tools to provide a suitable environment for seed germination root growth, weed control, soil erosion control and moisture conservation.
In the recent past, minimum tillage concept come into existence reduing time, labour and machine operations as well as conserving moisture and reducing erosion. The modern technology of herbicides & insecticides made it possible to achieve some tillage requirements without using implements.
Any tillage practice in dry lands which does not return more than its cost by increasing yield and improving soil conditions should be eliminated. Soil need to be worked only enough to assure optimum crop production and weed control.
Aims and objectives of tillage in Rainfed farming:
1. Moisture management: - Soil configuration for in situ moisture conservation, to increase infiltration rate to increase moisture storage capacity of soil profile, to increase aeration to reduce evaporation losses through intertillage operations to provide drainage to remove excess water etc.
2. Erosion control: - contour tillage contour cultivation tillage across the slope.
3. Weed control: - check weed growth & avoid moisture competition.
4. Management of crop residues: - Mixing of trash and decomposition of crop residues retention of trash on top layers to reduce erosion.
5. Improvement of tilth: - minimize the resistance to root penetration, improve soil texture & structure etc.
6. Improvement of soil aeration: - For good growth of crop.
7. Providing food seed - soil contact.
8. Preparing fine surface for seeding operation.
9. Incorporation of manures, fertilizers and agro chemicals (weedicide & soil amendments) into the soil.
10. Insect control.
11. Temperature control for seed germination.
Minimum Or Optimum Or Reduced Tillage
It denotes the reduction of number of operation by planting directly after harrowing without any other intervening cultivation which are usually carried out to give a fine seed bed. Or
Minimum tillage is a method aimed at reducing tillage to the minimum necessary for ensuring a good seed bed rapid germination satisfactory stand and favorable growing condition.
Objectives:-
1. Reducing energy input and labour required.
2. Conserving soil moisture and reducing erosion.
3. Increase organic carbon, improve structure of soil, increase hydraulic conductivity of soil, increase infiltration of water.
4. Providing optimum seedbed rather than homogenizing the entire soil surface.
5. Keeping the field compaction to minimum.
Minimum tillage made practicable and economical because of:
1. Development of good equipments for combined tillage & sowing operations.
2. Enormous progress in chemical weed control which has reduced unnecessary many other tillage operations.
3. Minimum tillage frequently gives as good as or even better yields than conventional tillage methods.
Advantages of minimum tillage:-
1. Increases organic carbon.
2. Improves soil structure
3. Increases hydraulic conductivity of soil.
4. Increases infiltration of soil.
5. Reduce soil compaction.
More advantages in coarse & medium soils than heavy soils.
Disadvantage of minimum tillage:-
1. Seed growth / intensity is increased
2. Less decomposition of organic manures & release of nitrogen
3. Less germination of crop seeds.
Minimum tillage can be practiced by different Methods:-
A) Ploughing planting: - In this method only a single trip over field is required. The tractor pulls a plough & planter simultaneously. The seed row is centered on the furrow slice. The area between the rows remains ploughed & weeds do not germinate easily.
This involves in less cost in seed - bed preparation and yields remain some to that of conventional tillage. The disadvantage in this method is that planting is slowed down & sowing is delayed beyond the optimum time.
B) Till planting :- (Special Till planter):- It prepares seed - bed & sows two rows in one operation. The seed - bed is prepared by an implement equipped with a narrow & deep penetrating sweep a wider & shallower sweep and selection of rotary her. The strip between the rows neither is nor disturbed.
C) Wheel track planting: - The field is ploughed as usual. The seedbed a prepared by wheels of the factor. The soil between rows remain rough & loose & absorb better moisture reduces runoff. Weeds seeds he dormant in loose soil until rainfall.
Save 40% villager cost ploughing + planting of seed shout be done at one time to avoid drying of upper soil surface.
Zero tillage
Zero tillage refers to tillage systems in which soil disturbances is reduced to sowing generals and traffic only and where weed country must be achieved by a genital nears. It can be considered as a men extreme form of minimum tillage 2010 tillage maintains more corposiders than any other tillage soil surface and it protect the grout against wind and water evasion.
Primary tillage it commonly avoided and secondary tillage restricted to Seedbed Corporation in the row zone only. It is also known no till and is resorted to who soil are subjected to wind & water erosion Zero tilled soil are homogenous in structure with high population earthworms. Organic matter content increases due to less mineralization.
Control of weeds is the main problem in zero tillage. Incomplete weed control is the main ebstoute to the further adoption. Zero tillage a widely used in humid areas.
Erosion losses and polities are minimized by zero tillage. Zero tillage will be useful concept where than.
i. Soils are subject to wind and water erosion eg. in sloppy bare compacted soils with high gilt fine sand.
ii. Timing of tillage operation 15 foods difficult.
iii. Conventional tillage to not yield more.
iv. Requirement of energy and labour too high.
v. In medium to fine textured soils use of heavy implements can result in formation of hard puncturing wet conditions. Much more research information is needed on cartilage.
Concept of Minimum Tillage is Useful In Rainfed Farming
How the concept of minimum tillage or zero tillage is useful in Rainfed farming:
1. It has been pressed hearing the experimental findings that the conventional tillage practices to not give higher yields over the maximum tillage practices in dry lands & hence the minimum tillage concept is useful in reducing additional cost on unnecessary tillage practices. The practice of harrowing alone may serve the purpose of seedbed preparation.
2. Frequent tillage operations results in loosening the top soil layer frequently which is subjected to more soil erosion due to intense rains. The research findings in dry lands have indicated that the frequent tillage operations lead to higher soil erosion as compared to untilled or less tilled soils. Hence the minimum tillage concept is useful in Dryland framing in reducing soil erosion.
3. The crop residues left over the soil surface acts as a much and helps in minimizing the evaporation losses. These crop residues also reduce the runoff losses, thus help in soil and water conservation in dry land.
4. The organic or crop residues get incorporated in top soil layers in subsequent period and increase the organic mater content of soils increase the infiltration rate of water reduce the bulk density increase the soil aggregation reduce the compaction of top soil layer thus increasing the productivity in dry lands.
5. Frequent tillage operations in dry lands also leads to formation of hard pans in heavy soils when worked under wet conditions & hence frequent tillage operations be avoided in heavy soils of dry lands.
6. The fine textured heavy soils of Dryland posses the self cracking habit extending to the depth of one meter and thus serves the purpose of ploughing Hence such soils should not be ploughed every year. The research findings have indicated that such soils can be ploughed once in three years.
7. The problem of weed control can be avoided by using the effective herbicides for various field crops in Dryland. Thus, the tillage operations required for weeds control can be reduced under Dryland conditions.
8. The concept of zero tillage is not applicable in any kind of Agricultural system including dryfarming at this stage since sufficient research information need to be generated for its successful application.
Harvesting Of Rainfall
(Water harvesting or Run off Farming in Rainfed Agriculture)
About 10 - 20 percent of the total rain goes as runoff in medium deep black soils. This also considerable soil loss by way of erosion. The extent of runoff varies with rainfall intensity and its duration land topography soil type and land use pattern. This runoff otherwise going as waste can be collected in suitable water storage structures such as farm ponds and used further for crop production. This technique of collection of runoff water during the period or excess rainfall and its further use for crop production is called "water harvesting" or "Runoff farming". Such collected water is used to provide supplemental irrigation to the crops at the most critical growth stages or during the prolonged period of drought.
In water harvesting the part of land from which the water is received is called "donor area" or "water producing area" or water harvesting area or watershed area or catchments area and the area in which it is used is called as "Recipient area" or crop production area. The donor area generally is not suitable for crop production.
Method Of Water Harvesting
There are three method of harvesting and recycling of runoff water.
i) Inter plot water harvesting: - In this method harvested water is directed to the crop. This method is suitable for area where rainfall is scanty (< 500 mm) and even there is difficulty of maturing a single crop. In this technique a portion of the area is cultivated & remaining area is used for harvesting water. Usually the uncultivated area is compacted or treated in such a way that runoff would be induced. Surface modification may be required to get runoff. Such method is suitable for arid regions. Runoff may be induced by using cover films (plastic or rubber) preparing hydrophobic layer (wax) compacting surface or spreading sodic soil on surface.
ii) Inter row water harvesting: - There may not be enough rain to support a crop in some areas & therefore by conserving more water in furrows and planting the crop in furrows may give some yields.
iii) Water harvesting in farm Ponds: - A portion of the excess runoff water after allowing maximum in situ moisture conservation is collected in farm ponds. As far as possible the pond should be located in the lower patches of the field to facilitate better storage and less seepage losses. The size of the farm pond should be worked out considering annual rainfall probable runoff and the catchments area. Generally, 10 to 20 per cent of the seasonal rainfall is considered as runoff in medium and deep black soils. A farm pond of 150 m3 capacity with side slopes of 1.5: 1 is sufficient for each hectare of catchments area in black soils. The farm ponds may be circular squared or rectangular. However eared or rectangular ponds are more convenient for harvesting of runoff water.
Under low rainfall situations to increase the runoff from catchments area the soil surface is treated with sodium salt betonies clay hydrophobic compounds like sodium ciliolate sodium rosinate etc. asphalt bitumen and water proofing membranes like paraffin. Some mechanical measures to increase runoff can be adopted such as land surface smoothening reducing surface depressions compacting the soil surface by rollers of spreading the clay blanket before rolling in sandy soils.
There are three important stages involved in water harvesting.
1. Collection of water in form pond.
2. Storage of water & problems
3. Applications of stored water to the crops.
1. Collection of water in form pond: - From the parameters like annual rainfall probable runoff and area of catchments the size of the farm pond can be work out. The location of the farm pond should be such that there v. should be proper storage and facilities to whiles storage and facilities to utilize stored water for crop production e.g. if farm is located in rocky and porous part, it would difficult to use stored water for crop production. Under such circumstances water may be increased and surface area may be required to convey for long distance. As for as possible pond should be located in lower patches of the field to facility better storage and seepage losses. The size of the farm pond should be decided by the quantum of water to be stored and nature of the soil strata. If the stratum is hard, rocky then it would be desirable to have shallow pond. If the structure is clay wool in that case depth may be increased and surface area may be reduced to have minimum evaporation. If the pond is located in upper patches water can be. How gravitationally and may create problems or water logging in low lying areas if proper care is not taken.
2. Storage of water problems: - Seepage and evaporation losses of stored water are the major problems of farm ponds. Nearly 40 to 50% quantity of stored water is lost through seepage and evaporation. When the pond is with murrum strata or under neath the total losses can be to the extent of 72% out at which 80% losses are due to seepage alone. In general the seepage losses in deep black soils are low. For preventing the seepage losses in farm ponds located in coarse textured soils the sealing materials such as natural clay, saling sodic soils, bentonite bituman, soil + cement mixture stones or brick in cement mortar asphalt compounds polyethylene / rubber sheets or plastering with soil + cowdung wheat straw etc. can be used for lining the pond surfaces depending upon the easy availability and cost of the material. However compacting and lining with natural clay soil is most economical.
The evaporation losses from free water surface can be reduced by spreading the materials on water surface such as plant residues oil emulsions long chain fatty alcohols i.e. Cetyl alcohol gum mixtures polyethylene oxides. Floating blocks of wax rubber and plastic floats are more effective in controlling the evaporation to the extent of 80 percent.
3. Application of stored water to the crops: - Since available water in the farm pond is a scare commodity its optimum use is the important consideration in entire runoff farming. In the case of application of water for crop production two considerations need to be borne in mind. First is the method of application and second the stage of crop growth.
For efficient application furrow irrigation or alternate furrow irrigation methods should be used than surface irrigation which will increase water use efficiency of stored water. When the stored water is to be used for post rainy season (Rabi) crops the water should be applied at the most critical growth stages.
For example: Rabi sorghum - When 2 irrigations are to be applied
First - stem elongation stage - 30 - 35 DAS.
Second - Flowering 65 - 70 Days. When stored water is limited and only one irrigation is possible in that case water may be applied before flowering to avoid storage losses. Here water should be stored in soil profile rather than in farm pond.
Safflower - 60 - 65 Days - Rosette stage.
Gram - 65 - 70 Days - pod development stage.
The research findings from Solapur have indicated that grain yields of Rabi sorghum safflower and gram can be increased by 100, 40 & 60% respectively by applying single irrigation at boot stage rosette stage & pod development stage respectively to above crops.
All these things discussed above should be combined into a method of management called "watershed based farming system". In this new approach the attempt is made to utilize water in all its stages and then excess water is drained out in to a farm pond connected to the field by protected grass water ways.
Methods Of Controlling Runoff
A. Mechanical Methods:
1. Contour bunding
2. Graded bunding
3. Biological Bunding or live Bunds or vegetative bunding; or Vegetative barriers
4. Water shed management- inter bund management
5. Broad bed furrow
6. Vertical mulching
B. Agronomical practices:-
1. Strip cropping
2. Mulching
3. Contour cultivation
4. Planting of grasses for stabilizing bunds.
5. Intercropping
6. Sequence cropping
7. Relay cropping
Vertical mulching: -
This is the practice followed in dryfarming areas for moisture conservation. The in filtration rate to black soils of dry lands is very low. In the event of high intensity rainfall much more water is lost as runoff instead of infiltrating into the soil profile. This process still accelerated under sloppy lands. Under these conditions the technique of vertical mulch has been found useful in Dryland farming.
This technique consists of digging suitable trenches across the shope and thus making more surface area available for absorption. The open trenches are filled with organic farm wastes like straw stubbles the stalks etc. which is called as filter. The filter should be resistant to decomposition and provide service for 3 - 4 years. The upper portion of filter should be 15 - 20 cm above the soil surface.
The trenun should be of 20 cm width in between two crop rows. The trench depth of 60 to 90 cm is optimum. The interval between trenches should be 4 m. the runoff water is trapped by the filter and allowed to percolate in the trenches the stored water in trenches recharge the soil profile by lateral movement of water. The findings on vertical mulching at Solapur & Mohole indicated 35 to 40% increase in grain yield of Rabi sorghum.
Vegetative or Biological bunding:-
The bushes like Subabul shevri of the grasses like vitiveria i.e. khus grass are planted in between the bunds in the fields across the slope or along the average contours. The system is called as vegetative bunding or biological bunding. The grasses or the bushes are cut close to the ground periodically leaving 20 to 30 cm top portion above the ground. This above ground portion helps to arrest the surface flow of excess water. The water halts temporarily along the vegetative bunds and helps in silting of soil particles. During this time water gets some time to infiltrate into the soil. Then partially clear excess water goes up to the field bunds with non erosive velocity which is further drained into field drains. The interval between two vegetative bunds will depend on the slope of the field. However 10 - 12 m interval between two bunds is convenient for carrying out field operations.
The bushes like Subabul or shevri can also be planted at 15 - 20 m intervals across the wind direction in the fields which acts as wind breaks and useful for checking soil erosion and moisture conservation.
Effective rainfall: -
From crop production point of view it is the portion of rainfall which contributes to the crop water needs is the effective rainfall. In other wounds the and of in tall watch becomes the part of consumptive use of water of a crop. An activicual farmer considers that the effective rainfall whiches that total rainfall which is useful in raising crops planted on his soil. Water which moves out of his field by surface runoff is the portion of total rainfall which is ineffective. Also the water that moves below root zone as deep percolation is ineffective. Any rainfall received after the soil has attained the field capacity up to rot zone depth is ineffective.
Factors Affecting Effective Rainfall
1. Rainfall characteristics:-
i) High intensity of rainfall - less effective rainfall
ii) More duration of rainfall - less effective rainfall
iii) Well distributed rainfall - more effective rainfall
iv) With light showers.
2. Land characteristics:-
i) Leveled land - more effective rainfall
ii) Sloppy land - less effective rainfall more runoff
iii) Ploughed land - More effective rainfall
iv) Vegetative cover - Less runoff, more effective rainfall.
3. Soil characteristics:-
i) Infiltration rate - high infiltration rate - more effective rainfall
ii) Storage capacity - More storage capacity - more effective rainfall
(Depth of soil)
iii) Initial water content - high initial water content then less will be the effective rainfall
4. Crop characteristics:-
More roof zone depth complete ground cover Active stage of growth - More uptake of water more will be effective rainfall.
5. Climate:
More radition High temperature and Low temperature Relative humidity – High crop requirement and more effective rainfall
6. Vegetative cover:-
Surface condition of soil canopy soil cover natures of roots mulches etc. affects the effectiveness of rainfall.
Drought Resistance And Characteristics Of Drought Resistant Crops And Their Varieties
Drought is a hazard to successful production. It occurs due to various combinations of the physical factor of the environment. Internal water stress in crop lands reduces their productivity. This reduction in productivity is brought by
1. Adely or prevention of crop establishment
2. Weakening or distraction of established crops
3. Predisposition of crops to insects & diseases.
4. Predisposition of crops to insects & diseases.
5. Alteration of physiological & bio - logical metabolism in plants & alternation of quality of grain forages fiber etc.
Drought:-
i) "Deficiency of available soil moisture which produces water deficits in the plant sufficient to cause a reduction in plant growth. Or
ii) "Drought is a period of inadequate or no rainfall over extended time creating soil moisture deficit and hydrological imbalances."
Classification of Drought:
A) On the basis of source of
water availability
B) On the basis of
occurrence
C) On the basis of
media
1) Meteorological drought
2) Agril. Drought
3) Hydrological drought
4) Socio - economic drought
1) Permanent drought
2) Seasonal drought
3) Contingent drought
1) Soil through
2) Atmospheric a drought
A) On the basis of water availability:-
1) Meteorological drought: - Ramdas (1960) defined this as actual rainfall is deficient by more than twice the mean deviation.
Indian Metrological Department (IMD) has defined meteorological drought as the situation when actual rainfall is less than 75% of the normal rainfall over an area. This is accepted principally because of its simplicity. The IMD uses two measures to define drought conditions.
i) Rainfall conditions
ii) Drought severity.
Rainfall conditions:-
i) Excess - 20% more than average of 70 - 100 yrs.
ii) Deficient - 20% less than average of 70 - 100 yrs.
iii) Deficient - 20 to 59% less than average of 70 - 100 yrs.
iv) Scanty 60% less than average of 70 - 100 yrs.
Drought severity:-
The IMD classifies droughts as follows from rainfall departures.
i) Slight drought when rainfall departure is 11 to 25% from normal rainfall.
ii) Moderate drought when rainfall departure is 26 to 50% from normal rainfall.
iii) Severe drought when rainfall departure is 50% and more from normal rainfall.
Drought years the year is considered drought when less than 75% of the normal rainfall is received.
2) Hydrological drought: - Definition of hydrological drought is concentrated with the effects of dry speels on surface & sub surfaces hydrology rather than with the meteorological explanation of the event. Linsley et al. (1975) considered hydrological drought as "a period during which stream flows are inadequate to supply established used under given water management system". The frequency and severity of hydrological droughts often defined on the basis of water depletion or shortage in reserve basins, reservoirs lakes wells etc. This drought affects industry and power generation.
3) Agricultural drought:-
Heathcoat (1974) defined agricultural drought as the shortage of water harmful to man's agril. Activities.
This is a situation resulted from inadequate rainfall when soil moisture falls short to meet the water demands of the crop during the growing period. This affects the crop growth or crop may wilt due to moisture stress resulting in yield reduction.
4) Socio - Economic drought:-
The socio - economic effects of drought can also incorporate features of meteorological hydrological and agricultural droughts. They are usually associated with the supply & demand of some economic goods. This drought should be linked hot only to precipitation but also trends of fluctuations in demand.
B) On the basis of time of occurrence:-
Droughts differ in time and period of their occurrence. As per thornithwaite the various droughts are:
1. Permanent drought:-
This is the drought area of permanent dry arid or desert regions. Crop production due to inadequate rainfall is not possible without irrigation in these areas. Vegetation like cactus thorny shrubs, xerophytes etc are generally observed.
2. Seasonal drought:-
In the regions with clearly defined rainy (wet) and dry climates seasonal droughts may result due to large scale seasonal circulation. This happens in monsoon area.
3. Contingent drought:-
This results due to irregular & variability in rainfall especially in humid & sub humid regions. The occurrence of drought may coincide with critical crop growth stages resulting in severe yield reduction.
C) On the basis of medium: - Maximov (1929) has defined into 2 types.
1. Soil drought: - It is the condition when soil moisture depletes & falls short to meet the potential Evapotranspiration (PET) of crop.
2. Atmospheric drought: - This results from low humidity dry and hot winds & causes desiccations of plants. This may happen even when rainfall & moisture supply is adequate.
Drought Prone Area
A drought prone area is defined as one in which "the probability of drought year is greater than 20%
Cronic drought prone area: A cronic drought prone area is defined as one in which the probability of a drought year is greater than 40%.
The criterion described above is useful for a continuous monitoring of the monsoon season. The sum of the seasons rainfall becomes the basis for describing a region under moderate or severe drought. When more than 50% of the area in the country is affected is described as severely affected by drought & when the area of 26 - 50% of the country is affected it is described as an incidence of moderate drought.
What is Drought Resistance?
It is the ability of a plant to maintain favorable water balance and turgidity even exposed to drought conditions there by avoiding stress and its consequences. Stress avoidance due to morphological anatomical characteristics which themselves are the consequences of the physiological processes induced by drought these zerophytic characteristics are quantitative and vary according to environmental conditions.
A favorable water balance under drought conditions can be achieved by transpiration before as soon as stress is experienced. These are called "water savers" or.
Accelerating water uptake sufficiently so as to replenish the lost water called as "water spenders"
A) The mechanism for conserving water:-
1. Stomatal mechanism: -Stomata of different species vary widely in their normal behaviour and range. In some species stomata remain open continuously or remain closed continuously. Many cereals open their stomata only during a short time in the early morning and remain closed during rest of the day. There is a difference in this respect between varieties of the same crop as shown by the example in two varieties of oat one is more resistant to drought open its stomata more rapidly in the early morning when moisture stress is at its minimum and photosynthesis can precede with the least loss of water (stocker 1960).
However mechanism of conserving water based on the closure of stomata will inevitable load to reduce photosynthesis and may lead to drought induced starvation injury (Leavitt, 1972).
2. Increased / Photosynthetic efficiency :- On possibility for overcoming limitations on photosynthesis, imposed bicoastal closure as means for increasing resistance to loss of water by transpiration there by transpiration there by accumulations of CO2 would be at higher rate for a given stomatal opening (Hatch & stack, 1970). A number of imperfect crop plants (maize, sugarcane sorghum prose, fox tail & finger millets) (Hatch et. al. 1987) as well as certain forage species Bermuda grass (Cynodon dactyl on) Sudan grass Bahia grass (Paspalum notatum) Rhodes grass (chloris Guyana) (Murata lyama 1963) and certain A triplex sp. fixed most of CO2 into the C4 of molic and aspartic acids so called C4 dicarboxylic acid (C4) pathway.
3. Low rate of cuticular transpiration: - The typical example is the cacturs. Thick cuticle results in low rate of transpiration.
4. Decreasing transpiration by a deposit of lipids layers on the surface of the leaves on exposure to moderate drought e.g. soybean (Levitt 1972).
5. Reduce leaf area: - The principal means of reducing water loss of xenomorphic plants is their ability to reduce their transpiring surface. Apart from the common means of keeping the aerial parts small perhaps the simplest form of this reduction of the transpiring surface is the sealing or of leaves at the time of water stress a characteristic phenomenon exhibited by many grasses. The rolling of leaves has been shown to reduce transpiration by almost 55 percent in semi conditions and by 75 percent in desert xerophytes (Stalfect - 1956).
6. Leaf surface: - Various morphological characteristics of leaves he reduce the transpiration rate and may affect survival of plants drought conditions. Leaves with thick cuticle waxy surface and the presence of spines etc. are common and effective.
7. Stomatal frequency and location: - A smaller number of stomata retard the development of water deficits. In certain species, the stom are located in depression or cavity in the leaves which is feature can further reduce transpiration by limiting the impingement of currents.
8. Effect of awns: - Awned varieties of wheat predominate in the drier at warmer regions and have been found to yield better than awnless one especially under drought conditions though there are exceptions (Gurandhacher 1963). Awns have chloroplasts stomata and so as photosynthesized. It has been found that the contribution of the away to the total dry weight matter of the kernels was 12% of that the entire plant.
B) To Improving water uptake (MC - Donough & Gauch 1959) :-
1. Efficient root system:-
The root systems of drought resistant plants are characterized by wide variety of apparent adaptations. These responded to such predominant soil conditions as the duration of soil dryness and the depth that is normally wet. Plants become adapted to dry conditions mainly by developing an extensive root system rather that structural modification of the roots (shields - 1958). The conceres "extensive root system" includes additional growth of secondary hair roots.
2. High root to top ratio (R/T):-
A high root to top ratio is very effective mean to adoption of plants to dry conditions of the growth rate of the roots considerably exceeds that of the shoots. The transpiring surface is there by reduced while root system of the individual plant obtains it's water from a large volume of soil (Simonis 1992) has shown that an increased root top ratio may actually result in greater amount of total dry matter of plants grown under dry conditions as compared a similar ones grown with full moisture.
3. Difference in osmotic potential of plants :-
Levitt (1958) has calculated a difference of 0.5% in soil moisture content that includes per manual wilting could supply a plant with enough water to keep it alive for 6 days. This could mean in certain cases the difference between survival and death.
4. Conservation of water spenders to water stress:-
Because of increased water absorption water spenders are characterized by very high rate transpiration. However as soon as the absorption rate becomes insufficient to keep up with water loss the water spenders generally develop some of the characteristics of the water savers (Cevitts - 1972).
C) Mitigating stress:-
1. Mitigating stress:-
Adoptions a drought basis mitigating effects of stress permit the plant to maintain a high internal water potential inspite of drought conditions. They therefore able to maintain cell tartar and growth avoid direct or indirect metabolic injury due to dehydration (Levit 1972).
D) Drought tolerance:-
When plant is actually submitted to low water potential it can show drought tolerance by either mitigating the actual stress induced by the moisture deficiencies or by showing high degree of tolerance to stresses.
1. High degree tolerance; Resistance to dehydration:-
The simplest method of avoiding drought induced damage is by resisting dehydration, preferably tot he extent .of maintaining turgur and at least by avoiding cell collapse after loss of turgur (Levit 1972) retain their turgur and therefore can continue to grow when exposed to drought stress. When plants are grown in their natural environment their osmotic potentials tend to be characteristic for each ecological group.
Characteristics Of Drought Resistant Plants
1. Early closure or stomata:
Opening stomata for short time in easy morning & remained closed during rest of day when moisture stress is minimum with photosynthesis with the least loss of water e.g. varieties of wheat, oats.
2. Increased photosynthetic efficiency:
The plant species using the pathways have a high rate or carbohydrate assimilation for given stomatal opening higher temperature & light optimum e.g. maize sorghum.
3. Low rate of cuticular transpiration:
Thick cuticle results in low rate in transpiration e.g. cactus.
4. Deposits of lipid layers:
On exposure to moderate drought conditions the lipids are deposited on leaf surface which in reduction transpiration losses e.g. soybean
5. Reduction in leaf area:
Rolling or curling of the leaves reduces the leaf surface exposed to sunlight thus helps in reducing the transpiration loss under stress conditions. E.g. Maize, Sorghum, grasses etc.
6. Waxy leaf surface:
The leaf surface becomes waxy forming thick cuticle and develops spines on leaves which help in reducing transpiration losses. Eg. Safflower.
7. Stomatal frequency and location:
Location of stomata in cavity or in depressions of leaves reduces the direct contact of stomata with wind currents & reduces the transpiration losses. In drought resistant plants, the number of stomata found more a lower leaf surface. Similarly, the number of stomata is also reduced which helps in reducing transpiration losses.
8. Effect of awns:
The Awned varieties of wheat barley etc. can thrive well under stress conditions as the awns contain chloroplasts & stomata & can continue photosynthetic activities even when the stomata on leaves get closed during day time.
9. Accelerating water uptake:
The water uptake by plants in increased efficiently due to following plant characteristics.
i) Efficient root system:
i) Extensive root system
ii) Deeper root system
iii) Secondary root etc.
iv) Ability of roots to go towards available water
v) Ability of roots to penetrate in soil
ii) High root to top ratio:
1. Transpiring surface is reduced.
2. Water absorbing surface is increased.
3. High osmotic pressure: Under stress conditions the osmotic (Low osmotic potential) potential in roots and aboveground plant parts in reduced resulting increased water movement through soil and plant.
10. Nature of varieties suitable for Rainfed farming:
1. Varieties should have medium height with early grand growth period. e.g. rabi sorghum varieties - Selection - 3. SFV - 86, M -35 - 1.
2. Varieties should have medium tillering habit, bigger ear head size & bold grain size. E.g. bajara variety - shraddha.
3. The variety should have deep and extensive root system.
4. The variety should be of shorter duration.
5. The variety should have High Harvest Index.
6. The intercrop varieties should be of longer duration with differentiation growth habit. E.g. Red gram varieties BDN - 2, No. 148.
7. Varieties should be resistant to moisture stress.
8. Varieties should have coating either with wax or other material which prevent the loss of moisture through evaporation from stem and leaves. E.g. Rabi sorghum varieties - white glumes on stem & leaf sheath. Safflower varieties - waxy surface & spines on leaves.
9. The varieties should be photo and thermo insensitive e.g. Gr. nut variety - TAG - 24.
Package Of Practices Of Crops Under Rainfed Conditions
Choice Of Crop And Varieties For Rainfed Agriculture
Dryland constitutes about 75 per cent of cultivatable lands in the country. The contribute about 42 per cent of off grains, almost all the coarse grains and 75 percent pulses and oilseeds. More than 90% of sorghum, Pearl millet, groundnut and pulses are grown in arid and semi arid areas.
At present, the cultivable area under Dryland agriculture in the state is 87% and only 13% area is under irrigation. After harvesting all available water resources, it is possible to bring it to 30%. It means 70% of the cultivable area will remain as Rainfed in the state. Under this situation the state will have to depend upon for its major share of food production on Dryland. However, the Dryland agriculture suffers from two problems viz. low productivity and high in stability.
The reasons for low productivity in Rainfed area are:
1. Lack of moisture conservation practices.
2. Low rate of fertilizer use.
3. Lack of timely farm operations.
4. Improper crop planning as per land capability.
5. Inadequate efforts to increase water resources.
6. Unpredictable rainfall situations.
7.Lack of improved Technology
The adoption of improved Dryland technology will be the only answer to mitigate above situation. Considerable research efforts are being made in the state to develop the improved the improved Dryland technologies since early seventies which will help to improve the crop production in Rainfed agriculture.
The important improved Dryland technologies are given below:
1. Selection of efficient crops and their varieties:
2. Crop planning as per length of cropping season:
3. Developing suitable varieties for dry lands.
4. Seeding time for Dryland crops
5. Timely seeding for pest avoidance
6. Planting pattern and plant densities
7. Intercropping
8. Fertilizer use in Dryland
9. Weed Management
10. Use of minimal irrigation
11. Crop planning as per land use capability
12. Crop planning for aberrant weather situation in dry lands
13. mid - season correction practices
14. Soil and water conservation practices
Improved Dryland Technologies
Selection of efficient crops and their varieties, Crop planning as per length of cropping season
1. Selection of efficient crops and their varieties:
Improved varieties and hybrids of Kharif and Rabi crops have higher moisture use efficiency as compared to local varieties. Hence improved varieties are adopted for efficient moisture use.
Kharif crops: Bajara - Shraddha (RHRBH - 8609, Saburi (RHRBH - 9824)
Sunflower - Modern, SS- 56, EC - 68414, KBSH - 11, APSH - 11)
Gr. Nut - SB X 1, K - 4 - 11, ICGS - 11, TG - 26, Koyana (B - 95)
Red gram - No. 148, BDN - 2, ICPL - 87; TT - 6, T - Vishakha - 1.
Cowpea - Konkan Sada bahar.
Soybean - MACS - 13 Pk - 472, Monetta, JS - 335.
Setaria - Arjun
Horse gram - Sina, Man (Kulthi or Hulga)
Green gram - PM - 2, S-8, Jalgaon - 781, BM - 4, THRM - 18.
Black gram - T - 9 TPU - 4, TAU - 1, TAU - 2.
Castor - Aruna, VL - 9, Girija
Kidneybean - MBS - 27 (Matki),
Grasses - Marvel - 8; Stylo, Siratro.
In general, the use of improved varieties increases the grain yields by 20 to 25 percent over local varieties. Hence sowing of these varieties should be carried out in Rainfed Agriculture.
Rabi Crops:
Rabi sorghum - M - 35 - 1 (Maldandi), Selection - 3, Swati (SPV - 504), CSV - 14 - R.
Gram - PG - 12, Vijay, Vishal, N - 59, Chaffa, Bharati,
Safflower - Bhima, Girana
2) Crop planning as per length of cropping season:
A) Cropping season with less than 20 weeks:
Single crop either in Kharif or Rabi.
Kharif - Bajara, Green gram, Gr. nut, black gram sunflower.
Rabi - Jowar, Safflower, gram.
B) Cropping season with more that 30 weeks:
Two crops with short duration Kharif crops following by 100 - 120 days rabi crops.
E.g. Bajra / Green gram - R. Jowar, Safflower, Gram.
C) Cropping season with 20 - 30 weeks:
Suitable for intercropping e.g. Pearl millet + Red gram (2: 1)
Developing Suitable Varieties For Dry Lands
The varieties or hybrids suitable for dry lands should have flowing characteristics.
i) Short duration, medium height, high yielding ability.
ii) Big ear head size with bold grains.
iii) Resistant to water stress conditions.
iv) Strong penetrating root system.
v) High Harvest Indes
Eg. Grunt JL - 24, TAG - 24, Bajra - Shraddha - Safflower - Bhima
Horse gram - Sina, Man etc.
Seeding time for dryland crops:
Proper time of seeding is important in dry lands as the let growing season is likely to be shortened. For this rainfall probabilities.
Eg. Cotton, red gram, horse gram dry seeding in 24th Meteorologist week at Solapur found optimum.
For this the off season tillage to be practiced to shorten the time aces between first rain and actual seeding time. It also helps to increases moisture.
Timely seeding of Rabi crops is also important eg. Sorgurti & Safflower - Traditional practice - end of September. Improved practice - first fortnight of September. This helps in better utilize of soil moisture and nutrients.
Timely seeding for pest avoidance:
Timely seeding of Kharif crops found useful in avoiding cest incidence.
E.g. Kharif sorghum should be sown before early. July to seed shoofly incidence at seeding stage and midge fly incidence at flowering to grain formation stage.
Planting pattern and plant densities:
Under adequate soil moisture conditions change in planting pattern has no advantage. However, it is necessary while adopting intercropping systems to accommodate intercrop rows.
E.g. Kharif - Bajra + Tur in paired planting in 2: 1 row proportion (30 - 15cm.). Under limited soil moisture paired planting is useful during the season for efficient moisture paired planting is useful during Rabi season by efficient moisture use.
E.g. Rabi sorghum 30 - 30 - 60 cm. or 45 - 45 - 90 cm spacing. This is due to deeper & more root growth and convenience in inter culture operations.
Plant density - While deciding the plant density, the availability of stored soil moisture needs to be considered.
Gram - Low soil moisture - wider planting - 60cm.
high soil moisture - closer planting - 30 cm.
Sorghum - Low soil moisture - 5 - 10 plants / M2.
High soil moisture - 5 -10 plants / m2.
Safflower - Not affected by plant density
Bajra - 10 - 15 plants / m2 optimum.
Safflower - 1 to 1.25 Lakhs plants / ha optimum.
The optimum plant population leads to higher production per unit area.
Sr.No.
Crop
Spacing (Cm)
Plant population in lakhs / ha
1.
Bajra
45 x 15
1.5
2.
Groundnut
30 x 15
2.5
3.
Red gram
60 x 20
0.75
4.
Horse gram
30 x 10
3.30
5.
Moth bean
30 x 10
3.30
6.
Setaria
30 x 5
6.0
7.
Sunflower
60 x 20
1 to 1.25
8.
Gram
30 x 10
3.3
Developing suitable varieties for dry lands, Seeding time for dryland crops, timely seeding for pest avoidance and Planting pattern and plant densities
Improved Dryland Technologies
Improved Dryland Technologies
Selection of efficient crops and their varieties, Crop planning as per length of cropping season
1. Selection of efficient crops and their varieties:
Improved varieties and hybrids of Kharif and Rabi crops have higher moisture use efficiency as compared to local varieties. Hence improved varieties are adopted for efficient moisture use.
Kharif crops: Bajara - Shraddha (RHRBH - 8609, Saburi (RHRBH - 9824)
Sunflower - Modern, SS- 56, EC - 68414, KBSH - 11, APSH - 11)
Gr. Nut - SB X 1, K - 4 - 11, ICGS - 11, TG - 26, Koyana (B - 95)
Red gram - No. 148, BDN - 2, ICPL - 87; TT - 6, T - Vishakha - 1.
Cowpea - Konkan Sada bahar.
Soybean - MACS - 13 Pk - 472, Monetta, JS - 335.
Setaria - Arjun
Horse gram - Sina, Man (Kulthi or Hulga)
Green gram - PM - 2, S-8, Jalgaon - 781, BM - 4, THRM - 18.
Black gram - T - 9 TPU - 4, TAU - 1, TAU - 2.
Castor - Aruna, VL - 9, Girija
Kidneybean - MBS - 27 (Matki),
Grasses - Marvel - 8; Stylo, Siratro.
In general, the use of improved varieties increases the grain yields by 20 to 25 percent over local varieties. Hence sowing of these varieties should be carried out in Rainfed Agriculture.
Rabi Crops:
Rabi sorghum - M - 35 - 1 (Maldandi), Selection - 3, Swati (SPV - 504), CSV - 14 - R.
Gram - PG - 12, Vijay, Vishal, N - 59, Chaffa, Bharati,
Safflower - Bhima, Girana
2) Crop planning as per length of cropping season:
A) Cropping season with less than 20 weeks:
Single crop either in Kharif or Rabi.
Kharif - Bajara, Green gram, Gr. nut, black gram sunflower.
Rabi - Jowar, Safflower, gram.
B) Cropping season with more that 30 weeks:
Two crops with short duration Kharif crops following by 100 - 120 days rabi crops.
E.g. Bajra / Green gram - R. Jowar, Safflower, Gram.
C) Cropping season with 20 - 30 weeks:
Suitable for intercropping e.g. Pearl millet + Red gram (2: 1)
Crop planning as per land use capability, Crop planning for aberrant weather situation in dry lands.
Use of minimal irrigation: Moisture due to low rainfall and limited soil moisture due to soil depth are the situations normally experienced in dryland agriculture. Mid season droughts and soil moisture deficiency could be mitigated by applying protective irrigations to the crops alermn growth stages. The harvested water in farm ponds or from seam functioning wells can be utilized for the purwabcdefghi~ X }hT5/as indicated that the grain yields of Rabi Jowar, Safflows a gram can be increased by 100, 40 - and 60% respective by arrive single irrigation at most critical growth stages. For this, the irrigation should be applied at boot stage rosette stage and pod development stage to jawar, safflower and gram respectively.
Crop planning as per land use capability: The cultivable land in wear has different depths ranging from few cm to several meters. Available so moisture depends on the soil depth. The water requirement of different crops varies from crop to crop. Therefore, crop planning as per vate storage capacity of the soil helps in increasing and stabilizing crop avoid with higher economic returns. Following crop planning is suggested to dryland farming in Maharashtra for different soil depths.
Soil type
Soil depth (cm)
Available
Crop planning
Soil moisture (mm)
1
2
3
4
1. Very shallow
<7.5
15.2
Dry land horticultural crops, grasses
2. Shallow
7.5 to 22.5
30 - 35
Horse gram, Kidney bean, castor,
grasses, agro - forestry, dryland
Horticultural crops. Bajra + Matki
3. Medium deep
22.5 to 45
40 - 65
Pearl millet, Red gram, sunflower
groundnut, Castor, Pearl millet +
Red gram (2 : 1), Sunflower & Red gum
(2: 1) intercropping systems.
4. Medium deep
45 to 60
65 - 90
Rabi jawar, sunflower, safflower, gram
Pearl millet + Red gram (2 : 1) in
Intercropping systems.
5. Medium deep
60 to 90
90 - 150
Double cropping Kharif green gram back
gram, Rabi sorghum, safflower or Sade
crops in rabi i.e. sorghum safflower and
Gram.
6. Deep
> 90
> 150
As above
Crop Planning For Aberrant Weather Situation In Dryland
The following common weather aberrations are observed in Solapur region of dryfarming area in Maharashtra.
1) Delayed onset of monsoon.
2) Good start of monsoon followed by dry spells.
3) Good start of monsoon followed by dry spells.
3) Early withdrawal of monsoon.
4) Extended monsoon.
The following crop management practices can be followed under different aberrant weather situations.
Delayed onset of monsoon: Onset of delayed monsoon is a common feature of the dryland agriculture. If the Kharif soils (< 45 cms) are diverted for rabi sorghum under such delayed rains, it not only affect the production of Kharif crops especially pulses and oilseeds but also results in poor production of rabi sorghum. Hence such shallow soils must be put under Kharif crops. Substantial research efforts were made at dryland centre. Solapur in this regards and following cropping pattern has been suggested depending on the lateness of monsoon during Kharif season.
Rainfall situation
Suggested crops
Remarks
1. Normal onset of
Monsoon. Rains during Ist fortnight of July
All Kharif crops Bajra,
Setaria, sorghum, grunt, castor, Red gram, Horse gram, Black gram, sunflower
Adopt intercropping of
Bajra + red gram in 2 : 1 preparation
2. Late onset of
monsoon Rains during 2nd
fortnight of July (Rains delayed by 15 days_
Setaria, Sunflower, castor, Red gram, Horse gram (delate Bajra, sorghum, gr. nut, black gram)
Intercropping of Red gram + Setaria in 2 : 2
Proportion.
3. Very late onset of
monsoon Rains during Ist
fortnight of august (Rains
delayed b 7 y 30 days)
Sunflower, red gram,
castor, castor, horse gram
(delese Setaria from above set)
Intercropping sunflower +
Red gram in 2 : 1 proportion
4. Very very late onset of monsoon Rains during 2nd fortnight of august (Rain delayed by 45 days)
Castor, sunflower red gram
(Delete horse gram from above set.)
Red gram in 2:1
proportion
5. Extremely late onset
of monsoon Rains during
Ist week of September (Rains delayed by 50 days)
Rabi jawar for fodder
i) Controlling plant population for conserving and effective are of available moisture.
ii) Checking weed growth to reduce moisture loss.
iii) Increasing interculturing to prevent evaporation.
iv) Choice of crops like red gram and castor which can sustain longer breaks.
Early withdrawal of monsoon: This situation creates two problems in rabi.
a) Sowing of Rabi crops may be suspended.
b) When crop is sown, requires moisture conservation practices such as :
i) Reduced plant density: Rabi jawar sown at early September with 1 to 1.35 lakh / ha require 50% reduction. This plant population needs to be adjusted before plants go for their grand period of growth (30 - 35 DAS)
ii) Use of surface mulch: Moisture can be conserved by using organic surface mulches. For this purpose apply mulch @ 5 t/ha.
iii) Protective irrigation: If possible protective irrigation may be given. Usually, protective irrigation is given at 55 - 56 days growth. However, due to early withdrawal of monsoon, the same may be applied at 35 - 40 days growth.
iv) Increase frequency of Intercultivation: Early stoppage of monsoon results in early cracking in soil. To prevent cracking and loss of moisture, frequency of Intercultivation may be increased. Untimely, 3 interculturing are recommended. Same can be increased to 5 or 6 which acts as a dust mulch.
v) Stripping of leaves: Upper 3 - 4 leaves are retained & lower leaves are removed to reduce transpiration.
Extended monsoon: Such situation is rarely experienced. Double cropping is possible in medium deep soils. Sowings of Rabi crops are extended. In certain areas sorghum may be replaced by gram and what as the sorghum may suffer due to cool speel.
Crop Planning For Aberrant Weather Situation In Dryland
The following common weather aberrations are observed in Solapur region of dryfarming area in Maharashtra.
1) Delayed onset of monsoon.
2) Good start of monsoon followed by dry spells.
3) Good start of monsoon followed by dry spells.
3) Early withdrawal of monsoon.
4) Extended monsoon.
The following crop management practices can be followed under different aberrant weather situations.
Delayed onset of monsoon: Onset of delayed monsoon is a common feature of the dryland agriculture. If the Kharif soils (< 45 cms) are diverted for rabi sorghum under such delayed rains, it not only affect the production of Kharif crops especially pulses and oilseeds but also results in poor production of rabi sorghum. Hence such shallow soils must be put under Kharif crops. Substantial research efforts were made at dryland centre. Solapur in this regards and following cropping pattern has been suggested depending on the lateness of monsoon during Kharif season.
Rainfall situation
Suggested crops
Remarks
1. Normal onset of
Monsoon. Rains during Ist fortnight of July
All Kharif crops Bajra,
Setaria, sorghum, grunt, castor, Red gram, Horse gram, Black gram, sunflower
Adopt intercropping of
Bajra + red gram in 2 : 1 preparation
2. Late onset of
monsoon Rains during 2nd
fortnight of July (Rains delayed by 15 days_
Setaria, Sunflower, castor, Red gram, Horse gram (delate Bajra, sorghum, gr. nut, black gram)
Intercropping of Red gram + Setaria in 2 : 2
Proportion.
3. Very late onset of
monsoon Rains during Ist
fortnight of august (Rains
delayed b 7 y 30 days)
Sunflower, red gram,
castor, castor, horse gram
(delese Setaria from above set)
Intercropping sunflower +
Red gram in 2 : 1 proportion
4. Very very late onset of monsoon Rains during 2nd fortnight of august (Rain delayed by 45 days)
Castor, sunflower red gram
(Delete horse gram from above set.)
Red gram in 2:1
proportion
5. Extremely late onset
of monsoon Rains during
Ist week of September (Rains delayed by 50 days)
Rabi jawar for fodder
i) Controlling plant population for conserving and effective are of available moisture.
ii) Checking weed growth to reduce moisture loss.
iii) Increasing interculturing to prevent evaporation.
iv) Choice of crops like red gram and castor which can sustain longer breaks.
Early withdrawal of monsoon: This situation creates two problems in rabi.
a) Sowing of Rabi crops may be suspended.
b) When crop is sown, requires moisture conservation practices such as :
i) Reduced plant density: Rabi jawar sown at early September with 1 to 1.35 lakh / ha require 50% reduction. This plant population needs to be adjusted before plants go for their grand period of growth (30 - 35 DAS)
ii) Use of surface mulch: Moisture can be conserved by using organic surface mulches. For this purpose apply mulch @ 5 t/ha.
iii) Protective irrigation: If possible protective irrigation may be given. Usually, protective irrigation is given at 55 - 56 days growth. However, due to early withdrawal of monsoon, the same may be applied at 35 - 40 days growth.
iv) Increase frequency of Intercultivation: Early stoppage of monsoon results in early cracking in soil. To prevent cracking and loss of moisture, frequency of Intercultivation may be increased. Untimely, 3 interculturing are recommended. Same can be increased to 5 or 6 which acts as a dust mulch.
v) Stripping of leaves: Upper 3 - 4 leaves are retained & lower leaves are removed to reduce transpiration.
Extended monsoon: Such situation is rarely experienced. Double cropping is possible in medium deep soils. Sowings of Rabi crops are extended. In certain areas sorghum may be replaced by gram and what as the sorghum may suffer due to cool speel.
Climatologically Approach For Crop Planning In Rained Areas
Agriculture production in India is closely related with rainfall India. About 75% of total cropped area is rained. Crop product on area is very uncertain due to erratic behavior of rainfall. The main for very low and highly unstable yields in these areas is unavailability adequate soil moisture occurring active growth period of crops. The moisture stress can be mitigated if it is followed by good rainfall. How prolonged stress period affects the rinal crop production. There are reasons for low productivity but primary constraint to this is lacs suitable tautology for soil and water management.
A sustainable farming system needs management strategies with respect varietals selection soil fertility programs and pest management agricultures order to reduce the input cost and provide a sustained avel of production profit from farming.
For planning an efficient agricultural production system information weather and climate is vital and also a major resource for agriculture productivity and sustainability especially in a stressed environment considering the complete macroclimate system. It is necessary to develop farming systems that are sensitive to climate and weather sustainable and to susceptible to degradation on account of climate.
In some areas the total rainfall is sufficient for one good crop and the some cases for two good crops in a year. However the rainfall distribution in root profiles some times exceeds and percolation of water to deeper layer or ground water recharge takes place. Because of the uncertainties and ever present risk of droughts the farmers are generally reluctant to adopt the use of available high yielding varieties, fertilizers and other input management which will effectively conserve and utilize soil and water.
Weather plays an important role in crop production, more so in India where 75% of the cultivated area is rained. The effective cropping season in rainy season is restricted by both rainfall quantity and distribution, thereby setting limits on choice of crops, cultivars and cropping systems. For post rainy season crops grown on conserved soil moisture, it is moisture storage at sowing time that determines the choice of crops and cultivars.
Crop growth rate at different ptenophases, length of growing season, efficiency of PAR interception, efficiency of solar energy conversion, efficiency in biomass conversion are explained to quantity the impact of evicemental parameters on growth and development of crops. However in arid and semi - arid areas water use plays a dominant role in crop production.
In many arid and semi arid areas crop production problems follow a familiar sequence:
i) Unfavorable crop growth environment:-
i) Limited choice of crops and cultivars, particularly in water deficit environments and aberrant weather situation.
iii) Low crop intensity.
iii) Low and onstable productivity.
Water deficits are responsible for low and unstable crop yields in both arid and semi arid areas. In addition, environment stresses / or nutrient stress may make the water deficit environment more unfavorable for the growth. The crops and cultivars currently popular in dryland areas are in necessarily the most stable and efficient in terms of moisture use. Many the existing cultivars of sorghum, pearl millet, pigeon pea, groundnut sunflower, castor and other crops are not adapted to rainfall pattern when they are grown for effective cropping season. The usually experience drogue stress at the most critical stages of their life cycle, which leads to low at unecrowic yield. In order to achieve yield stability it is necessary to ground crops and cultivars with water requirement patterns that watch the effective growing season
Climatic Variability In Rainfed Agriculture
In India about 70% of cultivated area is rained which contribute to about 40% of the country's food production. Appa Rao and Bhide, 1980). The main climatic parameters controlling crop growth are rainfall followed the temperature, adiation day length, humidity and wind speed. The inter seasonal and inter a variability in these climatic parameters play a major role in deciding the proper agronomic management options and subsequent realization of the yield. The major characteristics associated with the south west rainfall are high variability in its distribution in time and space in its onset and withdrawal and frequent and prolonged dry spells as a result of break in the monsoon. The uncertainty in rainfall received ouring the growth of crop become a major limitation factor in deciding about the final yield.
In the day sew arid areas the men annual rainfall exceeds potential
These areas suffer from one or more or a combination of factors such as moisture deficits. Limit of nutrients soil version and physical conditions, resulting in low infiltrations and poor crop establishment and subsequently larger yield gap. Thus crop yields in semi - arid India have remained low and variable because of aberrant weather and soil related constraint such as poor management of soil fertility and rain water.
Time and Length of Growing season - Tropical Regions
In tropical regions where low temperature does not limit growth, the time and length of the growing season for sorghum is determined by the seasonal precipitation pattern. Kassam et.al. (1978) and Kassam (1979) used precipitation data and computations of potential Evapotranspiration (PET) (Thorntwaite, 1948) to determine the growing seasons for crops in tropical Africa. This procedure is illustrated in Figure 1 and was used to determine the time and length of growing season for sorghum.
The first day (a) wren the normal precipitation becomes equal to or greater than half the normal PET is the beginning of the growing season and earliest planting time. The last day of the growing season (c) is the day when the normal daily precipitation becomes less than half normal PET plus time required to evaporate 100 mm of stored moisture from the period when precipitation exceeds PET.
The sorghum growing seasons for different tropical areas in eastern end western Mexico are shown is Table 1. The growing season at Villahermosa which receives 1902 mm. of rainfall is 333 days. At Apatzingan (716 mm rainfall) the season is only 125 days. A study by Kassm (1979) shows that a creed relationship exists between the amount of annual rainfall and the length as growing season in Africa.
Table: Growing season as related to precipitation at two locations to tropical Mexico.
Location
Rainfall
Growing season
Villahermosa (170 59 N 920 55 W)
1902
15-Apr
Apatzingan 190 05 N 1020 15 W)
716
4 Nov.
Growing Period Or Moisture Availability Periods
Length of the growing period is defined as the period during which the availability of moisture in the root zone of a crop is adequate to meet the water needs. Because the amount and distribution of rainfall varies considerably from year to year so does the effective growing period. The length also depends on the type of soil interacting with a given quantity on rainfall. In areas receiving rainfall for 2 months, the growing season may the 8 days in a coarse textured soils or 100 days in soils of clayey or day texture. Similarly in areas with 5 rainy months, the growing from 180 to 210 days depending upon soil texture and moisture tolding capacity (Virman - 1991).
Therefore, at a given location, the amount and distribution of rainfall, moisture storage capacity and the rate of Evapotranspiration determines the length and characteristics of the growing period. Soil moisture reserves have the ability a extend the growing period by as much as one to three months spending upon the soil texture and depth.
The soil moisture availability period determines effective cropping season. Based on the analysis of long term data in the arid and semi - arid areas of India effective cropping period have been delineated for a number of locations (Table 2). In arid areas, the effective cropping season is normally 11 - 17 weeks, which restricts the choice of crops and limits the farmer to a single crop in the rainy season. In semi - arid regions, the effective cropping season is normally longer (22 - 32 weeks) with exceptions of 8 weeks in Bellary (Karnataka) and 17 weeks in Bijapur (Karnataka) regions. Rainy season crops are grown on shallow to medium Vertisols at Bijapur, while post - rainy season
Table 2. Effective cropping season at various locations in arid and semi arid areas of India.
Zone
Location
Growing Season (Weeks)
Monsoon (23 - 39 mm)
Rainfall (mm) Post - monsoon
Arid
Jodhpur
11
353
8
Hissar
13
395
19
Anantapur
13
305
149
Rajkot
17
572
36
Semi
Hyderabad
22
603
108
Arid
Bangalore
32
400
226
Bijapur
17
381
130
Solapur
23
494
101
(Source: Single and Sebba Reddy, 1988)
crops are commonly grown on deep Vertisols at Bellary. The rainfall pattern and soil depth together determines the choice or crops and cropping systems. On shallow to medium Alfisols and related soils, only single season cropping mostly during the rainy season is possible. The amount of pre-monscore ram received in May determines whether or not double cropping is possible on demo Alfisols.
The water balance for different dryland research stations of SAI. The India has been calculated (Sing - 1993) and water availability periods haven been worked cut. The water availability period ranges between as low as 105 days at Bijapur and Bejary and as high as 210 days at Bangalore (Table 3).
Table 3. Water availability period at different dryland research centers of the SAT in India.
Soil type
Rainfall (mm)
Water availability
Total duration
& centre
Total Dependable
Period
(weeks)
Day
Range (mm)
1. Vertisols and related black soils :
Rajkot
674
532
134
25 - 44
20
Udaipur
661
572
164
25 - 48
24
Akola
878
702
196
25 - 52
28
Indore
1054
858
196
25 - 52
28
Jhansi
999
809
196
25 - 52
28
Solapur
743
584
168
23 - 46
24
Bijapur
537
434
105
33 - 47
15
Bellary
519
387
105
33 - 47
15
Kovilpatti
724
622
135
39 - 05
19
(Source: Singh, 1993)
Rainfall at 75% probability on long term basis Based on the information of water availability seriods potential cropping system have been suggested for different situations. The selection of efficient cropping system is also influenced by selection of suitable crops and their cultivers passed on duration and water use efficiency besides.
Climate, Soils And Socio Economic Factors (Singh, 1993)
Farmers have to adjust the cropping systems and crop management practices to the limitations imposed by the environment. The farming system which they have practiced has been developed by experience of generations without proper knowledge of agro climatic conditions, effective cropping pattern and schedule of supplemental irrigation can not be planned. For this study of moisture availability index (M.A.I.) is very important.
The cropping patterns are basically dependent on moisture availability index (M.A.I.). Hargreaves (1971) defined M.A.I. as there ratio of assured rainfall expected at 75% probability and estimated potential Evapotranspiration for the concerned period. However, Thormathwite and Mather (1965) calculated MAI by using water balance equation. Bistroni (1980) has defined M.A.I. as:
AE
MAI = ----
PE
Whereses,
AE = Actual Evapotranspiration
PE = Potential Evapotranspiration
For determining actual, Evapotranspiration (AE) following two conditions nave to be considered.
1) If P > PE, then PE = PE
2) IF P < PE, then ae = p + s
Where,
P = Precipitation
S = Change in soil moisture
Rainfall distribution over the country is highly erratic and tooth in time and space and there by Moisture Availability Index (M.A.I.) also becomes very underlain.
Moisture Availability Index the prime factor for especially in tropics waries both in time and space. The MAI on the basis of average monthly rainfall (Roman and Marth, 1971 and planning was done. However, in such system the monthly MAI values where truly representative as month is a longer period for planning any operation,. Moreover, If there are dry spells in between causing failure, the monthly MAI may not represent it. Hence, there is need is weekly MAI for agriculture planning. For planning of majority of crops the weekly MAI values would be most available.
Raskar (1994) determined crop growing period on the cases of availability index (MAI) of different rainguage stations of Pune, Ahmednagar districts of Maharashtra. In rainfall zone 1 to 3 of scarcity of these districts, the crop growing period at 0.3 MAI ranged between 18 a 19 weeks and at 0.5 MAI between 13 and 17 weeks during that season and 0.3 MAI between 9 and 11 weeks and at 0.5 MAI between 7 and 9 weeks during rabi season (Table 4). The dry spells of 3 to 6 weeks duration were observed.
Table 4. Weekly moisture availability period at 0.3 and 0.5 MAI in different soil type in various rainfall zone of scarcity tract of Pune and Ahmednagar districts.
Rainfall
Kharif
Rabi
Zone
Shallow
Medium
Deep
Shallow
Medium
Deep
0.3
0.5
0.3
0.5
0.3
0.5
0.3
0.5
0.3
0.5
0.3
0.5
1*
18
13
18
13
18
13
10
9
10
9
10
9
2**
19
16
19
16
19
16
11
7
11
8
11
8
3***
19
17
19
17
19
17
9
7
9
7
9
7
(Source: Rasker 1994)
Main of 5 iccation ** Mean of 8 locations *** Mean of locations at different locations. Drop planning on the basis of MAI was suggested sorghum grown on conserved soil moisture is sown in 39 the week but analysis suggests that it is quite possible to sow the crop well ahead of the present practice i.e. by 39 mm, preferably by 35 mm itself, when the assured amount of soil moisture is available for sowing as indicated by MAI more than 0.5. This will help the crop to have sufficient moisture in latter active growth stages such as elongation, flowering and grain filling.
Importance Of Rainfall Distribution
The average annual or seasonal rainfall at a place does not give sufficient information regarding its capacity to support crop production. Rainfall distribution pattern is the most important. This is illustrated by taking examples of Hyderabad and Solapur. These two locations are 500 km apart but have very similar amount of total rainfall (742 mm at Solapur, 764 mm at Hyderabad). At both the places, more than 75% of total rainfall is received September. However the distribution of rainfall at Solapur is highly erratic during Kharif. In comparison, Hyderabad has more dependable rainfall distribution pattern and thus more favorable for Kharif cropping than Solapur (Virmani et.al. 1982).
Field experiments at these two locations have shown that at Hyderabad, it is rossible to produce more that 500 kg grain ha-1 on deep Vertisols by adopting pigeon pea + maize intercropping C- maize - chickpea sequence cropping under good agronomic management. At Solapur Kharif cropping is undependable for a long duration crops but short duration crops of pearl millet sunflower or grain legume in Kharif followed by rabi Sorghum or gram is successful.
Some Practical Application Of Weather Data
Prostitution of rainfall within a season and the frequency of occurrence of dry speels of different durations can help to select the optimum time of planting and fertilizer application. If the probable dates of such saving irrigation, under taking or wittroiming of a nitrogen top dressing car also be made with greater confidence.
Temperature and humidity:
Temperature as the dominate factor controlling rate of development. The diurnal temperature cycle is more important than either the seasonal cycle or random effects of weather in the SAT (Monteeith, 1977) Even more important for plant growth processes and incidence of pests and diseases are the effects of microclimate. Humidity is also an important agro climatic factor because it is a major determinant of evaporation and incidence of pests and diseases. Nair et al. (1995) studied the influence of meteorological parameters on the incidence of shoot fly on Kharif sorghum order field conditions. They closer that egg laying and population dynamics stowed highly significant corretation with meteorological parameters like temperature, relative humidity, bright moisture tours and rainfall intensity while dead heart formation was not correlated
The incidence of powdery mildew on grape appeared early and more vigorously where relative humidity was high due to irrigation at shorter intervals (Chavan et. al., 1995). The temperature in the range of 11.8 to 32.42 C and relative humdity) 58.4% favored the development of powdery mildew. Wereas, temperature below 8.6 and above 34.09 C and relative humidity below 47.4% showed zero rate of multiplication indicating that disease did not multiply though, it existed. The incidence and multiplication was rapid in the months of December and Jawary when the climate was cool and humid.
Management Option In Relation To Weather Adjustment
While in irrigated condition timeliness of irrigation is important for higher production, a number of options such as choice of suitable crops and varieties, alternate crop strategies, mid season correction, crop life saving measures, alternate land use systems etc. are to be adopted in rained agriculture to adjust to aberrant weather conditions.
Cropping systems:
Suitable cropping systems aiming to adjust or reduce the intra - seasonal impact of climatic variability should be based on inter - seasonal variability of rainfall the water deficiency and the length and characteristics of growing season.
Intercropping:
In arid and semi - arid region of Hyderabad, the length of growing season varies from 15 to 30 weeks with variation in rainfall and soil moisture storage capacity (Table 6). In soils having medium available water storage capacity (150 mm in the soil profile) a crop with a 19 weeks growing season is likely to have adequate moisture only coce in 4 years. Under such conditions.
Table 6 Length of the growing season (week) for three soil conditions Hyderabad.
Rainfall Probability
Growing Season (weeks)
Available water storage capacity (mm)
Low (50 mm)
Medium (150 mm)
High (300 mm)
Mean
18
21
26
75%
15
19
23
25%
20
24
30
(Source : Virmani - 1989)
From seed germinating rains 25 June to put of season (time when profile moisture reduces AET / PET ratio of Actual evaportanspiration to potential evapotranspration to 0.5 )
* Low : shallow Altisol : medium : shallow to medium - deep Vertisols : high deep vertisoils.
intercropping of a short duration sorghum (105 - 110 days) with a long our at lon pigeonpa (150 - 180 days) yielded a land equivalent ratio of 1966. Pan and willey 1981). Thus, in case of random variability of rainfall, intercropping increases crop yield as well as provides stability. Based on 89 sorghum pigeonpea intercrop experiments conducted in diverse environments. It was been observed that on an average intercropping yielded equivalent of 90 mm solv sorghum yield and about 25% of sole pigeonpea yield.
Choice of the right intercropping will depend of the awards distribution pattern and soil moisture storage. In areas having be ental rainfall in the early part of the growing season drought tolent be (pigeonpea) may be useful. If rainfall is undertain is the later part of the growing season, then intercrop spould be storter in than the base crop Considering the high valves of pulses and outseeds and their soil restoring ability, these crops shouln find a place in any probulable intercropping programme.
Intercropping of pearl millet + pigeonpea (2:1) and sunflower + pigeonpea (2: 1) on medium deep soils are ideally suited for dryland conditions (Jadhav et.al., 1991) due to large difference in maturity periods of component crops which useful for harvesting the natural resources like solar rediation, soil moisture and nutrients more efficiently.
Table 7. Mean grain yield kg. ha-1, LER and gross monetary returns (Rs. ha-1) as influenced by treatements (Pooled data of 3 years : 1985 - 1988).
Treatments
Grain yield
LER
Gross monetary
Main crop
Intercrop
returns
Pearl millet + pigeonpea
1082
250
1.58
3564
Sunilower + pigeonpea
639
224
1.42
4049
Sole pearl millet
1053
-
1.00
2350
Soil sunflower
700
-
1.00
3222
Sole pigeonpes
442
-
1.00
2339
S.E.
-
-
-
390
C.D. (p 0.05)
-
-
-
1125
(Source : Jadhav et. al., 1991)
Proportionate Cropping
In this system land area allocated to crops of different growing duration on the basis of long term probabilities of soil moisture. Research conducted at OCS Haryana Agricultural University, Hisar allocating 40% of land to guar U 20 d durational. 40% to pearl millet (70 days) and 20% to mungbeen (50 days) enabled to harvest all three crops in good rainfall years and at least two crops in all but severe drought years (Virmani, 1989). Thus, proportionate cropping can help to decrease the risk of loss and increase over all productivity.
Moisture deliverinacy and cropping system:
In covered and rained regions because of combined effect of variable rainfall. High Evapotranspiration rates and poor water tolding capacity of soils crops are often exposed to suhoptimal moisture availability our mg our or more capital plenological stages of crop growth. The adverse effect of moisture deficiency can be minimized by choosing crop or crop varieties with duration appropriately fitting to moisture availability periods (Table B).
Table8. Potential cropping systems in relation to rainfall and soil type.
Rainfall (mm)
Soil type
Water availability
Potential clopping
period (week)
systems
350 - 600
Alfisols and shallow
20
Single Water if crop
Vertisols
350 - 600
Aridisols and Entisols
20
Single crop enther
water if or ran
350 - 600
Deep Vertisols
20
Single ran crop
600 - 750
Alfisols and entisols
20 - 30
Intercropping
750 - 900
Entisols, deep Vertisols
20
Double cropping with
Alfisols, Inceptisols
monitoring
0 - 900
Entisols, deep Vertisols.
20
Double cropping
deep Inceptisols
(Source: Katyal et al., 1994)
Contingent crop planning:
Weather aberrations are important features of deyland agriculture. One season seldom matches with another. As such every year poses a new situation. It if therefore, not enough to develop the tectrology for normal weather conditions but strategy needs to be developed for aberrant weather suitability. In fact these aberrations are the part of the propping situations.
Analysis of weather data and crop conditions at Solapur reveals that out of a years, 3 years are normal and ? Years are abserval in scar rate tract. Water delayed onset of monsoon 20 - 30% of the total cropped area team.
Table 9. Contingent crop planning on shallow and medium deep sols (45 cm depth) of scarcity zone of Maharashtra.
On set of monsoon
Crops suggested
(Fortnight)
June II
Pearl millet, sorghum, pigeanpea, sunflower, green
gram black gram, proundnut, horse gram, kindney bean,
castor, etc. and intercroppings.
July I
Pearl millet, sorghum, horsegram, kidney bean, pigeon pea,
groundnut, sunflower, castor etc. & intercroppings
July II
Pigeonpea, sunflower, horse gram, kindney bean castor
August I
Pigeonpea, sunflower, horsegram, castor.
August II
Pigeonpea, sunflower, castor
September I
Rabi sorghum (M - 35 - 1) for fodder or selection 3 for
grain
(Source : Patil et al., 1981)
monson for shallow to medium deep soils of scarcity tract of Maharashtra (Table 9).
Management Strategies Under Different Draught Conditions
Depending upon time and intensity of moisture stress, management strategies have to be adopted. Moisture stress periods are usually classified be (i) parly season moisture stress (ii) mid - season moisture stress (iii) terminal stress.
Early season stress:
Early season moisture stress occurs due to the failure of rains after sowing of crops /cropping systems or delayed start of rainy season. If produced dey spell occur immediately after sowing the seedlings may water.
Mid reserve stress may occur due to the period of monsoon after mateblislwent of crops. Under these situations adoption of frequent interculturing aerations use of organic mulches, lop dressing of outrage after rained of moisture steps formation of dead furrow red such dry spells in the same season, the likelihood is quite high Bhavanisagar (77%), while it is les at Solapur (15% once in 7 years) and the chance at Hyderabad is zero.
Extension advisors, field agronomists and district agriculture officials can use such information by using the data from their regional metrological stations in order to time tune the blanket recommendations to suit particular conditions.
Table 10. Probabilities of selected events at three locations.
Event or opportunities
Probability (%)
Solapur
Hyderabad
Bhavanisagar
Possibility of at least one off season
38
54
92
tillage in May
Success in early panting
77
92
15
Occurrence of one 21 day dry spell during
June to September rainy season
92
54
100
Occurrence of three 21 day dry speel in
one rainy season
15
0
77
Occurrence of three 14 - day dry spell in
the rainy season
62
38
100
(Source: Huda et al., 1988)
Management Strategies Under Different Draught Conditions
Depending upon time and intensity of moisture stress, management strategies have to be adopted. Moisture stress periods are usually classified be (i) parly season moisture stress (ii) mid - season moisture stress (iii) terminal stress.
Early season stress:
Early season moisture stress occurs due to the failure of rains after sowing of crops /cropping systems or delayed start of rainy season. If produced dey spell occur immediately after sowing the seedlings may water.
Mid reserve stress may occur due to the period of monsoon after mateblislwent of crops. Under these situations adoption of frequent interculturing aerations use of organic mulches, lop dressing of outrage after rained of moisture steps formation of dead furrow red such dry spells in the same season, the likelihood is quite high Bhavanisagar (77%), while it is les at Solapur (15% once in 7 years) and the chance at Hyderabad is zero.
Extension advisors, field agronomists and district agriculture officials can use such information by using the data from their regional metrological stations in order to time tune the blanket recommendations to suit particular conditions.
Table 10. Probabilities of selected events at three locations.
Event or opportunities
Probability (%)
Solapur
Hyderabad
Bhavanisagar
Possibility of at least one off season
38
54
92
tillage in May
Success in early panting
77
92
15
Occurrence of one 21 day dry spell during
June to September rainy season
92
54
100
Occurrence of three 21 day dry speel in
one rainy season
15
0
77
Occurrence of three 14 - day dry spell in
the rainy season
62
38
100
(Source: Huda et al., 1988)
Interaction Of Sowing Date And Climatic Variability
The effect of sowing wheat at different dates was simulated for all 138 locations (Das and Karla, 1995). It was apparent that as potential yield increased. The reduction in yield per day delay in sowing also increased. In general, the yield decrease was between 0.25% and 0.75% of potential yield when the latter was less than 4% hari, between 0.5 to 1.00% for yield potential between A and 6% hart and between 0.75 to 1.00% for yield potentials greater than 6. It is interesting first irrespective of potential yield, a few location showed a small yield reduction (less than 0.25%) with delayed sowing. For New Delhi environment, the maximum grain yield was obtained for sowings done between 1 and 15 November.
The effect of varying amounts of post sown irrigation for wheat was tested for New Delhi environment with WIGROWS model in relation to the seasonal climatic variability (using 20 years runs from 1971 - 93). The amount of moisture at the time of sowing was assumed to be 75% of the field capacity. The amount of water applied at each irrigation was assumed to be 60 mm. Nitrogen application at the rate of 150 kg hart was applied at the time of sowing. The result showed increased yield with increase in number of post sown irrigations and stabilizing beyond three irrigation. Variability width seemed to be dependent of the amount of post - son water received. It is decreased with increase in post - son water received. It is decreased with increase in post - son water received by the crop, indicating the reduced effect of climatic variability on yields under increment moisture availability condition. The variability index values ranged from about 0.59 up to one irrigation to around 0.135 (beyond for irrigations) with intermediate values of 0.42 (Two irrigations) and 0.20 Three
Fertilizer Use In Rained Farming, Levels And Methods Or Fertilizer Application
One of the important management practices to increase the crop production. In dry lands is the use of fertilizers. Fertilizer is next important component to moisture in dry lands. Therefore, it is said that the soils of dryland are not only thirsty but hungry also. Soils of this zone are generally poor in nitrogen content (Total nitrogen content 0.03 to 0.05%) and they respond to nitrogen application. Available phosphate status is low to medium (10 to 30 kg P2O5/ha.) Response to phosphate application is noticed only during Kharif on sallow soils, which are poor in phosphate. However, there has not response to the phosphate on medium deep and deep soils (rabi soils). The reason may be that these soils are medium in phosphate and the drop requirements like jawar (M - 35 - 1) are not very high. Potash content of the soils are quite high (300 to 750 kg available K2O/ha) than usually required for dry land crops. Potash is abundant and it would be difficult to expect any response to dry crops due to application of potash.
Experiment ants on use of inorganic fertilizers are in progress since 1957 at Solapur and other locations. The fertilizer use has done much progress in dry lands.
Kharif Crops:
1. Bajra: Bajra is an important Kharif crop. During last 15 to 20 years hybrid varieties are becoming popular in dryland areas. Bajra crop responded to nitrogen application very well. Response to P2O5 was very small. On shallow and malin help, there is likely to get reapions P2O5.It is recommended to apply 50 kg N + 25 kg P2O5/ ha. The whole does of N & P should be applied at sowing. There is no interaction between N and P. If money is short P2O5 application may be deleted.
2. Setaria: Setaria is a Kharif crop in dry lands for shallow and medium deep soils. It is particularly suited under delayed sowing conditions. From the results of experiments on Setaria it is observed that nitrogen application helped to increase production significantly and substantially. In case of P2O5 the response was very small. It is therefore, recommended to apply 50 kgN to Setaria crop at sowing.
3. Rabi Jowar : Rabi Jowar is the most important and major crop of the region. Earlier work on the fertilizer requirement revealed that there was only response to nitrogen application and as such 25 kg N for medium deep soils and 50 kg N for deep about 7 to 8 kg. The experiments were conducted to see the efficiency of fertilizer by applying part of nitrogen by foliar sprays. But in this experiment it was observed that foliar application and no advantage over soil application. With the use of new dry farming technology such as high yielding varieties and early September sowing, experiment on nitrogen requirements was started during 1973 - 74. The results of this experiment showed that in early sowing, the nitrogen utilization was proper which resulted in better response to the fertilizer. As high as 17 kg. grain and 36 kg. Fodder is prepuce per kg. of nitrogen applied. The optimum level of nitro in for different varieties tried was around 85 kg/in
Effect of despite application on rabi Jowar:
Studies of varieties conducted on the phosphate requirement of Rabi Jowar (M - 35 - 1) and it was observed that the phosphate application did not affect the grain production. Lack of response to phosphate may be attributed to two reasons. Firsts the soils on which the crop was grown contained medium level of phosphate (20 kg P2O5/ha). Secondly the requirement of the phosphate for M - 35 - 1 variety may be very low which might be supplied through native phosphate alone. On an average, M - 35 - 1 removes 25 to 28 kg P2O5/ha.
Safflower: Safflower is another important rabi crop in dry farming zone. It is, usually taken as mix crop. Studies at Solapur proved that mixing safflower along with jawar is harmiture. As a result, it has been recommended to cultivate this crop at a sole crop. This crop was found to respond extremely well to nitrogen application. Response to phosphate is small, erratic and noticed only in shallow soils in some years. Response to nitrogen is very good under good soil moisture conditions. Application of 50 kg N/ha is sufficient to get good and economic returns.
Methods Of Fertilizer Application
For dry land crops fertilizers are usually applied at the sowing time. For drilling the seeds and fertilizers together Jyoti ferti - seed - drill can be used. This implement can be drawn by a pair of bullocks. It is suitable for all crops except groundnut. The row to row spacing can be adjusted from 22.5 cm to 45 cm. The fertilizers are drilled 5 cm. away at proper depth developed by providing a traditional bowl rand tubes on locally available seed drills. Fertilizer needs to be placed at 10 cm. Depth and as close as possible to the seed row. The fertilizer is placed about 2 to 4 cm. deeper than seed in the same row. Locally used 3 or 4 countered seed drill can be converted to ferti - seed - drill by local carpenters.
Manure and fertilizer application schedule for dry land crops (Kharif)
Crop
Manure
T/ha
Fertilizers
Time of application
N
P
K
1
2
3
4
5
6
1.
Kharif Jowar
(Local, improved )
6-7.5
50
25
-
Whole quantity of N,P, applied at sowing.
2.
Rainfed Kharif
Hybrids of Jowar with assured rainfall.
6 - 7.5
75
62
62
1/2 N-at sowing 1/2 N at top dressing. Full dose of P and K and sowing.
3.
Maize Rainfed with assured rainfall.
12-15
90
40
40
1/2 N at sowing, 1/2 N at Knee high stage. Whole of P2O5 and K2o at sowing.
4.
Pearl millets
(Hybrids)
5-6
50
25
-
Whole of N and P at sowing.
5.
Pearl millet
(Local and improved varieties)
5-6
25
25
-
Whole of N and P at sowing
6.
Setaria
(Rala)
3-5
50
--
--
Whole quantity of N at sowing.
7.
Hill millet
5-6
50
25
25
Whole quantity of N,P,K, at sowing.
8.
Groundnut
5
12.5
25
-
Whole quantity of N and P at sowing.
9.
Sunflower
5-6
25
25
-
--do--
10.
Niger
5
25
25
-
--do--
11.
5
25
25
-
--do--
12.
5
25
25
-
--do--
13.
5
12.5
25
-
--do--
14.
5
12.5
25
-
--do--
15.
Kidney bean
5
12.5
25
-
16.
Red gram
5
25
50
-
Manures and fertilizers application schedule for Rabi crops
1.
2
3
4
5
6
1.
Rabi Jowar on
deep soils
6-8
50
25
--
Entire quantity of N & P at sowing.
2.
Rabi Jowar on
medium deep soils
6-8
25
12/2
--
Entire quantity of N & P at sowing.
3.
Safflower
5-6
50
25
--
Entire dose of N & P at sowing.
4.
Gram
6-7
12.5
25
--
--do--
5.
Linseed
3-5
30
15
--
--do--
6.
Sunflower
3-5
50
25
--
--do--
Concept Of Watershed Management
Introduction:
Out of the 20.1 million hectares of cultivable land in the state about 17.5 million hectares are under rained agriculture. At presents nearly 13 percent of the cultivated area is irrigated. After harvesting all the available water resources at the most 30 per cent of the cultivated area can be brought under irrigation. Thus, 70 per cent area would remain as rained in the state. The crop production under rained agriculture is most unstable due to inadequate, uncertain and ill - distributed rainfall. Besides. Non adoption of improved agricultural practices in rained agriculture has further deteriorated the socio - economic status of the farmers.
The major food grain requirement of the state is net from the rained areas which contain mostly all grains pulses and oilseeds while in many areas heavy soils are utilized only for rabi cropping. Crop production under rained agriculture is mostly subsistence oriented producing food grains for home consumption including cash crops and fodder for livestock. The cropping patterns vary according to soils, climate, and farmer preference and to a limited extent market demands. Sorghum, cotton, pearl millet, groundnut, pigeon pea, green gram, black gram, sunflower, wheat, gram and safflower are among the important crops grown in rained agriculture. However, the productivity of the crops is extremely low due to improper crop management practices including land management treatments adopted in rained agriculture.
Most of the community lands and privately owned marginal lands which are unsuitable for arable farming remain uncultivated and serve as grazing grounds for village livestock and source of fuel supply. The Government lands are normally located at higher elevations and are badly eroded and deprived off any vegetation. The communal grazing lands are also severely denuded and eroded leaving thin vegetative cover. As a result, these areas serve as an origin of erosion.
It is estimated that out of 30.6 million hectares of the geographical area of the state, nearly 13.8 million hectares suffers from moderate to heavy soil erosion. The detailed crosion studies made in Solapur district indicated that the percentage of deep soils (depth > 45 cm) came down from 46 to 29 in a period of 75 years indicating the severity of erosion hazard. From the studies, it is observed that the soil loss was in the range of 60 to 90 tonnes / ha per annum. With this rate is estimated that 20 cm of fertile soil may be lost within a pan of 24 years. However, under natural conditions of weathering process the process the formatting of 1 cm top soil layer will require more than 100 years.
Agricultural development of such rained areas has remained neglected compared to irrigated agriculture. The integrated development efforts in these areas initiated in most parts in the country under the name. "Water shed Development in Rainfed Areas" since 1984 - 85.
Definition of watershed:
i) Watershed is an area above a given drainage point on a stream that contributes water to the flow at that point.
ii) Watershed is a natural unit draining runoff water to common point of outlet.
iii) The watershed is geohydrological unit or a piece of land that drains at common point. Catchments basin or drainage basin are synonymous of watershed.
Broad Objectives of watershed Development
In general, the watershed development fulfills the following objectives.
1.To bring about increased productivity.
2.To make yields less subject to the effect of erratic rains.
3.To improve resource conservation (soil & water) and land use.
4.To create additional employment potential for the small / marginal farmers and agricultural labourers.
Principles or objectives of watershed management:
1. Utilizing the land according to its capability.
2. Putting adequate vegetal cover on the soil during the rainy season.
3. Conserving as much water as possible at the place where it falls. i.e. In situ conservation of rain water.
4. Draining out excess water with a safe velocity and diverting it to storage ponds avoiding situation hazards and store it for further sue for supplemental irrigation during stress periods.
5. Avoiding gully formation and putting checks at suitable intervals to control soil erosion and recharge ground water.
6. Maximizing productivity per unit area, per unit time and per unit of water.
7. Increasing cropping intensity and land equivalent ratio through intercropping and sequence cropping.
8. Safe utilization of marginal lands through alternate land use system such as horticulture, Agro forestry, silvipasture etc.
9. Ensuring sustainability of the eco - system benefiting the man - animal - animal - plant - land, water complex in the water complex in the watershed.
10 Maximum the combined income from the inter related and dynamic crop - livestock - tree - labour complex over years.
11. Stabilizing total income and cut down risks during aberrant water situation.
12. Improving infrastructural facilities with regards to storage, transportation and marketing.
13. Improving the socio - economic status of the farmers.
Classification Of Watershed
Classification of watershed:
1. Macro watershed: 400 to 2000 ha.
2. Micro watershed: Less than 400 ha.
Agricultural watersheds:
i) Sub watershed: 10,000 to 50,000 ha.
ii)Multiwatershed : 1000 to 10,000 ha.
iii) Micro watershed: 100 to 1000 ha.
iv) Miniwatershed: 1 to 100 ha.
Water shed Development Concept:
Watershed development refers to the conservation, regeneration and judicious utilization of all the resources viz. land, water, vegetation, animal and human within a particular watershed in integrated manner. Watershed development seeks to bring about an optimum equilibrium in the ecosystem between natural resources man and animals.
In the past, watershed development programme was aimed at mainly on the treatment of catchments for preventing situation in reservoirs. 8Xthe aim of the watershed development in present contest is quite different. It includes the improvement in productivity of dry lands through the components like
i) Crop management
ii) Soil and moisture conservation
iii) Water harvesting &
iv) Alternate land use system.
In the past full potential of new technology could not be exploited as these components were implemented in piece meal. Now, this is possible due to implementation of all there components in integrated manner in each hydrological unit of watershed.
Components of watershed development:
Following are the general items of watershed development which are required to be excuted in the catchments area depending upon the prevailing situation.
1. Soil and land management
i) Interceptor drains.
iii) Graded bunding
iv) Bench terracing
v) Interbund vegetative barriers
vi) Grass Waterways.
vii) Improvement of ill drained soils
viii) Nala training / improvement.
2. Water Harvesting Structures:
i) Nala bunding
ii) Farm ponds
iii) Percolation tanks
iv) Minor irrigation tanks
v) Stop dams in nalas
vi) Underground diaphragms.
3. Afforestation cum pasture development for rural energy and forage for animals:
i) On private marginal and culturable waste lands.
ii) On community and Government forest lands.
4. Agricultural development:
i) Selection of crops and their varieties suitable for local soil and climatic situation.
ii) Adoption of appropriate cropping system.
iii) Contour farming.
iv) Strip cropping.
v) Mulching and crop residue management.
vi) Adoption of alternate land use system depending on land capability such as Alley Cropping, Agro - horticulture, silvipastural management, dryland horticulture, tree farming, and pasture management.
Significant Gains From Watershed Development Programme
1. Soil and moisture conservation:
Soil and moisture conservation is the basic need in rained agriculture. Top soil is the most fertile part of the soil profile. This layer is lost due to erosion causing decrease in yield. Agronomic and mechanical measures for soil and moisture conservation are adopted in the watershed such as contour farming, strip cropping, mixed cropping, inter - cropping, contour / graded bunding, vegetative barriers etc.
2. Increase in water storage:
Due to construction of surface water storage structures like minor irrigation tanks, percolation tanks, nala bunds, farm ponds etc. the excess runoff water is collected in these storage structures which in turn is used either for supplement irrigation for field crops, horticultural crops or for drinking water to animals. Thus, additional area can be brought under irrigation.
3. Increase in number of wells:
Due to considerable improvement in ground water recharge, the numbers of dugout wells or tube wells are increased. The farmer can apply protective irrigation to various field crops whenever necessary. Thus the area under well irrigation is increased.
4. Increase in cropping intensity:
Due to increase in water resources and adoption of appropriate crop management practices, and area under double cropping is increased, which results in increasing cropping intensity.
5. Increase in fertilizer use:
Due to increase in water potential and moisture conservation measures, the fertilizer use by the farmers is increased.
6. Improvement in crop production and productivity:
Adoption of vegetative and mechanical conservator measures, results in considerable reduction in soil, water and nutrient losses from the watershed area. Further adoption of improved crop management practices results in appreciable increase in crop productivity and total crop production from these areas.
7. Animal and milk production:
Appropriate management of marginal lands with productive grasses and pastures, the total forage resources are increased which reflects in increasing animal component resulting increase in meat and milk production.
8. Increase in afforestation and alternate land use:
For producing fuel, fodder and timber, alternate land use programme is implemented in watersheds. Dryland horticultural species in addition to fuel and fodder tree species have shown promise in the watersheds.
9. Employment generation and increase in per capita income:
Due to optimization of available resources, there is increase in employment generation to farm families throughout the year. Due to overall increase in production and productivity in the entire watershed, there is considerable increase in per capita income.
Cropping Patterns
Cropping Pattern: The selection of crops and their varieties is to be made depending on the soil and rain fail situation in the rained areas. The photo insensitive crops and varieties with shorter duration should be chosen to escape drought of different intensities. There are wide variations, location to location in water availability periods in dryland areas. Thus depending upon water availability following are the different crops and cropping patterns to suit different climatic situations.
For rained areas:
Monoculture
Scarcity zone
Pearl millet, red gram, green gram, black
gram, Horse gram, groundnut
Rabi : Jowar Safflower
Assured rainfall
Cotton, sorghum, red gram, black gram,
green gram, soybean, sunflower
Double cropping
Scarcity zone
Kharif crops Mung /
Urid Mung / Urid
Sunflower
Bajra
Bajra
Rabi crops Safflower
Jowar
Gram
Gram
Safflower
Assured rainfall zone
Paddy
Soybean
Mung/Urid
Mung/Urid
Sunflower
Gram
Safflower
Jowar
Safflower
Gram
Irrigated areas
Jowar
Jowar
Maize
Grunt
Grunt
Wheat
Gram
Wheat
Jowar
Sunflower
Stable intercropping systems for rained areas:
Scarcity zone Bajra + Tur in 2: 1 row proportion
Assured rain Sorghum + Mung / Urid in 2: 1 row proportion fall zone.
Cotton + Mung / Urid in 1: 1 row proportion
Cotton + Tur in 8: 2 row proportion
Sorghum + Tur in 2: 1 row proportion.
Tur + Mung / Urid in 1: 3 row proportion.
Grassland or pasture management:
Most of the marginal lands are not able to sustain arable crops particularly during the drought years. Such lands can be developed into dependable pastures by following soil and water conservation measures like contour trenches and contour furrows. Controlled grazing may also help in building the forage resource.
At times, native pastures are stocked with low productive and less palatable species. These pastures lack legume component, thus, making the pasture lands nutritionally deficient. Artificial renovation of such pastures is likely to provide forage of good quality as well as sufficient quantity. In rained areas, different legumes from the genera Dolichos, Leucaena, Clitoria, Cassia and Stylosanthes have been found to do well with or without grasses like Cenchrus ciliaris. But Stylosanthes has been found to be excellent in all situations with regard to persistence, nutritive value and palatability. Different grasses from the genera Dichanthium, Cenchrus, Lasiurus, Chloris, Urochloa, Panicum, and Pennisetum etc. have been observed doing well. Cenchrus ciliaris has been found to be good in most of the situations.
The pastures are easily established if they are seeded at the beginning of rainy season. Seeds of Cenchrus ciliaris @ 1.0 Kg. Stylosanthes hamata @ 4.0 Kg and Stylosanthes scabra @ 1.0 Kg per hectare may be used as seed moistures. The seed moisture may be broadcasted on a drizzling day. After that, light raking of the soil may improve germination chances considerably.
Research investigations have revealed that application of 20 - 25 Kg N increases dry matter yield of grass species considerably. Similarly, 30 - 40 Kg. of P205 gives good response of legume component. For the establishment of pasture as well as for getting increased forage production the access of livestock to pastures should be controlled so that grazing pressure could be minimized.
Planning And Implementation Of Watershed Management Programme
The planning and implementation of watershed management programme should be carried out in systematic way with the active participation of farmers including constitution of co-operative watershed management societies. During implementation of the programme, following guidelines may followed.
1. The implementation programme should start from the ridge line of the watershed to the valley, not on piecemeal basis in isolated patches.
2. Development of arable and non - arable lands should be done together.
3. Forest, pasture, cultivable land and water lands should be treated as inter linked units of hydrological entity. The condition of all lands has to be improved to meet the demands of increasing man and animal population.
4. Essentially, all developmental activities are to be carried out on watershed basis. Whole watershed area needs to be covered, may be in planned phases.
The following points to be considered while preparing the master plan for watershed development.
Out line of master plan of Watershed:
For preparing of master plans of the watershed, specific formats are prescribed by the Central Research Institute for Dry Land Agril., Hyderabad. The out line for preparation of master plan for development of dry lands on watershed basis are given below -
I. Introductions: General description regarding aims & objectives of the watershed approach for Dry land Agril.
II. Characteristics of watershed:
1. General information i.e. the general description of its characteristics name of watershed, general special problems on use of natural resources like soil & water.
2. Climate: Annual of monthly rainfall in mm & no. of rainy days from the harvest, rainguage station, special problems of watershed.
3. Soils: Geological features: type of soils, series, physical & chemical properties; soil survey map & report.
4. Natural vegetation: General description of the type of vegetation & the level of management.
5. Present land use & capability of classification: Detailed land capability classification under each category. Area under each class of soil Existing cropping pattern through systematic survey of the farm.
6. Socio - Economic condition: Existing land holding pattern, irrigation facilities; available draft power; labour; credit & other facilities like marketing, transport, roads etc.
III. Analysis of Problems & Potentials:
1. Existing level of crop management & reasons for non adoption of technology.
2. Existing level of Erosion control measures & suggested control measures.
3. Present level of main water use efficiency & methods of insitu moisture conservation.
IV. Improved Technology:
1. Proposed land use: Management of practices of the alternate land use system.
2. Crop management: Description of the main features of the new technology i.e. use of different production inputs, proposals to tackle aberrant weather situations.
3. Soil & water management: Specification of the engineering measures e.g. diversion drains, bunds, terracing etc.
4. Pasture management: Silvi - Horti - Agril. Pasture development details.
V. Schedule of operation: Defining the sequence of operation keeping in view with weather & available resources.
VI. Cost benefit Analysis & budget :
a) Cost benefit ratio for each component.
b) Description of subsidy pattern under each item of work.
c) Year wise - budget.
d) Likely overall benefits from the plan.
VI. Supplemental information:
a) Soil survey reports.
b) Summery of formers survey report.
c) Design; Drawing & details of major structure.
d) Agencies involved & their responsibilities.
VIII. Maps
a) Soil survey reports
b) Land capability classification
c) Existing land use
d) Existing measures for erosion control, rills, gullies etc.
e) Proposed land use
f) Contour map
g) Proposed soil & water management measures.
IX) Provision of staff, farmers training, monitoring & evaluation of the project should also be made in the master plan.
X) Involvement of farmers in planning & executions of programme through formation of co-operative watershed development societies at village levels be considered.
Plant Population, Distribution Pattern And Weed Control In Rainfed Agriculture
Cropping pattern in dryland in dependent on quantity and distribution of rainfall, soil type and its depth. In general, cropping intensity in dryland is only 100 percent. It is observed in the farmers field that plant density is low ranging 50 to 60 thousand / ha in dryland. It is possible to increase density of population with early sowing and use of fertilizers. In fact, in may be said that in case of rabi sorghum it would be difficult to get higher production without change in plant density to higher side to about one lakh per ha is desirable for variety M - 35. In case of high yielding varieties it is advisable to go in still higher side. In case of safflower there is remarkable adjusting capacity to plant density. However it is desirable to have plant density between 50 to 100 thousands ha. It is advisable to adjust plant density towards higher side from practical point gives.
Plant geometrical studies revealed that paired planting for Rabi jawar found suitable for maintaining plant density. In case of sunflower planting in square or reciangular had little advantage. A plant density of about 74000/ha with 60 x 22.5 cm spacing is desirable. In subnormal season alternate plant could be removed to reduce density to half is desirable. Density of 1 lakh / ha (30 x 30 cm) give same yield but 1000 grain weight gets reduced. The object of keeping optimum plant population is to get higher production & grain / fodder / ha.
Crop Planning For Aberrant Weather
Crop production in dryland suffers from in stability due to aberrant weather condition from time to time. Delayed monsoon results in non sowing of traditional kharif crops which accounts for nearly 25 to 30% of the total area under crops. So also early withdrawal of monsoon interferes sowing of Rabi a crop which is main constraint of crop production in the region. Similarly, breaks in monsoon also after crop production adversely year 1972 was the lowest rainfall year which resulted in total failure of both Kharif and rabi crops under dry lands.
Mid - Season correction: Crop planning under aberrant weather condition in dry land.
Sr.No.
Nature of rainfall
Crops to be grown
1.
Delayed on set of Monsoon
2.
Rains during July & sowing of kharif crops by end of July or early August.
Setaria (Arjun) Red gram (No. 148) Sunflower (EC 68414), caster () Horse gram (Mans, Sinha)
3.
Rains during August & Sowing up to end of August
Red gram (No. 148) Sunflower (EC 68414) Caster (Aruna)
4.
Rains during late August &
sowing up to Early Sept.
Castor (Aruna). Jowar for fodder
5.
Good onset of monsoon
Sowing of all kharif crops
Common situation usually one or
two dry spells are noticed
6.
If dry spell exceeds tow weeks
Corrective measures
a) Control of plant population
b) Checking weed growth
c) Increasing interculturing
serious situation in drought
prone area
7.
Early withdrawal of monsoon
a) Reducing of plant population from lakh to 50 thousand as in case of rabi Jowar in 35 -1 before grand growth.
b) Use of surface mulch
c) Protective irrigation 30 - 45 days drought.
d) Increase frequently of inter culturing
e) Stripping of leaves
8.
Extended monsoon
It is rarely experienced
a) Sowing of grown and wheat instead of rabi sorghum.
b) Double cropping would be possible in medium deep soils.
c) Postponement of sowing of rabi crops.
Weed Control In Rainfed Agriculture
Weed cause considerable damage to the crops in general and in dryland particular. The weeds complete with crop plants in respect of moisture and nutrients. The moisture as such is already in short supply in dryland. In fact one of the measures of moisture conservation is to control weeds. The extent damage varies from 35 to 97% Pretillage perations usually deep ploughing reduces weed intensity control of annual weeds is not problem in rabi soils but control of perennial weeds like.
Hanjalic, Kunda is the problem in dry lands weeds are found in patches. Weeds in kharif lands are the problem. The cost involved in weed control is not likely to be compensated by the production. The major composition of the weed flora is celosia (Kurdu) comeliness (Kena) and cyanotis (Echaka).
Weed control methods:
1. Mechanical weed control: Hand weeding or hoeing carried out at 30 to 35 days of sowing at grand growth period. Competition is serious during first 30 days period. During this period plant growth is slow and there is set back to crop growth affecting tillers, panicle size and poor stand in general.
2. Chemical weed control: Under certain situations like shortage of labour, inaccessibility of fields due to rains and mechanical weed control is with great difficulty the chemical weed control has place in dry lands. In this regards reemergence of application of weedicide has a place. Use Atrazine @ 0.5 kg al / ha as a re emergence and 2.4 - D as post emergence.
Crop rotation And Its Factors and Advantages
Growing of set of crops in a regular succession over a same piece of land (field with) in a specific period of time.
In crop rotation soil improving crops should be rotated in time over the entire farm in a regular sequence as permissible by soil, climatic and economic factors. In general cropping intensity in dryland is only 100 per cent. At few places on partial lands occasionally two crops are taken in favorable season (Monoculture is the rule in dryland agriculture) Increasing the cropping intensity is one of the methods for increasing crop production. Cropping intensity is increased by sequence cropping and double cropping but intercropping may also prove effective measure for increasing production per unit area.
Factors to be considered for planning of crop rotation:
1. Soil type crop and its duration.
2. Livestock on the farm
3. Occurrence of pests and diseases
4. Price and availability of Agricultural produce
5. Cost of labour.
Advantages of crop rotation:
1. Crop rotation maintains and improves soil fertility.
2. Prevent - build up of pests, weeds & soil diseases.
3. Control of soil erosion.
4. Ensures balanced programme of work through out the year.
5. Prevent or limit periods of peak (requirements of irrigation water)
6. Conserve moisture from one season to next.
Characteristics of good rotation:
1. It should be adoptable to the existing soil climate and economical factor.
2. It should be based on proper land utilization.
3. It should contain a sufficient number of soil improving crops to maintain and build up organic matter content of the soil.
4. It should provide sufficient fodder for live stock reared on farm.
5. It should be so arranged so as to make economy in production and labour utilization.
6. It should be so arranged as to help in control of weeds, plant diseases and pests.
7. It should provide maximum area under most profitable cash crop adopted in the area.
Effect of crop rotation so soil:
1. On runoff and soil loss: Crop rotation of Bajra - red gram or groundnut recorded minimum runoff and soil less (82 to 90%) followed by Bajra red gram - horse gram.
2. On bio - logical yield: Legumes cereals or cereals legumes rotations are not only beneficial for runoff but also increase biological yields.
3. Use of crop rotations according to soil moisture:
a) Kharif season: (Shallow and poor moisture retention capacity soils.)
Crop: Bajra, Sorghum, pulses, groundnut followed by follow.
b) Rabi season: (Medium to deep soils fairly good moisture retention capacity soils)
Crop: Sorghum, safflower, gram are rotted with Kharif Bajra sorghum etc.
Monoculture growing of a crop on the same piece of land year after year is known as monoculture or single crop system. Fallow - Jowar
(R) Or safflower fallow in rotation. In scarcity areas only two crops are taken in three years as against one crop every year. Experiments at Dry farming Research Station Shown the variability in benefits of fallow in rotation in increasing the yield of crop in the succeeding year.
Intercrop system:
By following intercropping system risk is reduced (shared) cropping intensity is increased. Crop selected for intercropping (intercrop) should not compete for moisture quick growing and short duration. The medium soils, depth uptown 45 cm do not provide sufficient moisture to support two crops in sequence (double cropping) even in normal year. These soils are therefore ideal for intercropping. A base crop and intercrop should have different duration of life and growth rhythms. At the same time crops should be cooperative. Bajra + Red gram are ideally suited for this purpose. Red gram gets of benefits from Sept showers and gives high yields. In the events of failure of later rains in Sept bajara already sown gives good yields. In the even of failure of early rains red gram compensates the production. In normal and above normal seasons both these crops boost up total production. For very shallow soils (up to 20 cm depth) Gross like Marvels planted 60 cm apart and established and horse gram is sown as intercrop was found to be most profitable. Intercropping is uneconomic and undesirable during Rabi season because Rabi crops are cultivated mainly on receding soil moisture and thus, it creates Competition for moisture. Gram and Safflower consume more moisture during early period there will be moisture stress at ear head emergence for Rabi sorghum resulting in low yields, Sequence or double cropping. In normal your (normal rainfall) there is possibility of two cops in dry land area giving increased production ranging from 100 to 300 percent over single cropping.
At Solapur seq. Viz.
Green gram / black (gram (k) - Jowar (R) and Bajra (K) - Gram (R) was found beneficial -
Mixed cropping is extensively followed for Kharif crops. Usually 4 - 5 crops are mixed. The proportion of crops varies from place to place. Seeds of bajara, red gram, horse gram, moth bean and Sesamum are mixed. The practice is common because of shortage of labour for sowing separate rows. For Rabi season sorghum safflower is a common mixture. Usually 12 - 15 rows of sorghum followed by there rows of safflower. The proportion of rows changes as per the sowing implements in practice.
Crop mixture And Its Advantages
It is similar to inter cropping the difference that crops are either broadcasted seeds are mixed and sown or grown as mixture with in a row.
Types:
1. Cereals - legumes
2. Cereals - oilseeds
3. Fiber crops - oilseeds
4. Fiber crops - cereals
A) For Vidarbha - Khandesh tract
Jowar - black gram
Bajra - kidney beam / Green gram
Cotton 10 - 15 rows - Red gram 2 lines.
Deccan hemp - Sesamum - seeds mixed
B) For Deccan Dists:
Bajra - 5 - 6 rows - Red gram of row
Bajra - 2 - 1 rows - one row of tur.
R. Jowar - 8 rows - Safflower 4 rows
Sunflower - 2 rows - one row of tur.
Advantages:
1. To utilize available space and nutrients to the maximum extent.
2. To secure daily requirements like pulses and oilseeds.
3. To safeguard against hazards of weather, diseases and pests.
4. To provide balanced cattle feed.
5. To avail distribution of labour through out the year.
6. To get handy installments of cash returns.
Limitation: In Rabi this system is uneconomical as rabi crops are grown on recording moisture.
The growth rhythmus and duration of life cycle of the mixture is different. In this main crop get harvested earlier than mixed crop by which the mix crop produces high yield with benefit of September showers. Bajra + red gram where the duration of life cycle of bajara is less than that of red gram.
Inter Cropping And Its Advantages
Intercropping: Growing of two or more crops simultaneously on the same piece of land (field). There is a crop intensification in both time and space dimensions. There is intercrop competition during all or part of crop growth.
Type of intercropping:
1. Mixed intercropping
2. Row intercropping
2. Strip intercropping
4. Relay intercropping
Definitions of Intercropping system:
1. Mixed Intercropping: Growing two or more crops simultaneously with no district row arrangement.
2. Row Intercropping: Growing two or more crops simultaneously where one or more crops are planted in rows.
3. Strip Intercropping: Growing soil conserving and soil depleting crops in alternate strips running perpendicular to the slope of the land or to the direction of prevailing winds for the purpose of reducing errosion.
4. Relay Intercropping: Seeding planting two or more succeeding crops after flowering and before the harvest of the standing crop.
Advantages:
1. Intercropping gives higher income per unit area than sole cropping.
2. It acts as an insurance against failure of crop in abnormal year.
3. Intercrops maintain soil fertility as the nutrient uptake is made from both layers.
4. Reduce soil runoff.
Limitations: Intercropping system is uneconomical and undesirable during rabi.
Crops to be considered for intercropping.
A) Kharif crops:
1. Medium black soils:
a) Pearl millet + Red gram 2: 1
b) Pearl millet + Horse gram / Kidney bean / cow pea Inter row of pearl millet.
3. Soils up to 20 cm depth
a) Pearl millet + red gram (30 - 60 - 30 cm)
B) Rabi crops:
Safflower + Gram (2: 1)
D) Fodder for milch animals: Sorghum bajara + Cowpea or horse gram or kidney bean.
In rained areas of Maharashtra:
1. Sorghum / pearl millet / cotton + red gram / black gram or kidney bean or cowpea or groundnut.
2. Groundnut + Sunflower.
Cotton + soybean, cotton + Black gram
Safflower + gram
How intercropping economizes water use:
Selection of intercrop is one the basis of duration of crop and growth rethyms. The short duration crop gets harvested and long duration crop gets the benefits of September showers and produces more yields. E.g. Pearl millet + red grams.
LER: It is observed that under the rainfall situation deviating from 2090 to 50 percent, the intercropping system of bajara + red gram is more stable as cowpea to the pure crops tried. On an average, the land equivalent ratio (LER) comes to 77 percent compared to pure crop.
Alternate Land Use Like Agro Forestry Horticulture
Pasture, Diversified Farming Systems In Rainfed Agriculture
Introduction : Crop production on dry lands in general and marginal rained lands in particular results in low and unstable and often times in low and unstable, and often times, uneconomic yields, Marginal lands because of poor management are often subjected to the processes of degradation. It is estimated that nearly 70 m hectare out of a total 100 m ha under Rainfed cultivation are facing some kind of land degradation or the other. These marginal lands are not able to sustain arable crops particularly during the drought years. The Govt. of India is deeply concerned about the improvement of degraded / marginal lands. We have, therefore to think of developing some alternate land use systems for these lands.
The alternate land use systems are surer means of stabilizing both productivity of dryland and incomes of dryland farmers, besides generating more complement potential.
Day by day demand for food fodder and fuel is growing, which could be solved by selecting suitable land use system. One of the areas of research for Rainfed agriculture is improvement of degraded, marginal and sub - marginal lands by introduction of suitable. Alternate Land Use systems like alley cropping lay farming tree farming, dryland horticulture etc. Alternate land use systems not only help in generating much needed off season employment in monocropped dryland but also minimize risk tallies off - season rains which may otherwise go waste as runoff prevent degradation of soils and restore balance in the ecosystem.
Alley – Cropping And Its Advantages
Alley cropping is a system in which food crops are grown in alleys formed by hedge rows of trees or shrubs.
The essential feature of the system is that hedge rows are cut back at planting and kept pruned during cropping to prevent shading and to reduce competition with food crops.
Advantages:
1. It provides higher total biomass per unit area than arable crops alone.
2. It utilizes off - season precipitation which otherwise would go waste,.
3. It provides green fodder during the lean period of fodder availability.
4. It provides additional employment opportunities during the off season.
5. When planted along the contours on a sloppy land, it provides a barrier to run off water holds the silt and conserves moisture. Or
Alley cropping is a farming system in which arable crops are grown in alleys formed by trees or shrubs established mainly to hasten soil fertility restoration and enhance soil productivity.
Objectives of Alley - cropping:
The main objective of alley cropping is to get green and palatable fodder from hedge rows in the dry season and produce reasonable quantum of grain and Stover in the alleys during the rainy / cropping season.
Alley - cropping - a version of agro - forestry system, could meet the multiple requirements of food, fodder, fuel and fertilizers etc.
Three Versions (Types) of Alley cropping:
Three versions of alley cropping system, based on different objectives are.
1. Forage alley cropping.
2. Forage - cum - mulch alley cropping
3. Forage - cum - pole alley cropping
In all the three systems crops are grown in the alleys and forage is obtained from lopping of hedge rows. Two components from an essential part of the system these are at the hedge rows b) the crop grown in the alley.
Need - Based Alternate Land use System And Its Advantages
1. Among the several needs of a farmer Food always remains the first priority item, although fodder requirement is more as compared to food. Some of the need - based alternate land use systems matching the land. Capability classes are discussed below Alternate land use systems.
Sr.No.
Food (Arable Land)
II and III
Fodder
(Non - arable land)
IV and V
Fuel / Timber / Fiber
(Marginal degraded land)
VI and VII
1.
Alley cropping
Agro horticulture
Horti - pastoral silvi
pastoral
Tree farming Timber
cumfibre (TIMFIB)
2.
Agro - horticulture
Silvi - pastoral
3.
Intercropping with NFTs
Ley farming
Pasture management
2. Ley Farming: a rotation of arable crops requiring annual cultivation and artificial pasture occupying field for two years or longer.
3. A rotation is a cropping system in which two or more crops are grown in a fixed sequence. If the rotation includes a period of pasture (a lay) which is used for grazing and conservation the system is sometimes called "Alternate husbandry" or mixed farming. The term Ley - farming denotes a system where a farm or a group of fields is cropped entirely with leys which are reseeded at regular intervals some people described any cropping system which includes leys as "Lay Farming".
Types of Ley Farming:
1. Unregulated ley systems :
These are characterized by natural fallow vegetation of various grass species a certain amount of bust growth on the pasture, community grazing and lack of pasture management all of which make such systems often more short term fallow systems.
2. Regulated ley system:
Individual grazing fencing pasture management and rotational use of the grassland are the usuall characteristics of regulated ley system.
Advantages of Ley Farming:
1. It helps in soil conservation, improvement in structure and fertility. It acts as a self fertility regentrating system especially with respect to nitrogen.
2. With lay farming system the other important requirement I the farmer i.e. fodder for his cattle in addition to his food is easily met.
3. For rained farming it is a low risk system as they need not invest on the costly fertilizer input for the food grain crops but by the pasture legume.
4. Labour economy during the years under ley is yet another advantage. Some of the weeds which will be vigorous during the arable cropping years would be suppressed and eliminated and as such the weeding requirements of the crop would be reduced.
5. No tillage during the ley years would have other advantages like no compaction due to farm machinery more of earthworm and soil microbial activity. It will also have the other benefits like better soil sanitation less hibernation of pests and diseases of the crop plants.
Example of ley farming:
If a farmer has say 4 hectares land in which he want to grow sorghum and caston then he can plan four year rotation as follows.
Unit
Year 1
Year 2
Year 3
Year 4
A
Stylo
Stylo
Sorghum
Castor
B
Stylo
Sorghum
Castor
Stylo
C
Sorghum
Castor
Stylo
Stylo
D
Castor
Stylo
Stylo
Sorghum
Three Alternate Land Use In Dryland Ecosystems
Consistent with the policy of conservation and desirability of preserving the integrity of the ecosystem, the alternate land use systems could be classified into
i) agro forestry
ii) pastoralism and
iii) tourism which includes wild life.
Agro forestry systems of land use:
Agro forestry is a collective term for a land use system in which woody perennials (trees and / or shrubs) are eliberately mixed on the same land management unit as crop and / or animals either in some forms of spatial arrangement or in time sequence. An ideal agro forestry system should result in a sustainable increase in overall production using management practices compatible with social cultural and economic of the local population.
In agro forestry land use systems, there are three basic sets of elements of components that are managed by man viz. tree, the herb (agricultural crops including pasture species) and the animal. This leads to a simple classification of agro forestry systems as given below.
Agri silvi cultural - Crops and trees including shrubs / vines / tress.
Silvi pastorl - Pastures / animals and trees.
Agro silvopastoral - Crops / pastures / animals / trees
Agrihorticulture - Crops / fruits species
Silvi - horticulture - Trees / fruit species
Silvi Horti pastoral - Trees / fruit species / animal / pastures.
Agri Silvi system:
Agri silvi cultural system could be practiced in areas where wood lands can be created. The planting consists of both annual crops and perennial trees. This type of approach is most commonly observed in the cultivated areas. The perennial tree species are planted in a single row or multiple of rows in a strip at a interspaces distance of 15 - 40 m between two strips. The interspaces are utilized for growing annual / seasonal crops. The preference of choice for tree selection may lie in Acacia spp. Azadirachta indica, Dalbergia sissoo; Eucalyptus spp; Casuarinas spp; Albizzia spp; and Leucaena leucocephala, prosopis spp and caliandra spp. Growing of perennial tree species on bunds / strips may also act as wind breaks in areas where high wind velocity is a problem resulting in wind erosion and desiccation of soil moisture. Certain tree species offer the possibility of providing at least a portion of optimum crop nutrients by natural leaf drop or by lopping for purposes of green leaf manuring. This includes both fixed nitrogen as well as other nutrients recycled from the deeper soil depth. This is especially true with Acacia albida which when matures (after 3 years) is said to be deciduous in the Kharif season. As such it offers less competition for light and moisture at the time when crops need them most.
In India agriculture and forestry have co - existed for many years in close proximity. Agro - forestry systems of land use are not new to our rich heritage. Farmers from time immemorial have been growing useful tree species with agricultural crops which used to supply fodder, fuel and small timber for himself and his live stock. The best examples available are ; growing of Prosopis cineraria (Khajri) with agricultural crops in Rajasthan and in black soils of Northern Karnataka and the other parts of the country. The other practices then prevailing where growing of perennial tree species such as Acacia’s neem mango tamarind on farm boundaries.
Agro forestry offers a good scope for more efficient use of land; water, other natural and human resources. The main advantages of this system would be:
i) Progressive land improvement by providing vegetation cover and brief to bring about soil and water conservation and production of organic material for enrichment of soil.
ii) Recycling of plant nutrients is possible due to roots of perennial tree species penetrating deep into the soil and absorbing the plant nutrients and depositing on the soil surface through leaf litter.
iii) Perennial tree species are photosysnthetically active through out the year and hence produce large quantities of biomass.
iv) Legumes plants may provide for fixation of atmospheric nitrogen and thereby enrich the site conditions and
v) Provide employment opportunities to the people.
Structural basis of classification of agro forestry systems:
Structure of the system can be defined in terms its components (constituents) and the expected roles (functions) of each (manifested in terms of outputs). It is not only the nature of components that is important but also their arrangement.
Silvi - Horti / agro - Horti system:
The concept of silvi - Horti / agro - Horti or combination of agricultural crops, perennial tree and fruit species could profitably be adopted in both arable and non arable marginal and sub - marginal lands.
Semi wild but useful fruit species such as cashew, Ber, annonaceas fruit species, Chiranji, phalsa carrisa, mango, sapota, guava, tamarind and jack fruit trees are planted in regular strips or inter planted with silvi component. In areas receiving higher rainfall of 1000 m and above coconut can be planted as in being practiced in coastal Karnataka and Kerala. In the agro Horti - silvi system of land use the distance between the two horticultural plants within the strip may be quite apart to avoid competition. The inters trip space between the two horticultural plants can be used for planting fast growing economic silvi - cultural species such as leucaena casuarinas, Dalbergia teak and albizza. The tree plants are cut for wood after 4 - 6 years so that the competion could be minimized. The idea behind planting tree species as an intercrop with horticultural plants is to obtain biomass production before horticultural plants attain full growth, and later to obtain fodder or green manure material by frequent cutting and create thicker vegetation for better soil dwater conservation.
Many plant species of different heights and architecture, planted in an orderly manner form a multi stored and close cover vegetation with different biological cycles in agro - Horti / agro - Horti - silvi system. In coconut and areca nut plantations other perennial or semi perennial and / or annual crops like tapioca, elephant foot yam, dioscrea, turmeric, ginger, colocasia, sweet potato, groundnut, vegetables and pulses, pineapple, bana, papaya can possible by grown. High density multi species systems are capable of generating high biomass; high income and can meet various needs of the farmer.
Silvi pastoral system of land use:
The fodder requirement for the growing cattle population in the country by 2000 - AD is expected to be around 700 mit against the present supply of 540 m.t. The gap will be of the order of 250 m.t. and to meet this demand the country will require 10 m ha of additional area. To achieve this every demanding increase of fodder the area under soil erosion problems, marginal and sub marginal lands waste lands village grazing areas need to planted with suitable forage species or in combination with economic perennial tree species preferably tree species yielding fodder.
In such land use systems, ideal species of woody perennials should be fast growing, hardy, with wide ecological aptitude, tight crown with multilayer branching and leaf orientation and of multiple use to the rural population. The forage component need to be very hard, easily colonising, palatable, nutritious and with strong establishment through roots or self sown seeds. For arid and semiarid areas species like Acacia tortillas. Albizzia amara, Hardiwickia binata, ledcaena leucocephala with Cenchrus ciliaris, Cenchrus setigerus, Dichanthium annufatum chresopogon fulvus sehima nervosum etc find greater adaptability. Legume species such as stylosanthes spp., have been found very versatile. On difficult sites Desmodium, Alcidcarpus and sesbania would promise as primary colonisers. Tourism and wild life system of land use.
Tourism as a means of expoiting and developing the potential of arid and semiarid areas needs careful consideration. The wildlife fauna of the arid region is unique resource and need attention for their conservation. It would help to develop more and more desert parks which attract the tourism and provide employment opportunities.
Agronomy is the branch of agriculture sciences dealing with principles and practices of crop production and field management. Agronomy is mainly based on following basic principles Agrometerology, Soils and Tillage, Soil and Water Conservation, Dryland Agriculture, Mineral Nutrition of Plants, Manures and Fertilizers, Irrigation Water Management, Weed Management, Cropping and Farming Systems, Sustainable Agriculture.
Agrometerology: Agrometerology is the branch of meteorology, which investigates the relationship of plants and animals to the physical environment. Agrometerology describes Agrometerological Observatory, Atmosphere, Wind, Clouds and Precipitation, Solar Radiation, Air Temperature, Soil Temperature, Humidity and Evaporation, Weather Hazards and their Mitigation, Weather and Crop Productivity, Weather Relations of crops, Weather Forecasting and Classification of Climate and Agroclimate in relation to agriculture.
Soils and Tillage: Soils and tillage are necessary to know how soils should be managed and conserved for sustainable crop production. Under this principle of agronomy we can learn Physical Properties of Soil, Chemical Properties of Soil, Biological Properties of Soil, Soil Organic Matter, Salt Affected Soils, and Tillage.
Soil and Water conservation: We must conserve soil and water because these are the most critical resources. In this principle we will touch to Soil Erosion, Water Erosion, Wind Erosion, Soil and Water Conservation Measure.
Dryland Agriculture: Dryland farming is cultivation of crops in regions with annual rainfall more than 750 mm. Under this we need to read History of Dryland Agriculture, Problems of Dryland Agriculture, Monsoon and Length of Crop Growing Season, Drought, Moisture Conservation in Drylands, Water Harvesting and Protective Irrigation, Crops and Cropping Systems, Mitigating Adverse Effect of Aberrant Weather, Alternate Land Use Systems, Watershed Management and Improved Dryland Agricultural Implements.
Mineral Nutrition, Manures and Fertilizers: Nutrient Management is one of the most important principles in agronomy which includes Essentials in Plant Nutrition, Nutrient Uptake by Plants, Soil Fertility Evaluation, Manures, Fertilizers in Indian Agriculture, Nitrogen Fertilizers, Phosphatic Fertilizers, Potassic Fertilizers, Calcium, Magnesium and Sulphur, Micronutrients, Mixed Fertilizers, Fertilizer Application, and Fertilizers & Environment.
Irrigation Water Management: Irrigation Water Management is very important for success of agriculture. In irrigation management we need to read Irrigation in Indian Agriculture, Water Resource & Their Development, Systems of Irrigation, Soil – Water Relationships, Plant – Water Relationship, Evapotranspiration, Water Requirements of Crops, Measurement of Irrigation Water, Scheduling Irrigation, Methods of Irrigation, Irrigation & Water Use Efficiency, Irrigation Practices for Major Crops, Quality of Irrigation Water, Drainage, Cropping Pattern in Command Areas, Pricing Irrigation Water.
Weed Management: Weed is a plant grown at place & time which is not desire. Understanding of Common Weeds, Losses and Benefits, Weed Ecology & Classification, Crop – Weed Association & Competition, Methods of Weed Control, Classification of Herbicides, Herbicide Formulation, Herbicide Application, Absorption & Translocation of Herbicides, Mode of action of Herbicide, Selectivity of Herbicide, Herbicide Combination, Rotations & Interactions, Persistence of Herbicides in Soils, Herbicide Resistance, Chemical Weed Control in Different Crops, Parasitic & Aquatic Weed Control.
Cropping Systems: Cropping systems is gaining more importance in this day and includes Various Terminology, Major Cropping Systems, Agronomy of Rainfed Cropping Systems, Agronomy of Irrigated Cropping Systems, Evaluation of Cropping Systems, Farming Systems and Farming Systems Research
Sustainable Agriculture: Sustainable agriculture can be define as the form of agriculture aimed at meeting the food and fuel needs of the present generation without endangering the resource base for the future generations. It includes study of Impact of Improved Crop Production Technology, Factors Affecting Ecological Balance, Evaluation of Sustainable Agriculture, Components of Sustainable Agriculture, Sustainable Utilization of Land Resources, Sustainable Utilization of Water Resources, Sustainable utilization of Biodiversity, Integrated Nutrient Management, Integrated Nutrient Management, Integrated Plant Protection, Enhancing Sustainability of Dryland Agriculture, Enhancing Sustainability of Irrigated Agriculture, Agricultural Sustainability and Farming Systems.
Water Management Including Micro Irrigation
Water Resources & Irrigation Development in India and M.S
Water (H2O):
Water is indispensable for human, animals and plant life. It is a part of all organisms, some of which contain more than 90 percent. Water is essential part of protoplasm. It is an important ingredient in photosynthesis. About 400 to 500 liters of water is necessary for production of a one kilogram of plant dry matter. Water is also required for translocation of nutrient and dissipation of heat.
Properties of water:
Water molecule contains two hydrogen ions and one oxygen ions. The space occupied by each water molecule is mainly due to oxygen ions while two hydrogen Ions do not occupy practically any space. The shape of the water molecule is sphere and the position of two hydrogen ions is at the corners of a tetrahedron that exists within a sphere.
The positive valences of hydrogen ions are partially neutralized by negative valency of oxygen ion. Thus, one, end of water molecule has positive charge and another end has negative charge. This makes water molecules a dipole.
Water molecules do not exist in individually. Hydrogen in water serves as connecting link from one molecule to the other and it is known as hydrogen bonding. Water sticks to it self with great energy and this property is called cohesion, where as water attaches itself to surface of many substances and this property is known as adhesion. By adhesion, water is held tightly at the soil water interface and water is retained in the soil by adhesion and cohesion. The water molecules hold other water molecules by cohesion forces. Because of these forces, water fills small pores in the soil and is in fairly thick film in large pores.
Hydrological Cycle:
The earth’s outer solid crust is called Lithosphere. Most of the earth’s total water is contained in Oceans (96%), small portion (2%) as snow and ice and rest (2%) in the water bodies of the continents. Oceans, lakes, rivers and other water bodies of the Earth are called Hydrosphere.
Continuous circulation of water between hydrosphere, atmosphere and lithosphere is known as hydrological cycle. This has neither a beginning nor an end.
The physical and biological processes in the environment are sustained by the Hydrological cycle. Water from various water bodies evaporates due to energy provided by solar radiation and enters the atmosphere as water vapour. Oceans account for 85% of worldwide evaporation. Evaporation is the chief source of water vapour in atmosphere. Water vapour in the atmosphere constitutes only 0.001 percent of the total global water. Even if all water vapour present in the atmosphere at any amount could be precipitated, an average depth of only about 2.5 cm of water is added to the oceans. Though the quantity of water vapour present in the atmosphere is small, it provides vital hydrological link between oceans land.
Clouds are formed as the water vapour rises above in to the atmosphere. When condensation takes place in the atmosphere, water precipitates mainly as rain or to some extent as snow. Thus, water is constantly added to the atmosphere through evaporation and lost through precipitation. The annual average world precipitation is
1000 mm. As Oceans, occupy 2/3 of the total surface of earth, most of the precipitation that falls over oceans. Of the precipitation that falls over continents, about 65% is returned to Atmosphere through evapo-transpiration and the rest goes as a surface run off into the rivers and finally into the oceans. Thus, water occurs on earth in three forms viz solid, liquid and gaseous.
Water resources of the world:
About 97 percent of worlds in the oceans and this are not useful for irrigation. Of The total quantity of water, only 2.6 percent is fresh water, which is in the form of ice caps, icebergs and glaciers and only small fraction of water is present in the ground, rivers and atmosphere that can be harvested for irrigation of crops.
Water resources of India:
The average rainfall of India is 1194 mm. When considered over geographical area of 328 million hectares, this rainfall amounts to 392 million hectare meters (m. ha. m). This may round off to 400 (m. ha. m) by including the contribution of snowfall which is not yet fully determined. Out of 400 (m. ha. m) of rainfall, 75% is received during South-West Monsoon period (June to September) and rest in remaining months as shown below. A Major portion of water (215 m. ha. m) soaks into the soil, while 70 (m. ha. m) is lost as an evapo-transpiration.
Sources of Water & Functions of Water
Sources of water:
The major sources of water available either for agriculture or for human consumption is obtained from the precipitation in the form of rainfall or snowfall. Run-off from precipitation drains through streams and rivers or collects in surface depressions forming tanks or ponds. Water of streams stored in reservoirs or is diverted directly through canal system for irrigation. Run-off water stored in tanks or ponds is also regulated for irrigation through suitable conveyance system. Part of rainfall is stored as a Ground water. Of the annual rainfall of 400 (m. ha. m) about 215 (m. ha. m) infiltrates into the soil. A major part of it amounting to about 165 (m. ha. m) is retained as a soil moisture, which is essential for growth of vegetation. It is only after the soil has absorbed water to field capacity that water starts percolating down to water table and adds to ground water reservoir.
Functions of water:
Ecological importance:
The distribution of vegetation over the surface of earth is controlled by the availability of water than any other single factor. In heavy rainfall area, flush vegetation (forest) is observed.
Physiological importance:
The ecological importance of water is result of physiological importance.
· It is a constituent of protoplasm:
Water is as important quantitatively as qualitatively Constituting 80 to 90 Percent of fresh weight of most herbaceous plant parts and 50 percent of the fresh weight of woody plant.
· It is a very good solvent:
Water acts as a solvent in which gases, minerals (plant Nutrients) and other solutes are dissolved. The dissolved plant nutrients are absorbed by Plant through soil solution. It acts as a carrier of food nutrients.
· It is a reagent:
Water acts as a reagent in many important processes, such as photosynthesis and hydrolysis of starch and sugar.
· It maintains turgidity of plant:
Maintenance of turgidity is essential for cell Enlargement and growth. Turgidity is also important in opening of the stomata, movement of leaves, flower, petals etc.
· It controls the temperature of plant and soil.
· It is a major part of plant body
Classification of Soil Water or Kinds of Soil Water
When water is added to dry soil either by rain or irrigation, it is distributed around the soil particles, where it is held by adhesion and cohesive forces. It displaces air in the pore spaces and eventually fills the pores. When all the pores, large and small are filled, soil is said to be saturated and it is at its maximum retentive capacity.
Although the soil water cannot be sharply demarcated, yet for sake of understanding and as per utility of water to plant it is mainly classified into following categories.
· Hygroscopic water
· Capillary water a) Inner capillary b) outer capillary
· Gravitation water
· Water vapour
Hygroscopic water:
It is that part of soil water which is very tightly held on the surface of soil particles in very thin film by adsorption forces such as adhesion and cohesion. It is mostly in vapour form and forces with which it is held on surface of soil particles is estimated about 10,000 atmosphere towards the inner side and about 31 atmosphere at the outer side of hygroscopic water film. (One atmosphere at sea level is about 15 pounds per square inch, which means the force holding the water at one atmosphere is equal to about 15 pounds pre square inch or 1023 centimeters of water column height). This water is not any use to the plants.
Capillary water:
It is the water held by the forces of surface tension and continuous film around soil particles and in the capillary spaces. When soil particles absorb water even after the hygroscopic coefficient is reached, additional water is also held around the particles in the form thin film. This retension of water film continues until the film becomes quite thick and micro pores inside the soil mass get filled with water. A stage is then reached when the force of gravity becomes stronger and any further addition of water is pulled down by gravity and flows down as free water.
The capillary water is that water, which is held in the soil in excess of hygroscopic water but is up to the point where the gravity pull begins to move the water down wards, when free drainage conditions exist in the soil.
Capillary water is rather loosely held water (from 31 atmosphere to 1/3 atmosphere tension) and is capable of movement within the soil. The plant food nutrients are dissolved in it and therefore, it is most useful water for plants. The capillary water itself can be divided into two parts though there is no clear-cut line division.
· Inner Capillary Water:
It is that part of capillary water, which is nearest to the hygroscopic water and is in the form of a thinner film, held more tightly and moves rather very slowly than outer capillary water.
· Outer Capillary water:
It is that part of capillary water which is not very tightly held in the soil and there after moves readily from place to place. It is the most useful water for plants as it is very quick available.
A soil which has a finer texture and granular structure indicating larger proportion of micro pores than macro pores holds more amount of capillary water than a single grained sandy soil having more percentage of macro pores. Soil rich organic matter content also holds much grater quantity of capillary water.
Gravitational water:
It is that part of soil water, which moves freely in response to gravity and drains out of the soil. When the maximum capillary capacity of a soil gets satisfied and further addition of water comes under the force of gravity. This water starts moving as free water through the macropores and it is called gravitational water.
It is superfluous and as such, it is of no use to the plants. Gravitational water is held at zero atmosphere tension. When down ward movement of gravitational water is more, some plant nutrients are leached out and when it is slow, it will adversely affect the aeration of soil.
Vapour form:
In this category, the water is present in gaseous form in the soil atmosphere but it is not directly used by plants and is therefore, not important unlike the first three kinds.
Kinds of soil water (classification of soil water)
· Hygroscopic water (Water of adhesion)
· Capillary water (water of cohesion)
· Gravitational water
· Water Vapour
Absorption and Movement of Water in Soil
The movement of water from the soil surface into and through the soil is called water intake. It is the expression of several factors including infiltration and percolation.
Infiltration:
Infiltration is the term applied to the process of water entry into the soil generally (but not necessarily) through the soil surface and vertically downward. This process is of great practical importance since its rate determines the amount of run-off over the soil surface.
In other words, infiltration refers to the entry and downward movement of water in to the soil surface. Infiltration is a surface characteristic of a soil.
Infiltration rate:
It is the rate at which the water enters from the surface to the soil. Initially the infiltration rate is more but afterwards it decreases because the soil gets wet. According to the rate of entry of water from surface to the soil, infiltration rate is grouped in to four categories.
1. Very Slow: soils with less than 0.25cm per hour e.g. - very clay soils.
2. Slow: infiltration rate of 0.25cm to 1.25cm per hour e.g. Soils with high clay.
3. Moderate: infiltration rate of 1.25 to 2.5cm per hour. e.g. - sandy loam/ silt loam soils.
4. Rapid: infiltration rate is more than 2.5cm per hour e.g. deep/sandy silt loam soils.
Factors affecting the rate of infiltration:
· Compactness of soil surface: A compact soil surface permits less infiltration whereas more infiltration occurs from loose soil surface.
· Impact of rain drop: the force (speed) with which the rain drop falls on the ground is said to be impact of rain drop. Ordinary size varies from 0.5 to 4mm in diameter. The speed of raindrop is 30ft per second and force is 14 times its own weight. When impact of raindrop is more then it causes sealing and closing of pores (capillaries) especially in easily dispensable soils resulting in infiltration rate
· Soil cover: Soil surface with vegetative cover has more infiltration rate than bare soil because sealing of capillary is not observed.
· Soil Wetness: If soil is wet, infiltration is less. In dry soil, infiltration is more.
· Soil temperature: Warm soil absorbs more water than cold soils.
· Soil texture: In coarse textured soils, infiltration rate is more as compared to heavy soils. In coarse textured soil, the numbers of macro-pores are more. In clayey soils, the cracking caused by drying also increases infiltration in the initial stages until the soil again swells and decreases infiltration.
· Depth of soil: Shallow soils permit less water to enter into soil than too deep soils.
A coarse surface textured, high water stable aggregates, more organic matter in the surface soil and greater number of micro pores, all help to increase infiltration. As it is a dynamic and quite variable character of soil, it can be controlled by management practices. Cultivation practices that loosen the surface soil make it more receptive for infiltration e.g. course organic matter mulches increases infiltration.
Permeability:
It is defined as the characteristic that determines how fast air and water move through the soil describes what is known as permeability.
Once the water has entered into the top layer, its subsequent slow or rapid movement within the soil indicates its rapid or slow permeability. The permeability basically depends upon pore size distribution in the soil. Larger the number of macro pores (non-capillary pores), the greater is the permeability. The movement of water becomes slow in subsoil layers due to their compactness and low organic matter content but with deep-rooted plants, there is an increased permeability even in such sub soil layers. Permeability increases with the increasing fine texture.
Permeability depends up on:
· Number of micro pores: More the number of macro pores higher is the permeability.
· Soil aggregates: Larger the size of capillary pores, greater is the permeability.
· Depth of soil: Permeability decreases with the depth, as the sub soil layers are more compact and have less organic matter.
· Coarseness of soil texture: In coarse textured soil, permeability is more, however fine textured soil is less.
· Salt concentration: Salt concentration affects permeability adversely. If the sodium is high in water; it would cause ready dispersion of soil and thus reduces permeability.
· Soil moisture status: Permeability decreases as the soil becomes drier and increases when soil becomes wet.
· Organic matter content: more organic matter in the soil results in more permeability.
The permeability is considered slow, if it is less than 2.5 cm per hour, moderate if it is about 5.0 cm per hour. Like infiltration, permeability can be also controlled to a extent by suitable management practices. Continuous tillage reduces permeability, while the growth of deep-rooted crops like pulses or legumes, grasses and tress increases permeability. The permeability of soil varies with its moisture status and usually decreases as the soil becomes drier because air enters in to soil and reduces the permeability.
Percolation:
The down ward movement of water through saturated or nearly saturated soil due to the forces of gravity is known as percolation. Percolation occurs when water is under pressure or when the tension is smaller than about 1/3 atmosphere.
Percolating water goes deep into the soil until it meets the free water table. Percolation studies are important for two reasons-
1)Percolating water is only source of recharge of ground water, which can be again be profitably used through springs and wells for irrigation.
2)Percolating water carries plant nutrients like Calcium, Magnesium deep into lower layers and depositing them beyond the reach of roots of common field crops. In sandy or open textured soils, there is a rapid loss of water through percolation.
Percolation depends up on:
(i) Climate: If the rainfall is more than evaporation, then there will be appreciable amount of percolation. In dry region, percolation is almost negligible.
(ii) Nature of soil: sandy soils permit more percolation as these occupy large number of macro-pores. The macro-pores serve as the main channels of the gravitational flow. However, clayey soil permits less water to percolate.
Capillary movement:
Once the flow due to gravitational forces has been ceased (stopped), the water moves in the form of thin or capillary film from a wet region to dry region. This type movement goes through the finer or micro-pores and it continues until the thickness of moisture film surrounding the soil particles is equal to both the regions (wet and dry regions). Capillary may be in all directions i.e. it may be downward, lateral or upwards from a low tension to high-tension area, since thicker film have lower tension; water from thicker film around the soil particles flows to thinner film. The greater the difference between the thicknesses of the film, the quicker is the capillary movement up to certain point and as difference narrows, the movement of water film also becomes slow and may cease (stop).
Forces Causing Water Movement and Retention of Water in Soil
Force Causing Water Movement:
The forces which cause the water movement in soil are:
(1) Gravitational force or gravity tension: The flow of water due to gravity is very marked when the soil is in saturated condition and generally, the direction of such flow is downward although a little lateral flow takes place. The large pores i.e. macro-pores serve as the main channels for gravitational flow.
(2) Capillary force or capillary tension: In the soil, water is held by the forces of surface in the capillary spaces and around the soil particles. The movement of water under unsaturated soil conditions is due to force of surface tension. Once the flow due to gravitational force has ceased the water moves in the form of thin or capillary film from a wet region to a dry region through finer or micro-pores. The surface or capillary tension is responsible for the capillary movement of water to all directions from low tension to high tension.
(3) vapour tension: If the soil is not water logged, the movement of water vapour may take place to a very little extent from soil layers which gets more heated towards the cooler soil layers particularly when difference between their temperatures are very wide.
(4) Osmotic pressure: The movement of water takes place due to difference in osmotic pressure of the soil solution. the situation is only observed in only saline soil which has excessive salts.
In all these four forces, the gravitational and capillary forces are important because their significance in the movement of water in the soil is more. However, vapour transfer and osmotic pressure are less important because of their negligible significance in case of normal soils.
Retention of water in soil:
Water that enters in the soil is retained by means of the following three forces:
i) Force of adhesion: It is the attraction of solid surface of water molecules (It is the attraction of unlike materials to each other). Due to the force of adhesion, the water molecules are attached to the surface of soil particles and thus a thin film of water is tightly held around the soil particles. Finer the soil particles, greater the surface area and consequently, the water film is held or retained more tightly.
ii) Force of cohesion: It is attraction between similar molecules of like characteristics. Cohesion is attraction of water molecules for each other. When more water is added to the moist soil, the cohesive force comes into action and the freshly added molecules get attracted towards already existing water molecules. This results in thickening of water film around the soil particles.
iii) Soil colloids: (Clay or humus particles): The water is also retained in the soil due to soil colloids like clay or humus particles. The water thus retained in the soil is called imbibitional moisture.
Such retention of moisture is different in different soils. Fine textured soils having greater aggregation and more organic matter or humus retain much more quantity of water than those coarse textured single grained soils which are poor in organic matter.
Soil Moisture Constant
Soil Moisture Constant:
Water contents under certain standard conditions are referred as soil moisture constants.
Under field conditions, water content of soil is always changing constantly with time and depth of soil and is not static or constant. However, the concept of soil moisture constants greatly facilitates in taking decision in irrigation.
Important Soil Moisture Constant:
While studying soil water and discussing its availability or other wise to plant, some specific terms called as soil moisture constants are used. A brief explanation of some important and commonly used terms is given below and the methods of expressing them are indicated in the table below.
Appearance
of soil
Type of Soil
Soil Moisture Constant
Moisture Tension
in Atmosphere
Wet soil
Gravitational water
Maximum water
0.001
Moist soil
Available water
Field capacity
0.33 (1/3)
Water held in micro pores
Wilting point
15
Dry soil
Unavailable water tightly held
Hygroscopic coefficient
31
Air dry
1000
I
Oven dry
10,000
Important soil moisture constants:
1. Oven dry weight: This is the basis for all soil moisture calculations. The soil is heated in an oven at 105 degree Celsius until it looses no more water and final weight is recorded as oven dry weight. Equivalent moisture tension at this stage is 10,000 atmospheres.
2. Air-dry weight: Unlike oven dry weight, this is a variable constant. Soil exposed in humid atmosphere will have a higher weight than the same soil, if put in dry atmosphere. Under average conditions, moisture at air dryness is held with a force of about 1000 atmosphere.
3. Hygroscopic coefficient: It is the maximum quantity of water absorbed by any soil in a saturated atmosphere (i.e. at 99 percent relative humidity) at 25 degree Celsius temperature. The hygroscopic coefficient varies with the type of soil, its texture and organic matter content. This constant is equal to a force of about 31 atmospheres and determined by placing the soil in a saturated atmosphere at 25oC temperature. Water held by the soil at this constant is not available to plants because it is mostly in vapour form but it is useful to certain bacteria.
4. Permanent Witling Point (PWP): The wilting point is also known as a wilting coefficient or permanent wilting point or permanent wilting percentage.
After using the water from outer capillary portion, the plant roots begin to utilize although with difficultly the inner capillary water. Thus, as the moisture film becomes thinner, it is held more and more tightly and it is difficult for plant roots to remove each successive portion of the water film. But later on, a stage is reached at which plants cannot obtain enough water to meet transpiration requirement and remain wilted even under saturated atmosphere, unless water is added to soil. The soil moisture constant at this stage (wilting is called as wilting co-efficient or permanent wilting percentage. Water at this constant is with force of a 15 atmosphere. The wilting co-efficient differs in different soils. It is as low as 4 to 6 percentage in sandy soils and as high as about 16 to 20 percent in clayey soils which are rich in organic matter. The wilting point is a lower limit of available soil moisture.
5. Field Capacity (F.C.): Field capacity is the moisture content in percentage of a soil on oven dry basis, when it has been completely saturated and down ward movement of has practically ceased.
With 2 to 3 days after a heavy rains or irrigation, the gravitational or free water is drained. The moisture content at this stage in the soil is said to be at field capacity. The field capacity is the upper limit of available soil moisture range in the soil moisture and plant relations. The moisture tension at this stage is about 1/3 atmosphere. The fine textured granular soil with high organic matter content more soil moisture than sandy soil at field capacity.
6. Moisture equivalent: According to the modified technique, moisture equivalents is the amount of moisture in percentage on oven dry weight basis held by 30 grams of dry soil when subjected to 1000 times the gravitational force in a centrifuge for 30 minutes.
For practical purpose, field capacity may be considered as equal to the moisture equivalent. The value (moisture content may be considered as equal to the moisture equivalent are nearly equal in loamy soil but for sandy soils, the moisture equivalent is slightly higher than filed capacity.
7. Maximum capillary capacity: When water is added to the soil whose field capacity is already reached, that water goes on thickening the moisture film. A stage is then reached after which any further additional of water will get percolated down by the force of gravity. This is the point of maximum capillary capacity.
8. Maximum water holding capacity: Any further addition of water to the soil after its maximum capillary capacity is reached will start moving down by force of gravity, if it is a well drained soil but when drainage is restricted, maximum amount of water can be held until all micro and macro pores are filled with water. This stage is called the maximum water holding capacity. It is only in case of poorly drained soils or soils having hard pan near the surface that maximum water is retained in the soil for a long period.
The values of different soil moisture constant (moisture percent) differ according to soil type. The values for these moisture constant for some the soils are given below.
Table: Moisture constants for few typical Indian soils (in percent of oven dry soil)
Soil type
Air dry
moisture
Hygroscopic
co-efficient
Wilting
Coefficient
Moisture
equivalent
Maximum
water holding capacity
Heavy black
3.8
20.7
29.9
53.2
79.7
Medium black
2.1
13.3
20.6
45.6
66.6
Alluvial
1.6
7.6
13.5
40.4
48.7
Sandy
0.5
1
5.3
21.8
25.2
Laterite
0.8
2.8
5.5
32.9
39.6
Available and Unavailable Soil Water
It is evident that all the water present in the soil profile is not available for the use of plants. Even the capillary water which is considered to be loosely held by the soil particles is not utilized by plants.
Three tentative divisions of the soil water may be made on the basis of availability
i) Unavailable water
ii) Desirably available water
iii) Superfluous or excess of water not needed by plants.
Available and unavailable water
Type of water
Atmospheric Pressure
Status
Oven Dry
10000
Unavailable Water
Air Dry
100
Hygroscopic Co-efficient
31
Difficultly Water
Wilting Point
15
Field Capacity
0.33
Available Water
Ground Water
0.001
Unavailable Water
Unavailable soil water:
Types of water are not available to the plants are
a) Hygroscopic water
b) Fraction of inner capillary
c) Water vapour
Water below the hygroscopic co-efficient is held so tenaciously above 31 atmosphere that is unavailable to plants. The water held between the hygroscopic co- efficient (31 atmosphere) and the wilting point (15 atmospheres) is inner capillary water. Its movement is extremely sluggish and is only difficultly available to plants. Only certain type of plants under arid conditions make its use. So also some bacteria and fungi use the inner capillary water. It includes whole of the hygroscopic water plus a part of inner capillary water being below the wilting point.
Available or Desirably available water:
The range of water between the limits of field capacity and wilting point (co- efficient) is considered as the desirably or available water. The soil moisture between field capacity (1/3 atmosphere) and wilting point (15 atmosphere) is readily available moisture.
Superfluous water:
It includes gravitational water (excess of field capacity). This water is also unavailable to the use of plants because it is lost due to deep percolation. The preference of superfluous water in soil for longer period is harmful to plant growth.
Absorption of Moisture by Crops
Absorption of water is not dependent of process but it is related to transpiration. Absorption is controlled by rate of water loss in transpiration at least when water is readily available to the roots. Absorption and transpiration are linked by the continuous water column in xylem system of plants. Due to the loss of water in transpiration, it produces the energy gradient which causes the movement of water from soil in to the plants and from plants to atmosphere. In the maintenance of water column in xylem, the cohesive and adhesive properties of water play important role.
Moisture enters in to plant roots by process of osmosis (movement of liquid through semi permeable membrane caused by unequal concentration on the two sides). The concentration of soluble material in cell sap of roots is increased because of loss of water through transpiration. When concentration of soluble material in cell sap within roots is greater then the soil moisture, the water passes in the roots to equalize the concentration. A more correct view to consider the concentration of water molecule in cell sap reduced because of quantity of soluble substances present and hence the number of water molecules in the soil solution is greater. As a result more water molecules strike against cell wall and water passes into the roots from the zone of higher concentration of water to a zone of lower concentration of water.
When the concentration of soluble substances in the soil moisture exceeds that cell sap, situation will be reserved and water will pass out of the roots to the soil. Plants growing in saline soils with high concentration of soluble salts absorb water with difficulty due to high osmotic pressure of the soil solution.
The absorption of water by plants is closely related with transpiration. The sun provides energy for vaporization of water from leaves. Loss of water from leaf cells cause an increase in interior osmotic pressure which causes water to move in to them from xylem vessels. The xylem vessels of leaf are continuous with that of stem and roots and cause a tension created by loss of water from leaf to be transmitted to roots. Increased osmotic pressure in root cells occurs and uptake of water is encouraged. The absorption of water takes place in terminal portion of roots but the maximum absorption takes place in the zone of root hairs, 1 to 10cm behind root tip.
In other words, water is absorbed mainly through roots hairs. Root absorbs water both passively and actively.
Passive absorption takes place when water is drawn into the roots by negative pressure in the conducting tissues created by transpiration.
Under the conditions during which there is little transpiration, the roots of many plants absorb water by spending energy that is called active absorption. Under normal conditions of transpiration, the contribution of active absorption to the water supply of plant is negligible and it is usually less than 10 percent of total absorption.
Certain plants are able to absorb moisture from the atmosphere when soil is at permanent wilting point. This is known as aerial absorption or negative transpiration. Direct absorption of water by leaves that are wetted by rain, dew or overhead irrigation can help to resaturate dehydrated leaf tissue.
The leaves are borne through out the stem in all plants which are mainly responsible for the loss of water. The leaf surface shows small pores surrounded by two cells. The pores are called stoma and cells surrounding them are called guard cells. The stoma (stomata) regulates the loss of water as vapour and exchange of CO2 in leaf and other organs. It is thus the efficiency of these structures which possibly determine water loss from plant. The efficiency of the stomata up on their size and number per unit area.
Factors Affecting Absorption of Water
Factors affecting absorption of water:
A) Physical factors: The soil and atmosphere are the chief physical factors which determine the flow rate of water through plant.
Soil factors:
i) Soil water content: The plant roots can easily absorb the soil moisture in between field capacity and permanent wilting point. When the soil moisture decrease below the wilting point, plant roots have to exert more pressure and thus rate of absorption decreases. On the other hand, when the soil is completely saturated with water, then soil temperature and aeration are poor and this condition also affects the absorption of water.
ii) Soil temperature: Soil temperature is known to influence water absorption and ultimately transpiration to a considerable extent. In many plants, water absorption below a soil temperature of 10 oC is reduced sharply and 25 oC soil temperature up take of water is slowed down. In most instances, temperature above 40 oC does not support water absorption and plant can show signs of wilting. A freezing temperature reduces water absorption because of following causes.
a) Decreased root growth
b) Increased viscosity of water
c) Increased resistance to movement of water in to roots. thus is caused by decreased permeability of cell membrane and the increased viscosity.
iii) Soil aeration and flooding: Most of crop plants are not able to water while standing under water logged conditions. The following are the possible reasons of flood injury.
a) Poor availability of oxygen and occurrence if higher CO2 concentration around roots.
b) Accumulation of toxic substances either in the submerged roots or around them.
c) Changes in pattern of ion up take resulting in the accumulation of some toxic ions.
In water logged condition, the availability of oxygen is reduced which affects respiratory actively of roots. In addition, CO2 concentration is increased and it affects permeability of membranes and adversely influences water up take. Reduced oxygen also affects root growth adversely.
B) Atmospheric factor:
Classification of Crops According To Root Depth, Rooting Characteristic And Moisture Use Of Crops.
The amount of soil moisture that is available to a plant is determined by the moisture characteristics of the soil, the depth to which the plant roots extend and the proliferation or density of the roots. Soil moisture characteristics, such as field capacity and wilting percentage are peculiar to a soil and are a function of the texture and organic matter. Little can be done to alter these limits to any great extent. Greater possibilities lie in changing the characteristic of the plant enabling it extend its rooting system deeper into the soil, thereby enlarging its reservoir of water. The density of roots proliferation is important.
Water is an unsaturated soil moves very slowly, and only a distance of a few cm. To utilize effectively the moisture stored in the soil profile, roots must continue to proliferate into unexploited zones throughout the plants growth cycle. During favorable growing periods, roots often elongate so rapidly that satisfactory moisture contacts can be maintained even when the soil moisture content declines. Where transpiration is effected due to the different atmosphere factors such as wind velocity, humidity, sunlight, etc when temperature and wind velocity are more sunlight for longer period and humidity are less, under such conditions, transpiration is more. The increased rate of transpiration results more water uptake.
C) Biological factors:
Root system is the plant factor which is directly related to the absorption of water from soil. Under favorable soil water, potential soil temperature, aeration, and roots system of the plants strongly influence the uptake of water. When growth of roots (root system) is more, uptake of water is also more under favorable soil conditions. Root growth is influenced by soil and more therefore agronomic management practices can help to improve root growth.
Other plant factors such as morphology of leaves, stomatal mechanism and growth stage of the crop influence the rate of transpiration. The increased rate of transpiration results more water absorption.
Good root system has developed during favorable growing periods; a plant can draw its moisture supply from deeper soil layers.
Plants vary genetically in their rooting characteristics. Vegetable crops such as onions and potatoes have a spare rooting system and are unable to use all the soil water within the root zone. Forage grasses, sorghum, maize and such other crops have very fibrous, dense roots. Lucerne has a deep root system. Whether plant is an annual or perennial is another factor affecting its its moisture relations. An annual plant must extend its roots down into the soil to make availability root depth, and needs only to extend its small roots and hairs to be able to utilize the entire amount of available soil water.
Plants may be limited in their rooting by factors other than genetic. High water table, shallow soils and an impermeable formation near the ground surface restrict the depth rooting. Fertility and salt status of the soil influence the rooting of plants crop management practices, such as cutting the top growth at different physiological stages and the cultivation and cutting of surface roots after rooting habits. The rooting pattern of common and crop plants vary widely from soil. For example, roots of maize crop have been found to extend as deep as 1.5 meters in medium to textured soils, while in a fine textured soil the crop has a shallower root system.
Effective Root zone: Effective root zone is the depth from which the roots of average mature plant are capable of reducing soil moisture to the extent that it should be replaced by irrigation. It is not necessarily to have maximum root depth for ant given plant especially for plants that have a long taproot. Root development of any crop varies widely with the type of soil and other factors.
Table: Effective root zone depth of some crops and their classification.
Rooting Characteristic
Shallow Rooted
Moderately Deep Rooted
Deep Rooted
Very Deep Rooted
Rice
Wheat
Maize
Sugarcane
Potato
Castor
\Cotton
Citrus
Cauliflower
Ground Nut
Sorghum
Coffee
Cabbage
Pea
Bajara
Apple
Lettuce
Bean
Soybean
Grape Vine
onion
Chili
Sugar Beet
Safflower
Tobacco
Tomato
Lucerne
Moisture extraction pattern within root zone
The moisture extraction pattern shows the relative amounts of moisture extracted from different depths within the crop root zone.
It is seen that about 40 percent of the total moisture used is extracted from first quarter of the root zone, 30 percent from the second, 20 percent from third and only 10 percent from last quarter.
This indicates that the need for making soil moisture measurements at different depths within the root zone in order to have estimate of soil moisture status.
Methods of Soil Moisture Estimation Laboratory & Field Methods
By measuring soil moisture at regular interval and at several depths within the root zones, information can be obtained as to the rate at which moisture is being used by the crops at different depths. This provides the base for determining when to irrigate and how much water to be applied.
For practical purpose, irrigation should be given when about 50 percent of available moisture in the root zone is depleted. The amount of water to be applied is directly related to the water already present in the soil. The methods of measuring soil moisture are divided in to:
A) Direct method: Measurement of moisture content in the soil (wetness)
B) Indirect methods: Measurement of water potential or stress or tension under which water is held by the soil.
A) Direct methods:
I) Gravimetric methods: In the gravimetric method, basic measurement of soil moisture is made on soil samples of known weight or volume. Soil sample from the desired depths are collected with a soil auger. Soil sample are taken from desired depth at several locations of each soil type. They are collected in air tight aluminum containers. The soil samples are weighed and they are dried in an oven at 105 oC for about 24 hours until all the moisture is driven off. After removing from oven, they are cooled slowly to room temperature and weighed again. the difference in weight is amount of moisture in the soil. The moisture content in the soil is calculated by the following formula:-
Moisture content Wet weight –Dry weight
On weight basis = ----------------------------- X 100
Dry weight
PROBLEMS: Wet weight of a soil sample with can is 210 gms and weight with
can is 180 gms weight of empty container is 40 gms calculated moisture content of
soils sample?
Solution:
Weight of wet soil sample = wet weight – weight of empty can
= 210-40
= 170
Dry weight of soil sample = Dry weight – weight of can
=180-40
=140
Wet weight of soil- Dry weight of soil
Moisture content (%) = --------------------------------------- X 100
Dry weight of soil
170-140
= ----------------------------- X100
140
30
= ------ X 100
140
= 21.4%
II) Volumetric Method: Soil sample is taken with a core sampler or with a tube auger whose volume is known. The amount of water present in soil sample is estimated by drying it in the oven and calculating by following formula.
Moisture content = Moisture content (%) by weight x Bulk Density (%) by volume.
PROBLEM: Undisturbed soil sample was collected from a field, two days after irrigation when the soil moisture was near field capacity. The inside dimension of core sampler was 7.5 cm diameter and 15 cm deep. Weight of core sampling cylinder weight of the core-sampling cylinder was 1.56 kg. Determine the available moisture holding capacity of soil and the water depth in centimeter per meter depth of soil.
Solution:
Weight of moist soil = 2.76-1.56 = 1.20kg
Weight of oven dry soil = 2.61-2.56 = 1.05 kg
1.20-1.05
Moisture content = ------------- X 100
1.05
= 14.28%
Volume of core sampler = ----------------------------X d2 x h
= ------------X7.5X7.5X15
4
= 662 cu. Cm
Wt. of dry soil in grams
Apparent specific gravity = --------------------------------
Volume of soil in cu. Cm
1.05
= ------ = 1.58
662
Available moisture = Ap. Sp. Gr. X moisture content
= 1.58 X 14.28
= 22.56 cm / m depth of soil
The method is though accurate and simple it is used mainly for experimental purpose. Sampling, transporting & repeated weighing give errors. It is also laborious and time consuming. The errors of the gravimetric method can be reduced by increasing the size and number of samples. however the sampling disturbs the experimental plots and hence many workers prefer indirect methods.
III) Using Methyl Alcohol: Soil sample is mixed with a known volume of methyl alcohol and then measure the change in specific gravity of school with a hydrometer. This is a shot cut procedure but it is no in common use.
IV) Using calcium chloride: Soil sample is mixed with a known amount of calcium chloride. calcium chloride reacts with water and removes it in the form of acetylene gas. The moisture is determined has come in common use.
B) Indirect methods:
In those methods, no water content in the soil is directly measured but the water potential or stress or tension under which the water is held by the soil is measured. The most common instrument used for estimating soil moisture by indirect method is:
1) Tensiometer
2) Gypsum block
3) Neutron probe
4) Pressure plate and pressure membrane apparatus
In all these methods, the reading from above instruments and corresponding soil moisture content is determined by oven drying method are plotted on a graph. Subsequently, these calibration curves are used to know soil moisture content from the reading of these instruments.
1) Tensiometer: Tensiometer is also called irrometers since they are used in irrigation scheduling. Tensionmeters provide a direct measure of tenacity (tension) with which water is held by soil. It consist of 7.5 cm porous ceramic or clay cup, a protective metallic tube, a vacuum gauge and a hollow metallic tube holding all parts together. At the time of installation, the system is filled with water from the opening at the top and rubber corked when set up in the soil. moisture from cup moves out with drying of soil, creating a vacuum in the tube which is measured with the gauge. Care should be taken to install tensiometer in the active root zone of the crop. When desired tension is reached, the soil is irrigated. The vacuum gauge is graduated to indicate tension values up to one atmosphere and is divided in to fifty divisions each of 0.2 atmosphere value. The tensiometer works satisfactory up to 0.85 bars of atmosphere.
Merits of tensiometer:
1. It is very simple and easy to read soil moisture in situ.
2. It is very useful instrument for scheduling irrigation to crops which require frequent irrigations at low tension.
Limitations:
Sensitivity of a tensiometer is only up to 0.85 atmospheres while available soil moisture range is up to atmosphere and hence is useful more on sandy soils wherein about 80% of available water is held within 0.85 ranges.
2) Gypsum Blocks: Gypsum blocks or plaster of Paris resistance units are used for measurement of soil moisture is situ. These were first invented by Bouycos and Mick in 940. the blocks are made of various materials like gypsum, nylon fiber, glass, plaster of Paris or combination of these materials. The blocks are generally rectangular shaped. A pair or electronics is usually made of 20 mesh stainless steel wire screen soldered to copper lead wire. The common dimensions of screen electrodes are 33.75 cm long and 0.25 cm wide. The usual spacing between the electrodes is 2 cm. A similar block is 5.5 cm long, 3.75 cm wide and 2 cm thick.
Principal of working: It works on principal of conductance of electricity. When two electrodes A and B are placed parallel to each other in a medium and then electric current is passed, the resistance to the flow of electricity is proportional to the moisture content in the medium. Thus, when the block is wet, conductivity is high and resistance is low. Generally these read about 400 to 600 ohms resistance at field capacity and 50,000 at wilting point. the readings are taken with portable Wheatstone Bridge Bouycos water Bridge operated by dry cells.
While placing the gypsum block in soil, care should be taken that the blocks must have close contact with undisturbed soil. After placing, the blocks get wetted with soil moisture due to capillary movement. Pure gypsum block sets in about 30 minutes. The gypsum block is sensitive to soil to moisture from 1.0 atm tension to 20.0 atm. How ever, the gypsum blocks are not reliable in wet soils.
3) Pressure membrane and pressure plate apparatus: Pressure membrane and pressure plate apparatus (developed primarily by Richards) is generally used to estimate field capacity, permanent wilting point and moisture content at different pressures. The apparatus consists of air tight metallic chamber in which porous ceramic pressure plate is placed. The pressure plate and soil samples are saturated and are placed in the metallic chamber. The required pressure, say 0.33 bar or 15 bars is applied through a compressor. The water from the soil sample which is held at less than the pressure, Applied trickles out of the outlet till equilibrium against applied pressure is achieved after that, the soil samples are taken out and oven dried for determining the moisture content.
4) Neutron meter (neutron scattering method): Soil moisture can be estimated quickly and continuously another with neutron moisture meter without disturbing the soil. Another advantage is that soil moisture can be estimated from large volume of soil. This meter scans the soil to about 15 cm. diameter around the neutron probe in wet soil and 50 cm in dry soil. it consists of a probe and a scalar or rate meter. The probe contains fast neutron source, which may be a mixture of radium and beryllium or Americium and beryllium. Access tubes are aluminum tubes of 50 to 100 cm length and are placed in the field where moisture to be estimated.
Neutron probe is lowered into access tube to the desired depth. fast neutrons are released from the probes, which scatter into the soil. When neutrons encounter nuclei of hydrogen atom of water, their speed is reduced. the scalar or the rate meter counts the number of slow neutrons, which are directly proportional to water molecules. Moisture content of soil can be known from the calibration curve with counts of slow neutrons.
Limitations: The two drawbacks of the instruments are that it is expensive and moisture content from shallow top layers cannot be estimated. The fast neutrons are also slowed down by other source of hydrogen (present in the organic matter). Other atoms such as chlorine, boron and iron also slow down the fast neutrons, thus overestimating the soil moisture content.
5) Gama Ray absorption method: it is the technique of measurement of changes in soil water content by change in amount of gamma radiation absorbed. The amount of radiation passing through soil depends on soil destiny which varies chiefly with change in water content. This is suitable where change in bulk destiny is very small.
6) Feel and appearance method: A practical estimate of moisture content is obtained by the feel and appearance of soil samples taken from the desired depths. the soil sample is squeezed in the hand and its feel and appearance are taken into consideration. In this method, actual moisture content is not determined.
7) Soil moisture characteristic curve: The energy status of water and amount of water in the soil are related with the soil moisture characteristic curve. As the energy status of water decreases (moisture towards more negative values) soil water content also decreases. In other words, as soil moisture content deceases, more energy has to be applied to extract moisture from the soil. the relation between suction (externally applied force) and water content of the soil are represented graphically by a curve which is known as a soil are moisture characteristic curve.
Hysteresis:
The relation between energy status and moisture content can be obtained in two ways, (i) in absorption by taking an initially saturated soil sample and applying increasing suction to dry the soil gradually and (ii) in absorption by gradually wetting an initially dry soil. The measurement of energy status and moisture content during this process are taken and plotted on graph. The curves obtained through desorption and sorption is different for the same soil sample. the moisture content at a given suction is greater in desorption than in absorption and this phenomenon is known as hysteresis.
Evaporation, transpiration, evapo-transpiration, factors influencing ET
Rainfall and irrigation water are the main source of water. rainfall is the basic source of water. However, ground water can also be made available to crops. After precipitation or application of irrigation water, it is lost from soil in four ways.
1. Surface run-offs
2. Percolation (downward movement of excess water).
3. Evaporation from the soil surface
4. Transpiration
1) Surface run off: The loss of water through run-offs is the largest and is almost damaging because it causes soil erosion. The rate of loss of water through run-off depends upon the soil type, intensity of precipitation or quantity of irrigation water. When the intensity of rainfall is more for longer period, the loss of water from the soil surface through run-off is greater. The infiltration capacity of sandy soil is more than heavy soils and hence in sandy soil, loss of water through run-off is low.
2) Percolation: When rainfall is high and water-holding capacity of soil is less, the losses due percolation are very great. Such losses are very rapid particularly when the soils are sandy and porous. In heavy soils, percolation is low because of more water holding capacity. Besides rapid percolation of water, there is also heavy loss of plant nutrients viz. Ca, Mg, S, K etc. resulting in soil becoming acidic. Percolation losses are maximum in humid climate. When high rainfall is received, the loss of water through percolation is necessary otherwise, poor drainage conditions and water logging may develop in heavy soils. When water is in excess of water holding capacity of soils, it percolates through the soil due to gravity.
3) Evaporation losses: Evaporation is the process during which a liquid changes into a gas. The process of evaporation of water in nature is one of the fundamental components of the hydrological cycle by which is one of the vapour through absorption of heat energy. This is the only form of moisture transfer from land and oceans into the atmosphere.
Considerable quantity of water is lost by evaporation from the soil surface. Sunlight, temperature, wind velocity and humidity are the main climate factors influencing the rate and extent of evaporation. More the fine aggregates of black soil, more the heat absorbed resulting in more loss of water.
Man can do maximum control over such losses by adopting suitable soil management practices. The basic principle is to cover the soil with vegetation, mulching, keeping soil surface loose by tillage operation, use of wind brake etc. that can help to reduce evaporation losses.
4) Transpiration losses: Transpiration is the process by which water vapour leaver the living plant body and enters the atmosphere. It involves continuous movement of water from the soil into roots, through the stem and cut through the leaves to the atmosphere. The process include cuticular transpiration or direct evaporation in to the atmosphere from moist membranes through the cuticle, and stomatal transpiration or outward diffusion into the atmosphere through the stomata and lenticels vapour previously evaporated from imbibed membranes, into intracellular space within the plant.
Transpiration is an evaporation process. However, unlike evaporation from a water surface, plant structure and stomata behavior in conjunction with the physical principles governing evaporation modify transpiration.
The loss of water through transpiration is governed by temperature, humidity, wind velocity, moisture content in the soil and inherent characteristic of the plant. Since transpiration is a physiological process, which must continue, if the plant has to grow, the only way to save this loss is by growing such crops and their varieties whose transpiration co-efficient is low. Transpiration can be checked to some chemicals. Transpiration produces energy gradient, which causes movement of water into through plants.
Effective rainfall:
Effective rainfall is a part of rainfall available for the consumptive use of the crop.
Part of the rain may be lost as a surface run-off, deep percolation below the root zone of the crop or by evaporation of rain intercepted by foliage. When rainfall is of high intensity, only a portion of rainfall can enter the soil and stored in the root zone. In case of light rains of low intensity depending on the amount of moisture already present in the root zone of the crop, even the amount and intensity of rainfall, rate of consumption use, moisture storage capacity of soil, initial moisture content and infiltration rate of the soil. It is difficult to predict effective rainfall because of variation of soils, crops, topography and climate. However, in India it is assumed that 70% of the average seasonal rainfall to be effective in arid and semi-arid regions while 50% considered effective humid regions.
Water table:
The upper surface of the zone of saturation is called the water table. At the water table, the water in the pores of the aquifer is at atmospheric pressure. The hydraulic pressure at any level within a water table aquifer is equal to the depth from the water table point and is referred to as the hydraulic head. When a well is dug in a water table aquifer, the static water level in the well stands at the same elevation as the water table. The water table is not a stationary surface moves up and down rising when more water is added to the saturated zone by vertical percolation, and dropping during drought periods when the previously stored water flows out towards springs, streams, well and other points of ground water discharge.
Water Requirement and Irrigation Requirement
Water Requirement of Crop:
Water requirement of crop is the quantity of water regardless of source, needed for normal crop growth and yield in a period of time at a place and may be supplied by precipitation or by irrigation or by both.
Water is needed mainly to meet the demands of evaporation (E), transpiration (T) and metabolic needs of the plants, all together is known as consumptive use (CU). Since water used in the metabolic activities of plant is negligible, being only less than one percent of quantity of water passing through the plant, evaporation (E) and transpiration (T), i.e. ET is directly considered as equal to consumptive use (CU). In addition to ET, water requirement (WR) includes losses during the application of irrigation water to field (percolation, seepage, and run off) and water required for special operation such as land preparation, transplanting, leaching etc.
WR = CU + application losses + water needed for special operations.
Water requirement (WR) is therefore, demand and the supply would consist of contribution from irrigation, effective rainfall and soil profile contribution including that from shallow water tables (S)
WR = IR + ER + S
Under field conditions, it is difficult to determine evaporation and transpiration separately. They are estimated together as evaportranspiration (ET). IR is the irrigation requirement.
Factors influencing Evapotranspiration (ET):
ET is influenced by atmospheric, soil, plant and water factors.
A) Atmospheric factors:
1) Precipitation
2) Sunshine
3) Wind velocity
4) Temperature
5) Relative humidity
B) Soil factors:
1) Depth of water table
2) Available soil moisture
3) Amount of vegetative cover on soil surface.
C) Plant factors:
1) Plant morphology
2) Crop geometry
3) Plant cover
4) Stomatal destiny
5) Root depth
D) Water factors:
1) Frequency of irrigation
2) Quality of water ET.
Water requirement of any crop depends on crop factors such as variety, growth stage, and duration of plant, plant population and growing season. Soil factors such as temperature, relative humidity, wind velocity and crop management practices such as tillage, fertilization, weeding, etc. Water requirement of crops vary from area to area and even field to field in a farm depending on the above-mentioned factors.
Estimation of Evapotranspiration (ET):
Climate is the most important decides the rate of ET. Several empirical formulas are available to estimate ET from climate date. FAO expert group of scientists has recommended four methods for adoption of different regions of world.
1) Blaney and Criddle method
2) Radiation method
3) Pan evaporation method
4) Modified penman method
Estimation of ET Involves Three Important Steps:
a) Estimation of PET or evapotranspiration (ET) by any four above methods.
b) Estimation of crop co-efficient (KC) and
c) Making suitable adjustments to local growing conditions.
a) Reference Evapotranspiration (ETO): ETO can be defined as the rate of evapotranspiration of an extended surface of an 8 to 15 cm tall, green cover, actively growing completely shading the ground and not short of water.
Selection of a method for estimation of ETO depends on availability of metrological data and amount of accuracy needed. Among four methods for estimation of ETO, modified Blaney-Criddle method is simple, easy to calculate and requires data on sunshine (S.S.) hours, wind velocity (WV), relative humidity (RH) in addition to temperature (T).
Among these methods, modified penman method is more reliable with a possible error of 10% only. The possible errors for other methods are 15, 20 and 25% of pan evaporation, radiation and modified Blaney-Criddle methods respectively.
Modified Blaney method:
ETO = C [P (0.46 T + 8)] mm/day
Where ETO = Reference crop ET in mm/day for the month considered
T = Mean daily temperature in oC over the month considered
P = Mean daily percentage of total annual day time hours of a given month and latitude (from standard table)
C = Adjustment factor depends on minimum R.H., Sunshine hours and day time wind estimates.
Pan evaporation method:
ETO = Kp | Epan Where Kp = Crop factor
Epan = mean pan evaporation (Epan pan evaporation)
Modified penman method:
ETO = C [W.Rn + (1-w). f (U). (ea – ed)]
Where Rn = Net radiation in equivalent evaporation expressed as mm/day
W = temperature of altitude related factor
F (U) = Wind related function
Ea – ed= Vapour pressure deficit (mili bar)
C = the adjustment factor (ratio of U day to U night)
Rn (0.75-Rns)
Ea =Saturated vapour pressure (m.bar)
Ed = Mean actual vapour pressure of the air (m. bar)
Crop Coefficient:
Crop co-efficient is the ratio between evapotranspiration of crop (Etc) and potential evapotranspiration and expressed as T (crop) = Kc X ETo
Irrigation requirement:
Irrigation requirement is the total quantity of water applied to the land surface in supplement to the water supplied through rainfall and soil profile to meet the water needs of crops for optimum growth.
IR = WR – (ER + S)
Net irrigation requirement:
The net irrigation requirement is the amount of irrigation water just required to bring the soil moisture content in the root zone depth of the crops to field capacity. Thus, net irrigation requirement is the difference between the field capacity and soil moisture content in the root zone before application of irrigation water.
Gross irrigation requirement:
The total amount of water inclusive of water in the field applied through irrigation is termed as gross irrigation requirement, which in other words is net irrigation requirement plus application and other losses.
Consumptive use of water:
Sr. No
Crop
Consumptive Use ( cm )
Place
1
Jawar (Rabi )
450
Pune
2
Wheat
550
Pune
3
Sugarcane ( Suru )
2500
Padegoan
4
Sugarcane ( Adsali )
3300
Padegoan
5
Groundnut
560
Pune
6
Gram
250
Rahuri
7
Sunflower
350
Rahuri
Irrigation requirement of some common crops grown in India:
Crop
Growing Period ( No. of days )
Total Water Requirement
Daily Water Requirement
in cm
in inches
in cm
in inches
Jawar
114
64.25
25.70
0.575
0.23
Maize
100
44.50
17.80
0.450
0.18
Rice
93
104.50
41.80
1.075
0.43
Wheat
88
37.00
14.80
0.425
0.17
Groundnut
124
65.25
26.10
0.525
0.21
Linseed
88
31.71
12.68
0.350
0.14
Cotton
202
105.50
42.20
0.525
0.21
Sugarcane
365
237.50
95.00
0.650
0.26
Tobacco
132
98.00
39.20
0.750
0.30
Onion
120
75.00
30.00
0.625
0.25
Potato
88
30.00
12.00
0.750
0.30
Pea
88
30.00
12.00
0.350
0.14
Mustard
88
25.20
10.08
0.300
0.12
Barley
88
25.20
10.08
0.400
0.16
Oat
88
36.00
14.40
0.400
0.16
Ragi
127
74.50
29.80
0.575
0.23
Quantity of Irrigation Water or How Much to Irrigation
The net quantity of water to be applied depends upon magnitude of moisture deficit in the soil, leaching requirement and expectancy of rainfall. When no rainfall is likely to be received and soil is not saline, net quantity of water to be applied is equal to the moisture deficit in the soil i.e. the quantity required to fill the root zone to filed capacity. The moisture deficit (d) in the effective root zone found out by determining the field capacity moisture content and bulk density of each layer.
Problem: Find out the net quantity of irrigation water to be applied to wheat field with the following moisture status.
Sr. No.
Depth of Soil Layer ( cm )
Moisture % on oven dry basis
Apparent specific gravity g/cc
Field Capacity
Actual
1
0 - 15
25.0
16.4
1.39
2
15 - 30
24.0
17.8
1.47
3
30 - 60
22.3
19.2
1.51
4
60 - 90
22.2
20.5
1.53
Solution: Moisture deficit in the different layers will be as follows,
25.0 – 17.8
1. First Layer = ----------------- X 1.39 X 15 = 1.79
100
24.0 – 17.8
2. Second Layer = ----------------- X 1.47 X 15 = 1.36
100
22.3 – 19.2
3. Third Layer = ------------------ X 1.81 X 30 = 1.40
100
22.2 – 20.5
4. Forth Layer = ----------------- X 1.53 X 30 = 0.78
100
Therefore, net quantity of water to be applied is 5.33 cm to fill the root zone to field capacity again.
Requirement of irrigation water:
Units for water measuring:
Water is measured under two conditions. Water at rest measured in units of volume such as liter, cubic meter, hectare meter. Water in motion is expressed in rate off low units such as liters per hour and meters per day.
Liter: One liter is equivalent to 0.22 imperial gallons or 0.0353 cubic feet or 1/1000cubic meters.
Cubic meters: A volume of water equal to that of one cubic meter in length, one meter in breadth and one meter in thickness. One cubic meter of water = one kilo liters or 100 liters or 220 gallons or 35.3 cubic feet or one ton (approx)
Gallon: A gallon is 0.1602 cubic foot. One gallon of water weighs about 10Ib
Cubic foot: A volume of water equal to that of a cube 1 foot in length, 1 foot in breadth and 1 cubic foot in thickness. One cubic foot of water = 28.37 liters or 6.23 gallons or 0.0283 cubic meters or 0.028 ton.
Hectare centimeters: A volume of water necessary to ci\over an area of one hectare (10,000 aq. meters) surface to a depth of one centimeters (1hectare centimeter = 100 cubic meters = 100,000 liters)
Acre inch: the volume of water necessary to cover one-acre (43,560 sq. feet) surface to a depth of one inch. One hectare inch = 3630 cubic feet or 101 ton.
Acre foot: The volume of water necessary to cover one acre to a depth of one foot.
(One acre feet = 43,560 cubic feet)
Cusec: It is the quantity of water flowing at the rate of one cubic foot per second. As one cubic feet of water weighs about 62.4 Ib or 28.37 kg. One cusec of water flowing for one hour is equal to 62.4 Ib X 60 X 60 = 22464 gallons, 101 tons, or one- hectare inch (28.37 liter X 60 X 60 = 101952 liters or one-acre inch.
Duty of water: It denoted the number of acres covered by one causes of water flowing continuously through out the growing season of a crop. It is therefore varies with kind of crop, season, nature of soil, method of irrigation and method of cultivation.
Delta: It is the total depth of water required by a crop.
Problem: A pump with an average discharge of 15 liters/second irrigates one-hectare wheat crop in 12 hours. What is an average depth of irrigation?
Solution:
Discharge in 12 hours = 15 X 60 X 60 X 12
= 648000 liters
= 648 M^3
Volume of water (Cu. m)
Depth of irrigation (cm) = -------------------------------------- X 100
Area of land (sq. m)
648
= --------------- X 100
10,000
= 6.48 cm
Problem: Wheat crop requires 40 cm of irrigation water during 120 days irrigation period. How much land can be irrigation with a flow of 20 liters per second for 12 hours a day?
Solution:
20 X 60 X 60 X 12 X 120
Total discharge during irrigation period = ------------------------------------- M3
1000
= 1, 03,680 M3
40
Irrigation requirement per hectare = ------- X 10,000 M3
100
= 1, 03,680 M3
40
Irrigation requirement per hectare = ----------- X 10,000 M3
100
= 4000 M3
Volume of available water
Area irrigated = ------------------------------- X 10,000 M3
Volume of water required/ha (M3)
1, 03,680
= ---------------
40
= 25.92 hectare land can be irrigated
Devices Used for Measuring Irrigation Water
Several devices are commonly used for measuring irrigation water. They grouped into four categories
1) Volumetric Measures
2) Velocity-Area Methods
a) Float Method
b) Water Meters
3) Measuring Structures
a) Orifices
b) Weirs
c) Flumes
4) Tracer Methods
1) Volumetric methods (Using a container)
A simple method of measuring a small irrigation stream is to collect the flow in container of known volume for a measured period. An ordinary bucket or barrel is used as container. The time required to fill the container is recorded with a stopwatch or with seconds on wristwatch. The rate of flow is measured as below
Volume of container (liters)
Discharge rate liter/second = -----------------------------------
Time required to fill (seconds)
PROBLEM: A 24 liter capacity bucket is filled in 10 seconds by discharge from a Persian wheel. What is rate of flow?
24
Solution: Discharge ratio liter/second = -----
10
= 2.4 liter/second or 144 liter/minute
2) Velocity area method:
a) Float method:
The float method of making of rough estimates of the flow in a channel consists of nothing the rate of movement of a floating body. A long necked bottle partly filled with water or black wood, an orange or lemon may be used as float. A straight section of the channel about 30 meters long with uniform cross section is selected. Several methods of depth and width are made within the trial section to arrive at average cross sectional area. A string is stretched across each end of section at right to the direction of flow. The float is placed in the channel a short distance up stream from the trial section. The float needed to pass from upper end to lower end of the section is recorded. Several trials are made to get average time of travel.
To- determine the velocity of water at the surface of the channel, the length of the trial section is divided by the average time taken by the float to cross it. Since the Velocity of the float on the surface of the water will be greater than the average velocity of the stream; it is constant factor, which is usually assumed to be 0.85. To obtain the rate of flow , this average velocity ( measured velocity x co-efficient) is multiplied by the average cross sectional area of the stream.
Discharge or rate of flow = area x velocity
Q = A X V where Q= discharge rate in m3/sec. v = velocity of flow in m/s
a = cross section al area of channel in m2
b) Water meters:
Water meters utilize a multi blade propeller made of metal, plastic or rubber, rotating in a vertical or horizontal plane and geared to a tataliser in such a way that a numerical counter can totalize the flow in any desired volumetric units, water meters are available for a range of sizes suiting the pipe size commonly used on the farm. There are basic requirements for accurate operation of the water meter.
(1) The pipe must flow full at all times.
(2) The rate of flow must exceed the minimum for the rated range.
Meters are calibrated in the factory and field adjustments are usually not required. When water meters are installed in open channels, the flow must be brought through the pipes of known cross sectional area. Care must be taken that no debris or other foreign materials obstruct the propeller.
3) Water measuring devices:
a) Orifices:
Orifices in open channel are usually circular or rectangular openings in vertical bulk head through which water flows. The edges of opening are sharp and often constructed of metal. The cross sectional area of orifice is small in relation to the stream cross section. Orifice may operate under free flow or submerged flow conditions. The types of orifices are
I) Orifices below the level of inlet: The discharge through a closer orifice in which the orifice is situated below the level of inlet is calculated by the equation.
Q = Ca x under root (2gh)
Where, Q = Quality of flow in C. ft/Sec.
a+ Cross sectional area of water, the canal or orifice in sq. ft.
c = A constant which varies from 0.6 to 0.8 or more depending upon the position of orifice relative to the sides and bottom of vessels or the degree of roundness of the edge of orifice.
g= Acceleration due to gravity. (32 feet / sec/sec)
h= Height of water level in cistern from the middle of the orifice in feet.
II) Discharge through an orifice situated at higher level than inflow pipe: When the orifice is situated at a higher level than the inflow pipe, the discharge is calculated according to the equation.
Q = CLh1.5
Where D= Length of orifice in feet and
C= 2C 2g
H= head of water.
III) Discharge through submerged orifice:The discharge through a submerged orifice is given by the equation.
Q=0.61 LH 2gh
E.g. if L=1.0 H=0.5ft. h=0.25 ft. and g=Acceleration due to gravity (32ft/sec/sec) then Q=1.22 C, ft/sec.
b) Discharge through Weirs:
A wear means a notch in a well built across a stream. The notch may be (a) rectangular (b) Trapezoidal and (c) 90 degree V (Triangular) notch or weir.
(a) Rectangular notch or weir: The length of a weir may be equal to width of the upstream channel or less than it. The discharge through a rectangular weir, in case of complete end, contraction is given by the equation.
Q = 3.33 (L-0.2 H) H^1.5
Where L= measured length of the weir
L= effective length of weir in feet.
L= L-0.2H)
(b) Trapezoidal or Cipolletti Weir:
The discharge of water is given by the equation
Q= 3.367 LH ^ 1.5
L1 + L2
Where = --------------
2
(c) Discharge through 90oV notch:
The discharge is given by the equation:
Q= 2.49 H ^ 2.48 = 2.5H^2.5
c) Parshall flume or (Venturi flume):
Parshall (1950) has decided a device in which the discharge is obtained by measuring the loss in the head caused by forcing a stream of water through a throat or converged section of a flume with a depressed bottom. The loss in head is very small in this device. The accuracy of measurement in the Parshall flume is within allowable limits of 5% the flumes ranging from 3 inches to 10 feet throat width are used, which gives the range of discharge of 1/30 to 200 ousecs. The flumes of 3, 6 and 9 inch size are generally used in field measurement.
The ration between the reading at Hb and Ha point should be carefully studied. This ratio should not exceed 0/3 for 3 inch, 6 inch 9 sized Parshall flumes otherwise correction needs to be applied. When the ratio is less than 0.6, it is termed as free flow and exceeds 0.6, it is called submerged flow.
CUT THROAT FLUMES: Skogerboe eqal. (1967) have developed cutthroat flumes for measurement of water. Since there is no throat section (Zero throat flumes), the flumes have been given the name as out throat flumes by the designers.
The flumes have a level floor as apposed to the inclined floor in the throat and exit section in the partial flumes. it is placed in a concrete lined channel or on a channel bed conveniently. Every flume has the same all lengths in both the entrance and exit sections. These flumes consist of converging inlet section and diverging outlet section, under free flow conditions. The discharge Q through a cutthroat flume depends upon the upstream depth of flow Ha. The basic form of the free flow equation is-
Q=CH a 1.56
Where C=3.50 W 1.025 (W=throat d width infect)
4) Tracer Methods:
These methods are independent of stream cross section and are suitable for field measurements with out installing fixed structures. In these methods, a substance (tracer) is concentration form is introduced into flowing water and allowed to thoroughly mix. The concentration of the tracer is measured at down stream section. Since only the quantity of water is necessary to accomplish the dilution is involved, there is no need to measure velocity, depth, and head, cross sectional or any other hydraulic factor usually considered in discharge measurement. The relationship between size of stream, time of application, area to be irrigated and depth of water to applied is as below.
Qt=ad
Where Q=Size of stream or discharge (liter/second) or (ha. cm per hour)
t=the time of application of water (seconds or hour)
a=area (sq. m or hectare)
d=Depth in cm that the volume of water used would cover the land irrigated, if quickly spread uniformly over its surface.
Criteria for Scheduling Irrigation or Approaches for Irrigation Scheduling
An ideal irrigation schedule must indicate when to apply irrigation water and how much quantity of water to be applied; several approaches for scheduling irrigation have been used by scientist and farmers. These are as under
1) Soil moisture depletion approach:
The available soil moisture in the root is a good criterion for scheduling irrigation. When the soil moisture in a specified root zone depth is depended to a particular level (which is different for different crops) it is too replenished by irrigation.
For practical purpose, irrigation should be started when about 50 percent of the available moisture in the soil root zone is depleted. The available water is the soil moisture, which lies between field capacity and wilting point. The relative availability of soil moisture is not same field capacity to wilting point stage and since the crop suffers before the soil moisture reaches wilting point, it is necessary to locate the optimum point within the available range of soil moisture, when irrigation must be scheduled to maintain crop yield at high level. Soil moisture deficit represents the difference in the moisture content at field capacity and that before irrigation. This is measured by taking into consideration the percentage, availability, tension, resistance etc.
2) Plant basis or plant indices:
As the plant is the user of water, it can be taken as a guide for scheduling irrigation. The deficit of water will be reflected by plants itself such as dropping, curling or rolling of leaves and change in foliage colour as indication for irrigation scheduling. However, these symptoms indicate the need for water. They do not permit quantitative estimation of moisture deficit.
Growth indicators such as cell elongation rates, plant water content and leaf water potential, plant temperature leaf diffusion resistance etc. are also used for deciding when to irrigate. Some indicator plants are also a basis for scheduling irrigation e.g. sunflower plant which is used for estimation of PWP of soil is used in Hawaii as an indicator plant for irrigation sugar cane.
3) Climatological approach:
Evapotranspiration mainly depends up on climate. The amount of water lost by evapotranspiration is estimated from Climatological data and when ET reaches a particular level, irrigation is scheduled. The amount of irrigation given is either equal to ET or fraction of ET. Different methods in Climatological approach are IW/CPE ratio method and pan evaporimeter method.
In IW/CPE approach, a known amount of irrigation water is applied when cumulative pan evaporation (CPE) reaches a predetermined level. The amount of water given at each irrigation ranges from 4 to 6 cm. The most common being 5 cm irrigation. Scheduling irrigation at an IW/CPE ratio of 1.0 with 5 cm. Generally, irrigation is given at 0.75 to 0.8 ratios with 5 cm of irrigation water.
Problem: Calculate cumulative evaporation required irrigation at 0.5 0.6 0.75 0.8 with 5 cm of irrigation water.
Solution:
Cumulative pan evaporation at IW/CPE ratio of 0.5=IW/CPE=0.5
5 5 50
= ---------- = 0.5, CPE X 0.5 = 5 CPE = ------ = ------ 10cm
CPE 0.5 5
Irrigation of 5 cm is given when CPE is 10 cm
CPE at 0.6 ratio = 5/0.6 = 8.33cm
CPE at 0.75 ratio = 5/0.75 = 6.66cm
CPE at 0.8 ratio = 5/0.8 = 6.25cm
In IW/CPE ratio approach, irrigation can also be scheduled at fixed level of CPE by varying amount of irrigation water.
Problem: Calculate the amount of water for each irrigation for scheduling irrigation at 0.5 and 0.8 IW/CPE with 10cm of CPE.
Solution:
Amount of water to be given at IW/CPE ratio of 0.5=IW/10=0.5
IW=0.5 X 10= 5cm
Amount of water to be given at IW/CPE ratio of 0.8 =IW/10=0.8, IW=10 X 0.8=8cm
Estimating Evapo-Transpiration from Evaporation Data:
It is been observed that a close relationship exists between the rate of CU by crops and the rate of evaporation from a well-located evaporation pan. The standard United States weather bureaus class A pan evaporimeter or the sunken screen pan evaporimeter may be used for measurement of consumption use.
U.S class A evopometer:
It is most widely used evaporation pan. It is made of 20 gauge galvanized iron sheet 120 cm. in diameter by 25cm. in depth and is painted white and exposed on a wooden frame in order that air may circulate beneath the pan. It is filled with water to depth of about 20 cm. The water surface level is measured daily by means of hook gauge in a still well. Difference between two daily readings indicates the evaporation if there is no rainfall. When there is rainfall, record it separately with a rain gauge. Add that value to the initial water level in the still well. Difference between this reading and subsequent reading of the water would indicate evaporation. Water is added each day to bring the level to fixed point in the still well. A measuring cylinder can also be used for this purpose.
Sunken Screen Evapometer:
The sunken screen pan evaporimeter developed by Sharma and Dastane (1968) at the I.A.R.T., New Delhi provides a simple device to make reasonable estimate of CU. The ratio between evapo-transpiration and evaporation from U.S.W. class A pan (ET/E) is about 0.5 to 1.3 after establishment of the crop. the same ratio is the sunken screen pan evaporimeter was observed i.e. 0.95 to 1.05. in other words, it is claimed that the evaporation value obtained from it closely approximates the evapo-transpiration.
It consists of three parts, namely an evaporation pan, a stilling well and a connecting tube. The evaporation is 60 cm. in depth, is made of 20ngague galvanized iron sheet, and is painted white. it is fitted with a screen of 1/24 or 6/20 mesh, which is held tight over the pan by bending it at the rim and pressing hard. The stilling well is 15 cm. in diameter 45 cm. in depth and is fitted with a screen cover of the same mesh as that of the evaporation pan. It has a pointer to its side of the wall and bent upward in the center at right angle. The evaporimeter is installed by digging a pit of suitable size placing the pen and back filling the earth with due to compaction the top edge of the protrudes (sickout) 10 cm. over the soil surface. This is necessary to avoid run-off from the surrounding area entering the pan. The water level is maintained at same height as the soil level outside. Thus, the tip of the pointer free water surface in the pan and the pan and soil surface are at the same level.
The water level in the pan is brought in level with the pointed tip and pan is set at work. Observations of falling water level are recorded at suitable intervals say 24 hours. This is done by adding water with a measuring cylinder and recording the quantity of water added to bring the water level back to the pointer tip. The volume of water (ml) added is converted in to depth (mm) by dividing the area of pan plus that of stealing well.
The evaporimeter is installed in duplicate to enable leakage detection. The minimum distance between two evaporimeter is 3 meter. The pan is cleaned occasionally and painted white once in a year and cheeked scrupulously for leakages. The evaporimeter is located under natural conditions in a field, which does not provide obstruction to wind. It is aligned perpendicular to the main direction of wind to avoid mutual interference.
4) Critical growth approach:
In each crop, there are some growth stages at which moisture stress leads to irrevocable yield loss. These stages are known as critical periods or moisture sensitive periods. If irrigation water is available in sufficient quantities, irrigation is scheduled whenever soil moisture is depleted to critical moisture level. Say 25 or 50 percent of available soil moisture. Under limited water supply conditions, irrigation is scheduled at moisture sensitive stages and irrigation is skipped at non-sensitive stages. In cereals, panicle initiation, flowering, and pod development are the most important moisture sensitive stages.
Table: Moisture sensitive stages of important crops.
Sr. No.
Crop
Important Moisture Sensitive Stages
1
Rice
Panicle Initiation, Flowering
2
Wheat
Crown Root Initiation, Jointing, Milking
3
Sorghum
Seedling, Flowering
4
Maize
Silking. Tasseling
5
Bajara
Flowering, Panicle Initiation
6
Nachani
Panicle Initiation, Flowering
7
Ground Nut
Rapid Flowering, Pegging, Early Pod Formation
8
Red Gram
Flowering & Pod Formation
9
Green Gram
Flowering & Pod Formation
10
Black Gram
Flowering & Pod Formation
11
Sugarcane
Formative Stage
12
Sesamum
Blooming stage to Maturity
13
Sunflower
Two weeks before & after flowering
14
Safflower
From rosette to flowering
15
Soybean
Blooming & seed formation
16
Cotton
Flowering & Ball Formation
17
Tobacco
Transplanting to Full Bloom
18
Chilies
Flowering
19
Potato
Tuber Initiation to Tuber Maturity
20
Onion
Bulb Formation to Maturity
21
Tomato
From the Commencement of Fruit Set
5) Plant water status it self:
This is the latest approach for scheduling of irrigation. Plant is a good indicator of a soil moisture and climate factors. The water content in the plant itself is considered for scheduling irrigation. It is however, not yet common use for want of standard and low cost technique to measure the plant water status or potential.
Simple Technique for Scheduling Irrigation
Soil cum sand mini plot technique:
In this method, one cubic meter pit is dug in the middle of field. About five percent of sand by volume is added to the dug soil, mix well and pit is filled in the natural order. Crops are grown as usual in the entire area of the field including the pit area. The plants in the pit show wilting symptoms earlier than the other plants in the remaining area. Irrigation is scheduled as soon as wilting symptoms appear on the plants in the pit.
Sowing high seed rate:
In an elevated area, one square meter plot is selected and crop is grown with four times thicker than natural seed rate. Because of high plant density, plants show wilting symptoms earlier than in the area indicating the need for scheduling irrigation.
Feel and appearance method:
Moisture content can be roughly estimated by taking the soil from root zone in to hand and making in to small ball. It requires lot of experience to estimate the soil moisture by this method.
Irrometers or tensiometer:
Tensiometer is also called irrometers since they are used in irrigation scheduling. Tensionmeters provide a direct measure of tenacity (tension) with which water is held by soil. It consist of 7.5 cm porous ceramic or clay cup, a .0protective metallic tube, a vacuum gauge and a hollow metallic tube holding all parts together. At the time of installation, the system is filled with water from the opening at the top and rubber corked when set up in the soil. Moisture from cup moves out with drying of soil, creating a vacuum in the tube which is measured with the gauge. Care should be taken to install tensiometer in the active root zone of the crop. When desired tension is reached, the soil is irrigated. The vacuum gauge is graduated to indicate tension values up to inch atmosphere and is divided in to fifty divisions each of 0.2 atmosphere value.
Merits of tensiometer:
1. It is very simple and easy to read soil moisture in situ.
2. It is very useful instrument for scheduling irrigation to crops which require frequent irrigations at low tension.
Limitations:
Sensitivity of a tensiometer is only up to 0.85 atmospheres while available soil moisture range is up to atmosphere and hence is useful more on sandy soils wherein about 80% of available water is held within 0.85 ranges.
Plant indices:
As the plant is the user of water, it can be taken as a guide for scheduling irrigation. The deficit of water will be reflected by plants itself such as dropping, curling or rolling of leaves and change in foliage colour as indication for irrigation scheduling. However, these symptoms indicate the need for water. They do not permit quantitative estimation of moisture deficit.
Growth indicators such as cell elongation rates, plant water content and leaf water potential, plant temperature leaf diffusion resistance etc. are also used for deciding when to irrigate. Some indicator plants are also a basis for scheduling irrigation e.g. sunflower plant which is used for estimation of PWP of soil is used in Hawaii as an indicator plant for irrigation sugar cane.
Infra red thermometer:
Canopy temperature is measured with infrared thermometer. It also simultaneously measures canopy temperature (Tc) and air temperature (Tq) and displays Tc-Tq value. Tc-Tq values can be used for scheduling irrigation. When transpiration is normal, due to its cooling effect canopy temperature is less than air temperature. The negative values of Tc-Tq indicate the plants have sufficient amount of water. When Tc-Tq values are zero or positive, which indicates stress irrigation is scheduled. Stress degree days (SDD), useful for scheduling irrigation are summed in a manner that is analogous to growing degree days SDD = (Tc-Tq) canopy temperature is measured during midday when air temperature is maximum. Yield reduction is maximum, when total number of cumulative SDD’s exceeds 10 to 15 between irrigations.
Remote sensing:
In projects areas, where a single crop is grown on large area, irrigation scheduling can be done with the help of remote sensing data. Reflectance of solar radiation by the plants with sufficient amount of water is different from that of stressed plants. This principle can be used for scheduling irrigation. The following methods can be recommended to farmers for scheduling irrigation.
· Soil -Cum-Sand Mini Plot Technique
· Increased Plant Population
· Pan Evaporimeter
· Methods of Irrigation- Surface, Surge, Subsurface, Sprinkler, Raingun Sprinkler
·
· There are three principle methods of irrigation viz. surface, sub surface and aerial, overhead or sprinkler irrigation.
· A. Surface irrigation: There are four variations under this method viz.
· (1) Flooding,
(2) Bed or border method (Saras and flat beds),
(3) Basin method (ring and basin) and
(4) Furrow method (rides and furrows, broad ridges or raised beds)
· Flooding: It consist of opening a water channel in a plot or field so that water can flow freely in all directions and cover the surface of the land in a continuous sheet. It is the most inefficient method of irrigation as only about 20 percent of the water is actually used by plants. The rest being lost as a runoff, seepage and evaporation. Water distribution is very uneven and crop growth is not uniform. It is suitable for uneven land where the cost of leveling is high and where a cheap and abundant supply of water is available. It is unsuitable for crops that are sensitive to water logging the method suitable where broadcast crops, particularly pastures, alfalfa, peas and small grains are produced.
· Adaptations:
· (1) An abundant supply of water
(2) Close growing crops
(3) Soils that do not erode easily
(4) Soils that is permeable
(5) Irregular topography
(6) Areas where water is cheap.
· Advantages:
· (1) Can be used on shallow soils
(2) Can be employed where expense of leveling is great
(3) Installation and operation costs are low
(4) System is not damaged by livestock and does not interfere with use of farm implements.
· Disadvantages:
· (1) Excessive loss of water by run of and deep percolation
(2) Excessive soil erosion on step land.
(3) Fertilizer and FYM are eroded from the soil.
· Bed or border method (Sara and Flat beds or check basin): In this method the field is leveled and divided into small beds surrounded by bunds of 15 to 30 cm high. Small irrigation channels are provided between two adjacent rows of beds. The length of the bed varies from 30 meters for loamy soils to 90 meters for clayey soils. The width is so adjusted as to permit the water to flow evenly and wet the land uniformly. For high value crops, the beds may be still smaller especially where water is costly and not very abundant. This method is adaptable to most soil textures except sandy soils and is suitable for high value crops. It requires leveled land. It is more efficient in the use of water and ensures its uniform application. It is suitable for crops plant in lines or sown by broadcast. Through the initial cost is high requires less labour and low maintenance cost. This may also be called a sort of sara method followed locally in Maharashtra but the saras to be formed in this method are much longer than broader.
· Adaptations:
· (1) A large supply of water
(2) Most soil textures including sandy Loam, loams and clays
(3) Soil at least 90 cm deep
(4) Suitable for close growing crops.
· Advantages:
· (1) Fairly large supply of water is needed.
(2) Land must be leveled
(3) Suited only to soils that do not readily disperse.
(4) Drainage must be provided
· Basin irrigation: This method is suitable for orchids and other high value crops where the size of the plot to be irrigated is very small. The basin may be square, rectangular or circular shape. A variation in this method viz. ring and basin is commonly used for irrigating fruit trees. A small bund of 15 to 22 cm high is formed around the stump of the tree at a distance of about 30 to 60 cm to keep soil dry. The height of the outer bund varies depending upon the depth of water proposed to retain. Basin irrigation also requires leveled land and not suitable for all types of soil. It is also efficient in the use of water but its initial cost is high.
· There are many variations in its use, but all involve dividing the field into smaller unit areas so that each has a nearly level surface. Bunds or ridges are constructed around the areas forming basins within which the irrigation water can be controlled. Check basin types may be rectangular, contour and ring basin.
· Adaptations:
· 1) Most soil texture
2) High value crops
3) Smooth topography.
4) High water value/ha
· Advantages:
· 1) Varying supply of water
2) No water loss by run off
3) Rapid irrigation possible
4) No loss of fertilizers and organic manures
5) Satisfactory
· Disadvantages:
· 1) If land is not leveled initial cost may be high
2) Suitable mainly for orchids, rice, jute, etc.
3) Except rice, not suitable for soils that disperse easily and readily from a crust.
· Furrow method (rides and furrow, broad ridges, counter furrow etc.): Row crops such as potatoes, cotton, sugarcane, vegetable etc. can be irrigated by furrow method. Water is allowed to flow in furrow opened in crop rows. It is suitable for sloppy lands where the furrows are made along contours. The length of furrow is determined mostly by soil permeability. It varies from 3 to 6 meters. In sandy and clay loams, the length is shorter than in clay and clay loams. Water does not come in contact with the plant stems. There is a great economy in use of water. Some times, even in furrow irrigation the field is divided into beds having alternate rides and furrows. On slopes of 1 to 3 percent, furrow irrigation with straight furrows is quite successful. But on steeper slopes contour furrows, not only check erosion but ensure uniform water penetration.
· Adaptations:
· 1) Medium and fine textured soils.
2) Variable water supply
3) Farms with only small amount of equipment.
· Advantages:
1) High water efficiency
2) Can be used in any row crop
3) Relatively easy in stall
4) Not expensive to maintain
5) Adapted to most soils.
· Disadvantages:
· 1) Requirement of skilled labour is more
2) A hazard to operation of machinery
3) Drainage must be provided.
· B. Subsurface method:
· Subsurface irrigation or sub-irrigation may be natural or artificial. Natural sub surface irrigation is possible where an impervious layer exists below the root zone. Water is allowed in to series of ditches dug up to the impervious layer, which then moves laterally and wets root zone.
· In artificial sub surface irrigation, perforated or porous pipes are laid out underground below the root zone and water is led into the pipes by suitable means. In either case, the idea is to raise the water by capillary movement. The method involves initial high cost, but maintaince is very cheap. There is a risk of soil getting saline or alkaline and neighboring land damaged due to heavy seepage.
· It is very efficient in the use of water as evaporation is cut off almost completely. The plant roots do not suffer from logging, there is no loss of agricultural land in laying out irrigation system and implements can be worked out freely. This method is however rarely noticed in our country but followed in other countries like Israel.
C. Drip or trickle irrigation:
· It involves slow application of water to the root zone. The drip irrigation system consist of
· 1) Head
2) Main line and sub line
3) Lateral lines
4) Drip nozzles.
· The head consists of a pump to lift water and produce the desired pressure (about 2.5 tmosphere) and to distribute water through nozzles. A fertilizer tank for applying fertilizer solution directly to the field along with the irrigation water and filter which cleans the suspended impurities in irrigation water to prevent the blockage of holes and passage of drip and nozzles
· Mains and sub mains are normally of flexible material such as black PVC pipes. Laterals or drip lines are small diameter flexible lines (usually 1 to 1.25 cm diameter black PVC tubes) taking off from the mains or sub mains. Laterals are normally laid parallel to each other. Lateral lines can be up to about 50 meters long and are usually 1.2 cm diameter black plastic tubing. There is usually one lateral line for each crop row. By laying the main line along the center line of the field, it is possible to irrigate either side of the field alternately by shifting the laterals. A pressure drop of 10 percent is permitted between the ends of lateral.
· Drip nozzles are also known as emitters or values and are fixed at regular intervals in the laterals. These PVC values allow water to flow at the extremely slow rates, ranging from 2 to 11 liters per hour and they are of different shapes and design.
· The spacing between laterals is controlled by the row-to-row spacing of the crop to be irrigated. Drip laterals laid on soil surface are buried underground at the depth of 5 to 10 cm.
· Advantages:
· 1) The losses by drip irrigation and evaporation are minimized
2) Precise amount of water is applied to replenish the depleted soil moisture at frequent intervals for optimum plant growth.
3) The system enables the application of water fertilizers at an optimum rate to the plant root system.
4) The amount of water supplied to the soil is almost equal to the daily consumptive use, thus maintaining a low moisture tension in soil.
· Disadvantages:
· The initial cost of the drip irrigation for large-scale irrigation is its main limitation. The cost of the unit per hectare depends mainly on the spacing of the crop. For widely spaced crops like fruit trees, the system may be even more economical than sprinkler.
· D. Sprinkler or overhead irrigation:
· This method consists of application of water to soil in the form of spray, somewhat as rain. It is particularly useful for sandy soils because they absorb water too fast. Soils that are too shallow, too steep or rolling can be irrigated efficiently with sprinklers.
· This method is suitable for areas having uneven topography and where erosion hazards are great.
· In sprinkler irrigation, water is conveyed under pressure through pipes to the area to be irrigated where it is passed out through or sprinklers the system comprises four main parts
i. Power generator
ii. Pump
iii. Pipeline and
iv. Sprinkler
· The power generator may be electrical or mechanical. A centrifugal pump may be used for suction lift up to 37 to 50 cm. A piston type pump is preferable where water is very deep. The pipe consists of two sections, the main line and the laterals.
· The main line may be permanently buried underground or may be laid above ground, if it is to be used on a number of fields. The main pipes are usually made of steel or iron.
· The laterals are lightweight aluminum pipes and are usually portable. The sprinkler nozzles may be single or double, revolving or stationery and mounted or riser pipes attached to riser. Each sprinkler head applies water to circular area whose diameter depends up on the size of water, which varies from ¼ to ¾ inch per hour is determined by selecting the proper combination of nozzles.
· Adaptations:
· 1) A dependable supply of water
2) Uneven topography
3) Shallow soils.
4) Close growing crops.
· Advantages:
· 1) It ensures uniform distribution of water
2) It is adaptable to most kinds of soil.
3) It offers no hindrance to the use of farm implements
4) Fertilizers material may be evenly applied through sprinklers. This is done by drawing liquid fertilizer solution slowly in to the pipes on the suction side of the pump so that the time of application varies from 10 to 30 minutes.
5) Water losses are reduced to a minimum extent
6) More land can be irrigated
7) Costly land leveling operations are not necessary and
8) The amount of water can be controlled to meet the needs of young seedling or mature crops.
· Disadvantage:
· 1) The initial cost is rather very high.
2) Any cost of power to provide pressure must be added to the irrigation charges.
3) Wind interferes with the distribution pattern, reducing spread or increasing application rate near lateral pipe.
4) There is often trouble from clogged nozzle or the failure of sprinklers to revolve.
5) The cost of operations and maintaince is very high. Labour requirement for moving a pipe and related work approximately nearly one hour per irrigation.
6) It requires a dependable constant supply of water free slit and suspended matter and 7) It is suitable for high value crops
Micro Irrigation
Micro irrigation is defined as the methods in which low volume of water is applied at low pressure & high frequency usually an irrigation interval is in the ranges of 1 to 4 days. The system has extensive network of pipes at operated at low pressure. At pre-determined spacing outlets are provided for emission water generally known as emitters.
Drip irrigation:
In drip irrigation the required quantity of water is applied by means of mains, sub mains, manifolds & plastic laterals in the with equally spaced emitters usually laid on the ground surface at low pressure & at low discharge at the root zone of the crop.
Advantage of drip irrigation
1. Water saving is up to 40 to 60%
2. Enhance the plant growth & increases the crop yield
3. Savoring in level & energy most. Suitable for poor soil.
4. Weed infestation is minimum
5. Economy in cultural practices & easy operations.
6. Chance of using saline water.
7. Improve efficiency of fertilizers.
8. Very flexible in operation
9. No soil erosion.
10. Easy installation, no land preparation.
11. Minimizing quantity of produce.
12. Enhances the maturity of the crop.
Limitations
1. High maintenance requirement.
2. Salinity hazard
3. Economy limitations (40,000Rs/ha)
4. High technical know-how is required.
Irrigation
Definition: irrigation is artificial application of water to soil for the purpose to access the crop production. It is supplied supplementary to water available from rainfall & ground water.
Types of irrigation – (classification)
1. Flood
2. Surface
3. Sub surface
4. Sprinkle
5. Drip irrigation.
Surface irrigation:
Water is applied directly to the soil from channel located at upper ridge of the field proper land preparation adequate control of water is necessary for uniform distribution of water border. The entire field is divided into strips separated by low ridge of the strip to lower in form of sheet guided by the low ridges. Border should have uniform gentle slope in direction of irrigation. Each strip is independently by turning stream of water at upper ridge. Suitability-suitable for close growing crops some row crop & orchards under favorable soil & topographic condition. Not recommended for extremely low or extremely high infiltration rate soils.
Advantage:
1. Easy construct & operate
2. Person can irrigation more compares to check basin.
3. If properly designed use uniform distribution & high water use efficiency.
4. Large streams can be effectively used.
5. If can provide excellent drainage (surface) if have proper outlet facility at the lower end.
Disadvantages:
1. Required precise land leveling
2. Required large irrigation streams.
Check basin:
It is used in extreme condition of soil. It is well known method generally used for heavy soils with low infiltration rate or high permeable soil like deep sand. Used for orchards grain & folder production.
Disadvantages:
1. Labor requirement for land preparation is high.
2. Operation cost is more.
3. The ridges cause hindrances to implements by field operations.
Furrow method:
Furrow is preferably used for row crops like maize, sugarcane, potato, groundnut & other vegetable crops. Water is applied in small furrows betureoil the row crops. Water infiltrated into soil & spread within the root zone. Large as well as small sized stream can be effectively used for irrigation. It also acids for safe disposal of excess water i.e. facilitates drainage. Only 1/5 to ½ of land surface is in contact with water (wet). There by reducing the evaporation losses. Method is specially situated to crops like maize which are sensitive to water in contact with their strength. The cost of land preparation is reduced & there is no wastage of land under field channels. In clay or deep clay soils shadow furrow are made along with guiding ridge to take care of soil cracking behavior such furrow are called corrugated furrow.
Subsurface irrigation:
Water is applied below the ground surface by maintaining artificial water table at some depth depends upon the soil characteristic & root zone of crop. Water moves through capillaries within soil to meet plant requirement deep trenches & underground piper are the two ways for sub-surface irrigation.
Adaptability: Soils having low W.H.C. soil having very high-high infiltration rate. Soils surface method is not possible where sprinkle method of irrigation proves to be expensive.
Advantage:
1) Evaporative losses are minimum.
Disadvantage:
1) Salty water can not be used.
Sprinkler Irrigation
Definition: It is methods in which water is spread into air and allowed to fall on the ground surface some what resembling.
Water is forced under pressure through small nozzle/orifice which gets broken up to into droplets and fall back on the ground. Slow circular revolution is impacted to the nozzle uniformally covered the ground surface. The rate of application should not be more than the infiltration rate of the soil.
Adaptability of sprinkler irrigation
1. Sprinkler irrigation can be adopted where land reveling is uneconomical and other method of surface irrigation cant carried out.
2. Adapted to soils to pours highly avoidable or relatively impermeable which are difficult to irrigate by other methods like furrow, border etc.
3. Where it is designed to go for frequent irrigation.
4. It is designed to minimum cost towards labours, fertilizer, and irrigation.
Advantages of Sprinkler Irrigation:
1. It can be used for almost crops expect paddy & jute.
2. System can be adopted under varied topographic condition and especially suitable to steep-slope and irregular topography.
3. Soils-method is particularly suited for sandy soils having high infiltration rate.
4. It can eliminate surface run off of irrigation water (run off elimination)
5. To protect the crop against frost & high temp.
6. To reduce labour cost for irrigation as compared with surface method.
7. Savings in land construction of channel to the field.
8. It saves fertilizer & water as ferti-irrigation can be carried out.
9. Land leveling is not essential for sprinkle irrigation.
10. Gives higher water use efficiency.
Limitations of sprinkle irrigation:
1. Not suitable for very fine texture soil (<4mm/her)
2. Uneven distribution of water due to distortion by high water.
3. More evaporation losses.
4. Require clean, water free from debris sand slit & clay particles.
5. Saline water can no be used.
6. Initial cost is high.
7. High operating power is high (5-10kg/cm)
8. Unsuitable climate condition sprinkling may be encouraging spread of disease.
9. Ripening softy fruits need protection from the spray.
10. Systems of Sprinkle Irrigation
Systems of Sprinkle Irrigation
Based on Spraying Arrangement
Based on Portability
1
Fixed Head
1
Portable
2
Rotating Head
2
Semi Permeable
3
Perforated Pipes
3
Semi Portable
i) Dancing Water
4
Solid Structure
ii) Oscillating Arms
5
Permanent
11. Portable system:
12. In sprinkle irrigation system in which main line, sub main line, lateral and the pumping units all are the portable generally the pipers are made up of light weight aluminum to facillate easy transportation such system can be shifted from place to another.
13. Semi-portable system:
14. This system is parallel to portable except that location of water source and pumping unit is fixed.
15. Semi-permanent:
16. In this system the main and sub-main are fixed, usually buried under the ground where as the laterals are portables.
17. Solid straight system:
18. These have enough laterals present to eliminate their movement from one place to another. The system is fixed at the beginning of system of season and remains through out the season for short & frequent irrigation.
19. Permanent irrigation system:
20. The permanent system is suited to automation using soil moisture sensor and are generally preferred in orchard. The sub main, lateral are permanently buried below the ground level.
21. Based on spraying arrangement fixed head:
22. The fixed head type of sprinkler arrangement system sprays water in one direction.
23. Rotating head:
24. Rotating head removes slow rate to distribute water in a circular fusion. They may be single, double, multiple nozzle sprinkler head. Single nozzle sprinkles system are referred for their low application rate however the double nozzle sprinkle head gives good uniformity of application at low pressure.
25. Multiple nozzle type of sprinkler also called as giant sprinkler are used to covered more area with single set. The operating pressure required for such sprinkler may be more than 10kg/cm2.
26. Perforated Pipes:
27. Such systems are preferred for application of water under lower operating pressure usually between 0.5 to 2.5 kg/cm2. The system is not recommended under heavy winds as the jets are distorted more easily.
28. Generally pipes are provided with holes, perforated along the upper 1/3rd perimeter in a proper designated to covered with between 6 to 15m such system are preferred on plains moderately high infiltration rate used for irrigation of lawns or vegetable crop where the plant height ranges between 40 to 60 cm.
29. Systems of Sprinkle Irrigation
Systems of Sprinkle Irrigation
Based on Spraying Arrangement
Based on Portability
1
Fixed Head
1
Portable
2
Rotating Head
2
Semi Permeable
3
Perforated Pipes
3
Semi Portable
i) Dancing Water
4
Solid Structure
ii) Oscillating Arms
5
Permanent
30. Portable system:
31. In sprinkle irrigation system in which main line, sub main line, lateral and the pumping units all are the portable generally the pipers are made up of light weight aluminum to facillate easy transportation such system can be shifted from place to another.
32. Semi-portable system:
33. This system is parallel to portable except that location of water source and pumping unit is fixed.
34. Semi-permanent:
35. In this system the main and sub-main are fixed, usually buried under the ground where as the laterals are portables.
36. Solid straight system:
37. These have enough laterals present to eliminate their movement from one place to another. The system is fixed at the beginning of system of season and remains through out the season for short & frequent irrigation.
38. Permanent irrigation system:
39. The permanent system is suited to automation using soil moisture sensor and are generally preferred in orchard. The sub main, lateral are permanently buried below the ground level.
40. Based on spraying arrangement fixed head:
41. The fixed head type of sprinkler arrangement system sprays water in one direction.
42. Rotating head:
43. Rotating head removes slow rate to distribute water in a circular fusion. They may be single, double, multiple nozzle sprinkler head. Single nozzle sprinkles system are referred for their low application rate however the double nozzle sprinkle head gives good uniformity of application at low pressure.
44. Multiple nozzle type of sprinkler also called as giant sprinkler are used to covered more area with single set. The operating pressure required for such sprinkler may be more than 10kg/cm2.
45. Perforated Pipes:
46. Such systems are preferred for application of water under lower operating pressure usually between 0.5 to 2.5 kg/cm2. The system is not recommended under heavy winds as the jets are distorted more easily.
47. Generally pipes are provided with holes, perforated along the upper 1/3rd perimeter in a proper designated to covered with between 6 to 15m such system are preferred on plains moderately high infiltration rate used for irrigation of lawns or vegetable crop where the plant height ranges between 40 to 60 cm.
48. Components of Sprinkler Irrigation System
49. 1. Prime mover/pump suction pipe, foot value:
50. Pumping sets or pump is required for lifting water from the source and push it through distribution system i.e. main, sub main, laterals and finally through the sprinkler head under sufficient pressure.
51. The pumping set consists of a centrifugal pump (volume) or turbine type pump with a driving unit suction line and a foot value. Centrifugal pump are generally used where the lift is less than 5m i.e. when source is river, shallow well etc. for higher lift or if water level fluctuates widely turbine pumps are recommended.
52. The electric motors are generally used driving unit for fixed installation diesel engines are generally recommended for portable units.
53. 2. Main line:
54. It carries water from the source (pumping unit) to the various parts in the field. It may fixed or portable. Permanent lines are generally buried below the working depth inside the ground. Light weight aluminum pipe with quick couples are preferred for portable lines something HDPF (high density pipes are also preferred because of its longer life. The fixed are generally of steel pipe or PVC pipe of suitable diameter). Te or L section is provided to connect the main with sub main or lateral.
55. 3. Sub main:
56. It carries water from main to lateral lines.
57. 4. Lateral Lines:
58. It carries water from main or sub main pipe line to the sprinkler head through the rise pipe. They are portable and equipped with quick coupling devices. Commonly they are available in 5,6 or 12m length are provided with U shaped rubber gasket in the female portion of coupling. The water pressure forces outside of ‘U’ gaskets to form water seal when the water is turned off the seal is broken and water is drained out from the pipe making it easy to uncouple and more.
59. Sprinkler head:
60. Sprinkler heads are used for spraying water on the fields they may be-
a) Rotating Head
b) Fixed head Type
c) Perforated Type
61. Fixed Head Type: Used in landscape
62. Sprinkler lead can be classified on basis of pressure
63. 1) Low operating pressure sprinkler (1.5 to 2.5kg/cm2)
2) Intermediate pressure sprinkler (2.5 to 5kg/cm2)
3) High pressure sprinkler (5 to 10kg/cm2)
64. Problems:
65. Find the fertilizer does per settings of the sprinkler system if a lateral has 12 sprinkler 14m apart. Later lines are spaced 20m on the main line and the recommend does of fertilizer is 80kg/ha.
66. Solution:
Ds x DL X Ns X WP
WF = ---------------------
10,000
67. 14 X 20 X 12 X 80
DL 20 = --------------------
10,000
68. Irrigation Efficiency
69. Irrigation water is an expansive input and has to be used very efficiently. The main losses that occur during irrigation of fields as conveyance, run off, seepage and deep percolation. Irrigation efficiency can be increased by reducing these losses. Uneven spreading and inadequate filling of root zone are the other causes for low irrigation efficiency. Irrigation efficiency at the field level can be increased by selecting suitable method of irrigation, adequate land preparation and engaging an efficient irrigator. At the project level, it can be increased by proper conveyance and distribution system. Irrigation efficiency is the ratio usually expressed as percent of the volume of irrigation water transpired by plants, plus that evaporate from the soil, plus that necessary to regulate the salt concentration in the soil solution and that used by plants in building plant tissue to total volume of water diverted, stored or pumped for irrigation.
Wt + Ws - Rs
Ei = -------------------- X 100
Wi
70. Where,
71. Ei = Irrigation efficiency (percent)
Wt = the volume of irrigation water / unit area of land transpired by plants, evaporation from the soil during the crop period.
Ws = the volume of irrigation water per unit area of land to regulate the salt Content of soil solution.
Re = Effective rainfall
Wi = the volume of water per unit area of land that is stored in reservoirs or diverted for irrigation. Irrigation efficiency indicates how efficiency the available water supply is being used. The efficiency of irrigation projects in India is as low as 20 to 40%.
72. Water Conyenance Efficiency & Water Use Efficiency
73. Water Conyenance Efficiency:
74. It indicates the efficiency with which water is conveyed from source of supply to the field. It estimates the conveyance losses. It is expressed as
75. Wf
Ec = --------- X 100
Ws
76. Where,
77. Ec = Water conveyance efficiency (percent)
Wf= Water delivered at the field
Ws= Water delivered at the source
78. Water Application Efficiency:
79. Irrigation water applied to the field is lost due o surface run off and deep percolation. Surface run off occurs due in long furrow or long border strips if ridges are weak. The water moves from one plot to another due to weak bunds giving way to water which may collect in large quantities even to break strong bunds. In furrows, water is allowed most of the time at the beginning of furrow till the flow reaches the other end of the furrow. It results in deep percolation of water in the first quarter of furrow. Water application efficiency is the measure of efficiency with which delivered to the field is stored in the root zone.
80. Water stored in the root zone
Water application efficiency = ------------------------------------ X 100
Water delivered to the field
81. Water Storage Efficiency:
82. This parameter estimates whether the amount of water necessary for the crop is stored in the root zone or not. It is expressed as the percentage of water needed in the root zone prior to irrigation to that stored in the root zone during irrigation.
83. Water stored in the root zone
Water storage efficiency = ------------------------------------- X 100
Water needed in the root zone
84. Water Distribution Efficiency:
85. Water distribution efficiency is defined as the percentage of difference from unity of the ratio between the average numerical deviations from the average depth stored during the irrigation.
Water distribution efficiency = {1-Y/d} X 100
86. Where,
d = Average depth of precipitation along the run off during irrigation
Y = Average numerical deviation from –d
87. Water distribution efficiency indicates uniformity in distribution of water over the entire root zone.
88. Water Use Efficiency (WUE):
89. Water use efficiency is defined as yield of marketable crop produced per unit of water used in evapotranspiration.
90. WUE = Y / ET
91. Where,
92. WUE = Water use efficiency (kg/ha/mm of water)
Y = marketable yield (kg/ha)
ET= Evapotranspiration (mm)
93. If yield is proportional to ET, water use efficiency has to be constant but it is not so. Actually, Y and ET are influenced independently by crop management and environment. Yield is more influenced by crop management practices, while ET is mainly dependent on climate and soil moisture. Fertilization and other cultural practices for high yield usually increase in water use accompanying fertilization is often negligible. Crop production can be increased by judicious irrigation without markedly increasing ET. Under optimum water supply, ET is not dependent on kind of plant canopy provided the soil is adequately covered with crop.
94. Increasing the amount of plant canopy has there fore little or no effect on ET. Obviously, any practice that promotes plant growth and more efficient use of sunlight in photosynthesis without causing a corresponding increase in ET will increase WUE.
95. Factors affecting WUE:
96. 1. Nature of the plant: There are considerable between plant species to produce a unit dry matter per unit amount of water used resulting in widely varying values of WUE.
97. Water use efficiency of different crops:
Crop
Water Requirement mm
Grain Yield kg/ha
WUE kg/ha/mm
Rice
2000
6000
3.0
Sorghum
500
4500
9.0
Bajara
500
4000
8.0
Maize
625
5000
8.0
Groundnut
506
4680
9.2
Wheat
280
3534
12.6
Finger Millet
310
4137
13.4
98. There is also difference in WUE between varieties of the same crop. Selection of properly adopted crop, with good rooting habit ,low transpiration rates increase. WUE
99. 2. Climatic Conditions:
100. Weather affects both Y and ET. Manipulation of climate to any extent is possible at present. However, ET can be reduced by mulching, use of antitranspirant etc. To limited extent , but may not be economical or practical. Weed control is the most effective means of reducing ET losses and increasing the amount of water available to the crop thereby increasing WUE.
101. 3. Soil Moisture Content:
102. In adequate supply of soil moisture as well as excess moisture supply to the crop have an adverse effect on plant growth and production and therefore conductive to low WUE. For each crop combination of environment conditions, there is a narrow range of soils moisture level at which WUE is higher than with lesser or greater supply of water, proper scheduling of irrigation will increase WUE.
103. 4. Fertilizers:
104. Irrigation improves a greater demand for plant nutrients. Nutrient availability is highest for most of the crops when water tension is low. All available evidences indicate that under adequate irrigation suitable fertilization generally increase yield considerably, with a relatively small increase in ET and therefore, markedly improve WUF.
105. 5. Plant population:
106. Higher yield potential made possible by the favorable water regime provided by irrigation, the high soil fertility level resulting from heavy application of fertilizers and genetic potential of new varieties and hybrids, could be achieved only with appropriate adjustments of the population. The highest yields and WUE are possible only through optimum levels of soil moisture regime, plant population and fertilization.
107. Frequency of Irrigation
108. Irrigation frequency refers to the number of days between irrigation during periods without rainfall. It depends on consumptive use of rate of a crop and on the amount of available moisture in the crop root zone. It is function of crop, soil and climate. Sandy soils must be irrigated more often than fine texture deep soils. A moisture use ratio varies with the kind of crop and climate conditions and increases as crop grows larges and days become longer and hotter.
109. In general, irrigation should start when about 50 percent and not over 60 percent of the available moisture has been used from the root zone in which most of the roots are concentrated. The stage of crop growth with reference to critical periods of growth is also kept in view while designing irrigation frequency.
110. The interval that can be safely allowed between two successive irrigations is known as frequency of irrigation:
111. Allowable soil moisture depletion
Irrigation interval = ---------------------------------------
Daily water use
112. Problem: Calculate irrigation interval when F.C=20.0% dry weight basis
PWP = 8.0 dry weight basis, BD = 1.4 g/cc
Root depth = 60cm ET ratio = 0.5 cm/day
113. Allowable soil water depletion is equal to 25% of available soil water
114.
115. Solution:
116. (20.0 – 8.0) X 1.40
Available water = ------------------------------- X 60
100
= 10.08cm
117. 25 X 10.08 2.52
Allowable soil water depletion = ---------------- = -------- = 5.04 = 5 days
10.0 0.5
118. Irrigation must be given at 5 days interval.
119. Water Quality Parameters
120. Irrigation water contains impurities in varying concentration. The suitability of irrigation water mainly depends up on the amount and type of salts present in the water. The main soluble constituents are calcium, magnesium, sodium as cations and chloride, sulphate, bicarbonates as anions. The other ions present in minute quantities are boron, selenium, molybdenum and fluorine which are harmful to animals fed on plants grown with excess of these ions. Quality of irrigation water is judged with three parameters
121. 1. Total salt concentration
2. Sodium absorption
3. Bicarbonate and boron content.
122. 1. Total Salt Concentration:
123. Salt content of irrigation water is measured as electrical conductivity (EC). Conventionally, water containing total dissolved salts to the extent of more than 1.5 m mhos / cm has been classified as saline. Saline waters are those which have sodium chloride as predominant salt. Brackish water is one that is contaminated with acid, bases, salts or organic matter, where as saline water contains mainly dissolved salts, Based on EC irrigation water is classified as below.
Class
EC
Quality Characterization
Soil for which suitable
C1
< 1.5
Normal Water
All Soils
C2
1.5 to 3.0
Low Salinity
Light and Medium Soils
C3
3.0 to 5.0
Medium Salinity
Light and Medium Textured Soils for Semi tolerant crops
C4
5.0 to 10.0
Saline
Light medium textured soils for Tolerant crops
C5
> 10
High Salinity
Not Suitable
124. 2. Sodium absorption ratio (SAR) and boron content:
125. In addition to EC which has been used as a main criterion to determine the quality of irrigation water, sodium absorption ratio (SAR), residual sodium carbonate (RSC) and boron content are also used to find suitability of irrigation water.
126. Irrigation water which contains more than 3 ppm boron is harmful to crops, especially on light soils.
127. Factors Affecting Frequency of Irrigation
128. Humidity:
129. In rainy season, the humidity is high and rains may be received just when the crop is in need of water. In such case, some irrigation turns could be stopped and frequency may be extended to 20 days. During winter season, also the frequency will be longer than in summer because of less evapotranspiration, dewfall, nighttime humidity, and less sunshine. The frequency may therefore be 15 to 20 days in winter and 6 to 8 days in summer. In summer irrigation, water is given more frequently and hence more frequency of irrigation in summer, medium in winter and less in rainy season.
130. Stage of Growth of Crops:
131. During certain stages particularly at flowering and fruit formation stages of crop requires much larges quantities of water than earlier stages. In earlier stage, even if a little less water than estimated daily use is provided, the crop will stand the strain without any harm, perhaps a slight moisture stress may encourage better root growth.
132. Type of Crop:
133. The frequency of irrigation will also depend up on the crop. A succulent leaf vegetable will require irrigation more often than cereal crop like Jowar. Crops which are doses of fertilizers need more water than those with a little or no fertilizers.
134. Soil Type:
135. Light soil requires more frequent irrigation than the loamy soils. Sandy loam soil need to be irrigated every fifth day while clay loam may be irrigated every tenth day. Time required to irrigate an area: The time required to irrigate an area depends up on magnitude of discharge, quantity of water applied, irrigation efficiency and area. The time required to irrigate an area is calculated by formula.
136. IQT = Ad
137. Where,
I= irrigation efficiency
Q= discharge in cusec
T= time in hours
A= area in acres
d= moisture deficit in soil.
Problem: Calculate the time required to irrigate 4 acres of sugar cane when soil moisture deficit is 2.5 inch, discharge from a weir is 2 cusec and irrigation efficiency is 80 percent.
Solution:
138. IQT = Ad
= 80/100 X 2 X t
= 4 X 5/2
= 6.25hours.
139. Common Problems that Result From Using Poor Quality Irrigation Water
140. Salinity:
141. Salinity problems related to water quality occurs if total quantity of salts in the irrigation water is high enough for the salts to accumulate in the crop root zone to the extent that yields are affected. If excessive quantity of soluble salts accumulate in the root zone, the crop has difficult in extracting enough water from the salty soil solution. This reduces the water up take by plant and usually results in slow or reduced growth.
142. Permeability:
143. This problem occurs when the rate of water infiltration in to and through the soil is reduced by the effect of specific salts in the water to such extent that the crop is not adequately supplied with water and yield is reduced. The poor soil permeability causes difficulty like crusting of seedbed, water logging, and attack of disease, salinity, weeds, oxygen and nutritional problems.
144. Toxicity:
145. A toxicity problem occurs when certain constituents in the water are taken up by the crop and accumulate in amounts that result in reduced yield. This is usually related to one or more specific ions in the water viz. boron, chloride and sodium.
146. Miscellaneous:
147. Various other problems related to irrigation water quality occur with sufficient frequency and should be specifically noted. These include excessive vegetative growth, lodging and delayed crop maturity from excessive nitrogen in water supply, white deposits on fruits or leaves due to sprinkler irrigation with high carbonate water and abnormalities by an unusual pH of the irrigation water.
Quality of Water from Different Sources
Water quality of most the Indian rivers are good with EC values less than 0.7 m mhos /cm except in Krishna (1.4), Hagari (1.6) and Tungbhadra (1.7) rivers. Quality of most the tanks, lakes etc. is good except in those which are fed by stream passing through salt affected areas. Quantity of ground water is affected by and arid regions are generally poor with high salt content.
Irrigation water with poor quality:
In an area where there is no alternative source of good quality irrigation water, it is inevitable to use the available water of poor quality. However, the yield potential of such areas can be increased by adopting proper management practices such as
Improvement of sodium and bicarbonates rich water by gypsum application.
Choice of salt tolerant crops and their varieties.
Optimum fertilizer application and manuring
Proper irrigation management
Breaking any impervious layer by deep ploughing and
Adopting other management practices suitable for area.
A. Gypsum application:
The harmful effect of irrigation water can be minimized to some extent by modifying its ionic composition by adding such chemicals which tend to precipitate the harmful constituents such as bicarbonate and carbonate in the form of less soluble salts or tend to create a favorable catonic Ca : Mg : Na ratio.
Gypsum should be powered up to 0.5 mm size or passed through a 30-mesh sieve. The gypsum requirement of water should be calculated depending upon the relative concentration of sodium, magnesium and calcium 8.6 Q of gypsum of 100 percent purity per hectare meter of water be necessary. Gypsum can directly be mixed in irrigation water.
B. Choice of salt tolerant crops:
Some crops and their varieties are more salt tolerant than others. Hence, salt tolerant crops are to be grown in salt affected areas till the soil are improved by vegetation or other reclamation procedures.
Salt Tolerant Crops: Barly, Dhainacha, Sugar beet, Tobacco, Turnips, Mustard, Cotton, Wheat, Sugarcane, Turnips, Beetroots, Spinach, Date palm coconut etc.
Semi Tolerant Crops: Oats, Rice, Sorghum, Bajara, Maize, Red gram, Green gram, Sunflower, Castor, Sesamum, Linseed, Senji Lucerne, Berseem, Cowpea, Tomato, Cabbage, Cauliflower, Lettuce, Potato, Carrot, Onion, Cucumber, Pumpkins, Bitter ground, Pomegranate, Grape, Guava, Mango, Apple, Orange, Lemon.
Sensitive Crops for Salts: Field beans, Gram, Peas and Guar, etc.
C. Use of Fertilizers:
Generally saline and alkali soils, or irrigated with poor quality waters are low in their fertility status, especially with reference to nitrogen or something phosphorus. Better crop can be grown by raising their fertility status. Nitrogen response to crop better when it is applied to soil along with manures. It has been observed that for wheat, barley, bajara, and maize the usual loses of fertilizers as applied up to an EC value of 6.5 m mhos/ cm and an E.S.P. of about 30. However, excessive fertilization or addition of fertilizers on a highly saline, alkali soil is of no value.
D. Soil Management Practices:
When poor quality water is to be applied, it is important to have the detailed analysis of soil profile for their physical, chemical, and morphological characteristic. Soil analysis should include its structure, texture, pH, lime content, location and amount of gypsum, T.T.S., exchangeable cations, etc Information on water transmission properties on soil and depth of water table should be obtained Data on rainfall, its intensity and distribution and evaporation are obtained. Saline area should be leveled properly for uniform spread of water and its downward movement.
Medium textured soils with Kankar layers pose a problem of sodicity. Such soils are managed by deep ploughing and growing green manuring crop like dhaicha. Application of gypsum under condition of low water table may improve land productivity. Use of optimum fertilizers and manures and improving the surface drainage systems will help in improving productivity.
E. Irrigation management:
Accumulation of salts increase with the fineness of soil texture, it is essential to adopt irrigation practices such that the salinity at the root zone is kept minimum. The quantity of water and the frequency of irrigation are so kept that they could met the leaching requirement of the soil and consumptive sue off the crop grown. Salts often accumulate in the top few centimeters of soil during non-crop period and hence both crop germination and yield can be seriously reduced. A heavy pre-sowing irrigation to leach these surface salts will improve germination and early growth. It is done well in advance to allow cultivation to remove weeds and prepare the seedbed. Sowing the seed in the center of a single row raised bed will place the seed exactly in the area where salts concentrate. Alternate furrow irrigation is often advantageous. Similarly increasing the depth of water in the furrow can also be an aid to improve germination the use of sleeping beds with seeds planted on the sloping sides and the seed row placed just above the water line can help in better salinity control. Large seeded crops like maize planted in water furrows can improve germination.
Effect of salts on plants growth is reflected by increasing the osmotic pressure in the soil solution. Accumulating certain ions toxic concentration in plant tissue and by altering the plants mineral nutritional characteristics resulting in poor stand of crop, stunted growth and yield. It may cause leaf burns in some crops and blue green colour in others. The germination of seed is delayed and retarded. In general, grain yield is affected more than the height of the plants.
F. Salt Tolerance of Crops:
The ability of a plant to tolerate salt in the root zone is known as salt tolerance. Studies are important in selecting it for a particular or its variety to suit the soil conditions and for determining the leaching requirements. The effect of soil salinity on crop growth is negligible when the EC of saturated extract is less than 2 m mhos/ cm. Many crops are affected when EC is in the range of 4 to 8 m mhos/cm. crops with high salt tolerance can grow satisfactorily when EC values are in between 8 to 16 m mhos/cm. Only a few survive at EC beyond 16 m mhos / cm.
Definition of Drainage, Causes of Water Logging Effects of Bad Drainage
Drainage means the process of removing water from the soil that is in excess of the needs of crop plants.
Drainage is the removal of excess gravitational water from the soil by artificial means to enhance crop production.
A soil may need artificial drainage for one or two reasons.
When there is a high water table that should be lowered or
When excess surface water cannot move downward through the soil or ever the surface of the soil fast enough to prevent the plant roots from suffocating.
Advantages of drainage:
The field will net get waterlogged and crop can get sufficient water and air
After the rains are received, the soil comes in tilth earlier and it is possible to carryout agriculture operations properly and in time.
The structure of soil improves
There is good aeration and warmth in the root zone which are essential for proper growth.
Bacteria that change organic matter into plant foods get necessary air and warm temperature in the soil.
Desirable chemical reactions take place and nutrient become available to the plants easily.
There is proper root development and absorption of nutrients is accelerated.
Seeds germinate faster and better stand of crop is obtained.
Due to healthy growth of plants they can resist the attack of pest and diseases better.
Weed growth can be checked by timely weeding and inter culturing operations.
Roots go down deep and can draw up on moisture at greater depth and with stand periods of through better and
Good drainage permits the removal of many toxic salts and thus, reduces damage to crops.
Drainage problems:
Drainage problem occur on lands, which we consider as an arid. The causes of drainage problems are as follows. This is also termed as causes of bad drainage or why soils become water logged or ill drained.
1. Excessive use of water: Water that is plentiful and cheap often is used in excess. The result is general water logged condition. Wild flooding continuous irrigation or excessively long irrigation turns to promote water logging.
2. Seepage of canals laterals or ditches: The seepage enters underground strata at elevations higher than those of irrigated lands enter and often becomes a direct source of water logging of low lying areas.
3. Internal stratification or irrigated soils: The internal natural drainage of soils is often poor. The slowly permeable soils, which when irrigation water is applied, impede the percolation of the excess water. The water cannot move down wards fast enough and accumulate on the surface forming a thin layer and obstruct aeration.
4. Low lying area: The area is low lying and excess rain cannot be carried away as a surface runoff rapidly into the drain causing water logged condition.
5. The water table may be high and the additional gravitational water just accumulates and checks the air spaces and saturates the surface and sub soil.
6. There may be a hard pan that affects seepage of water to lower strata.
7. There may be salts affecting water absorption by roots.
Principles of drainage:
The main purpose of artificial draining is to remove the water that is harmful for plant growth. In areas with rolling topography, the excess water is carried away as a surface run off seepage water through natural depressions into the nalas and rivers. But in flat areas and in soils having an imperious substratum, the natural drainage system is not well developed and therefore water saturates and accumulates in low lying areas until evaporated or drained out slowly. The soils that remains saturated for long time needs artificial drainage.
The artificial of soil water consists of providing man made channels through which the free water is carried away to natural drains such as nalas, rivers. This can done either by digging open channels to the required depth or by laying underground tile pipelines of suitable dimensions at the proper intervals and at required depth. When such artificial openings are provided in saturated soil, the water in the underground water table is lowered until it reaches the bottom level of the drainage line. The surface line of the water table does not remain horizontal but it depress over the drains. This happens, because water over the drains has the shortest distance to travel and it has the least resistance to flow through the pore spaces of the soil.
The horizontal distance over which water will flow in the drains depends upon the type of soil. If the soil porous the distance is grater. Therefore, drainage must be at short intervals and at shallower depth if the soil is sandy and porous. Thus, it can be seen that the factors, which determine the depth and spacing of the drainage system, are the soil type and the desired of the water table.
Type of Drainage
Drainage is of two forms
A. Surface drainage and
B. Sub surface drainage or underground drainage.
A) Surface drainage (Natural system of drainage):
It may consist of open ditches that are laid out by eye judgment, leading from one wet spot to another and finally into a nala or river. This is often called natural system.
Open ditch drains: The pattern of ditches is regular. The method is adopted to land that has uniform slope.
Field ditches: Field ditches for surface drains may be either narrow with nearly vertical sides or V shaped with flat side slopes. V shaped ditches have the advantages of being easier to cross with large machinery.
Narrow ditches: Narrow ditches are most common where large farm machinery is not used.
In level areas, a collecting ditch may need to be installed at one side of the field and shallow shaped ditches are constructed to discharge into the collecting ditch. The field ditches should be laid out parallel and spaced 15 to 45 meters or more apart as required by the soil surface conditions and crop to be grown. They should be 30 to 60 cm deep depending upon the depth of the collecting ditch.
Farming operations should be parallel to the field ditches. The care that a ditch will drain satisfactorily depends up on how quickly water runs into the ditch how much rain falls on the land, slope, and the condition of the soil and plant cover.
B) Sub surface or under ground drainage:
A sub surface or underground drainage will remove excess soil water. It percolates in to themselves, just like open drains. These underground drains afford the great advantages that the surface of the field is not cut off, no wastage of lad and do not interfere with farm operations. On the other hand, they are costly to lie and are not effective in slowly permeable clay soils.
Underground drains may be classified as:
1. Tile or pipe drain
2. Box drains
3. Rubble (coarse stones or gravels filled) drains
4. Mole drains and
5. Use of pumps for drainage.
1. Tile drain: It consists of digging a narrow trench, placing short section of tiles at the bottom and covering the tiles with earth. The loose joints between two section of the tiles serve as a place where drainage water may enter into the drainage system. Water moves by gravity into the joins between tiles and through tile walls.
Porous tile gives no better drainage than tiles that water does not percolate and porous tile can easily broken or crushed. the drains are two types of tiles in use. Tile should be always placed at least 75 cm deep to prevent breakage by heavy machinery.
2. Box drains: Instead of pipes, underground drains may be made in V shaped cut or trench, sides of which are reverted with soil, restoring the surface of the field. Depth may be 90 cm below ground.
3. Rubble drains: A somewhat equally substitute for tile drains is made by cutting narrow V shaped drains or rectangular in section, as for box drains, filling them up with rough stones large and small and then covering the whole up with soil level with surface field soil. Depth may be 90 cm.
4. Mole drains: They are often used in clay, clay loam soils. A moling machine is one that draws a bullet nosed cylinder; usually 10-15 cm in diameter is therefore formed. A mole drain should be at least 75 cm below the surface to prevent closing of the holes by compaction from farming operations. Mole drains are extremely used in Europe.
5. Use of pumps for drainage: The pumps are used in U.S.A. and many other countries for drainage. River bottoms, lakes and costal plains, peat lands and irrigated lands are the main types of lands reclaimed by pump drainage. The subsequent must be sufficiently permeable for the ground water to move to the pipes enough for effective pumping.
Agro Technique under ill Drained Soils, Reclamation of Damaged Soils
The damaged lands comprise of
1) Water logged soils
2) Salt affected areas
Remedial measures to reclaim each of soil comprise of Preventive and Curative measures:
1. Preventative measures to control damage to lands:
Lining of canals and distributaries: Water percolating from canals and distributaries contribute a great deal to sub soil causing a rise in soil water table. Lining of canals prevents percolation of water largely and is being taken in the new canals.
Pre-irrigation soils surveys: Soil surveys prior to irrigation are quite necessary to select proper types of soils for perennial crops where by the utilization of irrigation for crops is maximum and contribution to the sub is the least. It is therefore, helps a remedy.
Fixing limits for perennial: Sugar cane is the most important crop under the canals in Maharashtra where it has acquired almost semi aquatic habitat. It makes splendid growth, if liberally supplied with soil moisture and the irrigation generally inclined to give water even to the extent of over irrigation with the result that it raises the sub soil water table where the drainage is obstructed. In many places, the soil water makes its appearance just below the ground level or appears as free water at the surface. Medium soils to 8’’ in depth are not suitable for sugarcane unless artificially drained.
Introduction of Block System: In a Block system a supply of water is provided for carrying on irrigated agriculture under conditions through out a block for a period of years. Block areas are de metered areas for which water is sanctioned for a term of years and within which any crops may be grown in the mansoon and Rabi season, subject to the provision that no more than one third of area shall be under sugar cane. During the hot season only allowed i.e. 11/2 acres of other perennial equal to 1 acre of sugarcane. Under block system, water is guaranteed for 6 years. Cane blocks allow 1/3 area under sugarcane and 2/3 area under seasonal crops.
Volumetric Supply of Irrigation to Sugarcane Factory Areas: The volumetric basis consists of the quantity of water to which the factory is entitled. It is fixed on acre-inches basis/acre of sugarcane area guaranteed. The inch depth fixed was 124’’ measured at distribution head. The volumetric rate is Rs 124/ acre-inches. The sugar owners have a freedom to arrange their programmer of plantation, harvesting within the guaranteed area. This system of volumetric supply of water has resulted in economic use of water and effective measures to control water logging.
2. Curative Measures:
Surface and Sub Surface Drainage: On construction of drainage scheme the sub soil water level go down the damaged areas are dried up and are brought back to cultivation after adopting reclamation methods.
Intensive well irrigation to keep the sub soil water level water under check: Another effective measure to improve the damaged areas is to have a network of working wells in suitable locations. Well irrigation forms an alternative solution where drainage cannot be adopted at economic cost.
Reclamation Method to Bring the Fertility of Soils for Growing Normal Crops: In a sound system of management, good tilth deserves first consideration. Regulation of the depth of water table by careful application of water and the disposal of surplus water by efficient drainage, natural or artificial are the very primary needs in the management of soils with a view to preserving soil fertility permanently. Agriculture practices, governing the maintenance of optimum amounts of basic factors such as soil moisture control etc. are not attended to maintain good surface and sub surface drainage therefore becomes very essential.
Partly water logged and fully water logged areas can be reclaimed by lowering sub soil water table to more than 4’ by artificial drainage. Preliminary agricultural operations are carried out on drying of the surface soil. The following sequence of operations is generally followed, of damaged lands due to water logging.
Effect of Excess Water on Soil and Plant Growth / Effect of Poor Drainage on Crop and Soil:
Drainage is the removal of excess gravitational water from the soil by artificial means to enhance crop production. If this water is not removed from the soil, the water logged or poor drainage condition occurs. Due to such condition, the soil as well as crop and soil are explained as below
Soil Aeration: Proper aeration in the root zone is necessary for development of healthy growth. The water air ratio in the pores of root zone of crop is such that it will not affect the yield. The increase in water content in soil pores is filled and the oxygen supply is reduced.
Effects on Plant Growth and Root Development: The crops become stunted with yellowing of leaves when the soil si saturated. In excess water, the plants usually die because of root damage caused by reduced supply of oxygen and accumulation of carbon dioxide with the related effects on the soil plant relationship. The adverse effects are not from direct presence of excess water, because crops will not suffer even in total from direct presence of excess water, because crops will not suffer even in total water culture, if they can get air. the root growth in such cases is also poor due to lack of aeration and they tend to remain largely near the surface and be subject to wilting when the surface becomes dry and even through there may be enough moisture below.
Anaerobic conditions in soil:
Nitrification: Crops depend for their growth on an adequate supply of nitrogen in the form of nitrates. The process of nitrification is carried out by bacteria, which requires oxygen from air in soil pores for their activity. Under anaerobic condition, marsh gas and hydrogen are formed. These gases reduce the nitrates. The nitrogen so released, escapes into the atmosphere alone with the hydrogen or converted into some form in which it is not available to crops. Thus, the suspension of microbiological activity in water logged soils directly.
Study of Water Table
Drainage investigation: It consists of getting necessary information regarding sources of water logging and ground water characteristics, extent and severity of water logging to decide the proposed line of caution and economical feasibility of soil. It includes topographical and ground water survey.
Contour map of the field:
Observation well: It gives depth of water table below the ground surface in water bearing strata. Water is at atmosphere pressure. An uncased an auger hole can be used for observation wells. However in sandy soils perforated casing may be provided to prevent collapsing of side wall.
Generally 2.5 cm diameter pipe with 3 mm diameter perforations are sufficient for the observation well however the perforation of stream depends upon particle size distribution of the surrounding formation.
Piezometer: When the soil strata, ground water character can be studied by installed piezometer. It indicates hydrostatic pressure of ground water at lower end of the part. The water enters through the opens bottom & there is no leakage through the sides.
Depending upon precisions required such observation well/piezometer are installed in grid of 30 to 300 m no of such piezometers can be installed at grid point, installed at different depth called as battery (piezometer battery.) The distance between individual piezometer should be minimum 60cm.
Observation of Data:
1. Record elevation of ground level at the piezometer / obs. well station with reference to the permanent bench mark on the farm.
2. Height of the pipe pre the level is to be noted (for observation wells piezometer)
3. Electrical depth gauge or tapes with chalked ends are used for measuring the depth of water table.
4. Observation are to be recorded periodically e.g. daily weekly seasonal etc. to study the water fluctuation etc.
e.g. R.L = 98.2m
Piezometer / obs. well is fixed at this height of pipe = 0.5m
Total height from ground = 98.2 to 0.5 = 98.7 m
If the height is measured by tape & if it obtain as 2m
Then the elevation of water table is 98.7-2 = 96.7m
Like this calculate for all points.
Water table contours:
In which direction water is flowing under the ground is known by water table contours. There are the lines of equal water table elevation above the datum. They are plotted similar to the ground surface contours on the base of map of the field it gives:
1) Visible (visual) information slope of water table
2) Information for analysis & solution of drainage problem.
Isobaths: Isobaths are the lines of equal depth from the ground level or they are the lines of equal depth to the ground water table lines.
These lines are plotted on map just like the controls & it helps to decide the surface drainage
1) Method of surface drainage
2) Method of sub surface drainage
3) Problems of conductivity drainage design in practical.
Surface drainage:
The process of removal of excess water from surface of field is termed as surface drainage. Generally the flat lands with low depressions & low infiltration rate requires surface drainage to remove the excess rainfall/excess irrigation water. Drainage can be achieved.
Land Smoothening for Surface Drainage:
Land smoothening also known as land grading is to produce plane land surface with uniform grade or slope. The finished surface is smooth & free from all minor depressions to prevent impounding of water & facilitate easy disposal of excess water along the slope within non-erosive velocity. The land smoothening is carried out two methods
1) Rough Grading-Bulldozers or Scrapers
2) Smoothening or Finishing-Float, Levelers
Drainage for pounded areas:
Low level sots accumulates run off water from adjoining areas can be removed out of the field by construction of fitted drainage. These drains are shallow with side field. Slop of 8:1 or more to facilities the crossing ditches by farm implements. This method is called random ditch system.
When the field operation (tillage) are performed parallel to ditch. The side slope of 4:1 for ditch can be preferred.
Drainage of flat lands (slope is less than 1.5%):
Bedding: In this method of surface drainage excess drains laterally from the crown strip of the land into the dead furrow & finally into the outlet. Area between two adjacent dead furrow is called bed.
The bed should be laid out dead furrow running in direction of greatest slope. Bed with is depends upon drainage characters of soil
i) 7-11-for very slow intend drained soil.
ii) 13-15-for slow internal drained soil.
Depth bed = 15-45cm.
Type of Land Requiring Drainage
1. Land having water table is high
2. Water logging lands. (When the water stands on the land surface for long period e.g. 2-4 hours for vegetable)
3. Excessive moisture content above the field capacity.
4. Humid regions where rainfall is less than evaporation.
5. Humid regions having high rainfall continuous or intermittent.
6. Lands with fine textured soils.
Drainage Properties of Soil:
1. The artificial drainage is required to be provided for two reasons
2. Lowering of high table.
3. Removal of excess accumulated water
Soil parameters plays imp. Role in deciding the extent & type of drainage system required. This includes following:
1. Permeable soils do not require artificial drainage unless the water table is high slow permeable soil often requires drainage specially when rainfall is high & field is leveled.
2. Texture: fine texture soil requires artificial drainage where as coarse textured soils may not require the artificial drainage.
3. Structure: platy structure soils poor drainage characteristics whereas blocky & granular soil structure exhibits good drainage property.
Soils having low infiltration rate & soils horizontal having less permeability require the drainage facility.
Types of drainage:
1) Surface drainage
2) Sub surface / internal drainage
The direction of ploughing should be paralleled to dead furrow, whereas tillage operation likes sowing, planting, perpendicular to dead furrow.
The collected drains collect the water from dead furrows to carry them out from the field. The spacing of collected drains is generally 90m for flat land to 300m for sloppy lands.
Parallel field ditch system:
Ditch is speed further apart and has greater capacity than the dead furrows. The ditches are not at equidistant and such system is adapted to flat. Poorly drained soil with numerous shallow depressions
Generally, ‘V’ shaped trapezoidal or parabolic drains are constructed having minimum depth 22.5 cm & cross at area 0.5 m2. The spacing is around 360m when water is moving towards both the sides in the drains.
Surface drainage: flat sloppy
Surface drainage: 1) flat flow 2) interminable strata with pervious soil
Subsurface drainage: 1) tile drains 2) open ditch
Subsurface drainage will essentially required when the land is flat or when surface drainage is not possible also if is pervious, underlined by impervious strata, subsurface-drainage is required.
Deep trenches or tile drainage are the two essential means for subsurface drainage. Many times under field condition combination of surface & subsurface drainage may be required.
Types of subsurface drainage:
1. Random
2. Herring bone
3. Grid iron
4. Interceptor drain/interception
Random subsurface drainage:
This method issued to drain the scattered wet spots in the field. The lines (drained files) are laid some what randomly to drain these depressions generally the main line follows largest natural depression of the field and sub main & lateral connects the scattered spot with the main.
For drainage areas, individual low depressions, spots can be drained using herringbone or grid iron system.
Herring bone system: it consists of parallel laterals that enter the main from either side at angle. The main line or sub main lies in the narrow depression, particularly suitable where laterals are long & required area to be thoroughly drained.
Laterals enters the main only from one direction hence the cost of this system is comparatively less. This system is used on flat land/regularly shaped field on uniform soil.
Placing the main on each side of depression serves a dual purpose intercept the seepage & provide outlet for the laterals.
Interceptor: Deep drenches are tiles, are used to intercept seepage water from the hillside. The interceptor should be laid along bottom of permeable layer.
Factors affecting flow into tile drains:
1) Hydraulic conductivity of soil horizons
2) Depth of drain below the ground surface
3) Spacing of the drain
4) Diameter of the drain
5) Joint spacing between tile drains (generally3 mm)
6) Depth of impervious layer below the ground surface.
Hooghouts for spacing of subsurface drain:
4 kh (2d + H)
S2 = ----------------------
V
Where,
k = hydraulic conductivity
d = depth of impervious layer below the drain
V = rate of replenishment of water by irrigation or rainfall in cm/sec
H = maximum water table from base of drain as shown in fig
S = spacing between drain
Benefit of drainage:
1. Provides better environmental for plant growth
2. Depth of plant rooting zone increased hence have larger rooting system
3. Improves the soil structure & infiltration rate of soil
4. Reduces soil erosion
5. Provides opt. tillage condition even in rainy season
6. Crop damage harvest can be reduced by removal of water from the wet lands
7. Makes the soil well created, maintains the soil temp, which enhances microbial activities.
8. Promotes leaching of undersible salts beyond the root zone of the crop.
9. Provides leaching climate & contributes for general prosperity of the region.
Material used Drip System Design (Manufacturing of Drip)
· PVC = Poly Vinyl Chloride
· LDPE = Low Density Polyethylene
· HDPF = High Density Polyethylene
· LLDPE = Linear Low Density Polythene
· PP = Polypropylene
· F.R.P. = Fiber Glossed Reinforced Plastic
· PP = Polysterrlene polyamide
Use of Above Mentioned materials:
· Plastic = thermoplastic, thermosetting plastic
· PVC = forcipes
· LDPE = for laterals drippers
· HDPE = pipes
· For laterals
· Values etc. drip components
· F.R.P. = fertilizer tanks
Two types of plastic are generally used.
Thermoplastic: It consists of material that can be molded in desired shape under hard & pressure and also be used for remolding after.
Definitions & Terms used in Irrigation
· Hydroscopic Water: That water is adsorbed from an atmosphere of water vapour because of attractive forces in the surface of particles.
· Hysteresis: It is the log of in one of the two associated process or phenomena during reversion.
· Indicator Plant: It is the plant, which reflects specific growing condition by its presence or character of growth.
· Infiltration Rate: It is the maximum rate at which a soil under given condition and at given time can absorb water when there is no divergent flow at borders
· Intake Rate or Infiltration Velocity: It is the rate of water entry into the soil expressed as a depth of water per unit area applicable or divergence of flow in the soil.
· Irrigation Requirement: It refers to the quantity of water, exclusive of precipitation, required for crop production. This amounts to net irrigation requirement plus other economically avoidable losses. It is usually expressed in depth for given time.
· Leaching: It is removal of soluble material by the passage of water through the soil.
· Leaching Requirement: It is the fraction of water entering the soil that must pass through the root zone in order to prevent soil salinity from exceeding a specific value.
· Oasis effect: It is the exchange of heat whereby air over crop is cooled to supply heat for evaporation.
· Percolation: It is the down word movement of water through the soil.
· Permanent Wilting Point (PWP): Permanent wilting point is the moisture content in percentage of soil at which nearly all plants wilt and do not recover in a humid dark chamber unless water is added from an outside source. This is lower limit of available moisture range for plant growth ceases completely. The force with which moisture is held by dry soil this point corresponds to 15 atmospheres.
· Permeability: Permeability is the property of a porous medium to transmit fluids It is a broad term and can be further specified as hydraulic conductivity and intrinsic permeability.
· PF: It is the logarithm of height in cm of column of water which represents the total stress with which water is held by soil.
· PH: It is the negative logarithm of hydrogen ion concentration.
· Potential Evaporation: It represents evaporation from a large body of free water surface. It is assumed that, there is no effect of addictive energy .It is primarily a function of evaporative demand of climate.
· Potential Evapo-transpiration: It is the amount of water evaporated in a unit time from short uniform green crop growing actively and covering an extended surface and never short of water. Penman prefers the term potential transpiration.
· Seepage: It is the water escaped through the soil under gravitational forces.
· Agricultural Drainage: It is removal of excess water known as free or ravitational water from the surface or below the surface of farm land to create favorable condition for proper growth and development of the plot.
· Surface Drainage: when the excess water saturates the pores spaces removal of water of water by downward flow through the soil is called subsurface drainage.
Principles of Agronomy
What is Agriculture?
· Agriculture is the backbone of our Indian Economy.
· Agriculture is a very broad term encompassing all aspects of crop production, livestock farming, fisheries, forestry, etc.
· Agriculture is the most important human economic activity.
· Agriculture is the activity of man for the production of food, fiber, fuel, etc. by the optimum use of terrestrial resource i.e. land & water.
Definition of Agriculture:
· The word agriculture comes from the Latin words ager, means the soil & cultura, means cultivation.
· “Agriculture can be defined as the cultivation and/or production of crop plants or livestock products.”
· Agriculture includes Crop Production, Animal Husbandry & Dairy Science, Agriculture Chemistry & Soil Science, Horticulture, Agril Economics, Agril Engineering, Botany, Plant Pathology, Extension Education and Entomology, which develops its separate and distinct branches of agriculture occupying now a days place in several Agril Universities in the country.
Conventional Agriculture:
· “Conventional Agriculture is the term for predominant farming practices and systems of crop production adapted by farmer in a particular region”
Agriculture can be termed as a science, an art & business altogether.
Science: because it provides new and improved strain of crop and animal with the help of the knowledge of breeding and genetics, modern technology of dairy science.
Art: because it is the management whether it is crop or animal husbandry.
Commerce (Business): because the entire agril produce is linked with marketing, which brings in the question of profit or loss.
Scope of Agriculture
Proverbially, India is known as “Land of Villages”. Near about 67% of India’s population live in villages. The occupation of villagers is agriculture. Agriculture is the dominant sector of our economy & contributes in various ways such as:
National Economy: In 1990 – 91, agriculture contributed 31.6% of the National Income of India, while manufacturing sector contributed 17.6%. It is substantial than other countries for example in 1982 it was 34.9% in India against 2% in UK, 3% in USA, 4 % in the Canada. It indicated that the more the more the advanced stage of development the smaller is the share of agriculture in National Income.
Total Employment: Around 65% population is working & depends on agriculture and allied activities. Nearly 70% of the rural population earns its livelihood from agriculture and other occupation allied to agriculture. In cities also, a considerable part of labor force is engaged in jobs depending on processing & marketing of agricultural products.
Industrial Inputs: Most of the industries depend on the raw material produced by agriculture, so agriculture is the principal source of raw material to the industries. The industries like cotton textile, jute, paper, sugar depends totally on agriculture for the supply of raw material. The small scale and cottage industries like handloom and power loon, ginning and pressing, oil crushing, rice husking, sericulture fruit processing, etc are also mainly agro based industries.
Food Supply: During this year targeted food production was 198 million tons & which is to be increased 225 million tons by the end of this century to feed the growing population of India i.e. 35 corer in 1951 and 100 corers at the end of this century. India, thus, is able to meet almost all the need of its population with regards to food by develop intensive program for increasing food production.
State Revenue: The agriculture is contributing the revenue by agriculture taxation includes direct tax and indirect tax. Direct tax includes land revenue, cesses and surcharge on land revenue, cesses on crops & agril income tax. Indirect tax induces sales tax, custom duty and local octri, etc. which farmer pay on purchase of agriculture inputs.
Trade: Agriculture plays and important role in foreign trade attracting valuable foreign exchange, necessary for our economic development. The product from agriculture based industries such as jute, cloth, tinned food, etc. contributed to 20% of our export. Around 50 % of total exports are contributed by agril sector. Indian agriculture plays and important role in roads, rails & waterways outside the countries. Indian in roads, rails and waterways used to transport considerable amount of agril produce and agro based industrial products. Agril products like tea, coffee, sugar, oil seeds, tobacco; spices, etc. also constitute the main items of export from India.
History of Indian Agriculture - Early Development:
The early Aryans (Bronze Age people)
Period: 1800 to 1600 of B.C
They depended on wheat, Barley, millets, pulses, sesame, mustard & Animal husbandry.
The Vedic age (1560-100B.C)
The profession of farming was regarded as only far the unlearned and those devoid of wisdom. It remained so far centuries.
The later Vedic period (1000-600B.C)
Wooden ploughs were provided with Iron ploughshares, their efficiency further improved. This Improvement helped the Aryans to cultivate the virgin land resulted to greater mastery over food production.
The Buddhist period (Sixth century BC)
Brahmans were found pursuing Village, Cow herding, goat keeping, trade, woodwork weaving, archery and carriage driving. The hired labour apparently was assigned a low social rank.
The Magadhan Empire (fourth century BC)
Formations of villages started in this period. Plantation of bushes & tree, collection of seeds, fruit, flowers, fiber etc started.
The Asoka Period
Promoted forestry & horticulture, encouraged plantation of trees in gardens and along roads in the farm of avenues
First century BC to second century AD
First plough agriculture to replace slash & burn cultivation. Knowledge of distant markets, origination of village settlements & breaded also some.
Age of the Guptas (300-500AD)
This period is called golden age of India. Provides information an agriculture besides other sciences. Deals with selection of land, manuring, cultivate, seed collection, sowing, planting & grafting. Amarasoka contains information on soil village & irrigation.
Empire of the Harshvardhana (606-647 AD)
The source of information on agriculture curling this period is writings of early Arab writers.
The Muslim Rule (1206-1761 Ad)
Land revenue system was improved. Taguai loans were given to cultivators in distressed circumstance for the purchase of seed & Cattle.
The British rule & free India (1757-1947)
History of Indian Agriculture - Historic Developments
The historic developments in agriculture during British rules and free India are:
Sr. No.
Year
Historic Developments
1
1871
Departments of Agriculture created
2
1878
Higher Education in agriculture at Coimbatore.
3
1880
Famine commission appointed.
4
1890
Higher Education in agriculture at Pune.
5
1891
Dr. J A Voekker report on improving Indian agriculture
6
1900
Forest research Institute
7
1901
First Immigration commission.
8
1905
Imperial (now Indian) Agricultural research institute at Pusa (Now at Delhi)
9
1921
Indian central cotton committee.
10
1926
Royal commission on agricultural headed by Lord Linlithgow.
11
1929
Imperial (now Indian) council of agricultural research at Delhi.
12
1936
Indian Central Jute committee.
13
1942
Department of Food created.
14
1942
Grow more food campaign.
15
1944
Indian central Sugarcane committee.
16
1945
Indian central tobacco committee.
17
1946
Directorate of planet projection & quarantine.
18
1946
Central Rice research institute.
19
1947
Food policy committee.
20
1947
Fertilizers & chemicals Travancore.
21
1956
Project for intensification of regional research on cotton, oil, seeds, millets(PIRRCOM)
22
1957
All India Coordinated maize improvement Project.
23
1960
Intensive Agriculture district programme( IADP)
24
1960
First agricultural University at Panthnagar.
25
1963
National seed corporation.
26
1965
Intensive Agriculture area programme( IAAP)
27
1965
National demonstration programme.
28
1966
High yielding Varieties programme.
29
1966
Directorate of Extension.
30
1966
Multiple cropping schemes.
31
1969
Second Immigration compassion.
32
1970
Drought prone area programme (DPAP)
33
1970
National commission on agriculture.
34
1971
All India coordinated project for dry land agriculture.
35
1972
ICRISAT
36
1973
Minikit trials programme.
37
1974
Command area development.
38
1976
Integrated Rural development programme (IRDP)
39
1977
Training & Visit system (T&V)
40
1979
National Agricultural research project (NARP)
41
1982
National bank for agriculture & Rural development (NABARD)
42
1985
National Agricultural extension project (NAEP)
43
1986
National Agricultural research project (Phase-II)
44
1990
National Agricultural Technology project (NATP)
Important Events in Early History of Agriculture
Period
Event
10000BC
Hunting & Gathering
8700BC
Domestication of sheep
7500BC
Wheat & Barley cultivation
6000BC
Domestication of Cattle’s & Pigs
4400BC
Maize Cultivation
3500BC
Potato cultivation
3400BC
Wheel invention
3000BC
Bronze tools
2900BC
Plough invention & irrigation
2700BC
Domestication of silkworm in China
2300BC
Cultivation of chickpea, Pear, sarson &cotton.
2200BC
Domestication of Fowl, Buffalo and elephant.
2000BC
Rice cultivation
1800BC
Finger millet cultivation
1725BC
Sorghum Cultivation
1700BC
Taming of horse
1500BC
Sugarcane cultivation & well irrigation.
1400BC
Use of Iron
15th Century
Cultivation of Oranges, Brinjal.
16th Century
Cultivation of several crops into India by Portuguese - Potato, Tomato, Chilles, Pumpkin, Papaya, Pineapple, Guava, Custard apple, groundnut, Tobacco, Cotton, Cashew nut.
History of Agriculture as a science
1. In pre scientific agriculture six persons could produce enough food for themselves and for four others. In years of bad harvest they could produce only enough for themselves, with the development of science and application of advanced technology five persons are able to produce enough food for nine others.
2. Van Helmet (1577-1644Ad): Experiments pertaining to plant nutrition in systematic way and concluded that the main “Principle” of vegetation is water.
3. Jethre Tull (1674-1741AD): Conducted several experiments and published a book “Horse Heeing Husbandry”. These experiments mostly on cultural practices and they led to the development of seed drill & horse drawn cultivation.
4. Aurthur young (1741-1820Ad): Conducted pod culture experiments to increase the yield of crops by applying several materials like poultry dung, litter, gun power, & publish his work-in 46 volumes at “Annals of agriculture”.
5. In 1809 soil science begin with the formulation of the theory of hums.
6. Research in plant nutrition & physiology was started in 18th century.
7. Sir Humphrey Davy published book “Elements of agri chemistry” in 1813
8. Sir John Bennet was begun to experiment on the effects of manures of crops.
9. Justus Libey on agriculture chemistry and physiology launched systematic development of agriculture in 1840.
10. 1842, Initiated the systematic fertilizers Industry by the patented process of hearting phosphate rock to produce super phosphate.
11. Gregor Johann Mendel (1866) discovers the law of heredity and the ways to mutations laid to modern plant breeding.
12. Charles Darwin Published the results of the experiments on cross and self ferlization in plants.
13. 1920, the application of genetics to develop new strains of plants and animals brought major charges of agriculture.
14. The first successful tractor was built in U.S in 1882 from implements & machinery was manufactured industrially on a large scale by 1930.
15. Due to economic pressure and decrease in labor availability, the application of electricity to agriculture was in 1920.
16. The first successful large scale conquest of a pest a chemical means was the control of grapevine powdery mildew in Europe in 1840.
17. The key date in history of argil research at education is 1862. When the US congress set up departments of agriculture & provided for colleges for agriculture in each state.
18. Scientific agriculture began in India when Sugarcane, cotton, & Tobacco were grown for purpose.
19. What is Agronomy?
20. The term agronomy is derived from Greek words “AGRO” meaning field & “NOMO” meaning to manage.
21. Definition of agronomy:
22.
1. Agronomy is branch of agril science which deals with principles & practices of soil, water & crop management.
2. It is branch of agril science that deals with methods which provide favorable environment to the crop for higher productively,
3. It deals with the study of principles and preaches of crop production and field management.
4. It is the study of planet in relation to soil and climate. It deals essentially with all aspects of soil, crop and water management to increase productively of crops.
23. Principles of agronomy deal with scientific facts in relations to environment in which crop are produced
24. Scope of agronomy:
25. Agronomy is a dynamic discipline with the advancement of knowledge and better understanding of planet & environment, agril. Practices and modified of new practices developed for high productively as follows:
1. Proper methods of filling the lands.
2. Suitable period for its cultivation.
3. Keeping farm implements in good shape and managing field crops in a efficient manner as experienced farmer.
4. Management of crops, live stock & their feedings.
5. Care and disposal of farm & animal products like milk & eggs.
6. Proper maintenance of accounts of all transactions concerning farm industry.
7. Availability of chemical fertilizers has necessitated the generation of knowledge on the method.
8. Availability of herbicides for control of weeds has led to development for a vast knowledge about selectivity, time & method of its application.
9. Water management practices.
10. Intensive cropping.
11. New technology to overcome the effect of moisture stress under dry land condition.
12. Packages of practices to explore full potential of new varieties of crops.
26. Restoration of soil fertility, preparation of good seedbed, use of proper seed rates, correct dates of sowing for each improved Variety, proper methods of conservation & management of soil moisture & proper control weeds are agronomic practices to make our finite land water resources more productive.
With the growth of other allied agril sciences, the present day agronomy not only embodies the act of soil management of crop production and obtaining maximum production at minimum cost but also establishing new facts and applying scientific knowledge to practical problems.
27. The emphasis of agronomy is now more towards the scientific study of the behavior of plant under the different environmental conditions like varing soils and climate, irrigation, fertilization etc. by conducting well laid out experiments in the fields, pots & laboratories.
28. It is also involves application of research in the field or forming suitable packages of practices under a given set of conditions.
29. Relationship of Agronomy with other Sciences
30. Agronomy is having relationship with both basis and applied sciences.
31. 1. Basic sciences are those which reveal the facts or secrets of nature and comprise subjects like chemistry, physics, math’s, botany, zoology.
2. Applied sciences are those in which the theories and laws propounded in basic sciences are applied to problems in agriculture and other fields. Agril chemistry comprising, soil, planet, fertilizer, and dairy chemistry developed from basic science of chemistry.
3. Agril Botany covers planet nutrition, plant physiology and planet breeding developed from botany & chemistry.
4. Planet pathology & economic entomology developed from botany & Zoology.
5. Agril extension developed from psychology, sociology and anthropology.
6. Agronomy is essentially an applied science and is largely dependent on basic and other applied science.
7. Knowledge of all the science is necessary to learn the basic facts, regardless, of whether they would be of any practical value of agriculture.
8. All the applied sciences are important for advancement of agriculture, which are closely related to each other and no branch can progress without to help of allied science branches.
9. Agronomy is synthesis of several disciplines like soil science, agril chemistry, crop physiology, planet ecology, biochemistry & economics. Agril chemistry & soil science deals with: a) Management of acidic, saline & alkali soils. b) Application of fertilizers. c) Effects of physical, chemical changes (modifications) on soil environment.
1. Physiology deals to meet their requirement.
2. Breeding deals with evolution of new verities & exploitation of hybrid vigor.
3. Economics deals for economically crop production.
4. Pathology & entomology deals with effective control of diseases & pests.
32. Coordinated Approach:
1. Since the applied sciences are so interrelated the specialists cannot work in isolation but have to work in coordination with each other to solve the problems of agriculture rapidly and efficiently.
2. For Example: the Planet breeder while evolving a HYV (High yielding Variety) of any crop must take the help of planet pathologist to test the resistant or susceptibility of the new strain to diseases, physiologist to make sure that the new strain has not developed any undesirable qualities and of the agronomist to test the behavior of variety under field condition.
33. Agronomist
34. An agronomist is called as an expert of agriculture except veterinary science. Also known as doctor of plant
35. Agronomist is a specialized scientist in agronomy, which deals with the science of utilizing plants for food, fuel, feed & fiber.
36. Agronomist are involved with many issues including food, feed & fuel production without impact on environmental.
37. Agronomist should be specializing in areas such as crop rotation, irrigation & drainage, planet breeding, soil science, weed control & disease & pest control.
38. Role of Agronomist:
1. Agronomist aims at an obtaining maximum production at minimum cost by exploiting the exploiting the knowledge developed by basic and allied/applied science.
2. In a board sense he is conceder with production of food and fiber to meet the needs of the growing population.
3. He has to test the suitability of research finding of others specialists in the field and accept them finally and also judge the reaction of the farming community.
4. He is a coordinator of different subject matter specialist and act as a physician who concern with other SMS.
5. He carries out research on scientific cultivation of crops taking into account the effect of factors like soil climate, variety of crops production techniques suitably depending on the situation.
6. He is person with working knowledge of all agril disciplines and coordinator of different subject matter specialists.
39. Introduction to Principles of Agronomy
40. “Principles of agronomy deals with basic concepts & common agronomic principles & much more than crop to crop management approaches”
41. This principle of agronomy is useful for the application with many crops.
42. The principle of agronomy is based on two major purposes:
1. To develop an understanding of the important principles underlying the management.
2. To develop the ability to apply these principles to production situations
43. Major Principles to Agronomy:
44. 1. Agrometerology: study of climatic factors in related to agriculture.
45. 2. Soils & Tillage: Tillage is the agricultural preparation of the soil by ploughing, ripping, or turning it. There are two types of tillage: primary and secondary tillage. Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics.
46. 3. Soils & Water conservation: Water conservation refers to reducing the usage of water and recycling of waste water for different purposes like cleaning, manufacturing, agriculture etc.
47. 4. Dry land Agriculture: Dry land farming is an agricultural technique for cultivating land which receives little rainfall.
48. 5. Mineral Nutrition of plants, Manures & Fertilizers: Plant nutrition is the study of the chemical elements that are necessary for plant growth.
49. 6. Irrigation & water management: Water management is the activity of planning, developing, distributing and optimum use of water resources under defined water polices and regulations
50. 7. Weed Management: Management of unwanted plant in field.
51. 8. Cropping & Farming systems.
52. 9. Sustainable Agriculture: Sustainable agriculture refers to the ability of a farm to produce fertile soil and cows, without causing severe or irreversible damage to ecosystem health
Divisions of Plant Kingdom
A crop is an organism cultivated & harvested for obtaining yield.
· According to the natural system the plant kingdom has been divided into two divisions. I.e. Cryptogams & Phanerogams.
· Phanerogams divided into two sub division i.e. Angiosperm & Gymnosperm.
· Angiosperm further divided into two classes i.e. Monocots & Dicots.
· Classes again divided into orders, orders into families, families into genera & species, some times species into varieties.
Divisions of Plant Kingdom:
Botanical Classification of Plant:
Dicotyledonous
(Embryo with two cotyledons)
Monocotyledonous
(Embryo with one cotyledon)
Importance of classifying the Crop Plants:
1. To get acquainted with crops.
2. To understand the requirement of soil & water different crops.
3. To know adaptability of crops.
4. To know the growing habit of crops.
5. To understand climatic requirement of different crops.
6. To know the economic produce of the crop plant & its use.
7. To know the growing season of the crop
8. Overall to know the actual condition required to the cultivation of plant.
Classification based on climate:
1. Tropical: Crops grow well in warm & hot climate. E.g. Rice, sugarcane, Jowar etc
2. Temperate: Crops grow well in cool climate. E.g. Wheat, Oats, Gram, Potato etc.
Classification Based on growing season:
1. Kharif/Rainy/Monsoon crops: The crops grown in monsoon months from June to Oct-Nov, Require warm, wet weather at major period of crop growth, also required short day length for flowering. E.g. Cotton, Rice, Jowar, bajara.
2. Rabi/winter/cold seasons crops: require winter season to grow well from Oct to March month. Crops grow well in cold and dry weather. Require longer day length for flowering. E.g. Wheat, gram, sunflower etc.
3. Summer/Zaid crops: crops grown in summer month from March to June. Require warm day weather for major growth period and longer ay length for flowering. E.g. Groundnuts, Watermelon, Pumpkins, Gourds.
Use/Agronomic classification:
1. Grain crops: may be cereals as millets cereals are the cultivated grasses grown for their edible starchy grains. The larger grain used as staple food is cereals. E.g. rice, Jowar, wheat, maize, barley, and millets are the small grained cereals which are of minor importance as food. E.g. Bajara.
2. Pulse/legume crops: seeds of leguminous crops plant used as food. On splitting they produced dal which is rich in protein. E.g. green gram, black gram, soybean, pea, cowpea etc.
3. Oil seeds crops: crop seeds are rich in fatty acids, are used to extract vegetable oil to meet various requirements. E.g. Groundnut, Mustard, Sunflower, Sesamum, linseed etc.
4. Forage Crop: It refers to vegetative matter fresh as preserved utilized as food for animals. Crop cultivated & used for fickler, hay, silage. Ex- sorghum, elephant grass, guinea grass, berseem & other pulse bajara etc.
5. Fiber crops: crown for fiber yield. Fiber may be obtained from seed. E.g. Cotton, steam, jute, Mesta, sun hemp, flax.
6. Roots crops: Roots are the economic produce in root crop. E.g. sweet, potato, sugar beet, carrot, turnip etc.
7. Tuber crop: crop whose edible portion is not a root but a short thickened underground stem. E.g. Potato, elephant, yam.
8. Sugar crops: the two important crops are sugarcane and sugar beet cultivated for production for sugar.
9. Starch crops: grown for the production of starch. E.g. tapioca, potato, sweet potato.
10. Dreg crop: used for preparation for medicines. E.g. tobacco, mint, pyrethrum.
11. Spices & condiments/spices crops: crop plants as their products are used to flavor taste and sometime color the fresh preserved food. E.g. ginger, garlic, chili, cumin onion, coriander, cardamom, pepper, turmeric etc.
12. Vegetables crops: may be leafy as fruity vegetables. E.g. Palak, mentha, Brinjal, tomato.
13. Green manure crop: grown and incorporated into soil to increase fertility of soil. E.g. sun hemp.
14. Medicinal & aromatic crops: Medicinal plants includes cinchona, isabgoli, opium poppy, senna, belladonna, rauwolfra, iycorice and aromatic plants such as lemon grass, citronella grass, palmorsa, Japanese mint, peppermint, rose geranicem, jasmine, henna etc.
Classification based on life of crops/duration of crops:
1. Seasonal crops: A crop completes its life cycle in one season-Karin, Rabi. summer. E.g. rice, Jowar, wheat etc.
2. Two seasonal crops: crops complete its life in two seasons. E.g. Cotton, turmeric, ginger.
3. Annual crops: Crops require one full year to complete its life in cycle. E.g. sugarcane.
4. Biennial crops: which grows in one year and flowers, fructifies & perishes the next year? E.g. Banana, Papaya.
5. Perennial crops: crops live for several years. E.g. Fruit crops, mango, guava etc.
Classification based on cultural method/water:
1. Rain fed: crops grow only on rain water. E.g. Jowar, Bajara, Mung etc.
2. Irrigated crops: Crops grows with the help of irrigation water. E.g. Chili, sugarcane, Banana, papaya etc.
Classification based on root system:
1. Tap root system: The main root goes deep into the soil. E.g. Tur, Grape, Cotton etc.
2. Adventitious/Fiber rooted: The crops whose roots are fibrous shallow & spreading into the soil. E.g. Cereal crops, wheat, rice etc.
Classification based on economic importance:
1. Cash crop: Grown for earning money. E.g. Sugarcane, cotton.
2. Food crops: Grown for raising food grain for the population and & fodder for cattle. E.g. Jowar, wheat, rice etc.
Classification based on No. of cotyledons:
1. Monocots or monocotyledons: Having one cotyledon in the seed. E.g. all cereals & Millets.
2. Dicots or dicotyledonous: Crops having two cotyledons in the seed. E.g. all legumes & pulses.
Classification based on photosynthesis’ (Reduction of CO2/Dark reaction):
1. C3 Plants: Photo respiration is high in these plants C3 Plants have lower water use efficiency. The initial product of C assimilation in the three ‘C’ compounds. The enzyme involved in the primary carboxylation is ribulose-1,-Biophospate carboxylose. E.g. Rice, soybeans, wheat, barley cottons, potato.
2. C4 plants: The primary product of C fixation is four carbon compounds which may be malice acid or acerbic acid. The enzymes responsible for carboxylation are phosphoenol Pyruvic acid carboxylose which has high affinity for CO2 and capable of assimilation CO2 event at lower concentration, photorespiration is negligible. Photosynthetic rates are higher in C4 than C3 plants for the same amount of stomatal opening. These are said to be drought resistant & they are able to grow better even under moisture stress. C4 plants translate photosynthates rapidly. E.g. Sorghum, Maize, napter grass, sesame etc.
3. Cam plants: (Cassulacean acid metabolism plants) the stomata open at night and large amount of CO2 is fixed as a malice acid which is stored in vacuoles. During day stomata are closed. There is no possibility of CO2 entry. CO2 which is stored as malice acid is broken down & released as CO2. In these plants there is negligible transpiration. C4 & cam plant have high water use efficiency. These are highly drought resistant. E.g. Pineapple, sisal & agave.
Classification based on length of photoperiod required for floral initiation:
Most plants are influenced by relative length of the day & night, especially for floral initiation, the effect on plant is known as photoperiodism depending on the length of photoperiod required for floral ignition, plants are classified as:
1. Short-day plants: Flower initiation takes plate when days are short less then ten hours. E.g. rice, Jowar, green gram, black gram etc.
2. Long day’s plants: require long days are more than ten hours for floral ignition. E.g. Wheat, Barley,
3. Day neutral plants: Photoperiod does not have much influence for phase change for these plants. E.g. Cotton, sunflower. The rate of the flowering initiation depends on how short or long is photoperiod. Shorter the days, more rapid initiation of flowering in short days plants. Longer the days more rapid are the initiation of flowering in long days plants.
Agricultural Seasons in India & Maharashtra
Agricultural Seasons in India
In India four agricultural four seasons are present in year as per Indian metrological department as follows:
1. Winter Season: This season is called as cold weather period. January & February months are the cold months in the most parts of the country. Temperature distribution over India shows a marked decrease from south to north. In north India average temperature during this season is about 10-15 degree and in south India is about 21-28 degree. Weather during this period is cool, dry & pleasant with dewfall during morning. This period is practically rainless except occasional drizzles.
2. Summer Season: This season is also called as hot weather period / premonsoon season. This period is characterized by high temperature. The temperature is higher in north compared south. March to May month is the summer season. The weather gets hotter steadily from the beginning of March. April & may are the hottest months of the year. The average temperature is 30-40C. The rainfall receives during this period are mainly useful for preparatory cultivation. In this period hot wind blows & sometimes dust storms also take place. Some time these dust storms create problems due to their intensity for considerable period.
3. Rainy Season: This season is also called as south west monsoon. This is the most important period major rainy period in India about 60 to 75% of total rainfall in a year is received during this period. During this period climate is warm, humid with bright sunshine except on rainy days. Rainy season or monsoon is result of wind movements. Which in turn are caused by difference in air pressure? In early summer the sun heats large landmass of central & southern Asia and warm air rises. As it rises suction is created & the moist air across the Arabian Sea & the Bay of Bengal is pulled from the south-west direction. This creates south-west monsoons.
4. Post Rainy Season: This season is also called as post monsoon season or North-East monsoon. Rainfall received during this period is 13% to 33% of annual rainfall. The temperature high up to the mid of October and later starts falling rapidly. The October to December month is the duration for the post rainy season in India.
Agricultural Seasons in Maharashtra: In Maharashtra whole year is divided into three seasons as follows:
1. Kharif / Monsoon/Rainy season: 15 June to 15 October.
2. Winter/Rabi/Cool season: 15 October to 15 February.
3. Summer season: 15 February to 15 June.
These four seasons are further subdivided into six seasons based on rules:
1. Shishir (Jan to Feb)
2. Spring/Vasant (March to April)
3. Summer (May to June)
4. Rains/Varsha (July to Aug)
5. Fall/Sharad (Sep to Oct)
6. Hemant (Nov to Dec)
Factors Governing Crop Production or Affecting Crop Growth
Crop production is concerned with the exploitation of plant morphological (or structural) and plant physiological (or functional) responses with a soil & atmospheric environment to produce a high yield per unit area of land. Growth is irreversible increase in size or weight.
Crop production provides the food for human beings, fodder for animals and fiber for cloths. Land is the natural resource which is unchanged & the burden of the population is tremendously increasing, thereby decrease the area per capita. Therefore it is necessary to increase the production per unit area on available land. This necessitates the close study of all the factors of crop production viz.
1. The soil in which crops are grown
2. The water which is the life of plant
3. The Plant which gives food to man & fodder to his animals
4. The skillful management by the farmer himself
5. The climate which is out of control of man & but decided the growth, development & production.
6. The genetic characters of crop plant which is the genetic makeup & can be exploited for crop production.
Broadly, the factors that influence the growth of crop or crop production can be classified as:
A. Internal or Genetic Factors
B. External or Environmental Factors
Internal or Genetic Factors
Genetic makeup decided the crop growth & its production. Crops vary in the genetic makeup which included desirable & undesirable characters as well. Breeders try to incorporate maximum desirable characters in one strain of crop & also try to exploit the hybrid vigour.
Desirable characters include:
1. High yielding ability under given environment condition.
2. Early maturity
3. Better resistance to lodging
4. Drought, flood & salinity tolerance
5. Greater tolerance to insect & diseases
6. Chemical composition of grains (Oil & Proteins)
7. Quality of grains (Fineness coarseness etc)
8. Quality of straw (Sweetness juiciness)
These characters are inherent in each individual and are transmitted from one generation to another by genes.
External or Environmental Factors
1. Edaphic or Soil Factors
2. Water
3. Plant Biotic Factor
4. Anthropic or Management
5. Climatic
1) Edaphic or Soil factors: Soil can be defined as: Soil is a thin layer of the earth’s crust which serves as a natural medium for the growth of plants. Soils are formed by the disintegrations & decomposition of parent rocks due to weathering and the action of soil organisms & also the interaction of various chemical substances present in the soil. Soil is formed from parent rock by the process of weathering over a long period by the action of rain water, temperature and plant & animal residues.
A vertical cut of 1.5 to 2 m deep soil indicates a layer varying from a few cm to about 30 cm of soil, called surface soil, elbow that a layer of sub soil & at the bottom, the unrecompensed material which is the parent rock.
Role of soil:
1. Soil is the natural media to grow the crop.
2. Soil gives the mechanical support & act as an anchor,
3. Soil supplies the nutrients to the crop plants,
4. Soil conserves the moisture which is supplies to the crop plants
5. Soil is an abode (house) of millions of living organisms which act on plant residues & release food material to plants
6. Soil provides aeration for growth of crop and decomposition of organic matter.
Soil profile: A vertical section of soil in the field extending up to the depth of the parent material shows the presence of more or less distinct horizontal layers such a section is called a profile & individual layers are regarded as horizon.
The depth of soil varies as shallow, medium & deep. The soil which remains where it is formed, known as soil in situ, the soil on the banks of river which is formed from the soil particles washed away by rains from hill slopes & deposited at lower levels is known as alluvial soil which is much deeper & more fertile.
Soil varies in their composition and the arrangement of soil particles depending upon the parent rocks from which they are formed. They also vary in physical properties such as texture & structure. Textural class decided its fitness, fertility & plant growth, infertile soil need to add the org. Matter & fertilizers. Problematic soils need addition of soil amendments (Lime-acid & Gypsum-alkali) and other management practices to correct them. The chemical properties of soil are decided by the parent rocks.
Soil is not an inert mass but an abode of millions of living organisms which act on plant residues & release food material to plants. The decayed OM also loosens the soil to allow circulation & retention of moisture, which are necessary for the life & growth of the plant, soil is not an ordinary mass of dead particles of rock but a medium humming with activity, responsive to the water, plant & management by the farmer.
External or Environmental Factors – Water and Plant or Biotic factors
Water:
Functions of water:
1. Major component of the plant body (90%).
2. Act as solvent for dissolving the nutrients & nutrient carrier.
3. Maintains/regulates the temperature of plant & soil as well
4. Maintains the turgidity of plant cells.
5. Essential for absorption of nutrients & metabolic process of the plants.
Plant tissues constitute about 90% of water. Rain and ground water are the sources of the water. Ground H2O is reused for irrigation through well, tank or canal, etc. Erratic rains are to be conserved properly so that plants make best use of it. Rainwater is to be supplemented by irrigation to meet the water requirement of crops for bumper yields.
Water Present in the soil helps the plants in many ways:
1. Supplies the essential raw material for production of carbohydrates by photosynthesis.
2. Promotes physical, chemical & biological activities in the soil.
3. Gaseous diffusion in soil for proper aeration.
Water is the life of plant & must be supplied in proper quantity. Too much water may suffocate the plant roots & too little may not be able to sustain the plant. The water requirement of crops differs from crop to crop & variety to variety as well, depending upon the growth habit, genetically & physiological make up, duration of the crop, etc. For example, sugarcane, rice, banana, wheat, groundnut, etc. are the high water requiring crops & Jowar, Mung, udid, Tur, gram, bajara etc. are the low water requiring crops.
Plant /Biotic factors: Biotic factors include plant, symbiosis & animals.
Plant: The soil & water are two variables which either has to be suitably adjusted for the plant to grow or the plant should be so bred & selected that it will adjust to a given soil & water condition, growing season, climatic requirement, etc. Some of the crops grow on only rain while some required irrigation water, Plant breeders are constantly at work to evolve varieties which will suit the given soil & water condition e.g. drought resistant, disease resistant, more nutrients absorbing capacity etc.
The unwanted plants, ‘weeds’ compete with crop plants fro solar energy, water nutrients & also for space which need to be controlled for better crop growth & production at proper time & methods.
Symbiosis: There are the some organisms which have mutual relationship with each other & with the prevailing environment of the place. This biological inter relationship among the organisms is termed as symbiosis. The symbiotic relationship between legumes & Rhizobia which results in ‘N’ fixation is of great significance to crop production. The legume bacteria use the carbohydrates of their host as energy & fixes up atmospheric ’N’ which in turn used by host plants. The free living organisms (Azotobacter) acquire their energy from soil OM, fix the free N & make it a part of their own tissue. When they die the ‘N’ available in their body tissues is used by the crop plants.
Animals: Soil organisms:
The soil organisms include:
1) Soil flora (plant kingdom) & 2) soil fauna (animal Kingdom).
Soil flora is of two types: i) Macro flora e.g. Roots of higher plants ii) Micro flora e.g. Bacteria, fungi, actinomycetes & algae.
Soil fauna is of two types: i) Macro flora e.g. earthworm, moles, ants, and ii) Micro fauna e.g. protozoa, nematodes. The soil fauna including protozoa, nematodes, rotifers, snails, insects constitute a highly important part of the environment for plant roots. All these organisms contribute decomposition, when using the OM for their living. Among these insects, nematodes cause considerable damage as crop pests.
Beneficial organisms: Insects like bees, wasp, moths, butterflies, beetles help in pollination of crops. Burrowing by earthworm facilitates aeration & drainage and the ingestion of OM & mineral matter results in a constant mixing of these materials in the soil & tends to make better plant growth.
Small animals: Like rabbits, squirrels, rats cause extensive damage to field & garden crops.
External or Environmental Factors- Anthropic or Management or Man or Skillful Mgt & climate
Anthropic or Management /Man or skillful management by the man:
Finally, man must so manage the soil-water-plant complex to produce efficiently food & fodder and for that purpose a number of mechanical devices & useful cultivation practices have been evolved such as ploughs for ploughing, harrows for seeded preparation, hoes for hoeing, seed cum fertilizer driller for sowing the seeds & application of fertilizers. Man has to perform the operations at proper time such as land preparation sowing, thinning & gap filling and also the plant protection measures, optimum plant population, recommended fertilizer application at right time & depth, proper water mgt Practices. The soil, water, plant& management are the four factors, which govern successful crop production.
Climate: Another factor that influences the growth, development, & production of crop is the climate which is out of control by the man but mgt. practices of the crops can be altered to harvest maximum yield. Climate is the most dominating factor influencing the suitability of a crop to a particular region. The yield potential of a crop mainly depends on climate. More than 50% of variation in yield of crops is solar radiation, temperature & rainfall Relative humidity & wind velocity also influence crop growth to some extent. Atmospheric factors which affect the crop plants are called climatic factors which include.
1. Precipitation,
2. Temperature,
3. Atmospheric humidity,
4. Solar radiation,
5. Wind velocity and atmospheric gases.
1. Precipitation: - It results from evaporation of water from sea water and land surfaces. The process involved in the transfer of moisture from the sea to the land & back to the sea again what is known as the hydrologic cycle. Continuous circulation of water between hydrosphere, atmosphere & lithosphere called as hydrologic cycle. Precipitation includes rainfall, snow or hail, Fog drip & dew also contribute to moisture. Fog consists of small water droplets while dew is the condensation of the water vapour present in the air. Precipitation influences the vegetation of a place. Most of crops receive their water supply from rainwater which is the source of soil moisture so essential for the life of a plant. The yearly precipitation, both in total amount & seasonal distribution greatly affects the choice of cultivated crops of a place.
2. Temperature: It is considered as a measure of intensity of heat energy. The range of maximum growth for most argil, plans is between 15 & 400C, every plant community has its own minimum, optimum & maximum temperature known as their cardinal points. Temperature is determined by the distance from the equator (latitude) and the altitude; Apart from the reduction in yield many injuries such as cold injury which included chilling injury, freezing injury, suffocation & heaving and heat injury.
Maize & sorghum (8-100C, 300C, 40ºC) Rice (10-110C, 35ºC) Wheat (50C, 25ºC, 30º-320C)
3. Atmospheric humidity: Water which is present in the atmosphere in the form of invisible water vapor, termed as humidity of the air, ET of crop plants increases with the temperature but decreases with high relative humidity affecting the quantity of irrigation water, Moist air favors the growth of many fungi & bacteria which affect seriously the crop.
4. Solar radiation: Solar energy provides two essential needs of plants:
a) Light required for photosynthesis & for many other functions of the plant including seed germination, leaf expansion, growth of stem & shoot, and flowering, fruiting & even dormancy.
b) Thermal conditions required for the normal physiological functions of the plant. Light helps in synthesis of chlorophyll pigment. Light affects the plants in four ways: intensity, quality (wave length), duration (Photoperiod) and direction.
5. Wind velocity: It affects growth mechanically (damage to crop) and physiologically (evaporation & transpiration), Hot dry winds may adversely affect photosynthesis & hence productivity, by causing closure of the stomata even when soil moisture is adequate. Moderate winds have a beneficial effect on photosynthesis by continuously replacing the CO2 absorbed by the leaf surfaces.
Tilth and Tillage
Soil is the medium in which crops are grown but in its natural state, it is not in an ideal condition to grow them satisfactorily. Surface soil in which seed are to be sown, should not be hard & compact, but soft & friable, so that tender shoots of germinating seeds can push above the soil surface without any difficulty and the young roots penetrate easily into the lower layers of soil in search of food, water & air, Soil should also be free from weeds which otherwise rob the crop of water & nutrients. It should also have sufficient water & air which are very necessary for plant growth.
Such ideal condition of soil can be achieved by manipulating the soil properly & bringing it in good filth through a series of mechanical operations like ploughing, clod crushing, dicing, harrowing, leveling, compacting, interculturing etc. by tillage implements.
Tillage: Tillage is as old as Agriculture, Primitive man used to disturb the soil for placing seed Jethro Till considered as ‘Father of Tillage’ Who Written’ Horse hocing Husbandry’ book. Tillage of the soil consists of breaking the hard compact surface to a certain depth and other operations that are followed for plant growth. Tillage is the physical manipulation of soil with tools & the tilling of land for the cultivation of crop plants i.e. the working of the surface soil for bringing about conditions favorable for Raising of crop plants. Tillage is the manipulation of soil with tools & implements for loosening the surface crust & bringing about conditions favorable for the germination of seeds and the growth of crops.
Soil Tilth: Soil Tilth is the term used to express soil condition resulting from tillage. Hence it is the resultant of the tillage. A soil is said to be in good Tilth when it is soft, friable & properly aerated. The Tilth is the physical condition of the soil brought out by tillage that influences crop emergence, establishment, growth and development. Tilth is a loose, friable, airy, powdery granular & crumbly structure of the soil with optimum moisture content suitable for working & germination or sprouting seeds & propagates Soil Tilth is that kind of physical condition of soil when it is loose. Not very powdery but granular & when these granules are felt between fingers they are soft, friable, & crumble easily under pressure, Such soils permit easy infiltration of water & are retentive of moisture for satisfactory growth of plants.
Characteristics of good tilth/Measurement of soil tilth: Tilth indicates two properties of soil, viz the size distribution of aggregates and mellowness or friability of soil.
Size distribution of soil aggregates: The relative proportion of different sized soil aggregates is known as size distribution of soil aggregates. Higher% of larger aggregates i.e. more than 5 mm are necessary for irrigated agriculture while higher% of smaller aggregates(1-2mm) are desirable for dry land agriculture. Theoretically, the best size of granules or aggregates ranges from 1 to 6 mm. However, it depends on soil, type, soil moisture content (at which ploughing is done) & subsequent cultivation.
Mellowness or friability: is that property of soil by which the clods when dry become more crumbly. They do not crumble into dust but remain as stable aggregates of smaller size.
A soil with good tilth is quite porous and has fee drainage up to water table. The capillary & non-capillary pores should be in equal proportion so that sufficient amount of water is retained in the soil as well as free air, The soil aggregates would be quite from or stable & would not be easily eroded by water or by wind.
Soil tilth: is easy to describe but rather difficult to measure/ Theoretically, best size of granules ranges from 1-6 mm differs with country e.g. England as more than 15mm and Russia 2-3 mm. Besides this, study of pore space, equal distribution of macro & micro pores is good tilth.
Ideal soil tilth : An ideal soil tilth is not the same for all types of crops & all types of soils e.g. small seeded crops like bajara, ragi, lucerne, Sesamum, mustard require a much finer seedbed, Jowar & cotton require a moderately compact & firm seed bed and not cloddy or loose. Bold seeded crops like gram, maize germinate even in cloddy seedbed.
As regards soil type, a very fine, powdery condition of the surface soil is decidedly bad for a heavy clay soil as it forms a caked surface under rainy condition and all the rain water is then liable to be lost by run-off, taking away also with loamy & lighter soils.
Tilth and Tillage - Objects of Tillage
Objects of Tillage: These can be summarized in brief as below.
1. To make the soil loose & porous: It enables rain water or irrigation water to enter the soil easily & the danger of loss of soil & water by erosion and run-off, respectively, is reduced. Due to adequate proportion of microspores (capillary), the water will be retained in the soil & not lost by drainage.
2. To aerate the soil: Aeration enables the metabolic processes of the living plants & micro organisms, etc. to continue properly. Due to adequate moisture and air, the desirable chemical & biological activities would go on at a greater speed & result in rapid decomposition of the organic matter and consequently release of plants nutrients to be used by crops. Similarly, the evolution of CO2 gas in this process will result in forming weak carbonic acid in the soil which will make more nutrients available to crops.
3. To have repeated exchange of air / gases: There should be an exchange of air during the growing period of crops. As the supply of O2 from the air that is being constantly utilized in several biological reactions taking place in the soil; should be continuously renewed. At the same time CO2 that is released should be removed & not allowed to accumulate excessively decomposition of org. residues by micro- organisms where O2 is utilized & CO2 released. Deficiency or excess of O2 may reduce the rate of reactions.
O2 in soil air & atm. Air is more or less same i.e. 20 to 21% CO2 in atmospheric air is about 0.03% & in soil air 0.2 to o.3% which is 8to 10 times more than atmospheric air. It is, therefore, very necessary to often introduce atmospheric air in the soil to keep the concentration of CO2 under by suitable tillage operations.
4. To increase the soil temperature: This can be achieved by controlling the air- water content of soil & also by exposing more of the soil to the heat of sun. This helps in acceleration of activities of soil bacteria & other micro organisms.
5. To control weeds: It is the major function of tillage; Weeds rob food & water required by crop & competition results in lowering of crop yield.
6. To remove stubbiest: Tillage helps in removing stubbles of previous crop and other sprouting materials like bulbs, solons etc in making a clean field/seedbed.
7. To destroy insect pests: Insects are either exposed to the sun’s heat or to birds that would pick them up. Many of the insect-pests remain in dormant condition in the form of pupae in the top soil during off season & when the host crop is again planted, they reappear on the crop. Some may harbor on stubbiest or other eminent of the crop. Grubs & cutworms can be destroyed by tillage.
8. To destroy hard pan: Specially designed implements (Chisel plough) are helpful to break hard pan formed just below the ploughing depth which act as barrier for root growth & drainage of soil.
9. To incorporate organic & other bulky manures: Organic manures should not only be spread but properly incorporated into the soil. Sometimes bacterial cultures or certain soil applied insecticides require to be drilled into the soil for control of pests like white grub. White ants, termites, cut worms e.g. Aldrin.
10. To Invert soil to improve fertility: By occasional deep tillage the upper soil layer rich in org. matter goes down thus plant roots get benefit of rich layer and lower layer which is less fertile comes to top.
Tilth and Tillage - Factors Influencing Preparatory or Tillage Operations
Factors Influencing Preparatory or Tillage Operations:
The preparatory cultivation of the lands done in various ways which is influenced by several factors but more important ones are:
1. The crop: The crop to be grown decides the type & preparatory tillage given to the land. Hardy crops like sorghum & other millets are not sensitive about tilth. Production of fine tilth will increase the cost of cultivation which is not economic. Small seeded or delicate crops like tobacco, chilli, coriander,sesamum, mustard etc. Require a fine seedbed for which land is repeatedly cultivated to get required fine tilth. Sugarcane & other root crops require deep cultivation of land to lose the soil to the required depth.
2. Type of soil: A clayey soil is amenable to cultivation only within a narrow range of moisture. Outside this range, the soil can’t be worked satisfactorily & increases the draft required. Too wet or to dry soils are difficult to cultivate. The lighter soils can be worked under a wide range of moisture & the draught required for their manipulation is much less. Loamy soils are easily brought to good tilt with little cultivation & expenditure of energy.
3. Climate: It in influences the moisture in the soil, the draught required for cultivation and depth & types of cultivation done, For example, in scarcity areas the rainfall is low & the moisture in the soil prior to sowing does not ordinarily permit deep cultivation which tends to dry up soil to a greater depth & reduce moisture available to the crops eventually (finally) Sowings cannot be done till depth of cultivated soil is properly moistened. This results in delayed sowing & consequently the effect on growth & yield of crop Deep cultivation is beneficial in regions having better rainfall, particularly temperate regions for promoting aeration, summer showers are received in South India which favors moist condition & ultimately beneficial for preparing the land for next season crops.
4. Type of farming: There are two types, irrigated & dry land/ rained farming. Under irrigated farming intensive farming is followed which includes cultivation of more than two crops. In a year continuously without much interval between them. During this narrow period of interval the land is to be cultivated repeatedly to bring required title without subjecting the soil for natural weathering for a long period. The frequency & extent of tillage operations increase the cost of cultivation which serious as the profitable crops is raised in an intensive manner. Dry land faming depends entirely on rains & in such areas only one crop is taken in a year. The interval between crops & successive cultivation operations is long. Weathering plays an important role than cultivation. Hence they are limited with wide intervals between them. The cost of cultivation is kept down & the low productivity of land does not warrant a higher investment.
Tilth and Tillage - Effects of Tillage on soil & Plant growth
Effects of Tillage on soil & Plant growth:
A) Effect on soil:
1) loosens the soil which favors the germination & growth of crop,
2) Improves the soil structure due to alternate drying and cooling,
3) Improves soil permeability, soil aeration & soil inversion,
4) Facilitates the movement of water in soil,
5) Results in soil & water conservation through higher infiltration, reduce run-off & increase depth of soil for moisture storage,
6) Holds more water in the soil,
7) Increased soil aeration helps in multiplication of micro-organisms,
8) Org. matter decomposition is hastened resulting in higher nutrient “availability,
9) Increase aeration helps in degradation of herbicide and pesticide residues & harmful allelopathic chemicals exuded by roots of previous crops or weeds.
Tillage operations also influence the physical properties of soil like:
1) Pore space: Tillage increase the pore spaces i.e. space between the soil particles, due to equal amount of capillary & non- capillary (Macro & microspores) pores. This facilities free movement of air & moisture in the soil & increases infiltration.
2) Soil structure: Soil with crumble & granular clods are considered as soil with good structure which can be achieved by proper tillage operations at optimum moisture. This reduces the soil loss due to erosion.
3) Bulk density: when soil is loosened, the soil volume increases without any effect on weight. Therefore, bulk density of tilled soil is less than untilled soil which is favorable in many ways for crop, micro organisms, etc.
4) Soil colour: Tillage increases oxidation and decomposition resulting in fading of colour The org. matter is mainly responsible for the dark brown to dark grey colour of soil.
5) Soil water: Tillage improves soil water in different ways which depends on soil porosity, soil depth & roughness. also increases rate of infiltration, water holding capacity (WHC) & hydraulic conductively.
6) Soil temperature: Tillage creates up to soil temperature for seed germination & seed establishment. Tillage loosens the soil surface resulting in decrease of thermal conductivity (rate of heat transfer at which the heat penetrates) and heat capacity (heat storage / unit area)
B) Effects on crop growth:
1) Tillage loosen the soil thereby favors the germination & establishment of seeding.
2) Tillage helps in maintaining the optimum plant stand,
3) Increases depth of root penetration,
4) Roots proliferate profusely in loose soil & increase the growth of seminal & lateral roots.
5) Reduce the competition within crop & weeds for light, water, nutrients & space thereby helps in better growth of crop,
6) Tillage reduce the pest attack on succeeding crop,
7) Tillage helps in availability of nutrients to crop in proper amount.
Tilth and Tillage: Types of Tillage Operations
Types of Tillage Operations: Tillage includes use of different kinds of implements at different times are classified on the basis of their timing into-3types:
1. Preparatory tillage: Tillage operations that are carried out from the time of harvest of a crop to the sowing of the next crop are known as preparatory cultivation/ Tillage. OR Operations carried out in any cultivated land to prepare seedbed for sowing crops are preparatory tillage. These are time consuming & costly but are to be performed at right stage of soil moisture & with right implements, otherwise it will not helps in good growth of crop. These includes in sequence, plouging, clod crushing, leveling, discing , harrowing, manure mixing & compacting the soil and implements to be used are ploughs, clod crushers, disc ploughs or harrow , bladed harrow etc.
It includes primary & secondary tillage:
a) Primary tillage: It mainly includes the ploughing operation which is opening of the compacted soil with the help of different ploughs. Ploughing is done to:
1) Open the hard soil,
2) Separate the top soil from lower layers,
3) Invert the soil whenever necessary and
4) Uproot the weeds & stubbles.
The cutting & inverting of the soil that is done after the harvest of the crop or untitled fallow or to bring virgin or new land under cultivation is called primary tillage. It may be done once or twice a tear in normal or settled agriculture or once in four to five years in dry land agriculture.
b) Secondary tillage : Lighter or finer operation performed on the soil after primary tillage are known as secondary tillage which includes the operations performed after ploughing, leveling, discing, harrowing etc.
2. Seedbed preparation: when the soil is brought to a condition suitable for germination of seeds & growth of crops, called as SEEDBED.
After preparatory tillage the land is to be laid out properly for irrigating crops if irrigation is available for sowing or planting seeding which are known as seedbed preparation: It includes harrowing, leveling, compacting the soil, preparing irrigation layouts such as basins, borders, rides & furrows etc. and carried out by using hand tools or implements like harrow, rollers plank, rider etc. After field preparation, sowing is done with seed drills. Seeds are covered & planking is done so as to level & impart necessary compaction.
3. Inter tillage/ Inter cultivation/ Interculture/ after care operation: The tillage operations that are carried out in the standing crop are called inter tillage operations. The tillage operation done in the field after sowing or planting and prior to the harvesting of crop plants known as inter cultivation. It includes gap filling , thinning , weeding , mulching, top dressing of fertilizers, hoeing, earthling up etc. unless these are carried out at right time, with suitable implements mainly hoes & hand tools the crop will not attain a vigorous growth. These operations are carried out in between the crop rows.
Tilth and Tillage- Tillage Operations and Implements
Tillage operations and implements:
A) Preparatory tillage:
i) Ploughing: It is considered to be the most essential operation for growing crops. It is done by different ploughs which are of 3 types:
1) Deshi or wooden or Indigenous plough
2) Iron mould board ploughs
3) Special purpose ploughs.
The iron mould board plough may be:
1) Reversible or Turn –wrest mould board plough and
2) Non-reversible or fixed mould board plough. Former is drawn by bullocks and later with the tractor. Depending up on the weight and no. of bullocks to be used the
Reversible I.M.B. plough s may be:
a) Light R.I. M.B. plough drawn by one bullock pair.
b) Medium R.I.M.B. Plough had drawn by two bullock pairs &
c) Heavy R.I.M.B. plough drawn by three bullock pairs.
The special purpose ploughs are
a) Disc plough used for discing or loosening of the soil.
b) Sub soil plough used to break hard layers or pans without bringing them to the surface.
c) Chisel plough used breaking hard pans & for deep ploughing (60-70cm) with less disturbance to the top layers.
d) Rider used to split the field in top ridges & furrows.
ii) Clod crushing: It is not always necessary. When there are the clods the rains received will soft & break the clods. It is necessary in Rabi season. Clods are broken by a plank, blade harrow or hand mallet, indigenous implement (a big log of wood) called maind. The best implement for this purpose is the Norwegian harrow which breaks the clods by piercing & breaking action.
iii) Leveling of land: It is required in irrigated area & carried out after ploughing to ensure even distribution of rain & irrigation water to avoid stagnation of water in low lying areas and also to stop soil erosion Implements such as bamboo petari, blade harrow tied with rope round the prongs, planker, plank- leveler, buck scraper, float, keni are used for leveling.
iv) Manure mixing: Manures are spread over the prepared bed by manually or with the help of country plough, shovel tooth cultivator, a blade harrow, disc harrow.
v) Compacting the soil: It is done by working an inverted harrow or single/ double plank.
vi) Cultivator: It is used to break & loose the soil.
B) Implements used for seedbed preparation:
i) Harrowing: is done by a blade harrow with the purpose of clod crushing, leveling, collecting stubbles, destroying germinating weeds and compacting the soil, a multipurpose implement commonly used by the farmer. Disc harrow drawn either by bullocks or tractor is an improvement which cuts & pulverizes the soil.
ii) Covering of seed: is carried by a light blade harrow or a plank.
iii) Ridging: Riders are used for opening ridges and furrows for sugarcane, vegetables, and irrigation layouts field channels
iv) Implements for sowing: Sowing may be done by putting the seeds behind plough, seed drills which may be doff an, tiff an or Chou fan, Seeding & fertilizer application are done at the same time by providing two separate bowls, called as feri-cum-seed drill. Seed may be sown mechanically to maintain row to row & plant to plant(R/R & p/p) distance. There may be sowing of seed and fertilizer application at the same time.
C) Implements for inter cultivation: Operations carried out in between the crop rows called
Intercultivation or inter tillage or inter culture operations.
These are necessary for destroying weeds, preventing cracking of soil, aerating the soil to absorb more moisture, pruning of roots, ear thing up of plants, destroying insects & thinning of crop plans.
1. Thinning & gap filling: These are done by manual labour/hand in which plants are uprooted from dense places and the gaps are filled to maintain the optimum plant population.
2. Wedding: It is done either by hand with the help of a khurpi/sickle or hoes drawn by hand or bullocks. Hoes may be of entire blade, slit blade, spring teeth or Akola hoe Japanese/Rotary paddy weeder, karjat hoe/Touchy gurma etc.
3. Ear thing up: may be done by country plough or rider in S.cane, banana,
Potato. Sometime it is done by manual labour with kudali.
4. Spraying: is done by sprayers which may be manually operated, mechanical/power drawn to control insects-pests & diseases.
5. Dusting: is done by duster used for dusting insecticides to control insect-pests.
D) Special purpose implements:
1) Reapers & harvesters used to harvest wheat or paddy.
2) Threshers used for threshing which may be bullock (olpad) drawn, tractor drawn, or electric motor driven.
3) Potato digger used to harvest potatoes
4) Groundnut digger used to harvest Gnat
5) Gnat Sheller used to separate kernels from the pods.
6) Maize Sheller used to separate maize grains from cobs.
7) Seed dressing drum used to treat the seed with chemicals.
8) Hand gin used to separate lint from seed cotton.
Tools used in agriculture: 1) Khurpi: To remove weeds
2) Kudali: To dig the pits & earthling up
3) Axe: To cut the wood & harvest sugarcane
4) Pickaxe: To dig out the pits.
5) Sickle: To cut the hardy weed & crop plants & forages.
6) Ghumella: To transport soil or produce from the one place to other.
7) Crop-bar: To open the hole in soil while fencing the thomy bushes.
8) Dibbler: For dibbling the seeds. (For other tools, refer practical manual)
Tilth and Tillage- Modern Concepts of Tillage
Modern Concepts of Tillage:
Tillage is time consuming, laborious & costly, owing to this new concepts like minimum tillage & zero tillage are introduced.
1. Minimum Tillage: It is aimed at reducing tillage operations to the minimum necessary for ensuring a good seedbed, rapid germination, a satisfactory stand & favorable growing conditions, Tillage can be reduced by:
1) Omitting operations which do not give much benefit when compared to the cost and
2) Combining agricultural operations like seeding & fertilizer application.
Advantages:
1) Improve soil condition due to decomposition of plant residues in situ,
2) Higher infiltration caused by decomposition of vegetation present on Soils & channels formed by decomposition of dead roots.
3) Less resistance to root growth due to improved structure.
4) Less soil compaction by reduced movement of heavy tillage vehicles.
5) Less soil erosion compared to conventional tillage.
Disadvantages:
1) Less seed germination,
2) More ‘N’ has to be added as rate of decomposition of organic matter is slow.
3) Nodulation may affect in some legumes.
4) Sowing operations are difficult with ordinary implements.
2. Zero tillage: It is an extreme form of minimum tillage. Primary tillage is completely avoided & secondary tillage is restricted to seedbed preparation in the row zone only.
It is followed where:
1) Soils are subjected to wind & water erosion,
2) Timing of tillage operations is too difficult &
3) Requirements of energy & labour for tillage are too high.
Advantages:
1) Soils are homogenous in structure with more no. of earth worms.
2) Organic matter content increased due to less mineralization.
3) Surface runoff is reduced due to presence of mulch. Several operations are performed by using only one implement. In these weeds are controlled by spraying of herbicides.
Disadvantages:
1) Higher ‘N’ is too applied due to slower mineralization of org. matter.
2) Large population of perennial weeds appears.
3) Build up of pests is more.
3. Stubble mulch tillage: The soil is protected at all times either by growing a crop or by crop residues left on the surface during fallow periods. It is year round system of managing plant residue with implements that undercut residue, loosen the soil and kill weeds. Soil is tilled as often as necessary to control weeds during the interval between two crops. However, it presents the practical problem as the residues left on the surface interfere with seedbed preparation & sowing operations. The traditional tillage & sowing equipment is not suitable under these conditions.
Modern methods of tillage are not practiced in Indian condition because:
a) Left over residue is a valuable fodder & fuel.
b) Limited use of heavy machinery & therefore problem of soil compaction is rare.
4. Peddling: Pudding is ploughing the land with standing water so as to create an impervious layer below the surface to reduce deep percolation losses of water and to provide soft seedbed for planting rice. This followed in rice as the growth and yield are higher when grown under submerged conditions. Maintaining standing water throughout the crop period is not possible without pudding. It aims at destroying soil structure and separates individual soil particles i.e. sand, silt & clay, during operation and settles later. The sand particles reach the bottom, over which silt particles settle & finally clay particles fill the pores thus making impervious layer over the compacted soil. It is done with several implements depending on the availability of equipment and the nature of land such as spade, wetland plough, worn out Dryland plough, mould board plough, wetland puddler, country plough, etc. It consists of ploughing repeatedly in standing water until the soil becomes soft & muddy. Initially, 5-10cm of water is applied depending upon the water status of the soil to bring saturation and above and the first ploughing is carried out after 2-3 days. By this operation, most of the clods are crushed and majority of the weeds are incorporated. Within 3-4 days, another 5cm of water is given & third ploughing is done in both the directions. Planking or leveling board is run to level the field.
5. Conservation tillage: It is disturbing the soil to the minimum extent & leaving crop residues on the soil. It includes minimum & zero tillage which can reduce soil loss up to 99% over conventional tillage. In most cases, it reduces soil by 50% over conventional tillage. Conventional tillage includes ploughing twice or thrice followed by harrowing & planking. It leaves no land unploughes & leaves no residues on the soil.
Seeds and Sowing
Seed is any material used for planning & propagation whether it is in the form of seed (grain) of food, fodder, fiber or vegetable crop or seedlings, tubers, bulbs, rhizomes, roots, cuttings, grafts or other vegetatively propagated material.
Seed is a fertilized ovule consisting of intact embryo, stored food (endosperm) and seed coat which is viable & has got the capacity to germinate.
As we say, “Reap as you sow”, the good quality seed must have following characters:
1. Seed should be genetically pure & should exhibit true morphological & genetical characters of the particular strain (True to type).
2. It should be free from admixture of seeds of other strains of the same crop or other crop, weeds, dirt and inert material.
3. It should have a very high & assured germination percentage and give vigorous seedlings.
4. It should be healthy, well developed & uniform in size.
5. It should be free from any disease bearing organisms i.e. pathogens.
6. It should be dry & not mouldy and should contain 12-14% moisture.
Seed is the basic input in the crop production which should be of good quality.
Seeds and sowing - Seed Germination
Seed Germination: Means the resumption of growth by embryo & development of a young seedling from the seed. Germination is an activation of dormant embryo to give rise to radical (root development) and plumule (stem development).Germination is the awakening of the dormant embryo. The proce4ss by which the dormant embryo wakes up & begins to grow is known as Germination.
Seed Emergence Means actually coming above and out of the soil surface by the seedling.
Changes During Germination:
1) Swelling of seed due to imbibition of water by osmosis.
2) Initiation of physiological activities such as respiration & secretion of enzyme.
3) Digestion of stored food by enzymes.
4) Translocation & assimilation of soluble food.
When seed is placed in soil gets favorable conditions, radical grows vigorously & comes out through micro Pyle & fixes seed in the soil. Then either hypo or epicotyls begins to grow.
Types of germination:
1. Hypogeal germination: The cotyledons remain under the soil. E.g.: cereals, gram.
2. Epigeal germination: The cotyledons pushed above the soil surface. E.g.: mustard, tamarind, sunflower, castor, onion.
Seed and Sowing- Factors Affecting the Germination
External Factors:
1.Moisture: It enables the resumption of physiological activities, swelling of seed due to absorption of moisture & causes bursting of seed coat & softening the tissue due to which embryo awakes & resumes its growth.
2. Temperature: A suitable temperature is necessary for proper germination. Germination does not take place beyond certain minimum & maximum temperature i.e. 0⁰C & above 50⁰C. Optimum temperature range for satisfactory germination of seed is 25 to 30⁰C.
3. Oxygen: It is essential during germination for respiration & other physiological activities which are vigorous during the process.
4. Light: It is not considered as essential for germination & it takes place without light. The seedlings grow more vigorously during darkness rather in light. However, for survival of germinating seedling, light is quite essential.
5. Substratum: It is the medium used for germinating seeds. In the laboratory, it may be absorbent paper (blotting paper, towel or tissue paper), soil & sand. Substratum absorbs water & supplies to the germinating seeds. It should be free from toxic substances & should not act as medium for growth of micro-organisms.
Internal Factors:
1. Food & Auxins: An Embryo feed on the stored food material until young seedlings prepares its own food. Auxins are the growth promoters, hence quite essential during the germination.
2. Viability: All seeds remain viable for certain definite period of time and thereafter embryo becomes dead. It depends on maturity of seed, storage conditions & vigour of parents and type of species. Generally, it is for 3-5 years and they remain for more than 200 years also as in lotus.
3. Dormancy: It is the failure of mature viable seed to germinate under favorable condition of moisture. Many seeds do not germinate immediately after their harvest, they require rest period for certain physiological activities.
Seeds and Sowing- Seed Dormancy
Seed Dormancy: Failure of fully developed & mature viable seed to germinate under favorable conditions of moisture & temperature is called resting stage or dormancy and the seed is said to be dormant.
Kinds of Dormancy in Seeds:
1. Primary dormancy: The seeds which are capable of germination just after ripening even by providing all the favorable conditions are said to have primary dormancy. E.g.: Potato.
2. Secondary dormancy: Some seeds are capable of germination under favorable conditions just after ripening but when these seeds are stored under unfavorable conditions even for few days, they become incapable of germination.
3. Special type of dormancy: Sometimes seeds germinate but the growth of the sprouts is found to be restricted because of a very poor development of roots & coleoptiles.
Causes of Dormancy:
The dormancy in seeds may be due to any single or a combination of more than one of the following causes.
1. Seed coats being impermeable to water: Some seeds have a seed coat which is impermeable to water. Such seeds even when fully matured & placed in favorable conditions; fail to germinate because of failure of water to penetrate into the hard seed coats. These seeds become permeable, if they are treated with H2SO4 or dipped in boiling water for few seconds. E.g.: Cotton.
2. Hard seed coat: Seeds of mustard, amaranths, etc. contain a hard & strong seed coat which prevents any appreciable expansion of embryo. Thus, if the seed coats fail to burst the embryo will remain dormant even after providing all the favorable conditions for germination.
3. Seed coats being impermeable to O: The seed coats are impermeable to O2 & if the seed coats do not rupture the seed fails to sprout.
4. Rudimentary embryo of seeds: The seeds which are apparently ripened contain a rudimentary or imperfectly developed embryo and the germination of such seeds naturally gets delayed until the embryo develops properly.
5. Dormant embryo: The seeds of an apple, peach, pinus, etc do not germinate even though the embryos are completely developed and all the favorable conditions for germination are provided. In such seeds, physiological changes called after ripening take place during the period of dormancy which enables the seeds for germination.
6. Synthesis & accumulation of germination inhibitors in the seeds: Plant organs synthesize some chemical compounds which are accumulated in the seeds at maturity and these chemicals inhibit the germination of their seeds.
Seed and sowing- Methods to Break the Dormancy
Methods to Break the Dormancy:
1. Scarification: The dormancy due to hard seed coat or impermeable seed coats can be broken by scarification of seed coats. It should be done in such a way that the embryo is not injured.
a. Chilling (Pre-chilling): The seeds are placed in contact with the moist substratum at a temperature of 5 to 10°C for 7 days for germination. E.g. Cabbage, Cauliflower, and Sunflower.
b. Pre-dying: Seeds should be dried at a temperature not exceeding 40°C with free circulation for a period of 7 days before they are placed for germination. E.g. Maize, Lettuce.
c. Pre-washing:In some seeds, germination is affected by naturally occurring substances which act as inhibitors which can be removed by soaking & washing the seeds in the water before placing for germination. E.g.: Sugar beet.
d. Pre-soaking: Some seeds fail to germinate due to hard seed coat. Such seeds should be soaked in warm water for some period so as to enhance the process of imbibitions. E.g. Chillar, Subabul.
e. Rubbing or puncturing seed coat: Some seeds are subjected to mechanical scarification either by rubbing them against rough surface or puncturing the seed coat with pointed needle. E.g.: Coriander, Castor.
f. Application of pressure to seeds: Germination of Medic ago sativa is found to be increased when a hydraulic pressure of 2000 atmosphere at 18°C is applied. It may be due to increase in permeability of seed coat to water and O2.
2) Stratification: In some seeds after ripening, low temperature and moisture conditions require in artificial stratification. Seed layer altered with layers of moist sand or appropriate material to store at low temperature. E.g.: Mustard & Groundnut.
3) Exposure of seeds to light: It also helps to break the dormancy & increase the germination.
4) Chemical treatments:
a. Potassium nitrate treatment (KNO3): The material used for placing the seeds for germination i.e. substratum, may be moistened with 2% solution of KNO3 (2g KNO3 + 100ml of water). E.g. rice, tomato, chilies.
b. Gibberellic acid treatment: The substratum used for germination may be moistened with 500 ppm solution of GA i.e. 500 mg in 1000ml water. E.g. Wheat, Oat.
c. Thio-urea treatment: Potato tubers are dipped in thio-urea solution (1%) for one hour when fresh harvested produce is to be used as seed material.
Seed and Sowing- The Indian Seed Act (1966)
It was enacted in 1966 and has been in force since Oct. 2, 1969 in all over states of India. This act aims at regulating the quality of seed sold for agricultural purpose through compulsory labeling and voluntary certification. Under compulsory labeling, any one selling the seed of a notified kind or variety, in the region for which it has been notified, should ensure that:
1. The seed confirms to the prescribed limits of germination purity.
2. The seed container is labeled in the prescribed manner, and
3. The label truly represents the quality of seed in the container.
Under voluntary certification, anyone interested in producing certified seed may do so by applying to the seed certification agency for the grant of certificate. The agency grants the certificate and certification tags after satisfying itself that the seed has been after satisfying itself that the seed has been produced according to the prescribed standards and procedures.
There are two bodies, viz., the central seed committee and the central seed certification board, which advise the central and the state governments in the matters related to the general administration of the seeds act and of seed certification, respectively.
Seed and Sowing- Multiplication & Distribution of Seeds:
In India, farmers depend for their seed supply primarily on the state department of Agriculture and the National Seeds Corporation. The Department of Agriculture in all states has a planned programme of seed multiplication.
Classes of Quality seeds: The various classes of seed that are used in a seed production programme are:
1. Breeder seed,
2. Foundation seed,
3. Registered seed and
4. Certified seed.
These different classes of seed have different requirements and serve different functions:
1. Breeder seed: It is the seed or the vegetative propagating material produced by the breeder who developed the particular variety. The production & maintenance of breeders stock on main research station is controlled by the plant breeder. It is produced by the institution where the variety was developed in case the breeder who developed the variety is not available. In India, it is also produced by other Agri. Universities under the direct supervision of the breeder of the concerned crop working in that University, this arrangement is made in view of the large quantities of the breeder seed required every year. It is generally pure having high genetic purity (100%). Off type plants are promptly eliminated and care is taken to prevent out crossing or natural hybridization & mechanical mixtures.
2. Foundation seed: It is the progeny of the breeder seed and is used to produce registered seed or certified seed. It is obtained from breeder seed by direct increase. It is genetically pure and is the source of registered and/or certified seed. Production of foundation seed is the responsibility of NSC. It is produced on Govt. farms (TSF), at expt. stations, by Agri. Universities or by component seed growers under strict supervision of experts from NSC. It should be produced in the area of adaptation of the concerned variety.
3. Registered seed: It is produced from foundation seed or from registered seed. It is genetically pure & is used to produce certified seed or registered seed. It is usually produced by progressive farmers according to technical advice and supervision provided by NSC. In India, often registered seed is omitted and certified seed is produced directly from foundation seed.
4. Certified seed: It is produced from foundation, registered or certified seed. This is so known because it is certified by a seed certification agency, in this case state seed certification agency, to be suitable for raising a good crop. The certified seed is annually produced by progressive farmers according to standard seed production practices. To be certified, the seed must meet the prescribed requirements regarding purity & quality. It is available for general distribution to farmers for commercial crop production.
Seed and Sowing- Seed Testing
The various classes of improved seeds are recognized to facilitate the maintenance of genetic purity of the variety and to ensure a continuous supply of good quality seed at a reasonable cost. It also helps in the multiplication of the seed rapidly while maintain its purity.
Seed Testing: Seed tests consist of a series of tests designed to determine the quality of seed. Seed tests are done in seed testing laboratories. Almost every state has a seed testing laboratory which performs the following function:
1. Conducting research on seed testing methods,
2. Training of personnel in seed testing,
3. Determining the standards for seed purity and seed quality for various crops,
4. Seed testing for certification and for implementation of seed laws of the country.
Following tests are conducted to determine the quality of seeds:
1. Purity test,
2. Germination or seed viability test and
3. Moisture content test.1.
1. Purity test: Purity denotes the percentage of seeds (by weight) belonging to the variety under certification.
Purity (%) = Weight of pure seed (g) x 100
Total weight of working samples (g)
2. Seed viability or Germination test: It is determined as per cent of seeds that produce or are likely to produce seedlings under a suitable environment.
The two tests most commonly used for the determination of seed viability are germination test and tetra zolium method.
3. Germination test determines the percentage of seeds that produce healthy root and shoot. Temperature requirement varies from 18 to 22°C. The duration of germination test varies from 7 to 28 days depending upon the crop species.
Germination % = Total no. of seeds germinated x 100
Total no. of seeds kept
For convenience, 100 seeds are planned in each sample. From each seed lot 4 or more samples are plated for a reliable germination estimate. If there is difference of 10% or more in the germination of different samples from the same lot, it is desirable to repeat the germination test.
Tetra Zolium Method: It determines the percentage of viable seeds which may be expected to germinate.
The chemical 2, 3, 5 – tetrazolium chloride in short, is colourless but it develops intense red colour when it is reduced by living cells.
Seeds are soaked in tap water overnight and are split longitudinally with the help of a scalpel so that a portion of the embryo is attached with such half of the seed. One half of each seed is placed in a Petridis covered with 1% aqueous solution of tetrazolium chloride for 4 hours. The seeds are then washed in tap water & the no. of seeds in which the embryo is stained red is determined.
Viable seed % = No. of half seeds stained red * 100
___________________________________
Total no. of half seeds.
The tetrazolium method is faster than the germination method and it does not require a controlled environment which is necessary for the germination test. It is relatively cheaper than earlier. Bu it cannot be applied to all the species, particularly to those species that have very small seeds & embryos, because splitting & examination of such seeds is tedius.
Real value of seed: It is the percentage of a seed sample that would produce seedlings of the variety under certification. This is also known as utility percentage of the seed & is a function of the Purity (P) and germination (G) percentage of the seed sample.
Real value of seed (%) = P x G / 100
1. Moisture content: It is determined as % water content of the seeds. Optimum moisture content reduces the deterioration during storage, prevents attack by moulds & insects and
Moisture content (%) = W1 – W2 x 100
W1
Where, W1 – Wt. of seed sample before drying
W2 – Wt. of seed sample after drying
Facilitates processing. It is determined by drying the seed in oven at 130°C temperature for 90 minutes. The loss in weight represents the weight of water lost due to drying.
Seed and Sowing- Seed Production Organizations
Seed Production Organizations: There are two types of Govt. / Public sector organizations responsible for seed production & certification in India. The first type of organization is represented by the National Seeds Corporation (NSC) which has responsibilities for the entire country. The second types of organizations are State Seeds Corporation (SSCs) and State Seed Certification agencies (SSCAs) that have state-wise responsibilities.
National Seeds Corporation: The NSC was initiated in 1961 under the ICAR. Later, on 7th March, 1963, it was registered as a limited company in the public sector. It was established to serve two main objectives:
1) To promote the development of seed industry in India and
2) To produce & supply the foundation seeds of various crops.
The present functions of NSC may be summarized as:
a. Production & supply of foundation seed,
b. To maintain improved seed stocks of improved varieties,
c. Interstate marketing of all classes of seed,
d. Export & import of seed,
e. Production of certified seed where required,
f. Planning the production of breeder seed in consultation with ICAR,
g. Providing technical assistance to Seeds Corporation & private agencies,
h. Coordinating certified seed production of State Seed Corporation,
i. Conducting biennial surveys of seed demand,
j. Coordinating market research & sales promotion efforts,
k. Providing training facilities,
l. Providing certification services to states lacking established and independent seed certification agencies.
Seed and Sowing- Seed Testing Laboratories:
Seed Testing Laboratories: A Central Seed Testing Laboratory is established at IARI, New Delhi. There are 18 State Seed Testing Laboratories spread over states of India. In M.S, it is located at the College of Agriculture, Nagpur. These have been provided with modern seed testing equipments & they are required to help in the seed certification & seed control programme.
Functions:
To analyze the seed samples for purity, moisture content, wed seeds (%) & germination, etc.
2. To assist the seed inspectors in determining whether correct labeling is being done as per requirements of the seed act.
13. Sowing Of Seed
Sowing Of Seed:
For cultivation of any field crop, one must follow the recommended practices of seeds and sowing to harvest maximum yield of the crop.
14. A. Seed Rate
B. Seed Treatment
C. Sowing Time
D. Depth of Sowing
E. Spacing & Plant Population
F. Methods of Sowing
15. Seed rate: The seed rate per unit area depends on germination of the seed, size of the seed, growing habit of the crop, etc. Extremes from the recommended seed rate (i.e. too high or too low) affect the plant population & then yield of crop. E.g. higher seed rate will influence higher plant population/unit area. It results in heavy competition within the crop plants and suppresses the crop growth. Lower seed rate will result lower plant population thereby lowers the yield/unit area. The seed rate is governed by the ultimate stand desired. Most crops are seeded at smaller rates under dry land than under irrigated condition. Seed rate depends on size, germination, growing habit, type of farming, time of sowing, variety, etc
16. Seed treatment: It is a process of application of chemicals or protectants (with fungicidal, insecticidal, bactericidal or nematocidal properties) to seeds that prevent the carriage of insect or pathogens in or on the seeds.
17. Objects of seed treatment: Some seeds need treatment with some specific objectives before sowing.
18. 1.To control disease: There are some seed borne or soil borne diseases, seeds are treated with fungicides or organo mercurial compounds like Thirum, captain, carbendazim, agrosan, cereson, etc. E.g. to control paddy blast, seed is to be treated with agrosan @ 3 g per kg (3g/kg) of seed).
19. 2.To have convenience in sowing: Difficulties are encountered in sowing certain crops due to special characteristics of the seed like fuzz of cotton seeds, coriander seeds, small seeds of chilli, ragi, bajara, etc. E.g.: coriander seed is to be splitted by rubbing it against hard surface. Seed of chilli, Sesamum, bajara are mixed with fine sand or soil.
20. 3. To have quick germination: Germination of certain leguminous crops is delayed due to thick seed coat which restricts water absorption. Such seed coats are broken to some extent by mixing them with coarse gritty sand & trampling or pounding it lightly in a morter with a wooden pestle for breaking the thick seed coat. Sometimes seeds are soaked in water for a specified time. E.g.: cotton seed or paddy seed is soaked in water before actual sowing. Seed of Lucerne and Indigo is pounded with pestle
.
4. To increase nitrogen fixation in legumes: Legume seeds are inoculated with a particular Rhizobium culture. This is mixed with jaggery solution & applied to seed and dried in shade. It increases nodulation & thereby N fixation.
21. 5. To protect the seed against insect pests: There are some insect pests like ants, white ants, in the soil which attack on seed and eat. Sometimes, seed may be picked up by birds after sowing. To avoid this, seed is treated with repellents like campor, kerosene or soil drenching with insecticides like BHC, heptachlor, etc. E.g.: the carbofuran treatment in Jowar.
22. 6. To induce earliness (Vernalization treatment): This is an important for breeding programme by vernalization treatment. As a result of this, life span is reduced. In this, seed is soaked in water & incipient germination is induced in the form of awakening of the dormant embryo & commencing the changes favoring germination in the endosperm. Such seeds are kept in cold storage for a specified time in which germination power remains intact but the process of germination is temporarily halted. Thus, the plant spends part of its vegetative period or phrase in the form of sprouted seed and the seed so treated as a dormant plant. The period from sowing to flowering is thus greatly reduced & with such adjustment, a variety which is normally a long duration one, can be made to flower early.
23. 7. To induce variation: Seed is treated to induce variation in its morphological & general structure by ‘X’ ray treatment. It changes the genetical make up & helps in selection of desired types.E.g. Sonora, a wheat variety, is the result of Sonora-64 treated with gamma rays.
24. 8. To break dormancy: Some crops are having seed dormancy in fresh harvested produce. Dormancy is the state of rest period of a seed in which it does not germinate even if all the favorable conditions are available for germination. Due to dormancy of seed we cannot use the fresh harvested produce for sowing. It is desirable if the crop get rains at maturity. E.g.: groundnut varieties. This dormancy is broken by treating seed with chemicals. E.g. Thiourea 1% treatment to potato tubers.
25. 9. Seed treatment for special purpose: In vegetatively propagated crops, planting material is treated with growth promoting hormones like colchicines, Gibberellic acid (GA), Indole acetic acid (IAA), Seradix, sometime cattle urine. These promotes sprouting & growth of plant. E.g.: onion bulbs or potato tubers are treated with Malic Hydrazine (MH) for avoiding sprouting and growth of sprouts and thereby reducing losses due to sprouting.
26. Seed treatment in important crops:
27. 1) Sorghum: Thirum or 300 mesh sulphur: Seed is coated in seed dressing drum or earthen pot @ 3.4 g/kg seed against smut disease.
2) Bajara: Brine solution treatment is given @ 20% against eat got and to discard light & diseased seed.
3) Paddy: Seed is treated with brine solution @ 3% against blast of paddy and to discard unfilled seed.
4) Cotton: a) Cow dung slurry treatment: Seed is rubbed with cow dung slurry in 1:1 proportion of dung and soil for convenience in sowing or Seed is delinted by treating the seed with conc. H2SO4 for 2 min. for convenience in sowing. b) Seed is treated with organo mercurial compound like ceresin, agrosan @ 3 g or Thirum @ 5g against seed borne disease like anthracnose.
5) Coriander & Garlic: Seed is rubbed to split the seed for even sowing.
6) Small seeded crops like Sesamum, bajara, tobacco, etc: Seed is mixed with fine sand or soil for even sowing of seed in the field.
7) Potato: a) Seed is dipped in 1% Thiourea solution for breaking the seed dormancy.
b) Seed is dipped in streptomycin solution @ 200 g in 100 lit. Water for 1 hour against Ring rots disease.
8) Legume crops like Mung, Udid, Soybean, Etc.
a) Seed is treated with Thirum @ 3 g/kg seed against seed borne disease.
b) Seed is treated with Rhizobium culture @ 250g/10kg seed for ‘N’ fixation & better nodulation.
9) Sugarcane: a) Hot water treat (500C) or hot air treat. (540C) is given to sets for 2 hrs. Against grassy shoot & other diseases.
b) Sets are treated with OMC 6% @ 500g in 100 lit. Water by dipping for 5 min. against smut & increase germination.
Or Bavistin @ 200g in 100 lit. For 5 min.
10) Wheat & Oilseed crops: Seed is coated with Thirum or Bavistin @ 5 g/kg seed against seed borne diseases.
28. Sowing Of Seed – Sowing Time, Depth of Sowing, Spacing and Plant Population
29. Sowing Time: It is the non monetary inputs which greatly influence the crop growth & yield. Therefore, sowing of crop should be done at recommended dates. Any fluctuation in optimum sowing time results in drastic yield reduction. E.g. Wheat.
30. Depth of Sowing: It is also non-monetary input which decides plant stand in the field. It influences the germination & emergence of seed. Sowing should be done at recommended depth. These vary with the kind of seed and its size. Bigger seeds may be sown at a greater depth while small sized seeds at shallow. Seed should be dropped in the moist zone. In Kharif, sowing should be shallow and in Rabi deeper except pre-sowing irrigation.
31. Spacing and Plant Population: Spacing between the row and within the plants decides the plant stand/plant population per/unit area. Optimum plant population results in normal crop growth & thereby yields. One can manipulate the R/R & P/P distance but care should be taken for maintaining the optimum plant population as per the recommendations. E.g.: Jowar & Bajara 1.37 – 1.5 lakh (45 x 15cm), cotton (irrigated) 12000 (90 – 120 x 60 – 0 cm), sugarcane 5000 (1 M R/R with 25000 sets.), Groundnut (bunch) 2 – 2.5 lakh (30 x 15 cm). A dense population results in competition for nutrients, moisture & light and thereby suppressed growth while less population results in low yield /unit area.
Yield of a crop is the result of final plant population which depends on the no. of viable seeds, germination % and survival rates. An establishment of optimum plant population is essential to get maximum yield. Yield/plant decreases gradually as plant population/unit are is increased. However, the yield/unit area is increased due to efficient utilization of growth factors. Optimum plant population depends on plant size, elasticity, foraging area, nature of the plant, capacity to reach optimum leaf area at an early date & seed rate used.
32. Sowing of Seed – Methods of Sowing
33. Methods of Sowing: The sowing method is determined by the crop to be sown. There are 6 sowing methods which differ in their merits, demerits and adoption. Those are:
1. Broad casting
2. Broad or Line sowing
3. Dibbling
4. Transplanting
5. Planting
6. Putting seeds behind the plough.
34. 1. Broad casting: It is the scattering of seeds by hand all over the prepared field followed by covering with wooden plank or harrow for contact of seed with soil. Crops like wheat, paddy, Sesamum, methi, coriander, etc. are sown by this method.
Advantages:
1) Quickest & cheapest method
2) Skilled labour is not uniform.
3) Implement is not required,
4) Followed in moist condition.
Disadvantages:
1) Seed requirement is more,
2) Crop stand is not uniform.
3) Result in gappy germination & defective wherever the adequate moisture is not present in the soil.
4) Spacing is not maintained within rows & lines, hence interculturing is difficult.
35. 2.Drilling or Line sowing: It is the dropping of seeds into the soil with the help of implement such as mogha, seed drill, seed-cum-ferti driller or mechanical seed drill and then the seeds are covered by wooden plank or harrow to have contact between seed & soil. Crops like Jowar, wheat Bajara, etc. are sown by this method.
Advantages:
1) Seeds are placed at proper & uniform depths,
2) Along the rows, interculturing can be done,
3) Uniform row to row spacing is maintained,
4) Seed requirement is less than ‘broad casting’
5) Sowing is done at proper moisture level.
Disadvantages:
1) Require implement for sowing,
2) Wapsa condition is must.
3) Plant to plant (Intra row) spacing is not maintained,
4) Skilled person is required for sowing.
36. 3. Dibbling: It is the placing or dibbling of seeds at cross marks (+) made in the field with the help of maker as per the requirement of the crop in both the directions. It is done manually by dibbler. This method is followed in crops like Groundnut, Castor, and Hy. Cotton, etc. which are having bold size and high value.
Advantages:
1) Spacing between rows & plants is maintained,
2) Seeds can be dibbled at desired depth in the moisture zone,
3) Optimum plant population can be maintained,
4) Seed requirement is less than other method,
5) Implement is not required for sowing,
6) An intercrop can be taken in wider spaced crops,
7) Cross wise Intercultivation is possible.
Disadvantages:
1) Laborious & time consuming method,
2) Require more labour, hence increase the cost of cultivation,
3) Only high value & bold seeds are sown,
4) Require strict supervision.
37. 4. Transplanting: It is the raising of seedlings on nursery beds and transplanting of seedlings in the laid out field. For this, seedlings are allowed to grow on nursery beds for about 3-5 weeks. Beds are watered one day before the transplanting of nursery to prevent jerk to the roots. The field is irrigated before actual transplanting to get the seedlings established early & quickly which reduce the mortality. Besides the advantages & disadvantages of dibbling method, initial cost of cultivation of crop can be saved but requires due care in the nursery. This method is followed in crops like paddy, fruit, vegetable, crops, tobacco, etc.
38. 5. Planting: It is the placing of vegetative part of crops which are vegetatively propagated in the laid out field. E.g.: Tubers of Potato, mother sets of ginger & turmeric, cuttings of sweet potato & grapes, sets of sugarcane.
39. 6. Putting seeds behind the plough: It is dropping of seeds behind the plough in the furrow with the help of manual labour by hand. This method is followed for crops like wal or gram in some areas for better utilization of soil moisture. The seeds are covered by successive furrow opened by the plough. This method is not commonly followed for sowing of the crops.
40. Systems Approach
41. Management practices are developed for individual crops and recommendations are made for individual crops. The residual effects of individual crops are not considered in crop based recommendations in which resources are not utilized efficiently. To a farmer, instead of a crop, land is a unit & mgt. practices should be for all crops that are to be grown on a piece of land. This approach is applied to agriculture for efficient utilization of at resources, maintaining stability in production and obtaining higher net returns. A system consists of several components which depend on each other.
42. A system is defined as a set of elements or components that are inter related & interacting among themselves.
43. Farming systems represent an appropriate combination of farm enterprises viz. Cropping system, live stock, poultry, fisheries, forestry, bee keeping, sericulture and the means available to the farmer to raise them for increasing profitability.
44. They interact adequately with environment without dislocating the ecological & socio-economic balance on the one hand attempt to meet the national goals on the other.
45. System Approach- Farming System
46. Farm resources – Land, labour, water, capital & infrastructure
Farm enterprises – Dairying, poultry, Honey bee keeping, sericulture, Laculture, Piggery, Sheep & Goat raising, Fishery.
47. Cropping system and Crop rotation: Cropping system represents crop’s (Cropping) patterns used on farm & their interactions with farm resources, other farm enterprises and available technology which determine their makeup. Crops pattern means the proportion of area under various crops at a point of time in a unit area. It indicates yearly sequence and spatial arrangement of crops & fallow in an area.
48. Types of cropping systems:
49. 1) Monocropping/ monoculture: It refers to growing of only one crop on apiece of land year after year. It may be due to climatologically, socio-economic conditions or due to specialization of a farmer in growing a particular crop. E.g.: Rice cultivation in A.P.
50. 2) Multiple cropping: Growing two or more crops on the same piece of land in one calendar year is known as multiple crops.
51. 3) Inter crops: It is growing of two or more crops simultaneously on the same piece of land with a definite row pattern. E.g.: Jowar + Tur, Cotton + Urd/Soyabean. Based on the percent of plant population used for each crop in inter crop’s system, it is divided into two types viz. additive series and replacement series.
a. Additive series: In this one crop is sown with 100% of its recommended population in pure stand which is known as the base crop. Another crop is known as intercrop, is introduced into the base Crop by adjusting or changing crop geometry. The population of intercrop is less than its recommended population in pure stand.
b. Replacement series: In these both, the crops are called component crops. By scarifying certain proportion of population of one component, another crop introduced.
Main objective of intercropping is higher productivity/unit area in addition to stability in production. It utilizes resources efficiently & their productivity is increased.
52. For successful intercropping there are certain important requirements:
1) The time of peak nutrient demands of component crops should not overlap.
2) Competition for light should be minimum among the component crops.
3) Complementary should exist between the component crops.
4) The difference in maturity of component crops should be at least 30 days.
53. System Approach- Types of Cropping
54. 1. Mixed cropping: It is growing of two or more crops simultaneously intermingled without any row pattern. It is a common practice that the seeds of different crops are mixed in certain proportion and are sown. E.g.: Kharif Groundnut + Jowar, Cotton + Mesta (Ambadi), Jowar + Mustard or Wheat + Mustard.
55. 2. Sequence cropping: It is growing of two or more crops in sequence on the same piece of land in a farming year. It Amy is doubles (2 crops), triple (3 crops) or quadruple (4 crops). E.g.: Cotton – Groundnut, Jowar – Wheat, Mung – Rabi Jowar, and Hy. Jowar – Gram. Etc.
56. 3. Relay Cropping: It refers to planting of succeeding crop before harvesting the preceding crop like a relay race where a crop hands over the land to next crop in quick succession. Ratoon cropping or rattooning refers to revising a crop with regrowth coming out of roots or stalks after harvest of the crop. E.g.: Sugarcane or Jowar rattooning.
57. 4. Efficient cropping systems: for a particular farm depend on farm resources, farm enterprises & farm technology. The farm resources include land, labour, water, capita; and infrastructure. When land is limited, intensive cropping is adopted to fully utilize available waer & labour. When sufficient and cheap labour is available, vegetable crops are also included in the cropping system as they require more labour. Capital intensive crops like sugarcane, banana, turmeric, ginger, etc. find a place in the cropping system when capital is not a constraint. In low RF (less than 750 mm/annum) monocropping is followed & when RF is more than 750 mm intercropping is practiced. With sufficient irrigation water, triple, quadruple cropping is adopted when other climatic factors are not limiting. When the farm enterprise includes dairy the cropping system should contain fodder crops as a component.
58. System Approach- Crop Rotation
59. Crop Rotation: It refers to recurrent succession of crops on the same piece of land either in a year or over a longer period of time. It is a process of growing different crops in succession on a piece of land in a specific period of time, with an objective to get maximum profit from least investment without impairing the soil fertility.
60. Characteristics of Crop rotation or Principles of Crop rotation:
61.
62. 1) It should be adaptable to the existing soil, climatic and economic factors.
2) The sequence of cropping adopted for any specific area should be based on proper land utilization. It should be so arranged in relation to the fields on the farm that the yields can be maintained and soil losses through erosion reduced to the minimum.
3) The rotation should contain a sufficient acreage of soil improving crops to maintain and also build up the OM content of the soil.
4) In areas where legumes can be successfully grown, the rotation should provide for a sufficient acreage of legumes to maintain the N supply of the soil.
5) The rotation should provide roughage and pasturage for the live stock kept on farm.
6) It should be so arranged as to help in the control of weeds, plant disease & insect-pests.
7) It should provide for the acreage of the most profitable cash crops adapted to the area.
8) The rotation should be arranged as to make for economy in production & labour utilization exhaustive (potato, sugarcane) followed by less exhaustive crops (oilseeds & pulses)
9) The crops with tap roots should be followed by those which have fibrous root system. This helps in proper & uniform use of nutrients from the soil & roots do not compete with each other for uptake of nutrients.
10) The selection of crops should be problem and need/demand base.
i) According to need of people of the area & family.
ii) On slop lands alternate cropping of erosion promoting and erosion resisting crops should be adopted.
iii) Under Dryland or limited irrigation, drought tolerant crops (Jowar, Bajra), in low lying & flood prone areas, water stagnation tolerant crops (Paddy, Jute) should be adopted.
iv) Crops should suit to the farmer’s financial conditions, soil & climatic conditions.
11) The crops of the same family should not be grown in succession because they act like alternate hosts for insect pests & disease pathogens and weeds associated with crops.
12) An ideal crop rotations is one which provide maximum employment to the family & farm labour, the machines and equipments are efficiently used so all the agril. Operations are done timely.
63. Advantages of Crop Rotation:
64. An ideal crop rotation has the following advantages:
65. 1. There is an overall increase in the yield of crops due to maintenance of proper physical condition of the soil and its OM content.
2. Inclusion of crops having different feeding zones and different nutrient requirements help in maintaining a better balance of nutrients in the soil.
3. Diversification of crops reduces the risk of financial loss from unfavorable weather conditions and damage due to pests & diseases.
4. It facilitates more even distribution of labour.
5. There is regular flow of income over the year.
6. The incidence of weeds, pests and diseases is reduced and can be kept under control.
7. Proper choice of crops in rotation helps to prevent soil erosion.
8. It supplies various needs of farmer & his cattle.
9. Agricultural operations can be done timely for all the crops because of less competition.
‘The supervisory work also becomes easier.”.
10. Proper utilization of all the resources and inputs could be made by following crop rotation:
66. Cropping systems & crop rotations followed in MS & Marathwada:
67. Maharashtra:
1. Cotton – Jowar/ Bjra, Cotton – Jowar – Groundnut.
2. Sugarcane – Rice – Gram.
3. Cotton – Groundnut, Cotton – Jowar/ Bajara – Groundnut.
4. Sannhemp – Sugarcane.
5. Pre Cotton – R.Jowar/ Wheat/ Gram.
6. Rice – Gram.
7. Groundnut – Cotton – Jowar.
Marathwada:
1. Mung – Jowar – Cotton + Tur
2. Sunflower – Jowar.
3.Soybean – Jowar/ Safflower/ Gram.
4. Hy. Jowar – Gram / Sunflower / Safflower.
5. Bajara – Gram, Mung/Urd/ Soybean – R.Jowar, Safflower.
Irrigated:
1. Cotton – Groundnut, Sannhemp – Sugarcane – Groundnut.
2. Rice – Gram/ Sunflower.
3. Hy. Jowar – Wheat/ Jowar/ Gram.
4. Jowar – Sunflower – Groundnut.
5. Sunflower – Potato – Groundnut.
6. Groundnut – Wheat – Vegetables.
7. Sorghum – Wheat – Green gram – Cotton – Groundnut.
8. Bajara – cabbage – Groundnut – Cotton – Groundnut.
68. Syatem Approach- Crop Mixtures or Mixed Cropping
69. It is the process of growing two or more crops together in the same piece of land simultaneously. The cereals are usually mixed with legumes viz. Jowar or Bajara mixed with Tur, udid, Mung, matki or kulthi. Wheat is mixed with peas, gram or mustard; Cotton is grown mixed with Tur or sunflower.
70. The objectives are:
71.
1) To get handy installments of cash returns especially in irrigated crops,
2) To achieve better distribution of labour throughout the year,
3) To utilize available space & nutrients to maximum extent possible,
4) To safe guard against hazards of weather, diseases & pests,
5) To secure daily requirements like pulses, oilseeds, fibers, etc.
6) To get balanced cattle feed.
In order to obtain the maximum benefit from the subsidiary crop mixed with the main crop, it should have the following characteristics: It should
i) Not abstract the growth of the main crop,
ii) Mature earlier or later than of the main crop,
iii) Preferably be a legume,
iv) Have diff. growth habits & nutrient requirements,
v) Have diff. rooting depths & ramification and
vi) Not be very exacting in climatic requirements.
72. Mixed cropping may be:
73.
1) Mixed crops: Mixing of seeds and raising two – three crops at the same time & in same field. E.g.: Jowar/wheat +mustard/ gram.
2) Companion Crops: Different crops are sown in different rows. E.g.: 6 to 8 rows of cotton + 2 to 3 lines of Tur, 4 – 6 rows of Jowar + 1 – 2 lines of Tur, Jowar + Mung/Urd, Jowar + Safflower.
i) Guard crops: Growing hardy or thorny crops (Mesta/Safflower) around the main crop (Jowar/Wheat)
ii) Augmenting crops: Growing sub-groups (augmenting) to maintain the yield of main crop. F. Jowar/Bajara + Cowpea.
74. Syatem Approach- Crop Mixtures or Mixed Cropping
75. It is the process of growing two or more crops together in the same piece of land simultaneously. The cereals are usually mixed with legumes viz. Jowar or Bajara mixed with Tur, udid, Mung, matki or kulthi. Wheat is mixed with peas, gram or mustard; Cotton is grown mixed with Tur or sunflower.
76. The objectives are:
77.
1) To get handy installments of cash returns especially in irrigated crops,
2) To achieve better distribution of labour throughout the year,
3) To utilize available space & nutrients to maximum extent possible,
4) To safe guard against hazards of weather, diseases & pests,
5) To secure daily requirements like pulses, oilseeds, fibers, etc.
6) To get balanced cattle feed.
In order to obtain the maximum benefit from the subsidiary crop mixed with the main crop, it should have the following characteristics: It should
i) Not abstract the growth of the main crop,
ii) Mature earlier or later than of the main crop,
iii) Preferably be a legume,
iv) Have diff. growth habits & nutrient requirements,
v) Have diff. rooting depths & ramification and
vi) Not be very exacting in climatic requirements.
78. Mixed cropping may be:
79.
1) Mixed crops: Mixing of seeds and raising two – three crops at the same time & in same field. E.g.: Jowar/wheat +mustard/ gram.
2) Companion Crops: Different crops are sown in different rows. E.g.: 6 to 8 rows of cotton + 2 to 3 lines of Tur, 4 – 6 rows of Jowar + 1 – 2 lines of Tur, Jowar + Mung/Urd, Jowar + Safflower.
i) Guard crops: Growing hardy or thorny crops (Mesta/Safflower) around the main crop (Jowar/Wheat)
ii) Augmenting crops: Growing sub-groups (augmenting) to maintain the yield of main crop. F. Jowar/Bajara + Cowpea.
Difference between - Inter Cropping & Mixed Cropping
Sr. No
Inter Cropping
Mixed Cropping
1
The main object is to utilize the space left between two rows of main crop
To get at least one crop under favorable conditions
2
More emphasis is given to the main crop
All crops are cared equally
3
There is no competition between both crops
There is competition between all crops growing
4
Inter crops are of short duration & are harvested much earlier than main
The crops are almost of the same duration
5
Sowing time may be same or different
It is same for all crops
6
Crops are sown in different rows without affecting the population of main crop when sown as sole crop
Either sown in rows or mixed without considering the population of either
System Approach- Fallow in Rotation
Fallow: is the practice of allowing crop land to lie idle during a growing season to build up the soil moisture & fertility content so that a better crop can be produced in the following year. A fallow year or season is one in which the field is not cultivated with any crop but left without a crop. The field may be left undisturbed in a ploughed condition or kept clean by frequent cultivations.
It is usually worked periodically to control weeds and improve moisture infiltration.
Points to be considered for planning the crop rotation:
Farmer should consider the following factors while planning the crop rotation
.
1. Net profit.
2. Growth habit & nutrient requirements of different crops.
3. Effect of one crop on the other hand that is succeeding.
4. Soil type & slope &
5. Infestation of weeds, diseases & pests.
These factors should be considered to set the good crop rotation based on these factors; one should also consider the following points:
1. A shallow rooted grain crop, a deep rooted cash crop and a restorative crop should be included in the rotation which will provide food, fodder & cash to the farmer & maintain soil productivity.
2. The selection of crops should be made, taking into consideration soil, climate & market demand.
3. In case of irrigated areas, the rotation should be fixed on the extent of availability of water supply so that 2 or more crops can be taken from the same field in one year.
4. In case of rain fed areas, if sufficient moisture is left over in the soil after the harvest of Kharif crops, some minor crops requiring less moisture like pulses may be grown.
5. Both wide row spaced crops & thickly planted crops should be included.
6. Crops of diverse botanical relationship should be alternated as an insect or disease will attack closely related species but will not injure unrelated species.
7. A logical sequence of crops should be set up making full use of all available information as to effect of each crop in rotation on the succeeding crops to ensure maximum yields & higher quality.
8. Ordinarily, the area devoted to each crop should be consistent acreage from year to year.
9. Enough elasticity may be kept in the rotation.
10. Depending upon the soil type, i.e. more or less fertile, low lying, acidic or alkaline soils, stress should be gien to the crop rotation considering its importance.
11. Importance, location of farm and region base crops should be included in the crop rotation.
12.Legumes should be included in the crop rotation with non-legumes as it is multi advantageous crop such as fixes atmospheric nitrogen, covers the land so prevent erosion, smother weeds.
“Cotton – Sorghum – Groundnut” Is The Best Crop Rotation
This crop rotation shows maximum characteristics of a good crop rotation, such as:
1. All these crops are of diverse botanical relationship which avoids the attack of pests & diseases.
2. It is a three course crop rotation followed in two years.
3. It provides food (Sorghum), fodder (Sorghum & groundnut) and cash (Cotton & Groundnut) to the farmer.
4. It includes a deep rooted cash crop, followed by a shallow rooted grain crop and a restorative crop which maintains the soil fertility.
5. It adds organic matter and there is maximum utilization of residual nutrients.
6. It gives higher net profit per hectare.
7. Nutrient requirement of these crops is different from each crop.
8. Groundnut fixes the atmospheric ‘N’ and increase the soil fertility by adding organic matter.
Criteria Determining Harvesting a Crop and Preparation for Marketing
Harvesting: It is the removal of entire plants or economic parts (grain, seed, leaf, root, or entire plant) after maturity from the field.
Time of harvesting: If the crop is harvested early the produce contains high moisture and more immature grains. Higher moisture results shriveling of seed and infestation of pests. The immature grains lead to low yields and reduce quality as well as germination %. Late harvesting results in shattering of grains, germination when it rains and breaking during processing. Hence, harvesting at correct time essential to get good quality grains & higher yield. Crops can be harvested at physiological or harvest maturity. Crop is considered to be at physiological maturity when the translocation of photosynthates is stopped to economic part. Physiological maturity refers to a developmental stage after which no further increase in dry matter occurs in the economical part. This is important only when a field is to be vacated for sowing another crop otherwise, one should go for harvesting the crop at harvest maturity. Harvest maturity generally occurs 7 dates after physiological maturity with following symptoms:
1. Loss of moisture in grains up to 12 to 14%.
2. Yellowing and dropping of leaves.
3. Drying and change in colour of grains or pods.
4. Life cycle completes which vary with crop to crop and variety.
5. General symptoms in various crops are:
A) CEREALS:
1) Lower leaves turn to yellow straw.
2) Lower & other leaves fall down.
3) Stem turn to straw colour.
4) Pith formation in stem takes place.
5) Grains become hard & fully developed.
6) Moisture % in grain becomes less than 20% on total weight basis.
7) In maize, drying of cob sheath and fibers take place.
B) COTTON: Picking of fully opened & bursted bolls is done in 3 – 4 stages.
C) PULSES:
1) Pods turn to brown,
2) Grains become hard,
3) Shedding of lower older leaves take place.
4) Yellowing of leaves.
D) SUGARCANE:
1) Yellowish colour to crop,
2) Flowers, if flowering variety is planted.
3) Swelling of eye buds,
4) Sweetness of juice,
5) Reads 21 to 24 Bricks Saccharometer reading.
E) GROUNDNUT:
1) Drying of vines.
2) Black colouring to the inner side of pods
3) Reddening or dark colouration to the seed coat,
4) Prominent margins on pod.
F) POTATO:
1) Dropping of leaves and drying,
2) Hardening of tuber.
Determination of harvesting date is easier for determinate crops and difficult for indeterminate crops as it contains flower, immature & mature pods. Therefore, such crop should be harvested when 75% maturity is achieved or periodical harvesting should be done.
Threshing & Winnowing
The threshing is the process of separating fruits or seeds from the plants or ears (cobs/panicle). It is followed by winnowing which consists of separating grain seed from chaff. Threshing methods vary with type of crop. In general these are:
1. Beating with sticks/mallets (safflower, green gram, Urd, etc.)
2. Beating against stone or hard material (harrow body). E.g. Arhar.
3. Trampling under the feet of bullocks or wheels of tractor or bullock cart. E.g. Cereals, pulses,
4. By using threshing machines bullock (olpad), tractor or electric motor drawn. E.g. almost all crops.
After threshing this material is winnowed. The grains are subjected for sun drying before storage or marketing. Sun drying is done by spreading the produce on floor in a thin layer (10cm) for 4 – 5 days and stirred at 2 hrs. Interval to have uniform & quick drying and to lower the moisture up to 12 to 14%. To fetch higher prices for the produce should be graded, baged and sent to market.
Weeds and Their Control
There are 3 serious pests of the crop plants which causes loss of yield, i.e.
1. Insect-pests,
2. Diseases,
3. Weeds.
The estimated losses in crop yields range from 5% in clean cultivated fields over 70% in neglected fields depending upon the degree of weed infestation. They compete with crop plants for nutrients, water, light and space. The loss of ‘N’ through weed is as high as 150 kg/ha.
WEED: Any plant not sown in the field by farmer is out of place, called weed.
The term, ‘weed’ used by Jethro Tull for the first time, suggested an useless and harmful plant that persistently grows where it is quite unwanted.
According to Robinson: Weeds are that species of plants which grow unwanted or are not useful, often prolific, persistent, interfere with agricultural operations, increase labour cost and reduce the crop yields.
Weed is a plant growing where it is not wanted, unwanted plant, out of place, extremely noxious, useless, and poisonous.
Characteristics of weeds:
Weeds are like any other crops plants in size, form, morphological & physiological characters but possess the following characteristics, on account of which they are considered as enemy of crops by the farmer.
1. The weed seeds germinate early and the seedlings grow faster. They being hardy, compete for light, moisture and nutrients.
2. They flower earlier, run to seed in profusion and mature ahead of the crop. They are difficult to control and it may be even impossible to eradicate some weeds completely.
3. They are non-useful, unwanted & undesirable.
4. They are harmful to crops, cattle and human beings.
5. They can thrive even under adverse conditions of soil, climate, etc.
6. They are prolific and have a very high reproduction capacity. E.g.: A plant of satyanashi (Argemone mexicana) produces over 5000 seeds while a plant of striga produces over half a million seeds.
7. Viability of weed seeds remains intact, even if they are buried deep in the soil. In some cases, the seeds may remain viable even after passing through the digestive tract of the animals.
8. The seeds may have special structures like wings, spines, hooks, sticky hair, etc. on account of which they can be easily disseminated over long distances.
9. Many weeds like Cynodon dactyl on are vegetatively propagated and spread rapidly all over the field even under adverse conditions.
Weeds & Their Control- Classification of Weeds
Weeds can be classified in many ways as:
A) Classification based on life cycle:
a) Annuals: Weeds complete their life cycle within a year.
i) Seasonal weeds:
1. Monsoon annuals or Kharif season weeds: Weeds complete their life cycle during Kharif or rainy season. E.g.: Hazardana, kurdu, Aghada.
2. Winter annuals or Rabi season weeds: Weeds complete their life cycle during rabi or during winter season. E.g.: Pisola
ii. Two seasonal weeds: Weeds complete their life cycle within two seasons. E.g.: Jungli gobhi Lunea sp.
b) Biennials: Weeds require two years for completion of their life cycle. E.g.: Wild carrot (Daucus carota)
c. Perennials: Weeds continue their life cycle for years together. E.g.: lavala, hariyali, Kans, lajalu.
B) Classification based on habitat or place of occurrence:
a. Weeds of cropped land: Bathua, Kurdu.
b. Weeds of pastures & grazing lands: Hariyali, Unhali, Kans.
c. Weeds along water channels: Jalkumbhi (Eichhornia crassipes).
d. Weeds along roadside: Tarota, Unhali.
e. Weeds of waste lands: Ber, Sarata, Reshimkata.
f. Weeds of lawn & orchards: Ganja, Ghaneri.g.
g. Weeds of forest lands: Ghaneri, Nagphana.
C) Classification based on dependence on other hosts:
a. Stem parasite: Amerbel
b. Root parasite: Striga on Jowar, Sugarcane, and Bambakhu on Tobacco, Brinjal or Chilli.
c. Independent: Chandvel.
D) Classification based on soil type:
a. Weeds of black soils: Hariyali, Kans, Kunda.
b. Weeds on sandy loam soil: Aghada, Kurdu.
c. Weeds of ill drained soil: Lavala, Panbibi.
d. Weeds in tank: It may be submerged, immersed or floating. E.g.: Aquatic weeds like water hyacinth, cattails.
E) Classification based on plant family:
a. Graminae: Hariyali, Kunda, Kans.
b. Commelinaceae: Kena, vinchu, Panbibi.
c. Cyperaceace: Nagarmotha.
d. Amaranthaceac: Aghada, math, Kurdu.
e. Euphorbiaceae: Dudhi, Pisola, Wild castor.
f. Composite: Gokhuru, Jakham Judi, Gajar Gawat.
g. Leguminous: Lajalu, wild Mung, Unhali.
h. Malvaceae: Petari, wild bhendi.
i. Tiliaceae: Wild jute.
j. Cruciferae: Wild mustard.
k. Chenopodiaceae: Chandan Bathua.
l. Solanaceae: Kamuni, Wild Brinjal.
m. Papaveraceae: Satyanashi, Dhatura.
n. Portulacaceae: Ghol
o. Orobanchaeceae: Bambakhu
p. Cactaceae: Nagphana
Damages Or Losses Caused By Weeds or Disadvantages of Weeds
1. Reduction in crop yield:
Weeds compete for water, nutrients & light. Being hardy & vigorous in growth habit, they soon outgrow the crops & consume large amounts of water & nutrients, thus causing heavy losses in yield. E.g.: 40% reduction in yield of groundnut & 66% reduction in yield of chilli. The loss of N through weeds is about 150 kg/ha.
2. Increase in the cost of cultivation: One of the objects of tillage is to control weed on which 30% expenditure is incurred and this may increase more in heavy infested areas & also cost on weed control by weeding or chemical control. Hence, reduce margin of net profit.
3. Quality of field produce is reduced: Weed seeds get harvested & threshed along the crop produce which lowers the quality. Such produce fetches fewer prices in the market. E.g.: Leafy vegetables, grain crop.
4. Reduction in quality of livestock produce: Weeds impart an undesirable flavor to the milk (Ghaneri), impair quality of wool of sheep (Gokhuru, Aghada), and cause death of animals due to poisonous nature of seed (Dhatura).
5. Harbour insect-pests & disease pathogens: Weeds either give shelter to various insect pests & disease pathogens or serve as alternate hosts & thus helps in perpetuating the menace from pests & diseases. E.g.: Gall fly of paddy, midge fly of Jowar, leaf minor of soybean & Groundnut, rust of Wheat, tikka of Groundnut, Black rust of wheat ,Downey mildew (Saccharum spontaneum).
6. Check the flow of water in irrigation channels: Weeds block drainage & check the flow of water in irrigation canals & field channels thereby increasing the seepage losses as well as losses through over through over flowing, so reduce the irrigation efficiency.
7. Secretions are harmful: Heavy growth of certain weeds like quack grass (Agropyon repens) or lavala lowers the germination & reduce the growth of many crop plants due to presence of certain phytotoxins secreted by weeds.
8. Harmful to human beings and animals: Weeds cause irritation of skin allergy & poisoning to human beings, also death of castles.
9. Cause quicker wear & tear of farm implements: Being hardy & deep rooted; the tillage implements get worn out early & cannot work efficiently unless they are properly sharpened or mended.
10. Reduce value of the lands: Heavily infested lands with perennial weeds fetch less price as require heavy expenditure to brought under cultivation.
Benefits Or Advantages Derived From Weeds:
1. Weeds when ploughed under, add nutrients, organic matter.
2. Weeds check winds or water erosion by soil binding effect of their roots (undirkani).
3. Useful as fodder for castles (Hariyali) & vegetable by human beings (Ghol, Tandulja).
4. Have medicinal value, Leucas aspera isused aga9inst snake bite, oil of satyanashi seed is useful against skin diseases, nuts of lavala are used in making scents (Udabattis/Incense sticks).
5. Have economic importance e.g.: saccharum spp used for makingthatches.
6. Reclamation of alkali lands (Satyanashi).
7. Serve as ornamental plants (Ghaneri).
8. Used for fencing (Cactus, Nagphana).
9. Used as mulch to check the evaporation losses of water from soil.
10. Used as green manuring & composting.
11. Fix atmospheric ‘N’ (Blue green algae, Tarota, Unhali, etc.)
Dispersal Or Dissemination Or Spread Of Weeds
Agencies responsible for dissemination are:
1. Wind: Seeds may be very small & light, equipped with parachute like arrangement, plumes or fuzz. They blow by wind to along distance. E.g.: Seeds of Rui/Ruchki, Striga, Gajar Gawat.
2. Water: The irrigation canals, drainage channels, surface runoff, flood water of rivers & streams carry weed seeds.
3. Animals like wild & domestic: Weeds having hooks (Gokhuru), twisted awns, spines, etc. E.g.: Ghaneri, weeds of Graminae family.
4. Man: Man disperse the weeds indirectly through compost (partially decomposed), feeding castles with hay or fodder having weed plants, using uncleaned farm machinery. E.g.: Ghaneri, weeds of Graminae family.
5. Crop weed: During harvesting, they get mixed with produce. E.g.: Jungli dhan, Bharad in rice and phallaris in wheat.
Principles Of Weed Control
For successful control, one has to consider the following points:
1. Habits of weed plants:
A xerophytes weed (E.g. Alhagi camelorum) thriving under dry & arid conditions will die if fields are flooded with water. Similarly weeds which thrive under marsh or ill drained condition of soil can be controlled by improving drainage.
2. Life cycle of the weed: Annuals & biennials can be controlled effectively if the land is cultivated before seedling stage of weeds. Perennials require deep ploughing to dig out rhizones, bulbs, etc. vegetative part by which they propagate.
3. Susceptibilities: Some weeds are susceptible to certain chemicals while others are not. E.g.: Dicots are susceptible to 2, 4-D while monocots are not, hence 2,4-D is used to control broad leaved weeds in monocot crops.
4. Dormancy period: While controlling dormancy weeds, period is to be considered as they have long dormancy period.
5. Resistance to adverse conditions without losing viability: Some weed seeds have hard seed coats which enable them to remain for a long time without losing their viability, hence they should be controlled before seed formation.
6. Methods of reproduction: Weeds propagate either by seeds, vegetative parts or by both. Seeded weeds should be removed or smothered before seed formation. Vegetatively propagated weeds should be exposed to sun heat to dry & die like rhizome, bulbs, solons, etc. by deep ploughing. Frequent cultivation leads to destroy green leaves & thereby exhaust the food reserves & starve the plants may have to be restored too. In weeds propagated by both mechanical & chemical methods may have to be followed.
7. Dispersal of seeds: Weeds can be controlled or kept in check if the ways in which different weed seeds disseminate are known and counter measures are undertaken.
Weed Control Methods
Broadly classified in two groups:
A)Preventive Measures.
B) Curative or Control Measures which includes:
i. Mechanical
ii.Cropping or Cultural
iii.Biological &
iv.Chemical
A) Preventive Measures: In this, the weeds are prevented from its multiplication, introduction & nipped off the buds. It consists of:
1) Use clean seed,
2) Use well decomposed FYM/Compost,
3) Cut the weeds before seeding,
4) Remove weed growth or keep irrigation & drainage channels clean or free from seeds,
5) Avoid feeding of grain screenings, hay or fodder containing weed seeds without destroying their viability by grinding or cooking,
6) Avoid use of sand or soil from weed infested areas to clean or cultivated areas,
7) Avoid allowing castles to move from weed infested areas to clean or cultivated areas,
8) Clean all the farm implements & machinery properly after their use in infested areas & before using in clean areas,
9) Keep farm fences, roads & bunds clean or free from weeds.
10) Watch seedlings in nurseries carefully so that they do not get mixed with weed seedlings & get carried to the fields.
B) Curative Measures: These measures are followed to remove or to smother the weed growth & further multiplication. It includes:
i) Mechanical methods (Physical): It comprises:
1) Hand pulling;
2) Hand weeding;
3) Burning;
4) Flooding;
5) Hoeing;
6) Tillage;
7) Moving;
8) Smothering with non-living material (mulching). Burning of seed bed is called as ‘rabbing’.
ii) Cropping and competition methods (Cultural): “One who establish first/early, will suppress other.” Therefore, the cultural practices are so managed that the crop plants should establish early and grow faster ahead of the weeds.
It includes:
1) Crop roations: It checks the free growth of weed due to change of crops season to season.
2) Kind of crop: Groundnut covering crops like legumes will smother the weed growth. E.g.: sun hemp, groundnut.
3) Use of fertilizers: Application of optimum doses of fertilizers to crop will help to grow faster.
4) Date & rate of planting or sowing: Sowing of crops at proper time with optimum seed rate will help the crop to cover the ground & will make the weeds deprive of light.
iii) Biological methods: It includes the use of living organisms for suppressing or controlling the weeds. Plant, animal or micro organisms may be used for destruction of weeds. These are called as bioagents which feed on only the weeds and not on crop plants. E.g.: Prickly pear or Nagphana weed in South India was controlled by Conchineal insects. (Dactlopius tomentosus). In Australia (Hawaii Islands) several kinds of moths were used to control Lantana Camara which eats the flowers & fruits. This method is very efficient & economical provided right type of predators, parasites or pathogens which even under starvation conditions will not feed upon cultivated crops are found out & introduced.
iv) Chemical methods: This is very effective in certain cases and has a great scope provided the chemicals are cheap, efficient & easily available. The chemicals used for weed control & which suppress or destroy the growth of weeds, called as herbicide. These either help in killing the weeds or in inhibiting their growth.E.g.2, 4-D, Atrazine, Glyphosate, etc.
Types of herbicide:
i) Selective herbicides are those which kill only weeds without injuring crop plants.
ii) Non-selective herbicides are those which kill all kinds of vegetations i.e. weed and crop plant.
iii) Contact herbicides kill all the plant parts which may get covered by the chemical by directly killing the plant cells. These chemicals are effective against annuals particularly when they are young but not perennials.
iv) Translocated/Systemic herbicides are first absorbed in the foliage or through roots and are then translocated to other parts of the plant. Or Kill plants after their absorption by accelerating or retarding the metabolic activities of plants. These are more effective in destroying deep rooted perennials.
Soil sterilents: are non-selective herbicides and have to be applied into the soil. They make the soil sterile and incapable of supporting any plant growth. As such any weed seeds or weed seedlings present in the soil are killed.
Based on relative time of application to weed emergence the herbicides are classified as:
I) Pre-plant applied (Before planting of crop)
II) Pre-emergence (Before emergence of weeds)
III) Post-emergence (After emergence of weeds)
Acid equivalent (a.e.) refers to that part of the formulation that theoretically can be converted into the acid.
Active ingredient (a.i.) is that part of the chemical formulation which is directly responsible for the herbicidal effects.
Pre and post-emergence treatments to control weeds: Both the terms, Pre and post-emergence treatments are related with time of application of herbicides for control of weeds.
Pre-emergence treatment or application of herbicides: Application of herbicides after sowing of crop but before emergence of crop and weeds is called pre-emergence application. It is done from first to fourth day of sowing and only selective herbicides are used. Generally germinating weeds are killed by pre-emergence application and gives competitive advantage of crop. E.g.: Pre-emergence application of Atrazine @ 0.5 to 2.5 kg/ha in sugarcane, Jowar, Alachlor @ 1.5 to 2.5 kg ai/ha in Groundnut, Duiron @ 2.0 kg ai/ha or Oxadiazon @ 1.5 kg ai/ha in cotton.
Post-emergence application of herbicides: Application of herbicides after emergence of crop is called post-emergence application. It is generally resorted to when the crop has grown sufficiently to tolerate herbicides and to kill weeds that appear late in the crop. Generally, it is done about 30-40 days after sowing. For example, application of Stam F34 @ 2 kg/ha or MCR 1 kg/ha in paddy 3 weeks after transplanting, 2,4-D @ 0.4 kg/ha in Wheat after 4-8 leaf stage, Pendimethalin @ 0.75 to 2.0 kg ai/ha in rice after 3-5 DAT, Isoproturon @ 1.0 kg ai/ha 30 – 35 days after sowing of Wheat.
Soil Fertility And Productivity
Soil fertility: is the capacity/ability of the soil to supply the plant nutrients required by the crop plants in available and balanced forms. Or
It is the capacity of soil to produce crops of economic value to man and maintain the health of the soil for future use. Or
The soil is said to be fertile when it contains all the required nutrients in the right proportion for luxuriant plant growth.
Plants like animals and human beings require food for growth and development. This food is composed of certain chemical elements often referred to as plant nutrients or plant food elements. These nutrients are obtained from soil through roots.
Plants need 16 elements for their growth and completion of life cycle. In addition to these, 4 more elements viz. sodium, vanadium, cobalt and silicon are absorbed by some plants for special purposes.
Classification and source of nutrients:
Class Nutrient Source
Basic C, H, O Air and water
Macro N, P, K, Ca, Mg, S Soil
Micro Fe, Mn, Zn, Cu, B, Mo & CI Soil
Four more recognized nutrients are NA, Co, VA & SI.
Basic nutrients (C, H, and O) constitute 96% of total dry matter of plants. Macro (Major) nutrients (primary-N, P, K, and secondary-Ca, Mg, S) are required in large quantities while Micro nutrients (Trace elements-Fe, Zn, Cu, B, Mo, Cl, and Mn) are required in small quantities. These trace elements are very efficient and minute quantities produce optimum effect. On the other hand, even a slight deficiency or excess is harmful to plants.
Function of the plant:
Elements that provide basic structure to the plant – C, H, O.
Elements useful in energy storage, transfer and bonding – N, S & P. these are accessory structural elements which are more active and vital for living tissues.
Elements necessary for change balance – K, Ca & Mg, act as regulators and carrier.
Elements involved in enzyme activation and electron transports. Fe, Mg, Cu, Zn, B, Mo & Cl are catalysers and activators.
Criteria of Essentlailty: Armon and Stout (1939) proposed criteria of essentiality which was refined by Arnon (1954) as:
The plant must be unable to grow normally or complete its life cycle in the absence of the element.
The element is specific and cannot be replaced by another.
The element plays a direct role in metabolism and
The deficiency symptoms of the element can be corrected or prevented by application of that element only.
In general, an element is considered as essential, when plants can’t complete vegetative or reproductive stage of life cycle due to its deficiency when this deficiency can be corrected or prevented only by supplying this element and when the element is directly involved in the metabolism of the plant.
Nicholas (1961) proposed the term functional nutrient for any mineral nutrient that functions in plant metabolism whether or not its action is specific. E.g.: Na, Co, Va and Si.
Soil fertility denotes the capacity of the soil to produce crops of economic value and maintain the health of the soil for future use. Or
It is the capacity of soil to supply essential nutrients to normal plants in adequate amounts and in a balanced proportion.
Or
It is better to cultivate small piece of fertile land than large nutrient needs of the crop. Or The soil is said to be fertile when it contains all sixteen of the required nutrients in the right proportion for luxuriant plant growth.
Manures and Fertilizers
Plant requires food/nutrients/elements for its growth and development which are absorbed through soil. The nutrient supplying sources are manures and fertilizers. Application of manures and fertilizers to the soil is one of the important factors which help in increasing the crop yield and to maintain the soil fertility. N, P and K are the 3 major elements required for the crop growth.
Manure: It is a well decomposed refuse from the stable and barn yards including both animal excreta and straw or other litter. Or
The term manure implies to the any material with the exception of water which when added to the soil makes it productive and promotes plant growth.
Fertilizers: These are industrially manufactured chemicals containing plant nutrients. Or
It is an artificial product containing the plant nutrients which when added to soil makes it productive and promotes plant growth.
Difference between Manures and Fertilizers:
Sr No
Characteristics
Manures
Fertilizer
1
Origin
Plant or animal origin
Chemical synthesized or manufactured
2
Nature
Organic in nature
Inorganic in nature
3
Type
Natural product
artificial product
4
Conc. Of nutrients
less concentrated
More concentrated
5
Material
Supply organic matter
Supply inorganic matter
6
Nutrient availability
slowly available
May or may not be readily available
7
Nutrients
Supply all the primary nutrients including Micronutrient
Supply specific type of nutrients one, two or three. micro nutrients may or may not be present
8
Effect on Soil Health
Improves physical condition of soil
Do not improve the physical condition of soil
9
Effect on plant growth
No bad effect when applied in large quantities.
Adverse effect on plant whenever there is deficiency or excessive application
Classification Of Manures And Fertilizers
Manures and fertilizers may be:
1. Natural or
2. Artificial.
1. Natural Or Organic Manures: Natural manures are those which are bulky in nature and supply nutrients in small quantities and organic matter in large quantities.
These are two types:
1. Bulky organic and
2. Concentrated org. manures.
1. Bulky OM: These are those which contain small percentage of nutrients and are applied in large quantities. E.g.: Farm Yard Manure (FYM), compost, Night soil, sludge and sewage, sheep and goat manure (Folding), Poultry dropping, Green manures, etc.
2. Concentrated OM: These are those which are organic in nature and contain higher percentage major plant nutrients like N, P and K as compared to bulky OM. These are made from materials of animal and plant origin. The examples of manures of plant origin are oilseed cake which may be edible or non-edible. Edible oil seed cakes are Groundnut cake, Linseed cake, Sesamum cake, Safflower cake (decort). Non-edible oil seed cakes are castor cake, Neem cake, Safflower cake (undercoat). The examples of manures of animal origin are Bone meal, Fish meal, Meat meal and blood meal.
A. Bulky Organic Manures:
a) Farm Yard Manure (FYM): FYM is a mixture of cattle dung, urine, litter or bedding material, portion of fodder not consumed by cattle and other domestic wastes like ashes, etc. collected and dumped into a pit or a heap in the corner of the back yard. Or
FYM refers to the decomposed mixture of dung and urine of farm animals along with the litter (bedding material) and left over material from roughages or fodder fed the cattle.
Because of the varied nature of the material, the composition of the manure itself varies widely but on an average well rotted FYM contains 0.5% N, 0.2%, P2O5 and 0.5% K2O. It also influences by various factors.
Factors Influencing The Composition of FYM
1) Source of manure: Composition of manures varies with kind of animal producing it. Poultry droppings is the richest followed by sheep manure for nutrient contents. Dung contains phosphate while urine contains N and K2O. Amount of urine soaked in bedding material also decides the composition and vary with kind of animal.
2) Food of the animal: The richer the food in proteins, the richer will be the manure in ‘N’ which comes out in the dung and urine.
3) Age and condition of the animal: Young animals need more proteins to build up their body; hence manure is poorer in N content than old animals. Manure of sick animal is richer than healthy animals.
4) Function of the animals: Milch cantles utilize proteins for milk production; hence manure is poor in N, P & K content than draft purpose animals as they utilize more carbohydrates.
5) Nature & proportion of litter: The composition of litter varies with the kind of straw and hence will affect the quality of manure. Bajara stalks are rich in N, P & K followed by wheat & maize.
6) Preservation: Under ordinary storage, there are losses of N. Potash get lost due to leaching when the manure is too moist.
There are 3 methods of FYM preparation:
1. Heap,
2. Box and
3. Pit or Trench method.
Compost & Composting
Compost is the well rotted plant and animal residue. Composting means rotting of plant & animal remains applying in fields. It is largely a biological process in which micro-organism of both the types, aerobic and anaerobic, decompose organic matter and lower the Carbon: Nitrogen (C: N) ratio of refuse.
Compost making is the process of decomposing plant residues in a heap or pit rather than in the soil with a view to bring the plant nutrients in more readily available form. The essential requirements of decomposing are air, moisture, optimum temp. And a small quantity of ‘N’.
Types of Compost/Methods of Composting:
Based on the composting material used and the composition of the final product, composting methods are classified in two types:
1. Farm or Rural Compost
2. Town or Urban compost.
Green Manuring
It is a practice of ploughing in the green plant tissues grown in the field or adding green plants with tender twigs or leaves from outside and incorporating them into the soil for improving the physical structure as well as fertility of the soil. It can be defined as a practice of ploughing or turning into the soil, undecomposed green plant tissues for the purpose of improving the soil fertility.
The object of green manuring is to add an organic matter into the soil and thus, enrich it with ‘N’ which is most important and deficient nutrient.
Types of green manuring: There are two types of green manuring:
1. Green manuring in-situ: When green manure crops are grown in the field itself either as a pure crop or as intercrop with the main crop and buried in the same field, it is known as Green manuring In-situ. E.g.: Sannhemp, Dhaicha, Pillipesara, Shervi, Urd, Mung, Cowpea, Berseem, Senji, etc.
These crops are sown as:
i) Main crop,
ii) Inter row sown crop,
iii) On bare fallow, depending upon the soil and climatic conditions of the region.
2. Green leaf manuring: It refers to turning into the soil green leaves and tender green twigs collected from shrubs and tress grown on bunds, waste lands and nearby forest area. E.g.: Glyricidia, wild Dhaicha, Karanj.
Characteristics/desirable qualities of a good manuring:
1. Yield a large quantity of green material within a short period.
2. Be quick growing especially in the beginning, so as to suppress weeds.
3. Be succulent and have more leafy growth than woody growth, so that its decomposition will be rapid.
4. Preferably is a legume, so that atm. ‘N’ will be fixed.
5. Have deep and fibrous root system so that it will absorb nutrients from lower zone and add them to the surface soil and also improve soil structure.
6. Be able to grow even on poor soils.
Stage of green manuring: A green manuring crop may be turned in at the flowering stage or just before the flowering. The majority of the G.M. crops require 6 to 8 weeks after sowing at which there is maximum green matter production and most succulent.
Advantages of green manuring:
i) It adds organic matter to the soil and simulates activity of soil micro-organisms.
ii) It improves the structure of the soil thereby improving the WHC, decreasing run-off and erosion caused by rain.
iii) The G.M. takes nutrients from lower layers of the soil and adds to the upper layer in which it is incorporated.
iv) It is a leguminous crop, it fixes ‘N’ from the atmosphere and adds to the soil for being used by succeeding crop. Generally, about 2/3 of the N is derived from the atmosphere and the rest from the soil.
v) It increases the availability of certain plant nutrients like P2O5, Ca, Mg and Fe.
Disadvantages of green manuring:
i) Under rain fed conditions, the germination and growth of succeeding crop may be affected due to depletion of moisture for the growth and decomposition of G.M.
ii) G.M. crop inclusive of decomposition period occupies the field least 75-80 days which means a loss of one crop.
iii) Incidence of pests and diseases may increases if the G.M. is not kept free from them.
Application of phosphatic fertilizers to G.M. crops (leguminous) helps to increase the yield, for rapid growth of Rhizobia and increase the ‘P’ availability to succeeding crop.
Artificial Or Chemical Or Inorganic Fertilizers
These can be classified as:
1) Straight fertilizers: These are those which supply only one primary plant nutrient, viz. N, P or K. Depending upon the nutrient present in the fertilizer, these are classified as:
a) Nitrogenous fertilizers: These are those which contain and supply only the nitrogen. Or are those fertilizers that are sold for their ‘N’ content and manufactured on a commercial scale.
These are classified into 4 groups on the basis of the chemical form in which ‘N’ is combined with other elements in a fertilizer (Chemical form of ‘N’).
i) Nitrate form (NO3): Sodium nitrate (Chilean nitrate), Calcium nitrate, Potassium nitrate and Nitrate of Soda Potash.
ii) Ammonical form (NO3): Ammonium sulphate, Ammonium Chloride and Anhydrous ammonia.
iii) Nitrate & ammoniacal form: Ammonium Nitrate, Calcium Ammonium Nitrate & Ammonium sulphate nitrate.
iv) Amide form (Cn2 or NH2): Calcium cynamide, Urea and Sulphur coated urea.
b) Phosphatic fertilizers: These are those which contain and supply only the ‘P’. P content in fertilizers is expressed in oxidized form, phosphorus pent oxide (P2O5) while its content in soil and plant is expressed in elemental form as ‘P’. The conversion factors for elemental to oxidized form and vice versa are 2.29 and 0.43, respectively.
These can be divided into 3 groups based on their availability to crop and solubility.
i) Containing water soluble phosphoric acid: Fertilizers are available in the form of mono calcium phosphate or ammonium phosphate. E.g.: single super phosphate, double super phosphate and triple super phosphate.
ii) Containing citric acid soluble phosphoric acid: These fertilizers contain citrate soluble phosphoric acid or dicalcium phosphate. E.g.: Basic slag, Di-calcium phosphate.
iii) Containing phosphoric acid not soluble in water or citric acid: E.g.: Rock phosphate, raw bone meal, steamed bone meal.
c) Potassic fertilizers: These are those which contain and supply only the ‘K’. Potassium in the fertilizer is expressed as K2O (Potassium oxide). The conversion factor to express in elemental factor (K) is 0.83 and oxide form is 1.2.
These are grouped in two as:
a. Chloride form: - E.g. Muriate of potash or pot. Chloride.
b. Non chloride form: - E.g. Potassium Sulphate, Potassium Magnesium sulphate, Potassium nitrate.
2) Complex or Compound fertilizers: These are those which contain two or three primary plant nutrients of which two primary nutrients are in chemical combination. E.g.: Diammonium phosphate, Nitro phosphates, Ammonium phosphate, Potassium nitrate, Ammonium Sulphate phosphate, Ammonium Nitrate phosphate, Ammonium Potassium phosphate.
a. Fertilizer mixtures/Mixed fertilizers: These are physical mixtures of straight fertilizers containing two or three primary plant nutrients.
These are made by thoroughly mixing the ingredients either mechanically or manually. Fertilizer grade refers to the guaranteed minimum percentage of N, P2O5 and K2O contained in fertilizer materials. E.g.: 20:20:0, 28:28:0, 18:18:10, 14:25:14, 17:17:17, 14:28:14 and 18:8:9, etc.
b. Micro nutrient fertilizers: These are the nutrients which supply the nutrients required in smaller quantities. These are the chemicals which supply the elements required by the plant in very small quantity. E.g.: Copper Sulphate, Zinc Sulphate, Borax, Sodium Borate, Manganese Sulphate, Sodium Molybdate, Ammonium Molybdate, Ferrous Sulphate, etc.
c. Soil amendments: These are those which improve the soil by correcting its acidic or saline, or alkaline conditions and neutralizing the injurious effects that may result from improper use of fertilizer. E.g.: Lime, Gypsum, Sulphur, and Molasses. These are the substances that influence the plant growth favourably by producing the soil one or more of the following beneficial effects:
1. Changing the soil reactions i.e. making the soil less acidic (Lime) or less alkaline (Gypsum).
2. Changing the plant nutrients in the soil from unavailable forms.
4. Improving the physical condition of soil (Molasses).
5. Correcting the effects of injurious substance.
d. Bio-fertilizers/Microbial innoculents: It may be defined as preparation containing live or latent cells of the efficient strains of N fixing, phosphate solubilizing or cellulytic micro organisms.
These are used for application to seed, soil or decomposing areas to increase the no. of such certain microbial process to make the nutrients in available form to plants such as Rhizobium, Azotobacter, Azospirillum, Blue-green algae and Azolla.
Fertilizer Mixtures (FM)
When two or more fertilizers are mixed together to supply two or three major elements i.e. N, P2O5 and K2O is known as fertilizer mixture or Mixed fertilizer. Or
A mixture of two more straight fertilizer materials is referred to as fertilizer mixture. Sometimes, complex utilizes containing two plant nutrients are also used in formulating fertilizer mixtures. Complete fertilizer refers to the fertilizers containing 3 major plant nutrients, N, P2O5 and K2O.
Types of fertilizers: There are two types of fertilizer mixtures:
a. Open formula fertilizer mixtures: The formulae of such fertilizers in terms of kinds and quantity of the ingredients mixed are disclosed by the manufacturers.
b. Closed formula fertilizer mixtures: The ingredients of straight fertilizers used in such mixtures are not disclosed by the manufacturers.
Materials used in fertilizer mixtures: Different materials go in to production of mixed fertilizers. In accordance with their principle function in the mixture, the materials can be grouped into:
1. Suppliers of plant materials: These are the straight fertilizers added to supply the plant nutrients mentioned in the grade, thus, are the primary materials most essential for preparing mixed fertilizers.
2. Conditioners: These are the organic substances which prepare the fertilizer mixture in good drilling condition and reduce caking. E.g.: Tobacco stems, Peat, Groundnut hulls and paddy hulls (Husks), bone meal, oilcakes.
3. Neutralizers of residual acidity: The substances used to neutralize the residual effects are known as neutralizers. For example, if the ‘N’-ous fertilizers used are acididic in nature like Amm. Sulphate, Urea, a basic material like lime stone is added to counteract the acidity.
4. Filler: Filler is the make – weight material added to a fertilizer mixture. It is added to make up the differences between the weight of the added fertilizers required to supply the plant nutrients and the desired quantity of fertilizer mixture, such as sand, soil, ground coal ashes, sawdust and other waste products.
5. Secondary and micro – nutrients: Some times, secondary and micro – nutrient carrying fertilizers are added to correct its deficiency.
An expression indicating the % of plant nutrient in a fertilizer mixture is termed as fertilizer grade and the relative proportion of major plant nutrients in the mixed fertilizer taking ‘N’ as one, called as fertilizer ratio. For example, in a fertilizer mixture of 6:12:6 grades, the fertilizer ratio is 1:2:1.
The low analysis fertilizers contain less than 25% of primary nutrients and the high analysis fertilizers contain more than 25% of primary nutrients. On the other hand, the low analysis mixed fertilizers contain less than 14% sum of the primary nutrients and high analysis mixed fertilizers contain more than 14% sum of the primary nutrients.
Advantages:
1. The balanced fertilizer mixture suited to crop and soil can be supplied,
2. All the required nutrients can be supplied at one time by the application of fertilizers mixture and thus, time and labourers are saved.
3. Storage and handling costs are reduced.
4. Micro nutrients can be incorporated.
5. Mixtures have better physical condition and are easier for application.
6. Residual acidity can be neutralized by using neutralizers in mixture.
Disadvantages:
1. The cost of plant nutrients is higher than straight fertilizers.
2. All only one nutrient is required by the crop, the fertilizer mixtures are not useful and sometimes farmers may add nutrients in excess or in limited quantity.
Precautions To Be Taken While Preparing Fertilizer Mixtures
1. Do not mix the fertilizer containing ammonia like Amm. Sulphate with basically reactive fertilizers like lime, basic slag, Rock Phosphate and Calcium Cynamide as losses of ‘N’ may result through escape of gaseous ammonia.
2. Do not mix water soluble phosphatic fertilizer (Super Phosphate) with the fertilizer containing free lime (basic slag, Calcium Cynamide) as this coverts the portion of soluble phosphate into soluble phosphate.
3. Do not mix fertilizers which are easily soluble and hygroscopic like urea, Calcium Ammonium Nitrate with other fertilizers because they will form lumps. The fertilizer mixtures are made manually or in the factory, having the grades 6:12:0, 12:6:0, 9:9:0, 9:9:5, 15:5:5, 10:5:5, etc.
Formulation of FM: The quantity of fertilizers for fertilizer mixture can be calculated by
Q = M * T \ F
Where Q = Quantity of fertilizers to be calculated
M = Total quantity of mixture to be prepared.
T = Parts of nutrients in the fertilizer grade.
F= % of nutrients in the supplier fertilizer.
Unit value of fertilizers: One percent of N, P or K present in one tone of a fertilizer is treated as one unit. A unit is thus equal to 10kg.
The unit value of plant food in a fertilizer is the price of one tone of fertilizers divided by the percentage content of that particular nutrient.
Unit value = Price of 1 tonne fertilizers/ % of nutrient in the fertilizer
The fertilizer having a lower unit value will be cheaper than a fertilizer having a higher unit value. It is made use in determining the price of fertilizer mixtures containing N, P and K and in comparing the cost of 2 or 3 fertilizers providing same nutrient.
Methods Of Fertilizer Application
In order to get maximum benefit from manures and fertilizers, they should not only be applied in proper time and in right manner but any other aspects should also be given careful consideration. Different soils react differently with fertilizer application. Similarly, the N, P, K requirements of different crops are different and even for a single a crop the nutrient requirements are not the same at different stages of growth. The aspects that require consideration in fertilizer application are listed below:
1. Availability of nutrients in manures and fertilizers.
2. Nutrient requirements of crops at different stages of crop growth.
3. Time of application.
4. Methods of application, placement of fertilizers.
5. Foliar application.
6. Crop response to fertilizers application and interaction of N, P, and K.
7. Residual effect of manures and fertilizers.
8. Crop response to different nutrient carrier.
9. Unit cost of nutrients and economics of manuring.
Fertilizers are applied by different methods mainly for 3 purposes:
1. To make the nutrients easily available to crops,
2. To reduce fertilizer losses and
3. for ease of application.
The time and method of fertilizer application vary in relation to
1) The nature of fertilizer.
2) Soil type and
3) The differences in nutrient requirement and nature of field crops.
Application of fertilizers in solid form: It includes the methods like (See chart):
I) Broadcasting: Even and uniform spreading of manure or fertilizers by hand over the entire surface of field while cultivation or after the seed is sown in standing crop, termed as broad casting. Depending upon the time of fertilizer application, there are two types of broadcasting:
A) Broadcasting at planting and
B) Top dressing.
A) Broadcasting at planting: Broadcasting of manure and fertilizers is done at planting or sowing of the crops with the following objectives:
1) To distribute the fertilizer evenly and to incorporate it with part of, or throughout the plough layer and
2) To apply larger quantities that can be safely applied at the time of planting/sowing with a seed-cum-fertilizer driller.
It is adopted with the following condition:
1) When N-ous fertilizers like amm. Sulphate, Amm. Sulphate Nitrate, Concentrated organic manures, are to be applied to the soil deficient in N or where N is exhausted by previous crops like fodder, Jowar, F. maize.
2) When citrate soluble P-tic fertilizers like basic slag and dia-calcium phosphate, are to be applied to moderately acid to strongly acid soils.
3) When K-ssic fertilizers like Muriate of potash and potassium sulphate are to be applied in potash deficient soil.
B) Top dressing: Spreading or broadcasting of fertilizers in the standing crop (after emergence of crop) is known as top-dressing. Generally, NO3 – N fertilizers are top dressed to the closely spaced crops like wheat, paddy. E.g.: Sodium Nitrate, Amm. Nitrate and urea, so as to supply N in readily available from the growing plants. The term side dressing refers to the fertilizer placed beside the rows of a crop (widely spaced) like maize or cotton. Care must be taken in top dressing that the fertilizer is not applied when the leaves are wet or it may burn or scorch the leaves. The top dressing of P and K is ordinarily done only on pasture lands which occupy the land for several years.
In some countries, aero planes are used for fertilizer application in hill terrains where it is difficult to transport fertilizers and where large amount are to be applied because of severe deficiency and under following situations:
1. Where very small quantities of fertilizers are needed over large areas. E.g.: Micro nutrients.
2. When high analysis materials are applied.
3. When fertilizer application may be combined with insect control or some other air operation and
4. As a labour and time saving device.
II) Placement: In this, the fertilizers are placed in the soil irrespective of the position of seed, seedling or growing plant before or after sowing of the crops. It includes:
1. Plough sole placement: The fertilizer is placed in a continuous band on the bottom of the furrow during the process of ploughing. Each band is covered as the next furrow is turned. By this method, fertilizer is placed in moist soil where it can become more available to growing plants during dry seasons. It results in less fixation of P & K than that which occurs normally when fertilizers are broadcast over the entire soil surface.
2. Deep placement or sub-surface placement: In this method, fertilizers like Amm. Sulphate and Urea, is placed in the reduction zone as in paddy fields, where it remains in ammonia form and is available to the crop during the active vegetative period. It ensures better distribution in the root zone, and prevents any loss by surface runoff. It is followed in different ways, depending upon local cultivation practices such as:
i) Irrigated tracts: The fertilizer is applied under the plough furrow in the dry soil before flooding the land and making it ready for transplanting.
ii) Less water condition: Fertilizer is broadcasted before puddling which places it deep into the reduction zone.
iii) Sub – soil placement: This refers to the placement of fertilizers in the sub-soil with the help of heavy power machinery. It is followed in humid and sub-humid regions where many sub-soils are strongly acid, due to which the level of available plant nutrients is extremely low. P-tic and K-ssic fertilizers are applied by this method in these regions for better root development.
III) Localized placement: It refers to the application of fertilizers into the soil close to the seed or plant. It is usually employed when relatively small quantities of fertilizers are to be applied. It includes methods like:
Advantages:
i) The roots of the young plant are assured of an adequate supply of nutrients,
ii) Promotes a rapid early growth,
iii) Make early Intercultivation possible for better weed control,
iv) Reduces fixation of P & K.
1. Contact placement or combined drilling or drill placement: It refers to the drilling of seed and fertilizer together while sowing. It places the seed and small quantities of fertilizers in the same row. This is found useful in cereal crops, cotton and grasses but not for pulses and legumes. This may affect the germination of the seed, particularly in legumes due to excessive concentration of soluble salts.
2. Band placement: In this, fertilizer is placed in bands which may be continuous or discontinuous to the side of seedling, some distances away from it and either at level with the seed, above the seed level or below the seed level. There are two types of band placement: It includes hill and row placement.
a. Hill placement: When the plants are spaced 3 ft. or more on both sides, fertilizers are placed close to the plant in bands son one or both sides of the plants. The length and depth of the band and its distance from plant varies with the crop and the amount of fertilizer as in cotton.
b) Row placement: When the seeds or plants are sown close together in a row, the fertilizer is put in continuous band on one or both sides of the one or both sides of the row by hand or a seed drill. It is practiced for sugarcane, potato, maize, tobacco, cereals and vegetable crops.
Higher rates of fertilizers are possible with row placement than hill placement. For applying small amount of fertilizers, hill placement is usually most effective.
3. Pellet application: In this method, fertilizer (N-ous fertilizers) is applied in the form of pellets 2.5 – 5.0 cm. deep between the rows of paddy crop. Fertilizer is mixed with soil in the ratio of 1:10 and make into dough. Small pellets of a convenient size are then made and deposited in the soft mud of paddy fields. It increases the efficiency of N-ous fertilizers.
4. Side dressing: Fertilizers are spread in between the rows or around the plants. It includes i) application of N-ous fertilizers in between the rows by hand to broad row crops like maize, S.cane tobacco, cereals which is done to supply additional doses of N to the growing crop. ii) Application of mixed or straight fertilizer around the base of the fruit trees and done once, twice or thrice in a year depending upon age.
Application Of liquid fertilizers
It includes:
1. Starter solutions: Solutions of fertilizers, generally consisting of N-P2O5 – K2O in the ratio of 1:2:1 and 1:1:2 are applied to young vegetable plants at the time of transplanting. It helps in the rapid establishment of seedlings and quick early growth.
Advantages:
i) The nutrients reach the plant roots immediately and
ii) The solution is sufficiently diluted so that it does not inhibit growth.
Disadvantages:
i) Extra labour is necessary and
ii) Fixation of phosphate is greater.
2. Foliar application: It refers to the spraying of leaves of growing plants with suitable fertilizers solutions. These solutions may be prepared in a low concentration to supply any one plant nutrients. It is preferable to soil application when:
i) The soil conditions or a competitive crop makes nutrients from soil dressing unavailable, like late application of N to crops raised under Rainfed condition,
ii) An accurately time response to fertilizers is required. E.g.: change in the reason,
iii) Routine applications are made of insecticidal or pesticidal sprays to which nutrients the crop prevents application of fertilizer to the soil but permits its application to the leaves from a high clearance sprayer or from a helicopter.
Difficulties (disadvantages) associated with this method are:
i) Leaf burn on scorching may occur, if strong solutions used.
ii) Small quantities of nutrients can be applied in one single spray due to low concentrations.
iii) Several applications are needed for moderate to high fertilizer doses, and
iv) Costly method than soil application.
3. Direct application to the soil: With the help of special equipment, anhydrous ammonia (a liquid under high pressure up to 200 PSI or more) and N solutions are directly applied to the soil. It allows direct utilization of the cheapest N source. Plant injury or wastage of ammonia is very little if the material is applied 10cm below the seed. Otherwise, the N from ammonia will be lost. If requires moisture content at field capacity and good soil tilth.
4. Application through irrigation water: Straight and mixed fertilizers containing N, P & K easily soluble in water, are allowed to dissolve in the irrigation stream. The nutrients are thus carried in solutions. This saves the application cost and allows the utilization of relatively in expensive soluble fertilizers, like N-ous fertilizers
Soil
Soil: The word ‘soil’ is derived from a Latin word, “Solum”, meaning ‘floor’. Soil is a complex system made up of mineral matter, organic matter, and soil water and soil air. Therefore, it contains not only the solid and liquid phases but also the gaseous phase.
Soil is a thin layer of earth’s crust which serves as a natural medium for the growth of plants. Soil is the unconsolidated mineral material on the immediate surface of the earth that serves as a natural medium for the growth of land plants. Soil is the unconsolidated mineral matter that has been subjected to, and influenced by genetic and environmental factors, parent material, climate, organisms and topography all acting over a period of time. Soil is a natural body, synthesized in profile form from a variable mixture of broken and weathered minerals and decaying organic matter which covers the earth in a thin layer and which supplies when containing the proper amounts of air and water, mechanical support and in part, sustenance for plans.
Some definitions of the soil,
According to Joffe (1949),”The Soil is a natural body of minerals and organic constituents differentiate into horizons of variable depth, which differs from the materials below in morphology, physical make up, chemical properties and composition and biological characteristics.”
Soil is a dynamic natural body developed as a result of pedogenic processes during and after weathering of rocks, consisting of minerals and organic constituents, possessing definite chemical, physical, mineralogical and biological properties having variable depth over surface of the earth and providing medium for plant growth of land plants.
The soil is heterogeneous, polyphasic, particulate, disperse and porous system, in which the interfacial area per unit volume can be very large. The disperse nature of the soil and its consequent interfacial activity give rise to such phenomena as:
1. Absorption of water and chemical,
2. Inoic exchange,
3. Adhesion
4. Swelling and Shrinking,
5. Dispersion and Flocculation and
6. Capillary.
Functions of soil:
1. Soil provides anchorage to root enabling plants to stand erect.
2. It acts as a store house of water and nutrients for plant growth.
3. It acts as an abode of flora and fauna which suitably transform nutrients for uptake by plant roots.
4. It provides space for air and accretion which creates healthy environment for the biological activity of soil organisms.
Soil is natural body, differentiated into horizons of mineral and organic constituents, usually unconsolidated, of variable depth, which differs from the percent material below in morphology, physical properties and constitution, chemical properties and composition and biological characteristics.
Soil profile: The vertical exposure of soil with its various layers (horizons) Or
A vertical section through the soil is called as the soil profile.
The various distinguishable layer of soil that occurs are called horizons.
Soil- Components Of Soil Or Phases Of Soil
Minerals soils consist of 4 major components: Mineral materials, OM, water and air in various proportions. Approximately 50% of the total volume of the surface horizon of many soils is made up of inorganic Materials (mineral matter) and OM (5%) and the remaining volume is per space between the soil particles. Water and air occupy these pore spaces in various proportions. The proportion of air and water varies from one season to another. At optimum moisture for plant growth, the 50% of pore space possessed is divided roughly in half 25% of water space and 25% or air.
The soil may be described as the three phase system: Soil solid, Liquid and gaseous phase.
1. Solid phase: Soil material less than 2 mm size constitutes the soil sample. It is broadly composed of inorganic and organic constitutes. Soils having more than 20% of org. constitutes are arbitrarily designated organic soils. Where inorganic constituents dominate, they are called mineral soils. The majority of the soils of India are mineral soils. It accounts for nearly 50% of the total volume and 95% without of the solid phase is made up of inorganic or mineral matter. The remaining 5% weight comprises of OM which is mainly derived from dead parts of the vegetation an animals.In inorganic constituents consist of silicates, certain preparation of carbonates, soluble salts, an free oxides of iron, aluminium and silicon. The humus and humus like fractions of the solid phase constitute the soil organic matter. Soil is the habitat for enormous number of living organisms like roots of higher plants (Soil Macro flora), bacteria, fungi, actinomycetes and algae (Soil Micro flora). A gram of fertile soil contains billions of these micro-organisms. The live weight of the micro-organisms may be about 4000 kg/ha may constitute about 0.01 to 0.4% of the total soil mass. Soil also consists of protozoa and nematodes (Soil Micro Fauna).
2. Liquid phase: About 50% of the bulk volume of the soil body is generally occupied by voids or soil pores which may be completely or partially filled with water. A considerable part of the rain which falls on soil is absorbed by the soil and stored in it to be returned to the atmosphere by direct evaporation or by transpiration through plants. The soil acts as the reservoir for supplying water to plants for their growth. The soil water keeps salts in solution which act as plant nutrients. Thus, the liquid phase is an aqueous solution of salts, when water drains from soil pores are filled with air.
3. Gaseous phase: The air filled pores constitutes the gaseous phase of soil system and dependent on that of the liquid phase. The N and O2 contents of soil air are almost the atmospheric air but the concentration of CO2 is much higher (8 – 10 times more) which may be toxic to plant roots. This phase supplies O2and thereby prevents CO2 toxicity.
The 3 phases of the soil system have definite roles to play. The solid phase provides mechanical support for and nutrients to the plants. The liquid phase supplies water and along with it dissolved nutrients to plant roots. The gaseous phase satisfies the acration (O2) need of plants.
Soil- Classification Of Soils
Soils can be grouped into categories based on their present properties. The most general soil category is called order. All world soils are place into 10 orders.
1. Entisols: Those soils that have natal, if any, profile development are known as entisols. Soils in desert belong to this classification. The productivity of these soils varies with their location and properties. With controlled water supply and proper fertilization, these soils have good productivity and good for vegetables, groundnut, citrus, wheat, paddy, etc.
2. Inceptisols: These soils have better profile development than entisols but are less developed. The horizons are formed mostly from alteration of the parent materials with accumulation of clay. The productivity is limited due to poor drainage. Found in humid regions.
3. Histosols: These are organic soils (pleats and mucks) consisting of variable depths of accumulated plant remains in bogs, marshes and swamps that have developed under water saturated environment. Highly rich in organic matter i.e. Org. C ranges from 12 to 18% in soils with low to more than 50% clay content.
4. Aridisols: Soils found in arid or dry areas with light in colour, poor inorganic matter and are not subjected to leaching, used for cultivation with irrigation. Process a horizon of CaCO3 (lime), Calcium sulphate (Gypsum) or more soluble salts. These are desert soils.
5. Mellisols: Mostly these are grasslands having thick surface horizon of dark colour, dominated by divalent cations. Process normal granular or crub structure, do not harden on drying and with moderate to have fertilization soil are productive.
6. Vertisols: These have a high content of clays that swell when wetted (more than 30%). During the dry season, these soils on tract and give rise to deep cracks which disappear in the wet season or after irrigation. Found in sub humid or semi arid (Temperate to tropical) climates where temp. are moderate to high. Good for crop production with fine texture which are plastic and sticky when wet and hard when dry. Difficult to manage due to very little time for their proper preparation by tilling good for the production of cotton, millet, sorghum, wheat, paddy, etc.
7. Alfisols: Develop in humid and sub humid climates (500 mm to 1300 mm rainfall) with gray to brown surface horizons. Soils are slightly too moderately acid and quite productive with good texture. Soils are frequently under forest vegetation.
8. Spodosols: Soils belong to forests with low content of bases, having coarse texture (sandy). Found in humid climates where temperatures are low. The subsurface horizons have accumulation of org. matter and sesquioxide.
9. Ultisols: These are strongly acid, normally forest soils with low content of bases extensively weathered soils of tropical and subtropical climates, respond to good mgt. practices, have clay of 1:1 type and give good crop production with adequate fertilization.
10. Oxisols: These are most developing in tropical and subtropical climates. The subsurface horizons are high in clay and acid. The soils are productive with supplements of ‘P’ micro-nutrients.
Soil Groups Of India
1. Red soils: Derived from crystalline, metamorphic rocks, which consist of granites, gneisses and schist’s, red or reddish brown, either in situ or from the decomposed rock materials washed down to lower level by rain, light textured with porous and friable structure. They have neutral to acid reaction and are deficient in N, humus, P2O5 and lime.
Cover large parts of TN, Karnataka, N-E AP, eastern part of MP to Chota Nagpur and Orissa, noticed in Up, Bihar, WB and Rajasthan.
2. Laterites and laterite soils: Formed in situ condition under conditions of high rainfall with alternating wet and dry periods, to reddish yellow, low in N, P, K, lime and magnesia. Formed due to the process of laterization in which silica is removed while Fe and Al remain behind in the upper layers.
Soils are common on the low hills in eastern AP, K, Kerala, eastern MP, Orissa, Assam and Ratnagiri district of MS.
3. Black soils: Highly clayey, 35 to 60% even up to 80% in valleys or depressions dark colored, from deep cracks during dry seasons, characterized by swelling and low permeability, neutral to slightly alkaline, High CEC, high content of K, exchangeable Ca and Mg poor in org. matter, N, P. The clay is mainly montmorillonite type, hence soft on wetting and contract on drying. These are called as regures or black cotton soils which are divided into: Very deep (More than 90 cm depth), Deep (45 – 90 cm), moderately deep (22.5 to 45 cm), Shallow (7.5 to 22.5 cm) and very shallow (below 7.5 cm depth). Black colour is not due to org. matter but due to presence of titaniferrous magnetite compounds and/or clay complexes. Major areas of black soils are in MS, MP and parts of AP, Gujarat and TN.
4. Alluvial soils: Develop from water deposited sediments. Do not show any prominent profile development. Varies in nature and properties which depends on sediments from which they develop the percent material in the respective catchments area and the place of deposition in valleys. Mostly poor drained, grayish colour, acidic but develop into saline and alkali soils in dry regions.
Occur in all states along rivers, for example, Indo-gangeric plains, Brahmaputra valley, Coastal areas of Gujarat, Ms, K, Kerala, TN, AP, Orissa, WB and Goa.
Sub-divided into: Old, Recent, Lacustrine, Coastal and Deltaic alluviums.
5. Desert soils: Formed in arid regions, as a result of physical weathering, sandy. Both wind and water erosion is severe in such soils, well supplied with soluble salts. Low in N and org. matter has a high pH.
Soils form a major part of Rajasthan, Southern part of Haryana and Punjab, northern part of Gujarat and receive 50 cm to less than 10 cm rainfall with high evaporation
.
6. Saline and alkaline soils: Soils show white crustation of salts of Ca, Mg and Na on the surface, poor drained and infertile. Occur in semi-arid areas of Bihar, UP, Punjab, Rajasthan Coastal and Deccan Canal Tract of MS.
7. Peaty and marshy soils: Soils are black, clayey, highly acidic (pH3.5) and contain 10 to 40% org. matter, poorly drained, high ground water table. Found in Kerala, Coastal tracts of Orissa, Sunder ban area of WB, SE and Coast of TN and in parts of Bihar and UP.
Soil- Physical Properties Of soil
The physical properties of soils are dominant factors affecting the use of a soil which determine the availability of O2 in soils, the mobility of water into and though soils and case of root penetration and also the chemical and biological behavior of soil. These depend primarily on the amount, size, shape and arrangement of its inorganic particles, shape and arrangement of it inorganic particles, kind and amount of org. matter, the total volume of pore spaces and the way it is occupied by water and air at a particular time.
Those are: Texture, Structure, Density, Porosity, Consistency, Colour and Temperature.
Soil Textures: It refers to the relative proportions of soils separates i.e. sand, silt and clay in particular soil. It is permanent or static property of soil.
Natural soils are comprised of soil particles of varying sizes. The soil particle size groups are called as soil separates as stone (more than 20mm dia). Gravel (2 – 20 mm dia), Fine earth (less than 2mm dia) coarse sand (0.2 to 2 mm dia), fine sand (0.2 to 0.02 mm), silt (0.02 to 0.002 mm) and clay (less than 0.002 mm dia).
1. Sand: Sand particles are large with very little surface area exposed (0.1 m2/g specific area). These are fragments of quartz, insoluble; nutrients supplying ability are practically nil. Pre space are bigger (macro pores) which facilitates rapid movement of air and water. Sand does not absorb water; do not exhibit properties swelling and shrinkages, stickiness and plasticity. Unless coated with clay or silt, they do not exhibit properties as Cohesions, moisture and nutrient retention, etc. Soils having high percent of sand can be easily cultivated with little or light draft requirements, low water holding capacity, less fertile, dry out quickly. As sand grains are large and coarse, soils dominated by sand are called as coarse textured or light soils.
2. Silt: These particles are intermediate in size to sand and clay. Because of adhering film of clay, they exhibit some plasticity, cohesions adhesion and absorption and can hold more amount of water than sand but less than clay. Soils dominated by silts armid way in properties, workability and productivity between sandy and clayey soils. The average specific area of silt particles is 1 sp. m/g.
3. Clay: It ultra microscopic size and large surface area (10 to 1000 sq. per. g.). The clay particles are smooth and in a colloidal state. It greatly influences the physical and chemical properties of soil. Clay particles absorb and retain water, sweel on wetting and shrink on drying, exhibit properties like flocculation (grouping/clustering)., deflocculating, plasticity and stickiness. Soils with high clay are poor drained, require very heavy draft for cultivation, can be worked in narrow range of moisture regime. Clayey soils are called as heavy soils as they are difficult or heavy for cultivation.
Textural classes: All soils have all the three soil separates in varying proportions. Based on their proportions, the soils can be grouped into textural classes and are named according to the soil separates which is predominant in them as:
Group
Class
Ranges (%) of
Sand
Silt
Clay
Very coarse textured
Sand
85-100
0-10
0-10
Loamy sand
70-90
0-30
0-15
Coarse textured
Sandy loam
43-80
0-50
0-20
Loam
23-52
28-50
7-27
Silt Loam
0-50
50-88
0-20
Silt
0-20
88-100
0-12
Medium textured
Sandy % clay Loam
45-80
0-28
20-55
Fine textured
Clay loam
20-45
15-53
27-40
Silty clay loam
0-20
40-73
27-40
Fine textured
Sandy clay
40-65
0-20
35-45
Silty clay
Clay
0-20
0-40
40-60
0-40
40-60
40-60
Significance of soil texture:
It influences physical and chemical properties like water holding capacity, nutrient retention and fixation and its availability, drainage, strength, compressibility and thermal regime. Suitability of a soil to a particular crop depends on texture in addition to soil depth, depth of water table, salinity and alkalinity. Loamy soils (Silty) exhibit intermediate properties, so best for agricultural production because they retain more water and nutrients than sandy and have better drainage, aeration and tillage properties than clay soils.
Soil Property- Soil Structure
The primary particles – sand, silt and clay are held together in clusters or peds of various shapes and sizes. Individual soil particles are joined together into groups or clusters by cementing agents just as bricks with cement or lime mortar to make buildings or various sizes and shapes, called as soil aggregates or peds. Natural aggregates are called as peds and artificial/aggregates by cultivation are called as clods.
The arrangement of primary particles and their aggregates (secondary) into certain pattern in the soil mass, called as Soil Structure. Soil structure influences the soil environment through its effect on the amount and size of pore spaces, water holding capacity, availability of plant nutrients and growth of micro-organisms. The size, shape and arrangement of the soil aggregates give indication of the ability of the soil to:
1. Allow air and water movements through the soil.
2. Allow plant roots to move through soil and make use of soil and
3. Hold enough soil moisture in a form available for plants use.
Types of soil structure:
There are four types on the basis of shape and arrangements:
1. Plate like/Platy: Horizontally, layered, thin and flat like the plates with horizontal dimensions greater than the vertical ones.
2. Prism like: Aggregates are elongated like pillars or prism, often six sided, up to 15 cm dia. They have vertical axis greater that oriental and the length of elongated pillars varies, depending upon soil and may go up to 15 cm or more and commonly found in sub soil horizon of arid and semi-arid region soils. Further divided as: with flat tops, called as prismatic and with rounded tops, called as Columnar aggregates.
3. Blocky like: These are cubes like 3 dimensions of about same size. When the edges or size are sharp, called as Angular blocky and when rounded, called as Sub-angular blocky. These usually found in the sub-soil horizon.
4. Spheroidal like: The aggregates are rounded or like a sphere. All the axes are approximately of the same dimensions, with curved or irregular faces, not more than 1 cm dia.
Further divided into:
I) Crumb: The aggregates are small and are weakly held together and are porous like crumbs of breads, found in pasture soils or grassy lands.
II) Granular: Similar to crumb except that the aggregates are harder, less porous and the individual soil particles are more strongly held together than in the crumb structure. Commonly found in cultivated fields.
Classes of structure: Aggregates/peds classified on the basis of their sizes as: Very fine, Fine, Medium, Coarse (or thick) and Very coarse (or very thick).
Grades of structure: Depending upon the stability, distinctness, durability, strength of the ease with which they can be separated, the aggregates are classified onto the four grades as: Structure less, Weak, Moderate and Strong.
Soil Property- Density Of Soil
The density of the soil i.e. mass per unit volume can be expressed tn two ways: The density of the solid particles of the soil, called as particle density and the density of the whole soil including pore space, is called as bulk density. Particle density is also called as true specific gravity and bulk density is called as apparent specific gravity.
1. Particle density: It is the weight of the soil solids (g) without pores per unit volume (cc). It varies from 2.6 to 2.7 g/cc in most of the mineral soils with average of 2.65 g/cc. It is not affected by texture and structure of coil and it is static property.
2. Bulk density: It is the mass (weight) per unit volume of the soil inclusive of pore spaces in its natural structure.
It varies from1.3 to 1.7 g/cc in sandy soils and 1.1 to 1.4 g/cc in clay soils. However, it is affected by texture, structure, organic matter and depth of the soil. Surface soils have low bulk density than lower surfaces.
Soil porosity: Soil has spaces which are occupied by water and air. The amounts of water and air present in pore spaces vary and depend upon their relative amounts. The amount of pore space depends upon the arrangement of solid particles, organic matter content, granulation and aggregation (texture), depth of the oil, cultivation and cropping pattern of the soil.
The pore spaces are of two types: 1) Macro or non-capillary (more than 0.06 mm) and 2) Micro or capillary pores (less than 0.06 mm) having bigger and smaller sizes, respectively. Pore spaces between the aggregates of soil particles are macro spaces which are occupied by air and those between the individual particles of the aggregates are micro pores which hold the water. Macro pores allow rapid movement of air and water as water than micro pores. Proportion of macro and micro pores is important than total porosity.
Porosity of the oil can be calculated by formula:
Porosity = 100 – (Bulk density * 100)/ particle density = 100 ( 1 – BD/ PD.
Sandy soils have 30 – 40%, clayey 50 – 60% porosity.
Soil colour: Colour indicates, approximately, the organic matter content of soil. The soils have various shades of black, yellow, red and grey colors. It may vary with the depth or horizons. Factors responsible for colour are:
1. Parent material from which soils are formed. E.g.: Red sandstone impart red colour to the soil.
2. Organic matter content imparts brown to blackish colour to the soil.
3. Minerals present in soil. E.g.: titanium (darker), Iron compounds like hematite (red) and limonite (yellow), silica or lime (whitish or grayish).
4. Accumulation of alkali – salts. E.g.: White or black depending upon type of salts.
Soil colour is useful for classification, to indicate organic matter and fertility, aeration, drainage, salt accumulation.
Soil air: In the gaseous phase of soil, water and air compete for the same pore space and their volume fractions are so related that an increase of one generally decreases the other. The amount and composition of soil air are believed to affect plant growth. Field air capacity is the fractional volume of air in a soil at field capacity which depends on texture. E.g.: sandy (25% or more), Loamy (15-20%) and clayey (below 10%). The circulation of air in soil mass is known as soil serration which is influenced by temperature water and diffusion. Soil air greatly varies in composition or CO2 than N and O2 gases present in atmospheric air i.e. 0.2 to 0.3% in soil air and 0.33% in atmospheric air. This needs continuous exchange of gas to avoid accumulation of CO2 in the soil.
Soil temperature: It affects the crop growth and activity of micro organisms. Optimum soil temperature requirement for germination and plant growth varies with crops i.e. 9°C to 50°C. The functioning of micro-organisms in the soil is very active within a certain range of temperature (27-32 °C). The major source of heat is sun and heat generated by the chemical and biological activity of the soil is negligible. Temperature can be controlled by maintaining optimum moisture content, providing drainage, mulching, organic matter, cultivation practices.
Soil consistence: It refers to the degree of resistance of a soil material to deformation or rupture or crushing which depends upon the degree and kind of forces (adhesion, cohesion) which attract one molecule to another. Adhesion is the force between similar materials.The consistence of soil is influenced by nature of clay minerals, exchangeable bases and humus. Thus helps to decide the time and type of tillage operations required to bring the soil at good tilth. The consistency also depends on plasticity of soil which is the ability to the kolded into different shapes when a certain amount of force is applied and then to retain even when the forces is removed.
Soil strength: Soil strength or mechanical resistance indicates the resistance offered by the soil to root penetration. It depends on soil moisture i.e. increase with decrease in soil moisture content and vice-versa. Soil compaction and bulk density also affect the soil strength.Soil compaction and soil crushing are also other physical properties of soil. These reduce the bulk density. These are useful for proper agril. Implements for land preparation, germination of seed.
Soil organic matter: It is mainly derived from the dead parts of vegetation and animal i.e. plant and animal residues. It forms a very small but important portion (5%) of the solid phase of soil. Its composition varies with type of vegetation, nature of soil population, drainage, rainfall and temp. Condition and the land management practices. The role of organic matter in maintenance, development and improvement of soil is well known as it enhances microbial activity, improves physical condition and fertility of soil and thereby soil productivity, enhances buffering capacity, prevent loss of nutrients, improves water retention and holding capacity etc. organic matter of soil cn be increased by addition of residues, green manuring, crop rotation etc. It influences the C?N ratio of soil. It is affected by climate which decides the nature of vegetation.
Biological And Chemical Properties Of Soil
Biological properties of soil:
Soil is not a dead mass but an abode of millions of organisms, which includes crabs, snails, earthworms, mites, millipedes, centipedes. These feed on plant residues burrow the soil and help in aeration and percolation of water.
The soil organisms are of two types: Microflora and Micro fauna, Bactro Actinomycetes, Fungi and Algae relate to former and Protozoa, Nematodes relate to some of these have symbiosis with other organisms. They act on plant and animal residue and release the food material which in turn used by plants.
Chemical properties of soil:
These are pH of soil, cation exchange capacity; buffering capacity and soil colloids. These are having more significance in the crop production.
PH of the soil decides the soil reaction as acidic, neutral and alkaline. The crops in the tolerance to the soil reaction. PH also influences the availability of nutrients. These with less than 7 are acidic, 7 neutral and above 7 alkaline. Acidic and alkaline soils need reclaim for crop production by addition of soil amendments.
Agricultural Meteorology
Introduction to Meteorology
1.Aristotle [384-322B. C.] defined Meteorology as a study of lower atmosphere.
[Meteor- Lower atmosphere and logus- means science]
2. It is also defined as the science of atmosphere and its phenomena, especially those phenomena which we call collectively as weather and climate.
3. Meteorology can be defined as the Science of atmosphere which deals with the physics, chemistry and dynamics of atmosphere and also their direct and indirect effects upon the earth surface, oceans and thereby Life in general
Study of weather elements comes under Meteorology and this Science and with Animals Science also.
Climatology:-
It is defined as a scientific study of climate. It discovers, describes, & interprets the climate on the basis of causes processes that generate them or
Climatology is the science which studies average condition of weather or the state behavior of the atmosphere over a place or region for a long period of time.
Ecology:-
1. According to Taylor 1936. Ecology is the science of all relation of all organisms to all their environment.
2. According to 1957. Ecology concerned itself with the inter relationship of Living organisms and their environment.
3. In general ecology is a branch of biology that deals with the relation of living things to their surroundings.
Agricultural Meteorology and Its Levels
1. J.W. Smith (1916) has defined Agricultural Meteorology as “Meteorology in its relation to agriculture”
2. It can be defined as the science investigating Meteorology, climates and hydrologic condition, which are significant to agriculture.
3. In short Agril. Meteorology is the applied branch of meteorology, which deals with the relationship between climates, weather and life and growth of the cultivated plants and animals.
Levels of Study of Meteorology:
Study of meteorology is organized at three levels.
1. Micro scale:
A process operating within vegetation canopies near earth surface its size is in few cm and Life span is few seconds.
2. Mesoscale:
The systems are approximately 10km in size and a lifetime is of few hours [up to5 hrs] eg. Thunder storm.
3. Macro scale: It is divided into two scales.
A) Synoptic scale:
These systems have a diameter of few thousand km. and life time of about 5 days
Eg. Tropical storm, cyclones.
B) Planetary scale:
These systems have a diameter of 5000 to 10000km and persist for several weeks
Eg. Waves in the atmosphere circulation.
Importance And Scope Of Meteorology
Almost all social, industrial, agricultural, commercial, transports etc. Activities directly or indirectly are affected by weather and climate. The atmosphere affects and sustains human life, animal, micro- organisms, insects, pests, plants, tree’s forests and marine culture at all times during every stage of growth and development Meteorology has therefore, greatest scope on every human enterprise in the modern Life.
The fields of applications are given below to illustrate the scope of meteorology.
1. Safe Navigation:
For safe navigation on sea the knowledge of adverse weather i.e. large tidal waves, ocean waves, high speed wind, cyclonic storms etc is needed which is supplied in weather forecast from meteorology.
2. Safe aviation:
For transport through air, the pilots need the information about atmospheric conditions such as the electric lightening, high speed winds and their directions, thunder storms, foggy atmosphere etc. So pilots can go safely. For this purpose accurate forecasts are needed and are only possible from meteorology.
3. Industry:
Many industries for their raw material depend on agricultural produce and accordingly location of industry is decided, so it is necessary to consider the weather and climate e.g. sugar mill, distillery, jute mill etc.
4. Animal Production:
Beef, poultry and milk production also depend on weather and meteorology provides the information for successful animal production and animal husbandry.
5. Fisheries:
Fishermen need information of atmospheric and oceanic changes before they proceed on sea for fishing and this is possible from meteorological knowledge.
6. Irrigation and water resources:
Meteorological and hydrological information assists in planning the location size and storage capacities of dams to ensure water supply for irrigation and domestic needs. When and how much to irrigate is also decided from the meteorological information.
7. Land use planning:
The meteorological data supplemented with soil and topographic information help to plan the sites for the specific land use for drop production, forests, urban residence, industry etc.
8. Human Life:
Human being tries to acclimatize himself with the prevailing weather conditions, for this they manage for type of clothing, housing food habit etc.
8.1 Clothing:
Warm cloths during winter and thin cloth during summer are used.
8.2 Housing:
Direction of windows, doors for proper ventilation, roofing-plain in low rainfall region whereas. Slanting roof in the areas where rainfall is more and frequent in occurrence.
8.3 Food habits:
Heavy diet during winter season is recommended whereas during summer season more quantum of water consumption is needed.
9. Human health:
If any sudden change in the climatic conditions is experienced it results into equdemics of material fever. Asthma patent suffers more during cloudy conditions.
10. Commerce:
Trading of any item is made according to need of the people in relation to weather prevailing e.g. Gum shoes, umbrella and raincoats are generally traded in rainy season only, woolen cloths in winter season and white cotton cloths. Cold drinks etc. are in more demand in summer season.
Importance and Scope of Meteorology in Agriculture
Weather and climate is a resource and considered as basic input or resources in agricultural planning, every plant process related with growth development and yield of a crop is affected by weather.
Similarly every farm operation such as ploughing harrowing, land preparation, weeding, irrigation, manuring, spraying, dusting, harvesting, threshing, storage and transport of farm produce are affected by weather.
The scope of Agril Meteorology can be illustrated through the following few applications.
1. Characterization of agricultural climate:
For determining crop growing season, solar radiation, air temperature, precipitation, wind, humidity etc. are important climatic factors on which the growth, development and yield of a crop depends Agro-meteorology considers and assess the suitability of these parameters in a given region for maximum crop production and economical benefits.
2. Crop planning for stability in production:
To reduce risk of crop failure on climatic part, so as to get stabilized yields even under weather adversity, suitable crops/cropping patterns/contingent cropping planning can be selected by considering water requirements of crop, effective, rainfall and available soil moisture.
3. Crop management:
Management of crop involves various farm operations such as, sowing fertilizer application. Plat protection, irrigation scheduling, harvesting etc. can be carried out on the basis of specially tailored weather support. For this the use of operational forecasts, available from agro met advisories, is made
e.g. 1) Weeding harrowing, mulching etc are undertaken during dry spells forecasted.
2) Fertilizer application is advisable when rainfall is not heavy wind speed is<30 km/hr and soil moisture is between 30 to 80%
3) Spraying/dusting is undertaken when there is no rainfall, soil moisture is 90% and wind speed is<25km/hr.
4. Crop Monitoring:
To check crop health and growth performance of a crop, suitable meteorological tools such as crop growth models. Water balance technique or remote sensing etc. Can be used.
5. Crop modeling and yield –climate relationship:
Suitable crop models, devised for the purpose can provide information or predict te results about the growth and yield when the current and past weather data is used.
6. Research in crop –climate relationship:
Agro-meteorology can help to understand crop-climate relationship so as to resolve complexities of plant process in relation to its micro climate.
7. Climate extremities:
Climatic extremities such a frost floods, droughts, hail storms, high winds can be forecasted and crop can be protected.
8. Climate as a tool to diagnose soil moisture stress:
Soil moisture can be exactly determined from climatic water balance method, Which is used to diagnose the soil moisture stress, drought and necessary protective measures such as irrigation, mulching application of antitranspirant, defoliation, thinning etc. can be undertaken.
9. Livestock production:
Livestock production is a part of agriculture. The set of favorable and unfavorable weather conditions for growth, development and production of livestock is livestock is studied in Agril. Meteorology. Thus to optimize milk production poultry production, the climatic normal are worked out and on the suitable breeds can be evolved or otherwise can provide the congenial conditions for the existing breeds.
10. Soil formation:
Soil formation process depend on climatic factors like temperature, precipitation, humidity, wind etc, thus climate is a major factor in soil formation and development.
Weather and climate And Its Difference
Weather:
Weather can be defined as the physical condition or state of the atmosphere at a particular time and place.
Climate:
Climate is defined as generalized or average condition of weather of a place or region.
Or
Climate:
It is a composite or generalized of the variety of day to day weather conditions.
Difference between weather and climate
Sr No
Weather
Climate
1
Instantaneous physical state of atmosphere at particular place.
Normal physical state or generated condition of atmosphere or long term average condition of a place.
2
Weather changes refer to specific instant of time( day or week)
It is generalized over a longer span of time and for a longer area.
3
It is expressed in terms of numerical values of meteorological elements.
It is expressed in terms of time averages and area averages of meteorological elements.
4
Weather is measured in observatory. So the observatory must at a place for which weather is to be described.
This is derived information on regional basis. So scripts of observatories extending over a region are necessary.
5
No statistical treatment is applied to the meteorological elements. They are used as observed and hence always changing.
Application of statistical method over a longer period I done. It is more or less stable with few random changes.
6
it provides meteorological information.
It constitutes geographical information in respect of weather.
7
Weather of two places having same numerical value must be same.
Climate of the two places having the same averages of weather can not be same, because their distribution over the years may be different.
8
Weather can be categorized as fair, unfair, excellent etc.
Climate is classified as desert climate, marine climate, tropical climate etc.
9
Weather decides the success or failure of a crop in a particular season.
Climate decides the type of crop suitable for a region, while introducing new crops climate is considered.
10
Adverse weather results into crop failure or loss and warrants short term contingent planning.
Climate is considered in long terms agricultural planning.
Climatic Controls
The value of weather elements are modified by the interference of the factors of determining causes like latitude, altitude, etc. Such factors are called as climatic factors of climatic controls.
1 Latitude:
The most important influence of latitude is on temperature of a place Temperature tends to decrease with increase with increase in latitude. Places far away from the equator are colder than those near it. This is because the angle of the Sun’s rays decreases as we go to higher latitudes and also the rays have to pass through a greater distance of the atmosphere before they strike the earth’s surface. They have therefore less heating effect than the rays falling on the equatorial region.
2 Altitude: Pressure and temperature generally decreases with increase altitude, and the capacity of the air to hold moisture also decreases.
3 Topography:
Wind velocity primarily changes with change in topography which may result in Change in temperature
4. Mountains:
High mountain chains fact as a barrier to free flow of winds and divide one type of climatic zone from another. For example moist monsoon current of the Indian sub-continent is not allowed by the Himalayas to crossing into our country in winter.
5. Land and sea distribution:
Distribution of land and sea has a profound effect on climate. Places near the sea have moderate climate. On the other hand places for away from the sea are very hot in summer and very cold in winter. So they are said to have an extreme climate.
6. Oscan currents:
Ocean currents have a considerable influence on the climate of the coastal regions and Islands near which they flow. The warm currents tend to raise the temperature of the place while the cold currents make a place colder.
Earth’s Atmosphere
Meaning:
The dynamic layer surrounding the earth above its surface containing various gases, moisture, aerosols etc. is called atmosphere.
Definitions:
1. Atmosphere can be defined as the gaseous envelope surrounding the earth.
2. Atmosphere can be defined as a grand body from the earth surface to the outer space and composed of number of gases.
The estimated mass of the atmosphere is 5.6 x 1014 metric tones. It extends over about 400 km height and meteorological events and effects occur in it. The thickness of gaseous envelope is equal to 1% of the earth’s mean radius.
Usefulness of the atmosphere:
1. It fulfils the biological oxygen demand (BOD) of the animal life.
2. It supplies the necessary precipitation or moisture.
3. It protects the biological life on the planet from harmful extraterrestrial radiations like UV, by absorbing it though ozone.
4. It maintains the warmth of the plannet through its green house effect, avoiding the temperature to fall to too extreme limits.(The earth’s temperature in the absence of atmosphere would have been +950C (day),and -1450C (Night)
5. It provides the necessary CO2 which is basic input required to run photosynthesis process in plants to build biomass.
6. It provides the necessary medium for the transport of pollens. Seeds spores and insets.
7. Many physical chemical and hydrological processes responsible for weather and climate occur in atmosphere only.
8. Atmosphere is a big reservoir of nitrogen. Some plants and microbes can fix this nitrogen for plant growth eg, Azolla pinara Azotobacter.
Composition of the atmosphere:
The various constituents of the atmosphere can be divided into following three categories.
Structure of Atmosphere,
1
GASES
Moisture
Solid impurities or Aerosols
1.
Nitrogen(N2)
Water Vapour
1
Dust particles
2.
Oxygen(O2)
2.
Carbon particles
3.
Argon (Ar)
3
Salt particles
4.
Carbon dioxide (CO2)
4
Water droplets and ice crystals.
5.
Ozone (O3)
5.
Spores
6.
Sulphur dioxide (NO2)
6.
Pollen grains
7.
Nitrogen dioxide (NO2)
8.
Ammonia (NH3)
8.
Smoke
9.
Carbon monoxide
(CO2)
10
Neon (Ne)
11
Helium (He)
12
Hydrogen(H)
13
Krypton(K1)
14
Xerox(Xe)
15
Melhane)(CH4)
16
Nitrous oxide(N2O)
17
Radon(Rn)
Aerosols
There exists different solid partials like dust, organic particles like carbon , inorganic particles like salt and also some liquid particles(Water droplets and crystals) which remain suspended in the atmosphere. There particles are dispersed in the atmosphere and are dispersed in the atmosphere and are known as aerosols.
Non Variable and Variable Components
1. Non-variable components:
Some gases of the atmosphere remain constant at surface of globe up to the height of 80 to 88 km. This is due to transportation of gases on continental* level, diffusion of gases, turbulent mixing and convection.
These gases are called non-variable components.
They are Non-variable components (permanent constituents)
Sr.No
Constituents
Symbol
Percentage by volume
1
Nitrogen
N2
78.084
2.
Oxygen
O2
20-946
3
Argon
Ar
0.934
4
Carbon dioxide
CO2
0.032
5
Neon
Ne
18.18x10-4
6
Helium
He
5.24x10-4
7
Crypt on
Kr
1.14x10-4
8.
Xenon
Xe
0.087x10-4
9.
Hydrogen
H2
0.5x10-4
10.
Methane
CH4
1.5x10-4
11.
Nitrous oxide
N2O
0.5 x 10-4
12
Radon
Rn
6 x 10-18
1. Variable components:
Some gases or components of the atmosphere ch anges with change with change in time, palce, season etc, and these components are called as variable component they are-
Variable components or constituents:
S.N.
Constituents
Symbol
Percentage by volume
1
Water vapour
H2O
<4
2.
Ozone
O3
<0.07x10-4
3.
Sulphur dioxide
SO2
<1x10-4
4.
Nitrogen dioxide
N02
<0.02x10-4
5.
Ammonia
NH3
1 race
6.
Carbon monoxide
CO
~0.2x10-4
7.
Dust (Salt2 Soil)
<10-3
8.
Water (liquid & solid)
Compositional layering of the Atmosphere
The atmosphere can be divided into two spheres on the basis of its chemical composition occurring with height i.e. (1) Homosphere. (2) Hereto sphere.
Homosphere:
In the lower region up to the height of 88 km the various gases are thoroughly mixed and are homogenous by the process of turbulent mixing, and diffusion. This sphere is called as Homosphere. Herein the presence of gases is governed by the diffusion and the composition remains normally.
Hydrosphere:
In hydrosphere gaseous composition changes and various gases form separate compositional layering individually.
Satellite data have shown the presence of different chemosphere in follows:
1
Nitrogen and oxygen
From 88 to 115 km
2
Automatic oxygen layer
From 115 to 965 km
3
Helium layer
From 965 to 2400 km
4
Hydrogen layer
From 2400 to 10,000 km
The distribution of the gases is governed by the earth’s gravitational field. Thus heavier gases sink downward while the lighter gases like hydrogen remain at higher altitude.
Physical Structure Of Atmosphere
(Stratification of atmosphere or layering of atmosphere)
On the basis of the vertical temperature difference, the atmosphere can be divided into four horizontal layers or shells, namely.
A) Lower Atmosphere: 1. Troposphere and 2. Stratosphere
B) Upper Atmosphere: 1. Mesosphere and 2. Thermosphere.
A) Lower Atmosphere:
1. Troposphere:
The altitude of the troposphere changes according to latitude. It has an elevation of about 16 km at the equator and only 8 km at the poles. Its average altitude is about 11 km. It contains near about 75% of the gaseous mass of the total atmosphere, water vapour and aerosols. It is the realm of clouds, storm and convective motion, The outstanding characteristic of the troposphere is the filmy uniform degree in temperature with increase in altitude until minimum temperature of -50% 0C-------600C is reached. The isothermal layer marking the end of temperature decrease is called tropopause and it separates troposphere and stratosphere. Through out the troposphere there is a general decrease of temperature with increase in height at a minimum rate of about 6.50C/km or 3.60F/1000 ft.0C
2. Stratosphere:
This is the second atmospheric layer above trop pause which extends upwards about 50 km. The stratosphere contains much of the total atmospheric ozone. The density of ozone is maximum at 22 to 24\5 km height approximately. The ozone at the upper layer of this sphere absorbs the ultraviolet rays from the Sun and temperature may exceed 00C. In stratosphere the temperature increases with increase in height.
B) Upper Atmosphere:
1. Mesosphere:
This is the third layer of atmosphere. A thin isothermal layer called a stratopause is the boundary layer, which separates stratosphere and mesosphere. Above the warm stratopause, temperature decreases with increase in height to a minimum of about-900C at about 80 km height Pressure in this layer is very low and decreases from 1 Mb at about 50 km to about 0.01 mb at 80 km nearly. The thin isothermal layer, which separates mesosphere from thermosphere, is called mesopause.
2. Thermosphere:
Outermost shell is known as thermosphere. It lies above 80 km height . In this sphere the atmospheric densities are extremely low. In this sphere temperature increases with increase in height due to absorption of ultraviolet radiation from the Sun. probably it reaches to 9500C at 350 km to 17000 C at an underfined upper limit but these temperatures are essentially theoretical. Such temperatures are not felt by the hands exposed by astronaut or the artificial satellite because of rarefied air.
Solar Radiation And Its Terms
Agriculture is the exploitation of solar energy under adequate supply of nutrients and water by maintaining plant growth. So it is but natural that any efforts of thoroughly understanding of solar radiation will be immense use for its fullest exploitation by the crop plants in terms of their growth and yield.
The sun is the primary source of energy. Supplying about 99.9% out of total energy available at the earth surface. The temperature of the Sun is 6000 K and gives out energy about 5.6 x10 27 cal per minute. The Sun radiates its energy in the form of wave lengths from 0.15 to 4.0 u and are generally called as short wave lengths. On contrary after absorption of solar energy, earth emits its energy between 4 to 100 u and is categorized as long wave length.
There are three methods of transfer of heat or energy that means there are three different ways by which heat can flow from one point to another are:
1. Conduction
2. Convection
3. Radiation.
For conduction and convection of heat, material medium is necessary. But for radiation material medium is not necessary, because radiation takes place in the form of Electro magnetic waves.
The ultimate source of all the energy for physical and biological processes occurring on the earth is radiation received from the sun that is why it is commonly called solar radiation.
Some Terms (Definitions):
1. Radiation:
The transfer of heat energy in the form of electro magnetic waves with the speed of light is known as radiation (Light speed is 3x105 km/second).
2. Solar insulation:
The heat energy received from the Sun is known as solar insulation.
3. Radiant flux density:
It is defined as the amount of energy received on a unit surface in a unit time. ( In Meteorology we commonly use cal cm -2 min or largely min -1 as the unit of radiant flux density)
4. Emissive:
It is defined as the ratio of the emittance of a given surface at a specified wave length and temperature to the emittance of an ideal black body at the same wave length and temperature.
5. Absorptive:
It is defined as the ratio of the amount of radiant energy absorbed to the total amount incident upon the substance.
6. Reflectivity:
Is defined as the ratio of the radiant energy reflected to the total that is incident upon the surface.
7. Transmmissivity:
Is defined as the ratio of the transmitted radiation to the total radiation incident upon the medium.
8. Short wave radiation (SW):
Radiation with wave length range 0.15 to 0.76 u is known as short wave radiation.
9. Long wave radiation:
Radiation with wave length range 0.76 to 100 u is defined as long wave radiation.
Laws Of Radiation
The radiation reaching to the earth surface from the sun, atmosphere and from earth to atmosphere, space follows certain physical laws known as radiation laws. They are
Plank’s Law:
The Electro magnetic radiation consists of a stream or a flow of particles or quanta. Each quantum having energy content
E=hv. Where, h=Plank’s constant (6.625x1027 ergs sec-1)
V=frequency of Electro-magnetic length.
Greater the frequency (i.e. shorter the wave length) greater is the energy content of the quantum.
Stefan Boltzman’s Law:
The intensity of radiation emitted by a radiating body is proportional to the fourth power of its absolve temperature.
E=ST
Where E=Emissive of the body
S=Stepen’s constant (5. 67x10-8W m-2.K-4)
T=surface temp of the body in absolute 0K
3. Weins displacement Law:
The wave length of maximum intensity of emission is inversely proportional to the absolute temp, o f that body.
µ Max (um) =2897 T
For example, the temp. of earth surface is 2870K then its peak emission will be close to 10 µ similarly for the sun having temp, of 6000 0K it will peak at 0.5π
Kirchoffs Law:
Kirchoffs Law state that the absorptivity of a material for a radiation of a specific wave length is equal to its emissivity for the same wave length at same temperature.
Solar Constant
The solar constant is a measure of the rate at which solar wave radiation is received at the rop of the atmosphere on a unit surface unit time.
It is customary to express the solar constant in terms of cal. cm2 min and a value of 1.94 or 1.95 cal cm2 /min has been generally accepted Recent measurements suggest that it might be slightly higher i.e. 2.0 cal/cm2/min and that there is some slight variability mainly because of fluctuations in the ultraviolet rays.
Albedo
The term albino is usually defined as the fraction or percent of the reflected solar radiation from the surface to incoming solar radiation.
Thus, it is usually refers to the reflectivity of a particular band or portion of the spectrum.The albedo of the whole earth and atmospheric system approximates 35%
Albino is also defined as the ratio of reflected radiations to the total incident radiation.
Green House Effect
Out of the total solar radiation about 47% is absorbed at the earth surface. As a result the earth becomes hot and starts re-radiating long wave radiation. The exchange between the sky and the terrestrial radiation is largest governed by the atmospheric gases. The important principle is that the short wave lengths of the radiation’s from the sun can penetrate the atmosphere without being fully absorbed. These short radiation’s fall on ground, they heat it , and ground starts no- radiating long wages, The long waves emitted by the earth are absorbed in the atmosphere by water waves emitted by the earth are absorbed in the atmosphere by water vapour, CO2 and Ozone. On absorption of earth radiations these gases become warmer and in turn they again radiate the heat in still longer waves towards the earth This also increases the earth’s warmth.
The gases namely water vapour, CO2 and Ozone allows the solar radiations categorized as solar short waves to pass through the atmosphere towards the earth and not allow to escape the long waves radiations from the earth is known as green house effect.
This heat retaining behavior is similar to the roofed glass or green house used for experiment.
The atmospheric green house effect keeps the earth warm and does not allow its temperature to fall. The mean temp, of the earth is 150C since long and is maintained by green house effect.
Radiation Balance Or Net Radiation
The net radiation is the difference between the total downward and upward radiation fluxes and is a measure of the energy available at the ground surface. The balance of energy after gain and loss of both short wave and long wave radiation fluxes is known as net radiation.
Net radiation represents the amount of energy, which is used for various kinds of activities. It is dispensed as sensible heat, latent heat and also in physiological processes such as photosynthesis and respiration.
The importance of this parameter is that it is the fundamental quantity of energy available at the earth’s surface to drive he processes of evaporation, air and soil heat fluxes as well as other smaller energy consuming processes like photosynthesis etc.
If we consider the extra terrestrial radiation reaching annually (338wm-2)as 100%; Then out of this-
The net radiation reaching (SW) =100-28+25)-47% the earth surface. =114%
Long wave radiation reaching at earth surface =+96%
Therefore, Net long wave radiation =-114+96 = -18%
Net all wave radiation at earth surface =+47-18 = 29%
This surplus energy is used at the earth surface for
a) Sensible heat (QH) =4%
b) Latent heat (Eva)(QE)=25%
-----------
29%
Factors Affecting Solar Radiations
The amount of insulation received at particular place and time depends on the following factors:
1. Distance from the sun.
2. Duration of daily sunlight period.
3. Solar elevation or inclinations of the solar rays to the horizon.
4. Transparency of the atmosphere towards heat radiation and
5. Output of solar radiation.
The first three of these reasons are intimately connected with revolution of earth, It is to be noted here that the earth revolves about the sun in elliptic orbit and makes one complete revolution in 365 days, simultaneously it spins about itself and complete one rotation in 24 hrs.
The average distance of the earth from the sun is 149.5 million km).
The duration f daylight also varies with the latitude and season. Longer the day light duration, greater is the insulation received, In the solar region the duration of day light is 24 hrs during summer and minimum of zero in winter season.
Significance Of Radiation In Agriculture
The importance of the radiation in crop production is as follow:
1. It provides the necessary energy for all the phenomena concerning biomass production.
2. Photo synthetically Active Radiations (PAR) are the real source of energy for photosynthesis process. Plants are the efficient biological converters of solar energy into biomass. Radiation defines the yield of crop in particular region.
3. It laso provides the energy for the physical processes taking place in plants, soil and atmosphere.
4. It conditions the distribution of temperature and hence crop distribution on the earth surface.
Atmospheric Temperature
Definition:
The degree of hotness is known as temperature increases.
Temperature is a fundamental elopement of climate from many points of view, the most important in controlling the distribution of life on the earth. Most of the weather elements are dependent on it, directly or indirectly. Air of atmosphere receives the heat energy from the sun and its temperature increases. Due to different amount of heat energy receipt at different places, the air temperature at different places also vary. The variation in air temperature basically results into air motion, so as to equalize the energy content of the different regions of the earth. Thus temperature of air can be regarded as the basic cause for weather changes.
Qualification of Atmospheric Temperature:
Atmospheric temperature is continuously changing; it is never steady or constant for a long time. Therefore quantification of atmospheric temperature is very important aspect. The atmospheric temperature can be quantified in the following ways.
1. Maximum temperature:
It is the highest temperature attained by the atmosphere in diurnal variation.
2. Minimum temperature:
It is the lowest temperature attained by the at by the atmosphere in diurnal variation.
3. Average temperature:
It represents the average temperature condition of the atmosphere during 24 hours of the day.
Temperature Variation
Air temperature at any location is changes during a day, week, month, year or for any period. On this basis it is classified as-
A Periodic variation.
1. Annual temperature variation or Annual temperature cycle.
2. Diurnal temperature variation or Daily temperature cycle.
B. Horizontal variation
C. Vertical Variation.
A) Periodic Temperature Variation:
The temperature continuously changes during a day, week, month, year or any period and this change is called periodic temperature variation.Periodic temperature variations are -
1. Annual temperature variation or Annual temperature cycle:
The annual temperature Variation gives rise to seasons i.e. summer and winter. The annual temperature range varies greatly from place to place. It reflects the daily increase in insulation from mid-winter to mid-summer and decrease in the same from mid-summer to mid-winter summer and decrease in the same from mid-summer to mid-winter usually there is a temperature lag of 30 to 40 days after the period of maximum and minimum insulation
In the Northern hemisphere winter minimum occurs in January and summer maximum in July and vice versa in the southern hemisphere. The smaller range occurs near equator and largest in high latitudes. The difference between the highest and lowest temperature for a given period is known as temperature range. In the northern hemisphere it is summer from 21st of March to 22nd of September and winter from 23rd September to 20th March and vice-versa in southern hemisphere.
2. Diurnal Temperature Variation or Daily Temperature Cycle.
The Diurnal Temperature Variation give rise to daily maximum and Minimum temperatures.
From the sun-rise, sun energy continuously supplied and the Temperature continuously rises, recording maximum at about 2.00 to 4.00.P. m. though the maximum amount of solar radiation is received at the solar None (i.e. 12.00 hrs). This delay in occurrence of maximum temperature is Caused by gradual heating of the air by convective heat transfer from the Ground which is known as thermal lag or thermal inertia.
Similarly minimum air temperature occurs shortly offer sunrise due to lag in transfer of heat form the surface to the air / space.
B Horizontal Temperature Variation:
The rate of change of change of temperature with a horizontal distance is known as Temperature Gradient.
Maximum solar energy is received in equatorial region and therefore and Therefore highest temperatures are observed in equatorial region. As the latitude Increases the solar energy received on the earth correspondingly decreases and so also temperature decreases with increase in latitude being lowest on the pole.
The Sum crosses the equator twice in a year therefore two maxima And two minima are observed in annual cycle. Outside this zone only one Maxima and one minima is observed.
Isotherm:
Isotherm is defined as the line on the weather map joining the places of equal temperature.
C.Vertical Tempe ration Variation:
Vertical temperature variation does not show uniform behavior and The atmosphere can be divided into four spheres.
1. Troposphere - Temperature decreases from 150 C at earth surface up to - 60 0C at 11 km height.
2. Stratosphere - Temperature increases from -600C to 00C at 50km Height.
3. Mesosphere - Temperature fall and reaches about -900C at 80 km Height.
4. Thermosphere- Temp increases. Due to absorption of solar radiation by
Atomic oxygen, up to 9500C at 350 km height and 17000C at undefined upper Limit.
Factors Affecting The Air Temperature
The distribution of temperature over the earth surface depends on following factors:
1. Latitude:
Highest temperatures are generally at the equator and the lowest at the poles. The temperature decreases with the increase of latitude.
2. Altitude:
Temperature decreases with height in troposphere.
3. Season:
Coldest temperatures are in winter and highest temperatures are in summer seasons.
4. Distribution of land and water:
Water bodies are great moderators of temperature. Because of high Specific heat of water, so on the oceans, the regularity in temperature is more as compared to continents.
5. Topogrtaphy:
Mountain ranges affect the temperature by acting as obstacles to the Flow of cold air cold air near the surface and they often set conditions of warm winds.
6. Ocean currents:
Hot and cold ocean currents affect temperature e.g. Gulag Stream (Warm) in North Atlantic, Benguela current (cold) along West coast of South Africa, Peru Current (cold) along West Coast of South America.
7. Winds:
Various types of wind affect temperature.
8. Clouds and rains:
Clouds by obstructing the heat from the Sun and rains by cooling the Atmosphere, affect the temperature.
9. Color of the soil:
Black color of soils absorbs more radiations and other types reflect them.
10. Slope of the soil:
Black color of soils absorbs more radiations and other types reflect them.
11. Forest and vegetation:
Due to Evapotranspiration and interception of sun – rays, temperatures are moderated.
Soil Temperature And Its Importance
The Soil mantle of the earth is indispensable for the maintenance of plant life, affording mechanical support and supplying nutrients and water.
Soil constitutes a major storage for heat acting as a sink of energy during the day and source to the surface at night. In annual terms the soil stores energy during the warm season and releases it to air during the cold portions of the year.
Importance of Soil Temperature:
1. In affects plant growth directly, that is all crops practically slow down their growth below the soil temperature of about 90C and above the soil temperature of above 50 0C.
2. For germination of different seeds requires different ranges of soil temperature e.g. maize begins to germinate at soil temp of 7 to 100C.
3. Most of the soil organisms function best at an optimum soil temperature of 25 to 350C
4. The optimum soil temperature for nitrification is about 320C.
5. It also influences soil moisture content, aeration and availability of plant nutrients.
Variations of Soil Temperature
There are two types of Soil Temperature:
1. Daily and Seasonal Variation of Soil Temperature.
a) There variations occur at the surface of the soil.
b) At 5 cm depth the change exceeds 10 0C At 20 cm the change is less and at 80 cm diurnal changes are practically nil
c) On cooler days the changes are smaller due to increased best capacity as the soils become wetter on these days.
d) On a clear sunny day a bare soil surface is hotter than the air temperature.
e) The time of the peak temperature of the soil reaches earlier than the air temperature due to the lag of the air temperature.
f) At around 20 cm in the soil the temperature in the ground reaches peak after the surface reaches its maximum due to more tune the heat takes to penetrate the soil. The rate of penetration of heat wave within the soil takes around 3 hours to reach 10 cm depth.
g) The cooling period of the daily cycle of the soil surface temperature is almost double than the warning period.
h) Undesirable daily temperature variations can be minimized by scheduling irrigation.
Seasonal variations of Soil Temperature:
a) Seasonal variations occur much deeper into the soil.
b) When the plant canopy is fully developed the seasonal variations are smaller.
c) In winter, the depth to which the soil freezes depends on the duration and severances of the winter.
d) In summer the soil temperature variations are much more than winter in trophies and sub trophies.
Thermal Properties Of Soils
1. Specific heat (Mass specific heat):
It is the amount of heat required to raise the temperature of one gram of substance by 1 0C. The values for most minerals present in the soil are between 0.18 to 0.20 cal/gm.
2. Heat capacity (volume specific heat):
It is the amount of heat required to raise the temperature of one cubic centimeter substance by 1 0C .Most soils have a heat capacity in the range of 0.3 to 0.6 cal/Cm3.
3. Thermal conductivity:
It is defined as the quantity of heat transmitted through unit length of substance per unit cross section, per unit temperature gradient per unit time.
Thermal conductivity is the ability of the substance to transfer heat from molecule to molecule to molecule. For this reason it is sometimes called inolcular conductivity. It varies with porosity, moisture content and organic matter content of soil. It is expressed in Jm-1 s-1 K-1
4. Thermal diffusivity:
Thermal diffusivity is the ratio of the thermal conductivity to volume specific heat.
Thermal diffusivity = Thermal conductivity/ Volume specific heat
Daily And Seasonal Patterns Of Soil Temperature
The range of soil temperature in summer and winter decreases with increasing depth. At 40 cm depth the change is very minor and at 81 cm no diurnal change occurs.
In summer soil temperature decreases with depth during the day time.Temperature gradients direct heat into the soil. At night hours the temperature is highest between 20 and 40 cm, and from that level heat is directed both upward and downward.
In winter the 81 cm depth is warmer and the diurnal change is still very minor at 40 cm depth. Heat is transferred upward from those levels though out the day and night, because of the low radiation intensity in winter. The daily range of surface temperature is very small; however the range is still greater at the surface than any below level. Only during the hours near noon does heat penetrate into the soil from the surface.
Soil Temperature Profiles
The heat is continuously moving in to or out of the soil and thermal energy is being continuously redistributed in the soil. Heat will not flow under isothermal condition.
The pattern of soil temperature profiles changes rapidly during & normal day. The soil surface is the coldest level in the early morning and the warmest in the early afternoon.
At midday heat is directed downward through the upper one metro soil. The profiles show that the heat exists from middle of the layer after sunset but some heat flow continuously downward throughout the night. During most of the day temperature profile indicate downward heat flux. This is summer there is a net daily gain or storage of heat in the soil.
Factors Affecting The Soil Temperature And Its Control
1. Solar radiation:
The amount of heat from the Sun that reaches the earth is 2.0 cal/cm2 min -1 the amount of radiation received by the soil depends on angles with which the soil faces the Sun.
2. Condensation:
Whenever water vapour from soil depths or atmosphere condenses in the soil, its heat increases noticeably.
3. Evaporation:
The greater the rate of evaporation, the more the soil is cooled.
4. Rainfall:
Rainfall cools down the soil.
5. Vegetation:
A bare soil quickly absorbs heat and becomes very hot during the summer and become very cold during the winter. Vegetation acts as a insulating agent. It does not allow the soil to become either too hot during the summer and two cold during the winter.
6. Colour of the soil:
Black colored soils absorbs more heat than light closured soils Hence black color soils are warmer than light colored soils.
7. Moisture content:
A soil with higher moisture content is cooler than dry soil.
8. Tillage:
The cultivated soil has greater temperature amplitude as compared to the uncultivated soil.
9. Soil texture:
Soil textures affect the thermal conductivity of soil. Thermal conductivity decreases with reduction in particle size.
10. Organic matter content:
Organic matter reduces the heat capacity and thermal conductivity of soil, increases its water holding capacity and has a dark color, which increases its heat absorbability.
11. Slope of land:
Solar radiation that reaches the land surface at an angle is scattered over a wider area than the same amount of solar radiation reaching the surface of the land at right angles. Therefore, the amount of solar radiation reaching per unit area of the land surface decreases as the slope of the land is increases.
Soil temperature can be controlled by:
1. Regulating soil moisture.
2. Proper soil management practices so a to have good drainage.
3. Application /use of mulching.
4. Sufficient addition of organic matter.
Air Pressure
Definition:
Atmospheric pressure can be defined as the weight exerted by air column on units surface of the earth.
Units of pressure:
1. Height of mercury column measured in inches, cm, and mm
2. Bar, bar is a force equal to 106 dynes/cm2
3. SI (standard International) unit or pressure is Pascal
1. Pascal = force of 1 Newton/m2
= 1 N m2
Standard atmospheric pressure:
The standard atmospheric pressure is given at mean sea level at 450K latitude and at temperature of 2730K
Standard Atmospheric = 29.92 inches or 76 cm or 760 mm
Pressure = 1013.25 mb
= 101.325 kilo Pascal (Kpa)
= 14.7 lbs/inch2
1.014 x 106 dynes/cm2
Isobar:
Any line joining the places of equal atmospheric pressure on the weather map is known as isobar. Where isobars are closely spaced, a rapid of steep change in reassure is indicated. When isobars are widely speeding, a slow change in pressure is indicated. Two isobars are never cross each other. Isobars are plotted on the map to show the distribution of pressure. The isobars are drawn at pressure intervals of 2, 3,4 or 5 mb.
Pressure gradient:
The rate of change of atmospheric pressure per unit horizontal distance between two points at the same elevation is known as pressure gradient or isobaric slope. This change tak3es place and is measured in the direction perpendicular to the isobars preferably from high to low pressures. This exerts a force on air particles and is important in determining the strength of wind. The pressure gradient is expressed in decrease in pressure per unit horizontal distance as mb/100 meters.
Variation in Atmospheric Pressure
1) Variation with height or vertical variation:
The pressure depends on the density or mass of the air. The density of air depends on its temperature. Its composition and force of gravity. I t is observed that the density of air decreases with increase in height so the pressure also decreases with increase in eight.
The pressure at sea level is 1013.25 mb at 50 km height it becomes 0.93 mb and 80 km it is only 0.03 mb. This indicates how rapidly the atmospheric gas becomes thinner to decrease density and so the pressure. The pressure decreases on an average at the rate of about 34 mb per every 300 meters height.
2) Horizontal variation of pressure:
The horizontal variation of atmospheric pressure depends on temperature, extent of water vapor, latitude and land and water relationship.
i)The equatorial low pressure belt :
Along the equator lies a belt of low pressure known as the equatorial low or doldrums or calm. This low pressure belt lies between 50 North and 50 South latitudes.
ii) Sub – tropical high pressure belt:
The high pressure belt are found between 24 – 300C latitudes in both the hemispheres.
iii) Low pressure belts near 600 latitudes:
The airs from this area get thrown outwards on account of the rotation of the earth and this is how the low pressure belts are created.
iv) Polar high pressure belts:
The temperature is extremely low in the Polar Regions. The air being cold and heavy throughout the year a high pressure belt is created in both Polar Regions.
3. Diurnal variation:
At a given station the pressure show the two high and two lows. On normal pressure day two maxima i.e. one at 10 a.m. and another at 10 p.m. and two minimasi.e. one at 4 a.m. and another at 4 p.m. are observed. Thus there is double oscillation caused by alternate heating and cooling of atmosphere.
Factors affecting atmospheric pressure:
1. Temperature of air
2. Altitude
3. Water vapour in air
4. Revolution and gravitation of the earth.
Wind And Its Importance
Definition:
The air that moves parallel to any part of the earth surface is called wind or The air moving horizontally on the surface of the earth is known as wind.
Air Current:
Vertically or nearly vertical movements of air resulting from convection ,turbulence or any other cause is known as air current.
Importance or Role or Effects Of Wind In Agriculture:
1. Wind increases the transpiration and intake of CO2
2. The turbulence created by wind increase CO2 supply and the increase in photosynthesis.
3. When wind is hot, desiccation of the plants takes place, because humid air in the inter cellular places is replaced by dry air.
4. The hot and dry wind makes the cells expanding and early maturity, it results in the dwarfing of plants.
5. Under the influence of strong wind the shoots are pressurized and get deformed.
6. Strong winds produces loading of crops.
7. The coastal area affected by strong wind bring salt and make the soil unsuitable for growing plants.
8. Strong winds affect the plants life both mechanically and physiologically.
Wind Direction and Wind Speed
A wind is named according to the direction from which it blows e.g. a wind coming from west is called west wind.
The direction from which wind blows is termed as windward direction and that to which it blows is termed as leeward direction.
Classification of Wind
Vertical current
Horizontal
Periodic
Regular
Local
1. Divergence
1.Monsoon Winds
1. Planetary Earth’s general circulation
1.Land and sea breeze
2. Convergence
2. Mountain and valley breeze
3. Eddies
3. Foehn/Chinnook winds
4. Convection
4. Tomadoes
Earth’s general circulation system (Surface wind)
The earth’s surface wind system or earth’s general circulation of wind can be represented by a simple model shown in fig. In this model, the earth surface been considered uniform, means either all and or all water and the effects of local systems have been ignored, therefore the actual wind system is much more complicated than the described in the model.
It is to be noted that unequal heating of the earth’s surface generate pressure gradient which give rise to wind. There are three latitudinal circulations and there are also important longitudinal variations around each hemisphere.
1. Trade winds:
The condition of greatest heating and expansion at the equator causes rising of air and creating low pressure belt (50 N to 50S latitude) known as doldrums or equatorial low or calm. The rising of air from equator causes increase in pressure at 350 N 350S which is known as sub-tropical high or Horse latitude belt. The winds therefore flow from horse latitude belt. The winds therefore flow from horse latitude to the equatorial region called “Trade winds” While moving these winds, they are deflected by corollas force to the right in the and nor them hemisphere and to left in southern hemisphere and become North – East trades and south –East Trades in northern and southern hemispheres respectively.
The blow of air from equator and accumulation of air over 25-35 0 latitudes giving rise to high pressure belt region of descending air is known as Hadley cell.
2. Westerlies wind:
There situated at about 600 – 650 latitudes a low pressure area in both the hemisphere is known as sub-polar low or polar front. The winds that flow from sub-tropical high pressure area (Located at 250 - 350 latitude in both the hemisphere ) to the low pressure area, situated at about 600 - 650 latitude in both the hemisphere, are known as Westerlies or prevailing wisterias ( anti trade winds) In the upper atmosphere the reverse air movement takes place. This circulation is known as feral cell. These winds instead flowing in straight line are deflected due to corollas force. In northern hemisphere their direction is North – West and in southern hemisphere it is South-West.
3. Polar winds or Polar Easterlies winds :
Near the poles due to shrinkage of air and due to cooling, there exists permanent high pressure on the poles. Therefore winds flow from the polar high to sub-polar low pressure area at about 60-650 latitude. The wind flow in North-East direction in northern hemisphere and in south-East direction in southern hemisphere. These winds consist of clod air. The air circulation is known as polar cell.
Local Winds:
These winds are generated due to local condition and hence influence over very small area, therefore such winds are called local wind.
1. Land and sea breeze :
An interchange of air between the sea and coastal land due to unequal heating and cooling is known as land and sea breezes. They are local in nature. During day time the coastal land and sea breezes.. They are local in nature. During day time the coastal land as heated very fast as compared to sea water causing low pressure over the land. Therefore the surface air blows from sea to land and this is known as sea breeze. While during night time, the land cools faster than the sea, causing high pressure area over land as compared to sea. Therefore air blows from land to sea and this is known as land breeze.
2. Mountain and valley breeze:
An interchange of air between the mountain and valley due to unequal heating and cooling of the two places is known as mountain and valley breeze. During daytime, the valley breeze. During daytime, the valley floors become more heated; the air over it expands and rises. This rising air slides up the mountain slope and is known as valley breeze. During night reverse process takes place. Due to cooling of the air in the valley contracts and consequently augmented by air from the neighboring hills and mountains. The air on the mountain slopes also cools and slides down into the valley which is known as mountain breeze.
3. Ketabatic winds:
A mass of cold air over an elevated plateau during the winter tends to become more dense through radioactive cooling and then will drain down the slopes into the valleys below. The resulting down slope, drainage type winds are called Ketabatic winds. Most are relatively gentle breezes, not exceeding 4 to 5 m/s occasionally how ever, the cold dense air may be set in motion by a migrating cyclone or anticyclone and the Ketabatic winds may then attain destructive violence.
Foehn Winds
The Foehn winds is a down slope flow of air that occurs in manyu mountainous areas but is it not caused by the drainage of dense air, It occurs when the prevailing winds in warm, moist air are directed against a mountain. The forced ascent on the windward side, as illustrated in fig given below, usually causes cloud to form, Frequently, precipitation will also occur. During most of this ascent the air is cooled at the moist mountain top, much of the moisture may have been removed. This means that the air at the top has absorbed the latent heat released by the condensation of the moisture it contained. As the air descends the lee slopes, it is warmed at the dry adiabatic rate (100C/km). When it arrives at the bottom of the mountain, the air is warmer than at the same elevation on the windward side, having been heated by the latent heat of condensation. It is also drier because it has lost some of its moisture through condensation and/or precipitation on the windward mountain slope.
The Indians on the lee slopes of the Rockies referred to the wind as snow eater,” encase of the starting way in which large amount of snow could be melted and evaporated by the warmth and dryness of the air.s
Monsoon Wind
An interchange of air between the land and oceans due to unequal heating and cooling of continents and oceans is known as monsoon winds.
It has an annual period of occurrence. During summer, the land is heated Very much as compared to the oceans which cause which oceans low pressure Over the land and the winds blow from the oceans to the continents. During winter, land cools down faster than the oceans causing high Pressure over continents and low pressure over the oceans and the wind Blows from continents to oceans. The Indian monsoon is the best known Example of this alternating circulation system. There are two types of Monsoons over India i.e. south – west monsoon and North- East monsoon.
1.South – West Monsoon:
India is positional situated in North – East trade winds and should have N- E winds throughout the year, but a low pressure through lies along the Ganges and upper India, due to which S.- W winds predominate. During April to September a low pressure center is formed over N – W India. The s-W trade winds of the Indian ocean blow to the equator and then turning to the right under carioles force and move on a S – W winds Around the low pressure center over India. [This monsoon blows from the African coast (150E)]. The moisture laden air while rising the mountain of Asia cools, condense and precipitate. As a result the pressure is lowered to increase the pressure gradient.
2. North – East Monsoon:
Complete reversal of the S – W monsoon winds takes place as the high pressure centre is located in eastern Asian (1035 mb) and low in about 1010 mb. During this time from North to South the cold season is established. This monsoon is active during October and November. The winds flow in North- East direction. This wind is generally dry but gives rains to AP, TN states. Monsoon winds also exist over west Africa, Brazil, eastern USA, Australia. Philippines etc.
Forces Acting to Produce Wind
Wind is motion of air in response to unbalanced forces acting in horizontal direction. The different forces involved in the flow of the wind are described below:-
1. Horizontal pressure gradient (PG) force:
The rate of change in atmospheric pressure between two points at the Same elevation is called the pressure gradient or isobaric slope. It is proportional to the difference in pressure and is the immediate Cause of horizontal air movement. The direction of air flow is from high to Low pressure and the speed of flow is directly related to the pressure Gradient. The pressure gradient is said tube steep when the rate of change Is great and the gradient the more rapid will be the flow of air. The direction of the pressure gradient is perpendicular to the isobars and pointing towards low pressure.
PG = 1/P* dp/dn
Where P= air density
Dp/dn = rate of change in pressure with distance.
2. The earth’s rotational deflective force [Coriolis force]:
This force comes into play due to rotation of the earth on it axis. It has most potent influences upon wind direction. The Coriolis force effect Causes all winds in the nor them hemisphere to move or deflect toward the Right and those of the sot herm hemisphere to move to the left with respect to the rotating earth. At the equator the effect has a value of zero (Sin 90=1).and it increases regularly towards the poles (and becomes Sin 90=1). The Coriolis effect changes wind direction but does not change wind speed.
3. Centrifugal force :
This force tends to throw the air particles outward from the centre of small circle path on which the particle is moving. The centrifugal force works against the gravitational attraction directed forwards the earth centre.
4. Frictional force:
The roughness of the surface provides frictional resistance to the air motion. It is the retarding effect of trees, buildings and other irregularities in the topography; It is always opposed to the direction of the air motion and therefore fends to decrease the wind speed. Friction causes a movement of air across the isobars towards low pressure.
5. Geotropic winds:
When a wind flows in a straight line with no acceleration or frictional force on it, the only forces acting are the carioles and pressure gradient foresee. The wind that blows under these conditions is called as geotropic wind.
Cyclone and Anticyclone
It is the atmospheric disturbance in which the air pressure decreases at a particular location (Low pressure at centre) and there is a wind movement towards centre.
A system of close isobars with the lowest pressure at the centre is called as cyclone.
The pressure gradient force and carioles force cause air, flow in cycle to be spurning convergent system. In the northern hemisphere the direction of rotation of cyclone is antilock wise while in the southern hemisphere it is clockwise. Cyclones are also known as Lows or press ions. The velocity of wind in cyclone is more than 34 knots.
Anticyclone:
When there is a area of high pressure at centre, the flow of air starts from centre to outer side.
A system of closed isobars with highest pressure at centre is known as anticyclone.
The air flow has spiraling divergent system so that it moves obliquely across isobars away form centre. The direction of rotation of antic clones in the northern hemisphere is clock wise while in southern hemisphere it is antilock wise. These are known as “Hights.”
Atmospheric Humidity
Humidity:
Water vapor present in the atmosphere is known as humidity.
Vapour pressure:
When water vapour mixes with other gases of atmosphere, it exerts a pressure in all directions as do the other gases. This partial pressure exerted by vapour is known as the vapour pressure.
Saturated vapour pressure :
When air contains all the moisture that it can hold to its maximum limit, it is called saturated air and the vapour pressure exerted by this air is called saturated vapour pressure.
Relative humidity (RH) :
Relative humidity represents the amount of water vapour actually present in air compared with the maximum amount of vapour can be held b same air at a given temperature.
RH= Actual quality of water vapour present in a given volume of air x 100
Maximum amount of water vapour the same volume of air can hold
Absolute humidity (AH):
Absolute humidity is defined as the ratio of actual mass of water vapour present to the total volume of moist air in which it is contained.
It is measured in grams per cubic meter of air or in terms of partial pressure of water vapour in air in mbor mm of mercury.
AH = Weight of water vapour
Volume of air
Specific humidity:
Specific humidity is defined as the ratio of mass of water vapour to the given mass of air containing the moisture.
Thus it will be measure in grams of water vapour per kilogram of air.
Mixing ration:
It is the ration of the mass of water vapour to the mass of dry air
Maximum ration = MV/Ma
Where
MV = Mass of water vapour
Ma = Mass of dry air
Psychometric: Measurement of humidity with different instruments is called psychometric.
Variation In Relative Humidity
Diurnal variation in RH
The diurnal variation in relative humidity is approximately inverse to that of temperature about sunrise the RH is maximum and between 14 to 15 hrs minimum RH is observed.
Annual variation in RH: The annual variation of relative humidity is largely depends upon the locality.
At regions where the rainy season is in summer and winter is dry, the maximum relative humidity occurs in summer and minimum in winter and at other regions maximum RH occurs in winter.
Over ocean RH reaches maximum in summer.
Variation of RH with latitude and altitude:
RH shows maximum at equation or about 80%. Therefore it decreases to 70% in the regions of high pressure belts in 30-350 and afterwards increases again to 80 to 90% in the polar region.
The vertical variation of RH is not governed by any exact law. In or near the clouds it is 100% but below or above it is different. The moist air masses carried out by advection at altitudes also change relative humidity.
Clouds, It's Types and Their Classification
Cloud:
Cloud can be defined as a mass of tiny water droplets ice crystals OR both condensed on hygroscopic nuclei and suspending in the atmosphere.
Clouds and fogs are composed of water droplets or ice crystals or both of the order of size 20 to 60 microns (0.008-0.024 millimeter).
Isoneph:
Lime joining places of equal clouds cover on a map is known as isoneph.
Principles of cloud classification :
The great variety of cloud forms necessitates a classification of weather reporting. The internationally adopted system is based upon (a) The general shape; structure and vertical extend of the clouds and (b) their altitude.
Types of clouds: There are four basic types of clouds:
1. Clrrus (CI):
Meaning “cur” and is recognized by its veil, like fibrous or featery form. It is the highest type of cloud, ranging from approximately 7-12 km in altitude. (20,000 to 35,000 feet).
2. Cumulus (Cu):
Meaning “heap”, is the wooly, bundly cloud with rounded top and flat base. It is the most common in the summer season and in latitudes where high temperature prevail and it always results from convection Its height is variable and depends on relative humidity of the air.
3. Stratus (St):
It is a sheet type cloud without any form to distinguish it. It is usually lower than cumulus.
4. Nimbus (Nb):
It is any dark and ragged cloud and from which precipitation occurs.
Classification Of Clouds
Clouds have been classified according to their height and appearance by world Meteorological organization (WHO) into 10 categories.
Cloud family and Height
Name of cloud and abbreviation
Composition
Possible weather change
Description and appearance
1
2
3
4
5
Family A High clouds 7 to 12 km
1 Cirrus (Ci)
Ice crystals
May Indicate storm showery weather
It is wispy and feathery, sun shines without shadow. It does not produce precipitations
2. Cirrocumulus (CC)
Ice crystals
Possible storm
Meekerel sky, often fore renners of cyclone, look like sippled sand
3. Cirrostratus(Cs)
Ice crystals
Possible storm
Meekeral sky, often fore runners of cyclone, look like sippled sand.
Family B middle clods 3 3-7 km
4. Altocumulus (As)
Ice & water
Steady rain or snow
Looks like wool peak, sheep bulk clouds.
5. Atmostratus (As)
Water and ice
Impending rain or snow
Fibrous veil or sheet, grey or bluish, produce coronos, usually ct.st shadow.
Family C low clouds from ground to km
6. Stratocumulus (Se)
Water
Rain possible
Long parallel rolls, pushed together or broken masses which look soft and grey but with darker parts, air is smooth above but strong updrafts occur below.
7. straus (St)
Water
May produce drizzle
A low uniform layer, resembling fog, but resting not on the ground, chief winter cloud.
8.Nimbostrauts
Water or Ice
Impending rain or snow
Fibrous veil or sheet, grey, grey or bluish produce coronas, usually
Family D clouds with vertical development from 0.5 to 16 km
9.Cumu-lus (Cu)
Water
Fair weather
Looks like wool pack, dark below due to shadow, may develop into cumulous –Nimbus flat base.
10, Cumulous –Nimbus (Cb)
Ice in upper level and water in lower level.
Violet winds rain, all possible thunderstorm hail lighting possible
Thunder head, towering anvil top, violet up and down drafts, aviators avoid them, develop from cumulus, chief precipitation makers.
10 cumulo-Nimbus(Cb)
Ice in upper level and water in lower level
Violet winds rain, all possible thunderstorm hail lighting possible
Thunder head, towering anvil top, violet up and down drafts, aviators avoid them, develop from cumulus chief precipitation makers.
Clouds, It's Types and Their Classification
Cloud:
Cloud can be defined as a mass of tiny water droplets ice crystals OR both condensed on hygroscopic nuclei and suspending in the atmosphere.
Clouds and fogs are composed of water droplets or ice crystals or both of the order of size 20 to 60 microns (0.008-0.024 millimeter).
Isoneph:
Lime joining places of equal clouds cover on a map is known as isoneph.
Principles of cloud classification :
The great variety of cloud forms necessitates a classification of weather reporting. The internationally adopted system is based upon (a) The general shape; structure and vertical extend of the clouds and (b) their altitude.
Types of clouds: There are four basic types of clouds:
1. Clrrus (CI):
Meaning “cur” and is recognized by its veil, like fibrous or featery form. It is the highest type of cloud, ranging from approximately 7-12 km in altitude. (20,000 to 35,000 feet).
2. Cumulus (Cu):
Meaning “heap”, is the wooly, bundly cloud with rounded top and flat base. It is the most common in the summer season and in latitudes where high temperature prevail and it always results from convection Its height is variable and depends on relative humidity of the air.
3. Stratus (St):
It is a sheet type cloud without any form to distinguish it. It is usually lower than cumulus.
4. Nimbus (Nb):
It is any dark and ragged cloud and from which precipitation occurs.
Classification Of Clouds
Clouds have been classified according to their height and appearance by world Meteorological organization (WHO) into 10 categories.
Cloud family and Height
Name of cloud and abbreviation
Composition
Possible weather change
Description and appearance
1
2
3
4
5
Family A High clouds 7 to 12 km
1 Cirrus (Ci)
Ice crystals
May Indicate storm showery weather
It is wispy and feathery, sun shines without shadow. It does not produce precipitations
2. Cirrocumulus (CC)
Ice crystals
Possible storm
Meekerel sky, often fore renners of cyclone, look like sippled sand
3. Cirrostratus(Cs)
Ice crystals
Possible storm
Meekeral sky, often fore runners of cyclone, look like sippled sand.
Family B middle clods 3 3-7 km
4. Altocumulus (As)
Ice & water
Steady rain or snow
Looks like wool peak, sheep bulk clouds.
5. Atmostratus (As)
Water and ice
Impending rain or snow
Fibrous veil or sheet, grey or bluish, produce coronos, usually ct.st shadow.
Family C low clouds from ground to km
6. Stratocumulus (Se)
Water
Rain possible
Long parallel rolls, pushed together or broken masses which look soft and grey but with darker parts, air is smooth above but strong updrafts occur below.
7. straus (St)
Water
May produce drizzle
A low uniform layer, resembling fog, but resting not on the ground, chief winter cloud.
8.Nimbostrauts
Water or Ice
Impending rain or snow
Fibrous veil or sheet, grey, grey or bluish produce coronas, usually
Family D clouds with vertical development from 0.5 to 16 km
9.Cumu-lus (Cu)
Water
Fair weather
Looks like wool pack, dark below due to shadow, may develop into cumulous –Nimbus flat base.
10, Cumulous –Nimbus (Cb)
Ice in upper level and water in lower level.
Violet winds rain, all possible thunderstorm hail lighting possible
Thunder head, towering anvil top, violet up and down drafts, aviators avoid them, develop from cumulus, chief precipitation makers.
10 cumulo-Nimbus(Cb)
Ice in upper level and water in lower level
Violet winds rain, all possible thunderstorm hail lighting possible
Thunder head, towering anvil top, violet up and down drafts, aviators avoid them, develop from cumulus chief precipitation makers.
Hydrological cycle
Water is essentially required for different life forms such as plants animals. Birds etc. For cell building and other purposes. The main source for the water is ocean. The water from the oceans is evaporated, clouds are formed and carried away by wind and they precipitate. The water received from precipitation is lost to the ocean back by different processes such as run- off evaporation from soil, lakes and ponds, streams, etc evapotranspiration from plants the water which is absorbed in the ground is also lost by direct or indirect way to the ocean, for example, some water which is absorbed in ground is utilized by plants and then evaporated, the ground waer which is absorbed in ground is utilized by plants and then evaporated. The ground water flows to the streams and the stretch finally lost in the oceans etc. Thus, we find that there is a constant circulation of water from oceans to the air and back again to the oceans. This process has not end beginning and therefore it is termed as hydrological cycle or water cycle. The hydrological cycle can be briefed by the following equation.
P = ET + DST + S
The total amount of water present on the earth surface remains constant but undergoes continuous transformation from water vapour to liquid. This equation is also called as water balance equation. Where P is the water received by precipitation, ET is loss by evapotranspiration, dst is the gain on loss by storage in the soil and S is the surplus run-off of water, from this mathematical relation, we can find out the value of other elements.
Precipitation and Forms of Precipitation
It can be defined as earthward falling of water drops or ice particles that have formed by rapid condensation in the atmosphere.
Forms Of Precipitation
A. Liquid form
B. Solid form
C. Mixed form
1. Rain
1. Snow
1. Sleet
2. Drizzle
2. Hail
2 Hail
3.Shower
A. Liquid Form
1. Rain:
Rain is defined as precipitation of drops of liquid water. The clouds consists of minutes of minutes droplets of water of about 0.02 mm diameter. When these minute water droplets in clouds combine and form large drops that become so large that they can not remain suspended in the air and they fall down as rain. The droplets are formed by repaid condensation. The rain drops have diameters ranging from 0.05 to 0.06 cm (0.5 to 0,6 mm) The line joining the places of equal rainfall called Isohyets.
Types of Rain:
I) Convectional rains:
Due to heating, the air near the ground becomes hot and light and starts upward movement (This is known as convection.) as air moves upward it cools at the DALR (9.80C/km) and becomes saturated(having RH 100%) and dew point is reached where the condensation. begins . This level or height is known as condensation level. Above condensation level air cools at SALR (5 0C/km) clouds are formed. Then further condensation results into precipitation. These rains are known convectional rains.
II) Ographic or relief rains:
When the moist air coming from sea encounters mountain or relief barrier, it can not move horizontally and has to overcome mountain. When this air rises upward, coolsdown, cloud is formed and condensation starts and giving precipitation. These rains are known as or orographic rains thus high rains are possible on the windward side of the mountain. After crossing the mountain divide, when air descends downward, the air is compressed and it warmed up at DALR. This warm air does not give any precipitation on the leeward region. This is known as rain shadow region.
III) Cyckibuc/Frontal and Convergent rains:
Frontal precipitation is produced when two opposing air currents with different temperature meet, vertical lifting takes place which gives rise to condensation and precipitation. When the humus and warm air mass meets the cold air mass, the colder air being denser tends to push below the warmer air and replace it. The boundary zones along which two air masses meet are called as fronts. When the mixing of warm and moist air with cold air mass takes place, the temperature of the warm and air falls down, saturation occurs and may give precipitation and it also responsible for cyclone formation and rains received from cyclones are called cyclonic reins.
Thunder Storms:
It is the atmospheric disturbance which is always accompanied by thunder and lightening and sometimes by hail. It is a local storm covering comparatively small area and often causing damage. Its chief
Characteristics are an immense cumulo-nimbus cloud accompanied by copious precipitation, a marked drop in temperature and a more or less destructive out rushing squall wind which precedes the rainfall. Thunder storms occur in every part of the world and their frequency decreases with increase in latitude.
Storms are of two types:
1) Frontal or general thunderstorm:
This occurs over wide areas in connection with passing of a cyclonic disturbance.
2) Local thunder storm:
This forms as a result of strong local convection.
3) Drizzle:
It is more or less uniform precipitation of very small and numerous raindrops which are carried away even by light wind. The drizzle drop is less than 0.5 mm in size, and precipitate at the rate usually less than 1 mm per hour.
4) Shower:
Precipitation lasting for a short time with relatively clear intervals is called shower. This occurs from the passing clouds.
B) Solid Form:
1. Snow:
Snow is defined as precipitation of water in the solid form of small Or large ice crystals. It occurs only when the condensing medium has a temperature below freezing temperature, snow is generally in the form of individual crystals or in flakes that are aggregates of many crystals. Snow flakes are formed in high clouds. Snow is measured with snow gauge.
2. Hail:
Hail is a precipitation of solid ice. On a warm sunny day, a strong Connective column may cause the formation of pellets having spherical Shape and concentric layers of ice. Such a formation is known as hail.
C. Mixed Form:
1. Sleet
Simultaneous precipitation of the mixture of rain and snow is called as sleet.
2. Hailstorm:
Rainfall associated with hail stones is called hailstorm.
Mechanism or process of Rain formation or Process of Precipitation:
There are two methods by which rain drop is formed.
1. Bergeron mechanism:
There are two methods by which rain drop is formed.
1. Bergeron mechanism:
The cloud having cold temperature is cold temperature is cold cloud. In these clouds Ice particles are formed due to very low temperature (-150C to -250C). These ice particles are grow rapidly by deposition of water vapors (sublimation) developing in to hexagonal shaped ice crystals. These ice crystals on collision form snow pellets and melt into water droplets when falling on ground through warm atmosphere. This mechanism is suggested by Swedish Meteorologist Bergeron in 1933. Artificial rain making is based on these mechanisms.
2. Collission and coalescence mechanism:
The cloud having slightly higher temperature is not cloud. In these Clouds fine water droplets exist instead of ice particles. This fine water Droplets colloid and coalesce (combine) and grow into the larger size and fall on earth as rain drop.
Drought and Its Classification
Definition:
Drought is a period of inadequate or no rain fall over extended time creation soil moisture deficit and hydrological imbalances.
Classification of Drought:
Drought on different basis is generally classified into three categories.
A) Based on source of
Water availability
B) Time of occurrence
1.Meteorological
Drought
Slight drought
Moderate drought
Severe drought
1. permanent drought
2. Hydrological drought
2.Seasonal drought
3. Agricultural drought.
3.Contigent drought
Drought classification
A. On the basis of source of water availability:
Drought is classified into three types on the basis of water availability.
1. Meteorological drought:
The meteorological droughts mainly indicate deficit rain of different quantum. The IMP classified this drought as follows from the rainfall departure.
Slight drought : When rainfall is 11 to 25% less from the normal rainfall.
Moderate drought : When rainfall is 26 to 50% less than the normal rainfall.
Severe drought : When rainfall is more than 50% less than the normal rainfall
2. Hydrological drought:
It is defined as the situation of deficit rainfall when the hydrological sources like streams, rivers, lakes, wells dry up and ground water level depletes. This affects industry and power generation.
3. Agricultural drought:
This is the situation resulted from inadequate rainfall, when soil moisture falls to short to meet the water demands of the crop during growth. Thus affects crop may wilt due to soil moisture stress resulting into reduction of yield.
B. On the basis of time of occurrence:
Drought differs in time and period of their occurrence and on this basis Thormathwite delineated following three areas.
1. Permanent drought area:
This is the area generally of permanent dry, arid p desert regions. Crop production due to inadequate rainfall is not possible without irrigation. In the these areas vegetation like cactus. Thorny shrubs, xerophytes etc. are generally observed.
2. Seasonal drought:
It occurs in the regions with clearly defined as rainy (wet) and dry climates. Seasonal drought may occur due to large scale seasonal circulation. This happens in monsoon areas.
3. Contingent drought:
This results due to irregular and variability in rainfall, especially in humid and sub humid regions. The occurrence of such droughts may coincide with grand growth periods of the crops when the water needs are critical and greatest resulting into severity of the effects i.e. yield reduction.
C. on the basis of medium:
On the basis of medium in which drought occurs. Mexico (1929) has divided the drought into two types.
1. Soil drought:
It is the condition when soil moisture depletes and falls short to meet potential Evapotranspiration of the crop.
2. Atmospheric drought:
This results from low humidity, dry and hot winds and causes desiccation of plants. This may occur even when the rainfall and moisture supply is adequate.
Strategy to mitigate drought OR How to overcome the drought:
1. Preventing and recycling of excess runoff
2. Deep tillage to absorb and hold maximum moisture.
3. Timely weed management to control water loss by ET.
4. Planning for suitable cropping system.
5. Selection of short duration and drought tolerant crops.
6. Contingency crop planning for abnormal weather situation.
7. Management of various inputs to suit the climate.
8. Conserving the soil moisture by agronomic practices like mulching use of antitranspirant on the crops to reduce ET.
9. To apply irrigation.
10. Reduction of plant population to reduce ET.
11. Timing of foliage to reduce ET.
Drought year:
The year is considered “drought year “when less than 75% of the normal rainfall is received. Drought prone area: It is defined as one in which the profanity of a “drought year “is 20 to 40.
Chronic drought prone area:
Is defined as one in which the probability of “drought year” is greater than 40%.
Weather Forecasting And Its Classification
Weather forecast:
Means any advance information about the probable weather in future, which is obtained by evaluating the present and past meteorological conditions of the atmosphere is called weather forecast.
Agricultural weather forecast:
Forecasting of weather elements viz sunshine hours, occurrence of dew, relative humidity, rainfall, temperature, winds etc. Which are important in agriculture and for farming operations is known as agricultural forecast.
In weather forecasting the advance information of weather elements like distribution of rain fall, warming for heavy rain fall, temperature change important special hazardous weather like if thunderstorm hailstorm, show or frost, sky cover, winds, humidity, dew drought, evaporation rate etc is provided.
Classification weather forecasting:
Weather forecasting on the basis of their validity periods or time scale is classified as follows :
1. Now casting:
It is based on synoptic situation prevailing at the time of forecasting and is valid up to 3 days on 72 hrs and is issued twice a day.
2. Short range forecast (SRF):
It is based on synoptic situation prevailing at the time of forecasting and is valid up to 3 days or 72 hrs. and are issued twice a day.
3. Medium range forecast (MRF):
Forecasting of meteorological elements over different agro climatic zones for periods ranging from3-10 days is known as medium range forecast.
4. Long range forecast (LRF):
The forecast valid for more than 10 days (i.e. a month or a season is knows as long range forecast.
Importance or Significance of Weather Forecast in agriculture
1. The forecast of the weather events helps for suitable planning of farm.
2. It helps in to undertake or withheld the sowing operation
3. It helps in following farm operation:
I) To irrigate the crop or not
II) When to apply fertilizer or not.
III) Whether to start complete harvesting or to withhold it.
4. It also helps in to take measures to fight frost.
5. It helps in transportation and storage of food grains.
6. Helps in management of cultural operations like plugging harrowing hoeing etc.
7. It helps in measures to protect livestock.
Crop Models And Its Techniques
Agrometeoorological forecasting is also concerned with the assessment of current and expected crop performance. It utilizes the past and the present weather data and crop data to predict the crop performance in the future. These forecasts may be about the occurrence of some phonological events viz. Emergence, flowering, fruiting, maturity and harvesting etc or may be about the possible crop production. Of the agro meteorological forecasts in use. Probably the most important economically are the forecasts of crop yield. The impact of weather and climate on crop growth and yield can be represented by crop weather models.
A model in general is an equation or set of equations which represents the behavior of a system. There are many types of the models as follows.
1. Statistical empirical model: Actual mechanism of processes is not disclosed.
2. Mechanistic model: mechanism of the processes involved id discussed e.g. photosynthesis based model.
3. Static model: Time is not a factor.
4. Dynamic model:These models predict changes in crop status with time.
5. Deterministic model: In which a definite output is given e.g. NPK doses are applied and the definite yields are given out.
6. Stochastic model: The models are based on the probability of occurrence of some event or external variable. Probabilities are given out.
The statistical techniques used in designing the models are as follows:
1. Simple regression analysis
2. Simple correlation technique.
3. Curvilinear correlations techniques
4. Multiple regression analysis
5. Stepwise regression analysis
6. Fishers orthogonal polynomial techniques
7. Mallow’s Cp techniques.
8. Marko cham model.
Bar (1979) has tried to classify the basic types of crop weather models as follows:
1. Crop growth simulation models
2. Crop weather analysis models
3. Empirical statistical model
Part 4
Rainfed Agriculture
Dry Land Farming
Indian agriculture is traditionally a system of Rainfed agriculture. Out of 143 million hectares of net cropped area, about 72% is Rainfed production about 45% of food grains and 75 - 80% of pulses and oil - seeds and a number of important industrial crops. Considering the present rate of development of irrigation facilities and also water potentiality of the country, express estimate that at any point of time 50% of cropped area in India will remain under Rainfed farming system.
Such vast areas as of now consume hardly 25% of total fertilizer consumption of the country. Due to poor level of management, crop productivity is also very low resulting in socio - economic backwardness of the people.
Dry lands: Areas which receive an annual rainfall of 750 mm or less and there is no irrigation facility for raising crops.
Dry land Agriculture: Scientific management of soil and crops under dry lands with out irrigation is called dry land agriculture.
Dry land crops: It refers to all such crops which are drought resistant and can complete their life cycle without irrigation in areas receives an annual rainfall less than 750 mm.
Drought: It is an condition of insufficient moisture supply to the plants under which they fail to develop and mature properly. If may be caused by soil, atmosphere or both.
Dry farming : In the country with low and precarious rainfall two types agricultures are usually met, one crop production on aerable farming land other animal husbandry, including management of grazing areas.
Definiuons:
The different definitions of dry farming given by various express are described below.
1. Dry farming is an improved system of cultivation in which maximum amount of moisture is conserved in low and untimely rainfall for the production of optimum Quantities of crop on economic and sustames basis.
2. Dry farming in short, is a programme of soil and water management designed to conserve the maximum quantity of water on a particular piece of land.
By Anand
3. Dry farming is the profitable production of useful crops without irrigation on land that receive annually a rainfall of 500 mm or less.
By Anonymous
4. In a more specific way dry farming may be defined as an efficient system of soil and crop management in the regions of low land and uneven distributed rainfall.
By Anonymous
Dry land Vs Rainfed farming.
Constituents
Dryland farming
Rainfed farming
1. Rainfall (mm)
< 750
>75
2. Moisture
Shortage
Enough / Sufficient
3. Growing season
<200
>200
4. Growing regions
Arid and Semiarid & up lands of sub humid & humid regions.
Humid and slub humid regions.
5. Cropping system
Single crop or
intercropping
Intercropping or double cropping.
6. Constraints
Wind and water erosion
Water errosion.
Rainfed Farming
Growing of crops on natural preciption without irrigation.
Dry farming areas : Dry farming areas (as per the IV five year plan) are those areas receiving an annual rainfall ranging from 375 to 1125 mm and very limited irrigation facilities. Areas which receive less than 375 mm of average rainfall are considered as absolutely arid or desert areas, which require special treatment. As many as 128 districts in the country falls under category of dry farming areas as defined above. Out of these 25 dists from the states of Rajasthan, Sourashtra and rainshado region of Maharashtra and Karnataka belong to very high intensity dryfarming areas (i.e. rainfall ranges from 375 to 750 mm and irrigated area belong 10% of the cropped area.)
As the Encylopedia Britanmputs Dry land farming consists of making the best use of limited water supply by storing in the soil and much of the rainfall as possible and by going suitable crop plants those make the best use of this moisture.
The major physiographic regions observed in India namely
i) Mountain region
ii) Indogangatic alluvial plains
iii) Peninsular or Deccan plateau &
iv) Coastal plains.
National Agricultural Research Project (NARP) launched in 1979 by ICAR with soft loan support from International Development Agency (IDA) of World Bank. Where in state Agricultural Universities were advised to divide each zone / state into subzons (NARP). Accordingly 120 sub zone map based primarily on rainfall, existing cropping pattern and administrative units was prepared.
Although the agro climatic regional approach considers an agro - climatic zone having a greater degree of commonality of the relevant basic fetures of soils, topography, climate and water resources. Yet in practice this approach neighter gave adequate consideration to soils and environmental conditions nor had a uniform criterion. Moreover, the use of state as a unit for sub - division may not be reconciled with, as it resulted is the creation of many sub - divisions having similar agro - climation characteristics, occurring in different states.
Since the agro - climatic regional planning a approach was intended take an integrated view of agricultural economy in relation to resource bas and linkage with other sectors, further development should be specific agro - ecoregions and considered to generate an agro ecological region my of the country giving due recognition to climatic conditions, length growing period, land form & soils.
Soil And Climatic Studies In Rainfed Agriculture
i) Soils
: -
Out of total cultivable land in M.S. 87 per cent area comes ur rained. Soils of drought prone areas of M.S. area derived from the be igneous rock Basalt commonly known as Deccan trap. The colours of soil vary from reddish brown to dark gray black and are called verti. The soils exhibit a definite to posegence of ridge medium dear 122 - 90 cm depth) soils on sloped land deep soils (more than 90 cm meen) end of watershed. The distribution of very shallow, shallow, medium deep and deep soils in drought prone areas of M.S. is about 10,20,45 and 25% respectively. They usually under lined partially decomposed rock locally known as murrum which overlies parent material. On account of more or less complete absence of leaching the soils are base saturated. The exchangeable calcium is predominant cation. The free lime is reserve is fairly high (3 to 10%) and at places excessive quantities of time nodules accumulate. The problematic soils viz. saline, saline sodic land sodic soils do occur in patches in low lying areas.
As regards the fertility status, the soils are generally low in organic carbon (0.35 to 0.5%) total nitrogen (0.03 to 0.05%) low to medium available phosphate (10 to 30 kg p2O5/ha) and high available potash (300 to 750 kg K2O/ha). Usually micro-nutrient deficiencies are not observed in dry land crops. However in eroded soils, crop like groundnut have shown some response to boron application. Cereal crops give fairly good response to nitrogenous fertilizers while oilseeds and legumes give good response to phosphatic fertilizers.
Soils exhibit adverse physical characters because of high clay content (35 to 65%) of type clay mineral. The soils exhibit high volume expansion when moist and shrink when dry. The infiltration rate of soils is moderately slow (0.5 to 0.9 cm/ha). During the process of shrinkage, wide land deep cracks are developed even up to Murrum strata in medium deep soils. The crack development accelerates the soil moisture loss from the deeper layers (phases). Further soils exhibit varying degree of erosion depending on the slope, tillage operations and cropping season. The soils classed as moderate to high erodible. Hence soil and water conservation is a pre - requisite for successful cropping. Limited soil depth puts limitations on availability of water and nutrients for cropping intensity. Usually soils having less than 45 cm depth are useful for Kharif crops as they are unretentive of soil moisture. Inter mittant wetting due to frequent rainfall during June to Aug helps to mature crops on such soils. Soils having depth more than 45 cm have high moisture storage and retentive capacity. Under dry land to bring the soil moisture in the available range (i.e. above PWP) the rainfall required is quite high since the precipitation in the early part of monsoon is quite inadequate the medium deep soils (beyond 45 cm deep) usually do not have adequate moisture for sowing. It is only due to receipt of about 200 mm of rains during September the medium deep and deep soils are adequately moistened for Rabi cropping. Hence Rabi cropping is predominant and medium deep and despoils one grown with Rabi crops.
The moisture storage capacity of soil mainly depends on clay content and soil depth. However, city content is generally above 45 percent in medium deep and deep soil the moisture deptetion of soil depends on the moisture held in the soil at different tensions. The soil moisture is always below the moisture at 15 bar (PWD) which ultimately results in faiture of crops in dry land agriculture.
ii) Climate: Wether, which is part of climate, plays an important role in crop planning in dry farming area. Out of the several elements of weather, rainfall has key position in success of dryfarming.
In dry land areas, South West Monsoon brings the bulk of rainfall. The South West Monsoon is followed by North East Monsoon which supplements to South West Monsoon are the main source of rainfall. There are four types of rainfall characterized by the nature in different parts of India. Generally, the rainfall is scanty, erratic and ill distributed. The draught prone area in Maharashtra State Covers about 1/3 of the total area of the state. The climate in this is usually hot and PE (Potential Evaporation) is for in excess of the precipitation is classified as semiarid e.g. Annual precipitation at Solapur is about 7/22 mm. but PE is about 1300 mm annually resulting in deficient 60%.
iii) Rainfall features :- The annual Average rainfall varies from 400 mm to 700 mm. Year to year fluctuations are so much that there is no guaranteed of fixed quantity of rainfall. Uncertain and ill distributions of rainfall are two qualities which makes the Rainfed farming difficult. Rainfall starts in lated June to Early July.
There is depression during late July and early August Again there is good rainfall in late August and September. The rainfall totally recedes but mid October. The probability of rainfall is more than half of the normal fairly good (P = 0.58) during September.
iv) Dry spells: - It is another rainfall feature. Breaks in monsoon a normally experienced (observed) during rate July and August. They month extend by 2 week to 13 weeks at a stretch. A break is defined as period receiving less than 15 mm rainfall in consecutive weeks. The normal rainfall during the week being more than 50 mm. A duration of break month than 4 week and frequently more than 3 times usually results in fatures than 4 weeks and frequently more than 3 times usually results in faitures crops.
Variation in the rainfall with in the district is also observed. In Solapur, particularly variation in annual precipitation is noticed from 500 mm in western part to about 700 mm in eastern parts.
v) Water availability period: - Water availability depends on rainfall and PE. Humid (when rainfall exceeds PE) and moist (when rainfall is less than PE but exceeds PET) period together provides congenial weather for active crop growth.
vi) Wind velocity: - Wind velocity is generally hitch during July and August. If wind velocity exceeds 18 - 20 km./hr. Such period coincided with dry spell. Hence Evapotranspiration is at high degree. If velocity is low the lowest evaporation rates are observed during November and December.
vi) Bright sunshine hours: - Bright sunshine is usually experienced during months of Jan. and Feb. At Solapur it is about 8 to 9 hours. During April and May the sky is usually have with more dust particles, lowest bright sunshine is noticed during Aug. (4 to 5 hours). This indicates the cloudy weather but no rainfall.
vii) Humidity: - Humidity is high during July and Sept. During Feb. to May it is low. During dry spell, less relative humidity is noticed. Evaporation demands are also accelerated with high temperature and low humidity.
viii) Temperature: - a Maximum temperature exceeds 410 C during late April and early May. Minimum temp. is noticed during December. Lowest weekly minimum temperature is about 14 to 150C. Generally climate is semi and with mild winter and hot summer. Crop like wheat and gram requiring longer cool period hence do poor while prolonged cold weather however, Jowar suffers considerably.
Why crop failures are common, yields are not static under Rainfed farming because.....
1. Inadequate and uneven distribution of rainfall.
2. Late on set and early cessation of rainfall.
3. Prolonged dry spells during the crop growth period.
4. Low moistone retension capacity of soils.
5. Low fertility of soils, low humidity, higher temperatures, higher wind velocity.
Different Soil Types And Their Characters In M.S
Particulars
Soil type
Shallow
Medium
Deep
A) Area of state
10%
65 to 66%
25%
1. Parent material
Trap basalt
Trap basalt
Trap basalt
2. Topography
Undulating
Undulating
Flat
3. Depth (Cm)
Up to 22.5
45 to 90
Above 90
4. Texture
Clay
Clay loam
Clay
5. Colour
Light black
Grayish black
Black
6. pH
7.5 to 8.0
5.0 to 8.5
8.0 to 8.5
7. T.S.S. %
0.2
0.2
0.2 to 0.3
8. Lime (CaCO3)%
0.5 to 5.0
1.0 to 10.0
2.5 to 15.0
9. Nitrogen kg /ha
Trace
80 to 120
100 to 200
10. C/N ratio
8 to 10
10 to 12
18 to 40
11. Available P2O5 kg/ha
8 to 10
15 to 30
18 to 40
12. Available K20 kg/ha
60
250 to 500
250 to 850
13. Base situation
10 to 15 mg/100
30 to 60
70 to 80
capacity
per gram
14. Sodium Saturation %
Trace
10
10
Agro Climatic Zones Of India In General
Introductions: - The important rational planning for effective land use to promote efficient is well recognized. The ever increasing need for food to support growing population @2.1% (1860 millions) in the country demand a systematic appraisal of our soil and climatic resources to recast effective land use plan. Since the soils and climatic conditions of a region largely determine the cropping pattern and crop yields. Reliable information on agro ecological regions homogeneity in soil site conditions is the basic to maximize agricultural production on sustainable basis. This kind of systematic approach may help the country in planning and optimizing land use and preserving soils, environment.
India exhibits a variety of land scopes and climatic conditions those are reflected in the evolution of different soils and vegetation. These also exists a significant relationship among the soils, land form climate and vegetation. The object of present study is to delianate such regions as uniform as possible introspect of physiographic, climate, length of growing period (LPG) and soils for macro level and land use planning and effective transfer of agro - technology.
Agro Climatic Zones: - Agro climatic zone is a land unit in Irens of mator climate and growing period which is climatmenally suitable for a certain image of crops and cultivars (FAO 1983). An ecological region is characterized by district ecological responses to macro - climatic as expressed in vegetation and reflected fauna and equatic systems. Therefore an agro-ecological region is the land unit on the earth surface covered out of agro - climatic region, which it is super imposed on land form and the kinds of soils and soil conditions those act as modifiers of climate and LGP (Length of growing period).
With in a broad agro climatic region local conditions may result in several agro - ecosystems, each with it's own environmental conditions. However, similar agro ecosystems may develop on comparable soil, and landscape positions. Thus a small variation in climate may not result in different ecosystems, but a pronounced difference is seen when expressed in vegetation and reflected in soils.
India has been divided into 24 agro - climatic zone by Krishnan and Mukhtar Sing, in 1972 by using "Thornthwait indices".
The planning commission, as a result of mid. term appairasal of planning targets of VII plan (1985 - 90) divided the country into 15 broad agro - climatic zones based on physiographic and climate. The emphasis was given on the development of resources and their optimum utilization in a suitable manner with in the frame work of resource constraints and potentials of each region. (Khanna 1989).
Agro climatic zones of India :- (Planning commission 1989)
1
Western Himalayan Region
Ladakh, Kashmir, Punjab, Jammu etc.brown soils & silty loam, steep slopes.
2
Eastern Himalayan Region
Arunachal Pradesh, Sikkim and Darjeeling. Manipur etc. High rainfall and high forest covers heavy soil erosion, Floods.
3
Lower Gangatic plants Regions
West Bengal Soils mostly alluvial & are prone to floods.
4
Middle Gangatic plans Region
Bihar, Uttar Pradesh, High rainfall 39% irrigation, cropping intensity 142%
5
Upper Gangatic Plains Region
North region of U.P. (32 dists) irrigated by canal & tube wells good ground water
6
Trans Gangatic plains Region
Punjab Haryana Union territory of Delhi, Highest sown area irrigated high
7
Eastern Plateaus & Hills Region
Chota Nagpur, Garhjat hills, M.P, W. Banghelkhand plateau, Orissa, soils Shallow to medium sloppy, undulating Irrigation tank & tube wells.
8
Central Plateau & hills Region
M. Pradesh
9
Western Plateau & hills Region
Sahyadry, M.S. M.P. Rainfall 904 mm Sown area 65% forest 11% irrigation 12.4%
10
Southern Plateau & Hills Region
T. Nadu, Andhra Pradesh, Karnataka, Typically semi and zone, Dry land Farming 81% Cropping Intensity 11%
11
East coast plains & hills Region
Tamil Nadu, Andhra Pradesh Orissa, Soils, alluvial, coastal sand, Irrigation
12
West coast plains & Hills Region
Sourashtra, Maharashtra, Goa, Karnataka, T. Nadu, Variety of cropping Pattern, rainfall & soil types.
13
Gujarat plains & Hills Region
Gujarat (19 dists) Low rainfall arid zone. Irrigation 32% well and tube wells.
14
Western Dry Region
Rajasthan (9 dists) Hot. Sandy desert rainfall erratic, high evaporation. Scanty vegetation, femine draughts.
15
The Island Region
Eastern Andaman, Nikobar, Western Laksh dweep. Typical equatorial, rainfall 3000 mm (9 months) forest zone undulating
Rainfall, Its Distribution And Its Effectiveness In Rainfed Agriculture
Distribution of Rainfall: - The amount of rainfall received at periodic intervals like weeks, months, seasons etc. indicate distribution. In addition distribution of rainfall can be known by the length of dry spell, wet spells land rainy days. Distribution of rainfall is more important than total rainfall.
Rainfall pattern at three locations:-
Sr. No.
Index
Hyderabad
Solapur
Dhule
1
Annual rainfall (mm)
764
742
625
2
Seasonal rainfall (mm)
580
556
450
3
Coefficient of variation%
4
PE (mm)
1757
1802
1502
5
Growing season
130
148
125
6
Soil
Vertisols
Vertisols
Medium deep
From the above data the growing season is slightly less at Hyderabad as compared to Solapur, However rainy season crops are more successful at Hyderabad and annual yields range 50 to 70 q/ha. While at Solapur and Dhule rainy season crops are risky and annual yields range from 10 to 12 q/ha. Low yields at Solapur and Dhule are mainly due to discontinuous rains or long breaks in rainfall during crop growth period.
Rainfall distribution is based on:
1. Weekly or monthly rainfall will give distribution of rainfall in weeks during a crop season.
2. Wet and dry spells - A wet spell is a number of continuous days of rainfall. A dry spell is a number od continuous rainless days.
3. Rainy days: If the rainfall received is more than 2.5 mm on any day. This particular day is called rainy day.
4. Periodicity of rainfall.
5. Onset of monsoon.
6. Recurrence of rainfall events.
7. Dependability of rainfall
8. Certificient of variation. If C.V. is more variation in rainfall is more and vice - a - versa.
9. Length of the growing season (LGS): If LGS is less a short duration crop should be selected. L.G.S. depends on duration of rainy season and moisture retention.
Rainfall being a single most important factor for success of crops in the dry farming areas. It is generally known that India receives its annual rainfall by the particular phenomenon called monsoon which consists of series of cyclones those arise in the Indian Ocean. These travel in the North East direction and enter the peninsular India along the Western coast. These cyclones occur from June to Sept. is known as south West monsoon. This is followed by second third and fourth rainy season during periods from Oct. to Nov., Dec. To Feb. and March to May respectively. South West Monsoon is the most important as it covers major parts of India and brings bulk of the total annual rainfall.
The North East of Returning monsoon: By the end of Sept. South West Monsoon ceases to penetrate North West India but continues a full month longer in Bengal. On account of south East North easterly winds being to flow on the Eastern coast. Some times some of these cyclones penetrate In land and give supplementary rainfall to dry region of the plateau of the peninsular India. This is known as returning monsoon.
Precipitation And Its Factors
Precipitation is reaching of atmospheric humidity either as rain or snow to the ground. OR Precipitation can be defined as earth word falling of water drops of ice particles that have formed by rapid condensation in the atmosphere and are too large to remain suspended in the atmosphere.
Factors influencing precipitation:-
1. Only blowing of winds coming even over the sea is not enough to produce precipitation.
2. Horizontal movement is not conductive to precipitation.
3. The rain bearing clouds, hills, mountains, slanting slopes of the river ralleys lake dynamic cooling of the clouds.
4. Water vapour in atmosphere and moat conditions which promote greater precipitation.
5. Regiour covered with thick forest contributes more water vapour by transportation and thus provide favorable condition for preciption.
6. The prevalence of dry winds, higher temperature absence of barriers and cutting of monsoon currents these are unfavorable for precipitation.
7. Long & short breaks in the monsoon caused due to prevalence of dry winds slowing over land or desert plains from North East.
8. On the other hand geographical position, physical configuration and meteorological conditions are responsible for precipitation.
Type Of Rainfall In Dry Areas
1. First type rainfall: Rainfall receives from south west Monsoon. Rainfall receives up to 60% in the first three months viz. June - July - August - Rontak Jodhpur Jalgaon.
2. Second type rainfall: Rainfall receives from south - West Monsoon (40 to 55%) and supplemented with North East Monsoon (40 to 50%) Pune. Wal A Nagar Raichur - Maximum rainfall receives in July & Sept.
3. Third type rainfall: Rainfall receives from North East Monsoon (60%) Solapur Bijapur a Karnataka.
4. Four type rainfall: Rainfall receives uniformly (Well distributed) from Both Monsoon currents, places of rainfall - Chennai. Total rainfall received in 5 to 6 months.
Decennial rainfall: The mean total rainfall received during past 10 years:
Winds coming over land surface from the North - East are dry and cold and man cause of breaks in the monsoon or they tend to decrease the rainful of a tract by diluting the moisture laden masses of the atmosphere. Indian be divided into three zones of the basis of rainfall.
A) Heavy rainfall zone: above 1250 mm.
B) Moa crate rainfall zone: 750 to 1250 mm.
C) We rainfall zone: Less than 750 mm annual rainfall.
The average rainfall of Solapur varies from 500 to 720 mm and had bimodal stribution. The first peak is usually experienced during June and Second during Sept. Rainfall during Sept. is more assured and is in the rage of 150 to 200 mm. Even though Monsoon sets in by the end of June, July and August are characterized by dry spells of varying duration (2 to 8 weeks at stretch) and frequencies 1 to 5. Usually dry speels of more that 4 weeks duration or 3 dry spells of 2 week duration result in failure off Kharif crops. Such occasions are observed twice in fire years. Usually high wind velocity (18 to 20 km / hr)
At Solapur under dry land areas year to year fluctuatins are so much that there is no guarantee of a fixed quantity of rainfall. Generally rainfall starts in late June to early July. There is depression during late July to early August. Again there is good amount of rainfall in last Aug. and Sept. The rainfall totally recedes by mid October. This is the usual pattern of rainfall in draught prone areas. The probability of rainfall is more than half the normal is fairly good. (P = 0.58) during September.
Techniques Of Soil And Water Conservation In Rainfed Agriculture
Soil and water are most essential for the growth and sustenance of plant life. Soil is important as it provides, foothold for plants and majority of nutrients needed by them. Water is essential as it forms larger part of the living matter and acts as a nutrient carrier.
Though, both soil and water a sources are available in plenty, they are not distributed equally in quality and quantity in every part of the world and are not inexhaustible. Their abuse would mean a great loss resulting in poverty. It takes centuries to form one inch layer of soil, but it does not take long to lose it by erosion. Research work carried out in Maharashtra State which has an undulating topography, has shown that loss of soil from unprotected land is as much as 125 tons per hectare every year and may be as high as 300 tons in a single year. The weight of one hectare of soil 2.5 cm. deep is about 325 tons.
Similarly, rain water which can sustain a good crop, if not conserved properly will not only cause scarcity and famine, but also wash way the soil which is a valuable national asset. There are many examples which show how once fertile plains and valleys have become deserts or barren lands due to neglect by mankind. It is, therefore, the prime responsibility of each generation to conserve soil which is the main capital of the farmer as well as the nation, at all costs and pass it on in good condition from one generation to another, so that the posterity will not blame them.
Soil and water conservation cannot be achieved only by individual efforts. The problem is too big, involving collective efforts on the part of farmers, technicians and Government. Recognizing the seriousness of erosion problem, the Central Government established the Central Board of Soil Conservation to assist the States and River valley Projects. It has established soil conservation research stations at Dehradun, Kotah, Ootacamand, Bellary, Vasad and Jodhpur, arranges for training of technical personnel and also served as clearing house for soil conservation information.
On account of chronic scarcity conditions prevailing over 3 major portions of the Deccan tract. Soil and water conservation research was started in 1924 and soil conservation work was taken up on a large scale in Maharashtra from 1943 - 44 onwards. At present Maharashtra contributes nearly 50 p.c., of the total progress in respect of soil conservation measures in the country.
Erosion- Factors Affecting Soil Erosion
The factors that influence erosion are:
1. The amount and intensity of rainfall and wind velocity.
2. Topography with special reference to slope of land.
3. Physical and chemical properties of soil.
4. Ground cover its nature and extent.
Soil erosion is the wearing away detachment and transportation of soil from one place and its deposition at another place by moving water blowing wind or any other cause.
1. The amount and intensity of rainfall and wind velocity: Rainfall is the most forceful factor causing erosion through splash and excessive run off.
Rain drop erosion is splash, which results from the impact of water drops, directly on soil. Although the impact of rain drops on water in shallow streams may not splash soil, it does cause turbulence, providing a greater sediment carrying capacity. Large drop may increase the sediment carrying capacity of run off as much as 12 times.
If rain falls gently, it will enter the soil where it strikes and some will slowly run off, but if it occurs in torrents, as usually the monsoon rains doe, there is not enough time for the water to soak through the soil and it runs off causing erosion. Run off that causes erosion, therefore, depends upon intensity, duration, amount and frequency of rainfall. It is observed that rains in excess of 5 cm. per day always caused run off whereas those below 1.25 cm. usually do not.
(The results of soil and runoff losses from air dry deep black and later tic soils with 2 p.e., slope under a rainfall simulator with a constant rainfall immensity of 8.75 cm. per hour indicate that soil loss per 2.5 cm. of siuautated ram) in case of latertic soil is 0.25 tons per hectare. Thus the soil loss in case of deep black soil which is heavier than latertic soil is ten times more.
2. Topography will special reference to slope of lands: Slope accelerates erosion as it increases the velocity of flowing water. Small differences in slope make big difference in damage. According to the laws of hydraulics, a four - time increase in slope doubles the velocity of flowing water. This doubled velocity can increase the erosive power four times and the carrying capacity by 32 times. In one of the experiments in United States of America, it was observed that the loss of soil per hectare due to erosion in a maize plot was 12 tons when the slope was 5 p.c., but it was as high as 44.5 tons under 9 p.c., slope.
3. Physical and chemical properties of soil: Some soils erode more readily than other under the same conditions. The crodibility of the soil is influenced by its texture, structure, and organic matter, nature of day and the amount and kind of salts present. There is less erosion in sandy soil because water is absorbed readily due to high permeability. More organic manure in the soil improves granular structure and water holding capacity. As organic matter decreases, the crodibility of soil increases. Fine textured and alkaline soils are more crodible.
In general, soil detachability increases as the size of the particle increases but soil transportability increases with the decrease in particle size. Clay particles are more difficult to detach than sand, but are easily transported on a level land and much more rapidly on slopes.
4. Ground cover, its nature and extent: The presence of vegetation ground cover retards erosion. Forests and grasses are more effective in providing cover than cultivated crops. Vegetation intercepts the erosive beating action of falling raindrops retards the amount and velocity of surface fun off, permits more water flow into the soil and creates more storage capacity in the soil. It is the lack of vegetation that creates erosion permitting condition.
Normal And Man Made Erosion
Weathering of parent rock and erosion are natural processes by agencies like water and wind. This type of erosion occurring in nature is normal or geological erosion. If both the processes are equal i.e., erosion removing as much top soil as the weatchring processes from it, there is not much harm done, but it is generally not so. In order to provide food and shelter, man has cut down forests indiscriminately, allowed grazing of grasses excessively and ploughed the land and exposed it to nature with the result that erosion of soil has been faster than it was formed.
This is man - made erosion and is a result of bad land management. The worst form of cultivation is shifting cultivation. The practice is common with tribal communtics. They fell the forest and burn all vegetation and cultivate the cleared areas for 2 to 3 years and then abandon them for some years. This accelerates erosion and many good hill slopes have been denuded of vegetation and top soil, making tem barren.
Damage Caused By Erosion
Erosion does not only cause considerable damage to good fertile and but is also detrimental in many other ways which are discussed below:
1. Washing away of fine soil: The top 18 cm. of soil is most important from the point of plant growth. Eighty p.c. roots of the plants are found in the surface soil and they absorb their nutrition and water from that zone. If the top soil is washed away by erosion, the water holding capacity of the soil is decreased and productivity goes down.
2. Deposition of coarse material in low lying areas: Low lying areas are exposed to the danger of deposition of coarser particles which are washed from higher hilly areas. This makes the soil less productive. It is also a common experience that during floods good fertile soils on the river banks are corded and covered with layers of sand with the result that they become infertile.
3. Silting of tanks: Tanks get filled every year during monsoon season by water from catchments area. This water also brings with it large quantities of silt and day. If proper antierosion measures are not taken in catchments area, reservoirs get silted and their storage capacity is considerably reduced.
4. Lowering of the underground water table: If surface run off is allowed to go on unchecked, the quantity of water that should infiltrate into the soil is very much decreased. Water table in wells goes down as underground water is not replenished and irrigation cost goes up.
Water Conservation
Along with soil water is another important factor essential for all life and production of food. The main source of water is precipitation. In India precipitation is not property distributed throughout the year. It is received within a few months of rainy season and that too in a critic manner. It may rain 50 to 125 mm. in one day causing flood and damage to crops and then there may be a dry spell for some days when crops may begin to will. Hence proper conservation of water as well as collecting surplus water in tanks and reservoirs of letting it out into the rivers assume great importance. To understand water conservation it is necessary to study the hydrologic cycle.
Hydrologic Cycle
Water moves in a continuous cycle from ocean to clouds to earth and back to ocean. The water in the ocean is converted into vapour by the heat of the sun and this vapour moves in the form of clouds over the land and condenses into rain. Some rainwater enters the soil while the rest flows into streams and rivers and is either stored in tanks and reservoirs or allowed to go back to sea. Of the water that enters the soil some is stored for use by the plant some gets evaporated from the surface of the soil and some moves down to replenish the water table. This becomes the source of water for wells and springs. This cyclic movement of water is known as the hydrologic cycle. The water that is held by the soil in available form is essential for plant growth. It is not yet possible for the man to control rainfall but its infiltration and run off can be regulated to a great extent by improved management practices. Efforts should be made to store rain water either in the soil or in the reservoirs when it is in plenty and carry over to periods when rain water is not available. The former is known as conservation of water in soil, while the latter, conservation in reservoirs.
Loss of Water From Soil
Water is lost from soil in four ways:
1. Surface run off.
2. Downward movement of drainage.
3. Evaporation from soil surface.
4. Transpiration through leaves of plants.
Out of this loss of water through run off is the largest and is also the most damaging as it causes erosion main factor in conserving moisture relates to increasing infiltration and storage capacity of soil and reducing run off and evaporation. Uncontrolled water is the main cause of soil erosion. Almost all methods that deal with soil conservation are in principle the methods to control and conserve water. Soil and water conservation are, therefore, dealt together, Sufficient studies on all phases of hydrologic cycle such as evaporation, precipitation, run off, infiltration and deep percolation which occur simultaneously have not been carried out in India as yet, though 2 beginning has been made at many agricultural research stations.
Soil And Water Conservation Methods
The loss of soil and water under natural vegetation is the lowest. But lands must be cultivated and grown with crops to produce food. This can be done without much harm to the soil if proper soil and water conservation methods are followed. Such methods aim at encouraging water to infiltrate into the soil, reduce its velocity and check run off losses.
The most common soil and water conservation methods are
A) Management practice viz.
a) Strip cropping,
b) Mulching,
c) Crop rotation,
d) Contour cultivation,
e) Planting of grasses for stabilizing bunds,
f) Planting of trees and a forestation,
g) Cashew nut plantation, and
B) Mechanical practices such as
a) Bunding,
b) Terracing,
c) Gully or nala control,
d) Control of stream and river banks.
Soil And Water Conservation Methods - Management Practices
a) Strip cropping: This consists of growing erosion permitting crops and erosion resisting crops in alternate strips. The erosion permitting crops are cotton, jawar, bajara, etc. which allow the run off water to flow freely within the rows. The erosions resisting crops are mostly legumes like groundnut, much (Phaseolus aconitiolius), hulgn (Dolichos biflorus), Sow bear (Glycine max) which spread and cover the soil and do not allow run off water to carry much soil with it the soil which flows from the strips growing erosion permiuming crops is caught by the alternating springs.
In selecting a suitable legume crop it should be seen that the maximum canopy and root development of the crop coincide with the period of high intensity of rainfall.
b) Mulching : A mulch is natural or artificially applied layer of plant residues or other material on the surface of the soil with the object of moisture conservation, temperature control, prevention of surface compaction or crust formation, reduction of run off and erosion, improvement in soil structure and weed control. Artificial mulches of different kinds such as Jowar or bajara stubbles, stubbles, paddy straw or husk, sawdust etc., increase absorption of water and minimize evaporation. They also control run off and soil losses.
c) Rotation of crops: Rotation means growing a set of crops in a regular succession over the same field within a specified period of time. Continuous growing of Jowar or bajara crop causes more erosion, but if followed by a legume crop viz., hulga, matki or gram which covers the soil is causes less erosion. Rotation also helps in removal of plant nutrients in a uniform way from future depth of soil and in maintaining the fertility of the soil in dry farming region of Maharashtra adoption of gram Jowar rotation not only helps in conservation of moisture but also in increasing the crop yields the beneficial effect of rotation can be seen from the following table.
d) Contour cultivation: Tillage operations viz., ploughing, harrowing, sowing and Interculture should be done across the slope of land. This will help in creating obstructions to the flow of water at every furrow, which acts like a small bund and results in uniform distribution of water. This helps more initration of water less run off and erosion, and gives higher crop yield. Any cultivation done along the slope will accelerate golly formation, more run off and erosion and consequently permanent damage to land.
e) Planting of grasses for stabilizing bunds: Grasses prevent soil erosion and improve soil structure. The entire soil mass is penetrated by countless roots and soil aggregates and particles are enmeshed by the root system. Grasses should be grown on bunds which are not suitable for cultivation, both for checking erosion and providing pasture for cattle. Several grasses as well as legumes were tried on bunds at the Agricultural Research Station; Solapur which receives about 600 mm. of rainfall to see which of them will withstand drought conditions, give maximum root growth and canopy coverage, and stabilize bunds effectively. It was observed that anjan planted with spacing of 15 x 15 cm., produced the highest quantity of roots, followed by marvel - 8, Rhodes, thin Napier, blue panic, and kusal .Legumes do not have many roots but produce better canopy within a short period, while grasses are under the process of establishment. Planting of legumes mixed with grasses is, therefore, advantageous in preventing soil erosion in initial stages.
f) Planting of trees and afforestation: Forests conserve soil and water quite effectively. They not only obstruct the flow of water, but the falling leaves provide organic matter which increases the water holding capacity of the soil. If tree planting is done in the planned manner in open areas, it will serve as good wind break and if done along the banks of streams and rivers, it will regulate their flow. Farm forestry is another important aspect in soil and water conservation. The danger caused by deforestation has been only recently appreciated and a big plantation programme of hybrid eucalyptus, teak, casurina has been taken up by the Forest Departments in reserve forests, catchments areas of irrigation projects and on Government waste lands Vanamahotsava is also observed every year in the early part of monsoon and millions of trees are planted by the public with the help of the maff of the Agricultural and Forest Departments local bodies like Zillah Paris had, Panchayat Samitis and Gram Panchayat What is however important is to pay proper attention planted.
g) Cashew ant plantation : In coastal districts of Maharashtra which receive more than, 1,250 mm. rainfall a new programme of cahsewnut plantation has been undertaken from 1963 - 64 on hills having slope between 10 and 20 p.c.The sea breeze is conducive to the growth of cahsewnut plants and they do not require much aftercare once they establish in the soil. Staggered trenches of 300 x 30 x 30 cm. size are dug on contours at a distance of 6m. Cashew plants are raised in polythene bagsin nurseries and two months olds a plings are planted on the lower side of the trench with plant to plant distance of 6m.
Soil And Water Conservation Methods - Mechanical Practices
The above measures control erosion by good management practices. Bunding, terracing, gully or nala control, and construction of tanks and bandharas are mechanical measures requiring engineering techniques and structures. They reduce run off and impound water for longer time to help infiltration into the soil. Their construction and design will depend upon rainfall, soil slope and such other factors. These measures are costly but if properly maintamed will improve the land over a long period of time.
Bunding:
i) Block bunding: Bunding for control of soil erosion and conservation of surface run off was known to farmers for centuries. It was not uncommon to find Tals i.e., big bunds across large blocks of sloping lands. These bunds are constructed of earth or stone or both, at a great cost, to impound water and arrest soil washed from the fields lying above. They are high and broad enough to withstand the force of water from the catchments. Water is let out at the end of the monsoon and land which has received fertile silt is sown with crops. Such type of big bloods bunds are not constructed now as contour bunding has been taken up on catchments basis.
ii) Contour bunding: It consists of construction of a series of earthen bunds of suitable sizes along contours at a lateral distance of every 60 mm or a fall of 1 to 1.5 m. The shope of land is thus broken into smaller and more level compartments which hold soil as well as rain water. It has been estimated that about 75 million hectares of land i.e. about one fourth of the common land surfaces suffering from soil erosion. In Maharashtra State, the problem is more acute and it is estimated that out of 186 lakh hectares about 144 lakh hectares require bunding. The planning Commission has, therefore laid great stress on contour bunding programme, because bunding alone has been found to increase crop yield by 20 to 30 p.c.
The size, cross- section and interbund spacing depend upon the nature of rainfall, soil and slope of the area. In order to improve the technique of bunding, studies have been carried out in respect of spacing of bunds, shrinkage of bund sections and hydraulic gradients and kind and location of outlets etc. in different soil and rainfall conditions of Maharashtra State. On the basis of such studies it has been observed that the spacing between bunds should not be allowed to exceed 1.5m. Vertical drop or 67.5 m. lateral spacing. The following table21 is a fair guide.
iii) Graded bunding: In high rainfall areas, while conservation of soil is important, drainage of surplus water has to be attended to, for avoiding waterlogged condition of soil. The bunds are therefore, slightly graded longitudinally about 7.5 cm. per running 33 m. to prevent safe disposal of water into the nala. The cross sections into for safe removal of excess run off water it is essential to provide suitable waste water or outlet structures at proper places so that no damage is done to bunds in case heavy precipitation is received on any single day. Normally stone outlets are provided low rainfalls are as. Channel weirsor pipe outlets may also be provided. Grass outlets have been found to be effective and cheaper in heavy soil. The crest wall should be 30 cm. above the contour level and its length should be so designed as to discharge the surplus water from the maximum intensity of rainfall with are asonable period. 1,250 mm. Terrace bunds consist of comparatively narrow embankments constructed at intervals across the shope and the vertical spacing between bunds may vary from 1to 2 m., depending upon the slope, type of soil, rainfall etc. Bench terracing is done when gradient is stceper than 10 p.c. as in hilly ranges of Himalayas, Sahyadry etc. and consists of a series of step like platforms along contours. These terraces are like table tops sloping outwards and are provided with stone wateweirs to drain away surplus water. Angular and big boulders should be used for terrace outlets because round and small boulders will slip and get dislodged under the gushing water.
Gully or nala control: Gully or nala control is very essential to prevent its extension and further destruction of cultivated lands and grasslands. The sloping sides are planted with grass and trees. Suitable temporary and permanent structures such as check dams, overflow dams, drop structures are also provided. Small gullies can be stabilized by converting them into paddy fields. So far 17,034 nalas have been controlled and the target for sixth plan (1980 - 85) period is 2005.
Control of stream and river banks: Vulnerable sharp bends nalas by the sides of the rods and river bends near village sites cause considerable damage to property. These should be protected by providing spurs, jetties, rivets and retaining walls. Adjoining areas should be stabilized under permanent vegetation. Spurs are constructed at an angle to reduce the velocity of water and there by enabling the flood water to flow away but deposit coarse sand which will cause obstruction to successive water currents from cutting into the bank and thus straightening their course.
Runoff, And Their Types
Definition:” It is that portion of rainfall, which makes its way towards streams, rivers etc. After satisfying the initial losses etc. is called as runoff.
Types of Runoff:
1. Surface runoff.
2. Sub - surface runoff, and
3. Base flow.
1. Surface Runoff: It is that portion of rainfall which enters the stream immediately after the rainfall. It occurs. When all losses are satisfied and if rain is still continued, with the rate greater than in filtration rate; at this stage the excess water makes a head over the ground surface (surface detention) which tends to move from one place to another, known as overland flow. As soon as the overland flow joins to the streams, channels or oceans, termed as surface runoff.
2. Sub - surface Runoff: That part of rainfall, which first leaches into the soil and moves laterally without joining the water - table to the Streams Rivers or oceans is known as sub - surface runoff. Sometimes sub - surface runoff is also aerated under service ninoff due to reason that it takes very title time to reach the river or channel in comparision to ground water. The sub - surface runoff is usually referred as interflow.
3. Base flow: It is delays flow, defined as that part of rainfall which after talling on the ground surface in fill rated into the soil and meets so the water table and flow to the streams oceans etc. The movement of water in this type of runoff is very slow that is why it is also referred as delayed runoff. It takes a long time to join the rivers or oceans. Some times base flow is also known as ground water flow.
Thus,
Total Runoff = Surface runoff + Base flow (Including sub - surface runoff)
Factors Affecting Runoff
The runoff rate and its volume from an area, mainly in influenced by following tow factors:
a) Climatic factors and
b) Physiographic factors
Factors Affecting Runoff - Climatic Factors:
The climatic factors of the watershed affecting the runoff are mainly associated with the characteristics of precipitation, which include.
1. Type of precipitation
2. Rainfall intensity
3. Forms of precipitation
4. Duration of rainfall
5. Rainfall distribution
6. Direction of prevailing wind and
7. Other climatic factors.
1. Type of precipitation: Types of precipitation have a great effect on the runoff. For example a precipitation which occurs in form of rainfall, starts immediately in from of surface flow over the land surface, depending upon its intensity as well as magnitude, while a precipitation which takes place in form of snow or hails the flow of water on ground surface will not take place immediately, but after melting of the same. During the time interval of their melting the melted water infiltrates into the soil and results a very little surface runoff generation.
2. Rainfall intensity: The intensity of rainfall has a dominating effect on runoff yield. If rainfall intensity is greater than infiltration rate of the soil the surface runoff takes place very shortly while in case of low intensity rainfall, where is found a reverse trend of the same. Thus high intensities rainfall yield higher runoff and vice-versa.
3. Duration of rainfall : Rainfall duration is directly related to the volume of runoff due to the fact, that infiltration rate of the soil goeson decreasing with the duration of rainfall till it attains constant rate. As a result of this even a mild intensity rainfall lasting for longer duration may yield a coverderable amount of runoff.
4. Rainfall distribution: Runoff them a water sheed depends very much on the distribution of rainfall. The rainfall distribution for this purpose can but expressed by a team "distribution coefficient which may be defined as the ratio of maximum rainfall at a point to the mean rainfall of the watershed. For a given total rainfall, if all other conditions are the same, the greater the value of distribution coefficient, greater will be the peak runoff and vice - versa. However, for the same distribution coefficient, the peak runoff would be resulted from the storm, falling on the lower part of the basin i.e. near the outlet.
5. Direction of prevailing wind: The direction of prevailing wind, affected greatly the runoff flow. If the direction of prevailing wind is same as the drainage system then it has great influence on the resulting peak flow and also on the duration of surface flow, to reach at the outlet. A storm moving in the direction of stream slope produces a higher peak in shorter period of time than a storm moving in opposite direction.
6. Other climatic factors: The other climatic factors, such as temperature wind velocity, relative humidity, annual rainfall etc. affect the water losses from the watershed area to a great extent and thus the runoff is also affecter accordingly. If the losses are more the runoff will be less and vice -versa.
Current Category » Rainfed Agriculture
Factors Affecting Runoff - Physiographic Factors
Physiographic Factors:
Physiographic factors of watershed consist of both, the watershed as with as channel characteristics. The different characteristics of watershed and channel, which affect the runoff, are listed below.
1. Size of watershed
2. Shape of watershed
3. Slope of watershed
4. Orientation of watershed
5. Land use
6. Soil moisture
7. Soil type
8. Topographic characteristics, and
9. Drainage Density.
1. Size of watershed: Regarding the size of watershed, if all other factor including depth and intensity of rainfall are being same them two watershed irrespective of their size, will produce about the same amount of runoff .However a large watershed takes longer time for raining the runoff to the outlet as result the peak flow expressed are depth is being smaller and vise versa.
2. Shape of watershed:The shape of watershed has a great effect of runoff. The watershed shape is generally expressed by the terms "from factor and "compactness coefficient".
3. Shope of watershed: The shope of the watershed has an important roel over runoff but its effect is complex. It controls the time of overland flow and time of concentration of rainfall in the drainage channel which provide accumulative effect on resulting peak runoff. For example in case of a sloppy watershed. The time to reach the flow at outlet is less, because of greater runoff velocity which results into formation of peak runoff very soon and vice -versa.
4. Orientation of watershed: This factor affects the evaporation and transpiration losses from the area by making influence on the amount of heat to the received from the sun. The north or south orientation of watershed, affects the time of melting of collected snow. In a mountainous watershed the part of wind ward side of the mountain receives high intensity of rainfall resulting into more runoff yield while the part of watershed typing towards leeward side has reverse find of the same.
5. Land use: The land use pattern and land management practices used have great effect on the runoff yield. For example an area which is under forest cover, where a thick layer of much of leaves and grasses etc. has peen accumulated there formed a little surface runoff due to the fact that more rain water is absorbed by the soil. While in a barren field where not any type of cover is available a reverse trend is obtained.
6. Soil Moisture: The magnitude of runoff yield depends on the amount of moisture present in the soil at the time of rainfall. If rain occurs over the soil which has more moisture the infiltration rate becomes very less which results in more runoff yield. Similarly if the rain occurs after a long dry spell of time when the soil is dry, causing to absorb huge amount of rain water. In on the other hand, if the rain occurs in a close succession as in the rainy season; runoff yield has reverse effect.
7. Soil Type: In the watershed surface runoff is greatly influenced by the soil type as loose of water from the soil is very much dependent on inflientation rate which varies with the types of soil.
8. Topographic Characteristics: Topographic characteristics include mores topographical features of watershed which create their effect on runoff it is mainly undulating nature of the reason that runoff water gets additional power to flow due to slope of the surface and altitude time to infiltrate the water into solid.
Regarding channel characteristics to describe their effect on runoff the channel cross-section, roughness storage and channel density are mainly considered. These also have significant effect on runoff.
9. Drainage Density: The rain age density is defined as the nation of the trial channel length in the watershed to two total watershed areas it is expressed at.
(Tranned length (Total))
Drainage density = ------------------------------
Watered area
I
D.D. = --
A
A watershed having greater D.D. and incites formation of peak rain off very shortly to that of lesser D.D. watershed.
Different Agronomical Practices for Soil and Water Conservation
Conservation In Rainfed Areas
Soil conservation is a preservation technique, in which deterioration of soil and its losses are conserved by using it within its capabilities and applying conservation techniques for protection as well as improvement of soil. In hilly regions. Where land topography has steep slope and is subjected to erosion problem the vegetation cannot get established. Lack of the vegetative cover on sloppy soil surface accelerates the erosion and a large amount of soil is transported into the stream through runoff. In addition, the uncovered sloppy land also a cause extensive damage to the cultivable land at foothill through exporsition of sedimentson them.Sediment disposition covers the top fertilesoil layerand thus makes them unsuitable for cultivation.
Under this circumstance it becomes very necessary to treat such areas by adopting appropriate agronomical measures, so that they can be reclothed with negetations. The vegetation helps in reducing the surface runoff and soil cravsion both. The agronomical measures include contouring strip cropping and niluge practices to control they soil erosion. The use of these measures is entirely dependent upon the soil types land shope and rainfall characteristics.
In soil and water conservation programmes, the agronomical practices are counted as second line of defense the first being mechanical or engineering measures which are employed to arrest the soil erosion immediately. The role of agronomic measure is more economical long-lasting and effective. Always it is advisable to used but when its use is either inadequate or not sulpewant to achieve the goal of erosion control then use of mechanical measures to control erosion is recommended.
The agronomical measures are referred by the practices of growing vegetables on mild sloppy lanks to cover them and to control the erosion from there in living vegetation above the soil surface dissipates the crove power of agents either they are water or wind In case of water erosion it affects by several ways such as by enhancing infiltration rate and relucing together and thereby reducing runoff velocity to scour the soil particles screening the eroded particles to reach them into the channels or reservoirs; by dissipating the kinetic energy of falling raindrops and thus reducing the splash erosion. The effect of vegetation on wind erosion is also significant as it directly makes a hinderance in blowing path and thus deflecting the wind current at some distance away towards down stream side. The wind - strip cropping is a well known agronomical practice comployed for controlling the wind erosion in wind erosion susceptible areas.
The role of agronomical measures in achieve of soil & water conservation, has immense importance, perhaps much more than the others. It can be explained by considering the Universal Soil Loss Equation (A = R K L S C P) in which agronomical practices reflect the factor of crop management (C). The other factors such as R & K are the natural factor; we do not have any control on them. The L S and P factors may have value as I under worst conditions; although these can be reduced maximum up to 0.5 by applying an ideal soil and water conservation measures. The factor 'C' which is crop management factor has value as I for worst conditions, but it can be reduced up to 0.02. At this small value of C, the soil loss can be minimized up to one - fifteenth which is about 10.25 times more than the other factors. Looking this important effect of agronomical measures on soil loss, its scope is assumed to be more dominating in soil and water conservation programmes.
1. Contouring
2. Trip Cropping
3. Tillage Practices
These are the important agronomical practices employed for controlling the soil erosion from sloppy areas. Basically these measures create an obstruction in flow path of surface runoff by making the land surfaces rough due to channels ridges etc. formed under them. Each of these measures also have a direct relation with the infiltration rate and thereby presence of moisture in the soil profile. Infiltration rate is an effective factor in reducing the surface runoff and soil loss.
Different Agronomical Practices For Moisture Conservation In Rainfed Areas - Contour Cultivation
Contour cultivation refers to all the tillage practices or mechanical treatments like planting tillage and Interculture performed nearly on the contour of the area applied across the land slope. In low rainfall regions the primary purpose of contour cultivation is to conserve the rain water into the soil as much as possible. While in humid regions its basic purpose is to reduce the soil erosion / or soil loss by retarding the overland flow. In this farming system the furrows between the ridges made on the contours hold the runoff water and stored them into the soil in this way they reduce the runoff and soil erosion both.
Prior to start the contour farming on straight hilly land which is not engaged under bounds or lerrces a contour guide line should be established which should run across the field approximately at a constant level. At agricultural operators should be done with reference to the guide line established. In a relatively small field of conform shope, only one guide line is sufficient but in large area having long and uneven shope several guide lines may be required.
For locating the first contour line on a sloppy land it should be started from the highest point of the field and then preceded down the general slope. The contour lines are located at distance of 25 to 33 meters. Depending upon steepness of the land. On a long and gentle slope the first contour line is generally fixed at about 50 meters apart from the top of the hill. When contouring is done on steep shope and the area falls under high rainfall then there is probability to arise a scope for gulling problem. This may be overcome by applying contour farming practices along with strip cropping bunding or lerracing like practices.
Limitation of Contour Farming: Contour farming gives a better result in the field of relatively uniform slope. It is impracticable on the fields having irregular topographical features. Similarly the use of grassed waterways in conjunction with contour farming system is essential to reduce development of the gully.
When and Where to use Contour Cultivation: Contour cultivation is most efficient for reducing the runoff and soil erosion from gentle land slopes. Intense rain storms on steeper slopes cause water to accumulate behind the ridges until it breaks overuses downhill and crodes rills and gullies.
Table 10.1 Slope - Length Limits for contour farming:
Land slope (%)
Maximum slope length
1 - 2
120
3 - 5
90
6 - 8
60
9 - 12
35
13 - 16
25
17 - 20
18
20 - 25
15
Longer slopes until more crosion occurs in the gullies on contoured land than in the nills found between crop rows on the non - contoured land. There is some limit of land slope and its length on which contour cultivation is successful for controlling the soil crosion. Wischmeir and Smith (1978) have reported the values of kind slope and slope length for better contour farming which is cited in table. 10.1
The limits of slope - length change with the soil characteristics type of crops grown and rainfall of the area. The length of slope is used as greater on more permeable soils for more protective covers crops such as small grain crops and for less intense rainfall. Apart from the above the experience also reveated that with no - till and other reduced tillage systems that make the soil surface very well protected with crop residues allow the field length far in excess of those given in Table 10.1 can also be used safely for contour cultivation provided that the soil must be adequately protected with the crop residues every year
Strip Cropping
Strip cropping is also a kind of agronomical practice in which ordinary crops are planted / grown in form of relatively narrow strips across the land slope. These strips are so arranged that the strip crops should always be separated by strips of close growing and erosion resistance crops.
Strip cropping used as a technique for erosion control is a most effective method in certain soils and topography. This method becomes more effective for erosion control, which it is followed with crop rotations in the area where terraces are not practically feasible due to the fact that the length of slope is divided into different small segments. The strip crops check the surface runoff and force them to infiltrate into the soil, thereby facilitates to the conservation of rain water. Strip cropping is more intensive practice for conserving the rain water than contouring (i.e. about twice as effective as contouring) but it does not involve greater effect on soil erosion as terracing and bunding. Generally the use of strip cropping practice for soil conservation is decided in those areas where length of slope is not too longer.
Strip - cropping to control soil erosion caused by runoff derives its effectiveness mainly from following two factors:
a) Reducing the runoff flowing through the close - growing sod strips.
b) Increasing the infiltration rate of the soil under cover condition.
The reduction of runoff velocity between the row strips is achieved by making an observation in the flow path. The observations created by row crotion are also responsible to dissipate the kinetic energy of flow checking the flow of surface water. From field studies it has been observed that the strip cropping on the contour plays a key role in conserving the soil and water, when combined with terracing. The width of these strips depends on the topographical features of the area.
Field Strip Cropping: It is modified form of contour strip cropping in which crop strips are laid parallel across the land slope but not always exactly on the contour may be changed. This type of strip cropping is frequently used only where the topography is either too imegular or undulating as it makes accurate layout of contour strip cropping, impractical. The depressed areas should be avoided from field strip cropping they may be left for establishing the grassed water ways.
Buffer Strip Cropping: In buffer strip cropping the strips of grasses or legume crops are laid between contour strip crops in regular rotation. The width of these strips may or may not be even. The buffer strips are usually 2 to 4 m wide and are placed at 10 to 20 m meters. They can also be placed on critical stops of the field (The main purpose of buffer strip cropping is to provide a protection to the land from soil croson.)
Wind Strip Cropping: In wind strip cropping system the strip crops of uniform width are laid at right angles to the direction of preventing winds without regard of the contour. The main objective of this system is to control the wind crosion father than water crosion. This cropping is recommended for level or nearly level topography where wind crosion is more effective.
A guideline for deciding the width of wind strip - cropping can be have from the values given in table 10.2
Table 10.2 Recommended strip widths for wind strip
Cropping (FAO 1965)
Soill Types
Strip width (m)
Sandy soil
6.0
Loamy sand
7.0
Sandy loam
30.0
Loam
75.0
Silt loam
85.0
Clay loam
105.0
Layout of Contour Strip Cropping: In layout of a field for contour strip cropping the first step is to decide the width of strips at narrower points let the minimum width is assumed to be as 25 m. The next step is to establish a point for locating the contour line that will form the lower boundary of first strip. This point is located at 25 m apart from the top boundary of field by measuring along the steepest part of the stop. Now a contour line is drawn passing through this point up to the field boundary. This procedure is repeated until the entire field is laid out.
Width of Strips: It varies with the degree and length of land slope allowable soil loss soil types arrangements of crops grown in rotation and size of farm equipments used in tem aced fields the width of strip is adjusted according to the terrace interval but in untraced areas narrow width than the standard terrace interval is frequently used. In general steeper the slope narrower will be the strips of cultivated and dense growing crops both. An approximate range of trip widths based on average land slope and soil types is given in table 10.3
Table 10.3 Approximate range of strip width
Sr.No.
Percent Trand note
Width of strips (m)
(average)
Good soil
Fair soil
Poor soil
1
2
51
42
33
2
5
42
33
25
3
8
33
25
17
4
11
25
17
17
A buffer strip is more or less in a permanent contour strip usually varies in width which is normally kept between 3 to 5 m.
Crop Rotation: Crop rotations can be more effective for controlling soil crosion accompanied with strip cropping system. It can be used on the same piece of land by growing tilled crops; small grain crops hay crops or grasses either under a strip cropping system or a separate field system. In areas where perennial grasses and legumes are not feasible to grow, the row crops of small grain and annual legume crops can also be grown in strips. It is a general rule that no two cultivated strips should have the same planting or harvesting dates. The sequence of crops should be in such a manner that there could be form a dense - fibrous root system to hold the soil and retard the erosion, until the roots are croken down by tillage operations. All these activities of crop rotation also increase the organic matter in the soil thereby the physical condition of the soil become improved ultimately soil absorbs more water and also increases the capability of soil to resist the erosion.
Under use of crop rotation practices for controlling soil crosion, the simplest way to combine different crops in roa form and grow them in consecutive rotations. The frequency with which row crops should be grown depends upon the severity of crosion, taking place in the area. For example where crosion rate is very low the row crops can be grown at every alternate year but on the contrast in high erodible areas or where soil erosion is being more there may be practiced only once in five or even seven years cycle.
For erosion control by growing the crops in notation system probably the most suitable crops are legumes and grasses. The main benefits credited by these crops are mentioned as under:
* Reduction of soil erosion resulting from high degree of good ground cover.
* Help to maintain or improve the status of organic content in the soil thereby contributing the soil fertility and enable to develop more stable aggregates in the soil.
* Increase in soil nitrogen resulting from nitrogen fixation associated with legume crops.
Different crops and management practices used for growing them have different effects on soil structure. The crop affect the soil structure by the activities of their root system and the amount of organic residue contents added from the roots and top of the plants. The organic contents help in arranging and stabilizing the soil particles into granules or aggregates form. This in rum to provide greater pores in the soil mass causing rapid water take in the soil. Apart from above the soil aggregates are also developed by tillage operations wetting and drying of soil freeing and thawing of soil activities of micro organism and small animal like earth worm.
Interilled crops including vegetables and grain crops usually do not have effective root systems for improving the soil structure However most of the grain crops return a considerable amount of organic matter to the soil provided that the resides after grain movable should be covered into the soil by ploughing operations. The vegetable crops rectums very little organic matter to the soil. The dense root system of grass does much to create soil structure and also helps in binding the soil aggregates together.
Tillage Practices
Tillage is defined as mechanical manipulation of soil to provide a favorable environment for good germination of seeds and crop growth to control the wees to maintain infiltration capacity and soil aeration. A well planned tillage practice provides a favorable environment, suitable for better seed germination and effective plant growth. In addition, it also protects and maintains a strong soil structure to fight against erosion.
Tillage for Soil Conservation: Tillage is an important and primary tool for conservation of the land. As per definition, its primary purpose is to provide a favorable soil environment for the plant growth which is indirectly related to the soil conservation. The effect of tillage on soil erosion is the function of its several effects on soil such as aggregation surface sealing infiltration and resistant to crosion destruction of soi8l structure either by excessive tillage or tillage operations at improper soil moisture condition tends to increase the soil erodibility, causing significant soil loss. To achieve a best result for soil conservation the following points should be considered for tillage operations.
1. Till no more than necessary
2. Till only when soil moisture is in the favorable limit and
3. Vary the depth of ploughing.
Types of Soil Conservation Tillage Practices: There are a number of modified tillage practices have been developed; each of them related to the specified objectives for providing a better soil and water - plant relations. Reducing the runoff as well as soil crosion by enhancing infiltration capacity of the soil. The important types of soil conservation tillage practices are described below:
Mulch Tillage: It is performed either by making the soil surface cloddy or mulched with the help of crop residues. Mulch tillage is happened to be an effective measure to minimize soil erosion and to conserve the moisture when it is combined with strip cropping system. This type of tillage is also practiced to utilize the crop residues as mulch and also performing farming operations simultaneously. It can be defined as a method which permits the crops to grow where all or most of the residues from previous crops are left on the soil surface. The use of mulch tillage is based on the following profits.
1. The mulch intercepts the falling raindrops over the land surface and thus dissipating their kinetic energy which result in reduction or climination of their dispersing action on the oil structure.
2. The match ultge increases the infilte capacity.
3. The obstacles caused by leave stems and roots over the field reduce the velocity of surface flow and thus controlling the sheet crosion.
4. It maintains the soil relatively cool and moist which are essential for good plant growth and
5. Increases the crop yield by developing several conducive effects on soil.
Mulching:
It is defined as the application of any plant residues or other materials ot cover the top soil surface for.
* conserving the soil moisture.
* reducing the runoff and thereby to control soil erosion.
* checking weed growth
* protecting from winter climate.
* improving the soil temperature.
* modifying the micro - environment of soil to meet the needs of seeds for their good germination and better growth of seedlings.
The mulching is known to attribute the suppression of the weed growth conservation of moisture by checking evaporation and runoff to protect the soil against erosion (mainly from wind) to increase infiltration of water to fluctuate the soil temperature to enhance mineral nutrient availability to enhance nitrification to add nutrients and organic matters derived from decomposing of residues or other materials used as mulch to preserve or improve the soil structure. Mulching also improves the soil aeration creates better biological activates and thus to make a consequent beneficial effect on the soil fertility.
Mulching Materials:
The followings are used as mulching materials:
* Cut grasses or foliage
* Straw materials.
* Wood chips
* Saw dusts
* Papers
* Sand stones
* Glass woods
* Metal foils
* Cetto phanes
* Stones
* Plastics
Types of Mulches:
The mulches may be following types
a) Natural and
b) Synthetic
c) Petroleum
d) Conventional
e) Inorganic and
f) Organic
The natural mulches are borned by nature itself no man's effort is required.
Synthetic Mulches: Includes organic and inorganic liquids that are sprayed on the soil surface to form a thin film for controlling the various atmospheric happenings taking place over the top soil surface. The different synthetic mulching materials are as under.
* Rasins
* Asphalt emulsions
* Latex and out back asphalt
* Canvas
* Plastic and paper products
* Polythene and polyvinyl chloride (PVC).
* Bitumen emulsions.
The plastic mulches are very useful for nurseries in semi - arid and arid regions but their demerit is to have more cost and difficult to apply on large scales. The plastic mulching is also not suitable for the taller vegetations. In nurseries the dark colored plastic mulches make the soil surface very warm during the day hours because black body absorbs greater heat from the sunlight. This type of characteristic results in lower diurnal and higher nocturnal temperature.
Petroleum Mulch: The petroleum mulches are easier to apply and also less expensive. These mulches are available inform of emulsions of asphalt in water that can be sprayed on the soil surface at ambient temperature to form a thin film in continuous form that clings to the soil but not penetrate deeply. A thin film of petrol cum substance made so is termed as mulch film. The mulch film promotes uniform and rapid seed germination and also plays a significant role for vigorous growth of seedlings. An ideal surface film is also stable against erosion sufficiently porous to allow water in the soil yet insoluble in water and resistant enough to the forces of weather causing it to last as long is necessary for permanent vegetations to cyme established.
Conventional Mulch: The mulches such as hay or straw are more effective than the petroleum mulches. These mulches not only conserve the moisture and reduce the fluctuation of soil temperature but also protect the soil from rain drop impacts and hold the excess surface water in contact with the soil so as to increase the infiltration rate and thereby reducing the runoff and soil erosion. In skit on during day hours these mulches also absourth as resulting the surface of the mulch becomes hot and the soil on the other hand, during night hours, the mulch cools down and permitting the soil to remain warm. The papers mulches are also counted under conventional mulch are reported to give a remarkable result. Paper mulches are observed to increase the soil temperature especially of the surface soil layers. There are several evidence to show that paper mulching proves bettle performance in improvement of soil condition besides promoting the carthwarn activity. List at the same time the toxic elements of chemicals are coached out of the paper which has to be guarded against. The treated papers such as pitamanised have toxic effect on the plants.
Inorganic Mulches:
Soil mulch: It is an important mulch for the conditions of arid and semi - arid regions. Its application during summer and rainy seasons should be avoided. The soil mulch is also effective to reduce the evaporation particularly where the soil is saturated as a lower depth below the top surface or the moisture content is in excess of field capacity but hot in contact with a continuous water - table. Sometimes, the soil mulches are not effective under ordinary conditions as large amount of moisture evaporation establishes a protective dry layer of the soil which if worked will cause excessive so moisture loss.
In soil mulching a loose and dried soil layer of 5 to 8 cm thick is established on the soil surface. For this purpose the land surface is ploughed for the depth as specified above and left over for sometime to get dry of the ploughed soil; after that by planking operation the tilled soils are planed in this way a layer of dry soil in loose condition is prepared over the land surface which acts as soil mulch. The soil mulch prepared so obstructs the capillary loss of water from the lower layers due to following reasons.
* Lack of close contact with moist soil lying below.
* Increase in non - capillary pore space.
* Resistance to wetting.
These effects are said to be more apparent under isothermal conditions in regards of soil and temperature. Soil mulching has beneficial effect on soil aeration also.
The formation of crust on top soil surface is also counted as soil mulching it results in clogging of the soil pores which effectively seals the lower horizons from contact with the atmosphere and also prevents the diffusion of O2 and CO2.
The soil mulching becomes more effective when it is composed of crumbs and clods of proper size which are not liable to be broken down in form of surface crust by the impact of subsequent rains. In sundy areas the soil mulch should be prepared immediately after runs and renewed after subsequent rains when they get infiltrated downward and rap the maximum amount of moisture.
The general function of mulch is to raise the soil temperature during winter season and to lower the same during summer season by allowing low heat conduction through the same during summer season by allowing low heat conduction through the mulched layer and thus to maintain the soil temperature at a uniform level. In many cases the soil mulching also plays an important role to diminish the weeds growth from the soil.
Store Mulching:It involves the spreading of stone pieces on the ground surface to conserve the moisture and also to reduce the wind crosion. It is a very old practice followed in arid zones. Soil under the stones tends to be in moist condition but the temperature of that soil is slightly higher. The soils lying below the stones Harbour small animals and involve a high nitrification. The stone mulching is also used for tapir the dews particularly in those locations where significant dew fall takes place. Central Arid Zone Research Institute Jodhpur has reported the use of rubble much which is simply combination of mall fragments of stones and bricks provides better result on moisture conservation compared to the stone mulching synthetic mulching and mulching made by straw materials.
Organic Mulches: The tree bunches twigs leaves leaf litter grasses weeds etc. and used as organic mulch to cover the soil surface. The organic mulches are found superior than the artificial mulches in respect of conservation of moistures reduction in evaporation and runoff. By this mulch the control of evaporation is more effective particularly when rainfall takes place at frequent intervals but not found much effective when the rains are few and scattered in other words the infrequent rains and small showers may not be saved at all but for large rains which result we surface for several days with excess surface water for deep percolation these mulches may have their efficiency considerably more. Further more the light mulches are almost ineffective for controlling the evaporation because moisture conserving efficiency of mulch is inversely related to their capacity to absorb water or to extract it from the soil by capillary action. Resistant mulches do not decary sonly but last for a long time as a result they are more effective for conserving the soil moisture.
Benefits of Organic Mulches:
The various advantages are listed as under:
1. Very effective in reducing the soil erosion heatuse they promote interception loss and infiltration of rain water.
2. They obstruct the import of rain drops over the ground surface and thus dissipate the corrosive power of rainfall.
3. Very effective in preserving and impacting the soil structures by criminality the crusting of soil surface and sealing of pores by runoff.
4. Organic mulches also chance the dew fall by insulating the soil the really and electrically from the atmosphere.
5. The ascorbic molehes under the condition of bighorn temperature keep the sad temperature below the highest temperature.
Crop Residue Management- Use Of Mulches And Antitranspirants In Rainfed Agriculture
A Residue management: Consists of incorporating the crop residue like straw Stover, leaves, stubbles saw dust wood chips in soil at adequate level so as to develop and improve the physical and chemical properties of the soil.
Importance of crop residue management in Rainfed. Agril:
1. Crop residue management helps in controlling loss of water through runoff.
2. It increases infiltration and decreases evaporation of water.
3. It controls weeds, soil temperature through radition shilding.
4. It adds soil nutrients through organic matter.
5. It improves mineral solubility soil structure, soil biological regimes through organic matter addition.
Mulch, Their Types And Disadvantages
Mulch: Any material used (spread) at surface or vertically in soil to assist soil and water conservation and soil productivity is called much.
To achieve optimum advantage from the mulch the mulch should be applied immediately after germinationofcrop@5 ton/ ha (organic mulch). The practice of applying mulches to soil is possibly as old as agriculture itself. Mulches are used for various reasons but water conservation and erosion control are the most important objects in agriculture in dry regions. Mulches when property managed definitely aid wind and water erosion control. Other reason for high mulching is followed includes soil temperature modification soil conservation nutrient addition, improvement in soil structure weed control and crop quality control.
Disadvantages Or Limitations:-
1. Mulch is not been found effective other than Rabi Jawar.
2. In excess rainfall years mulch may not be effective.
3. Residue production in dry land is inadequate to result in sustainable water conservation.
Types of mulches: Materials used for mulches are crop residues levees clippings, bark manure, paper, plastic films, petroleum products, gravels etc.
1. Plastic films: Plastic fnms are more widely used as mulch. They help in maintaining higher water content in soil resulted from reduced evaporation, induced infiltration, reduced transpiration from weeds or combination of all these factors. They are relatively expensive expensive and difficult to manage under large scale field conditions for low value crops. (Polythene, polyvinyl).
2. Petrolium products: These are less expensive than plastic films and more readily applicable materials e.g. petroleum and asphalt sprays, resins etc.
3. Crop residues or stubble mulch: - Crop residues and other plant waste products (Straw, cloves, leaves, corn, and sawdust) are widely used as mulch. These materials are cheep and often readily available. The permit water to enter in the soil easily, when maintain at adequate level. These materials result in increased water content and reduced evaporation. Amongst the mulches tried light and thin stem material like dry grass was most effective as it provide good canopy, followed by gram stalks and wheat. Jawar stubbles were not as effective as other because of it is heavy weight and less canopy (cover). Use of mulch @ 5 tons / ha is found to be most effective in dry farming area. The mulch should be applied immediately after crop emergence to get optimum advantage. When these mulches are used the other crop operations like interculturing are not physible hence saving in cost of cultivation.
The effectiveness of various other materials as a mulch has been investigated. These materials have favourably influenced soil water content and evaporation but their use does not appear practically under large scale conditions e.g. gravels stones, granular materials, manure etc.
4. Vertical mulch: - Rainfall in dry farming area is with high intensity; due to moderately slow rate of infiltration the runoff is heavy. The water thus running as runoff could be stored in profile itself. In the recent past new technique has been evolved to tap such water.
Vertical mulch is a technique which consists of digging suitable trenches across the slope and thus making more surface are a available for water absorption. The open treaches are likely get silted in short period. This however can be prevented by inserting organic form waste material like straw stubbles or stalks which is called filter. The filter should be resistant to decomposition and provide service for 3 - 4 years. Such trenches at suitable intervals provide portion of low density which helps to intake water at higher rates. Water thus percolates in a trench and gets distributed in the profile. The width of trench should be adjusted in such a lastion that least area temains uncultivable. If trench could be accommodated between crop rows, there is practically no area wasted for trenches. Width of 20 cm is ideally suited for these propose. Depth of trench in black clay soil should be up to merum level and distances between two trenches may be about 4 m.
5. Soil or Dust mulch: If the surface of the soil is loosened, it acts as mulch for reducing evaporation. This loose surface of soil is called soil mulch or dust mulch. Interculturing creates soil mulch in growing crops and helps in closing deep cracks in Vertisols.
Effect of mulches on soil and plants:-
1. Soil water: - When soil surface is covered with mulch helps to prevent weed growth, reduce evaporation and increase infiltration of rain water during growing season. The water infiltrated in soil can be utilized by crops there by crop yields are increased. Mulches obstruct the solar radition reaching to soil. 2. Soil structure: - Crop residues when applied at adequate level increase infiltration rate. Decomposition of these residues results in improving soil aggregation and suability. Mulch slows (reduce) velocity of runoff.
3. Soil erosion: - Soils from dry region are nightly susceptible to water erosion and wind erosion because rainfall occurrence is frequent during intense storms and surface is adequately protected by vegetation effectively retard runoff. Therefore to reduce erosions by wind and water is an important reason for using mulches in dry regions.
4. Soil temperature: - Mulches results in greater water content and lower the evaporation. However effects on soil temperature are highly variable. White mulches decrease soil temperature while clear plastic mulches increase soil temperature.
5. Crop plants: - The effects of mulches on plants are operative through the effects of mulches on soil water, soil temperature structure and erosion. Reduced evaporation is major reason for the growth of the plants and there by high crop production due to mulch.
Antitranspirants
Antitranspirants are the materials or chemicals which decrease the water loss from plant leaves by reducing the size and number of stomata. Nearly 99 per cent of the water absorbed by the plant is lost in transpiration. Antiranspirants and is any natural applied to transpiring plant surfaces for reducing water loss from the plant. There are of four types.
1. Stomatal closing type: Most of the Tran spirants occur through the stomata on the leaf surface. Some fungicides like phenyl mercuric acetate (PMA) and herbicides like Atrazine in low concentration serve as antitranspirants by inducing stomatal closing. These might reduce the photosynthesis. PMA was found to decrease transpiration than photosynthesis.
2. Film forming type: Plastic and waxy material which form a thin film on the leaf surface and result into physical barrier. For example ethyl alcohol. It reduces photosynthesis eg. Tag 9; S - 789 foliate.
3. Reflectance type: They are white materials which form a coating on the leaves and increase the leaf reflectance (albedo). By reflecting the radiation, vapour pressure gradient and thus reduce transpiration. Application of 5 percent kaolin spray reduces transpiration losses. eg. Diatomaceous earth product (Celite), hydrated lime, calcium carbonate, magnesium carbonate, zincs sulphate etc.
4. Growth retardant: These chemicals reduce shoot growth and increase root growth and thus enable the plants to resist drought. They may also induce stomatal closure. Cycocel is useful for improving water status of the plant.
Antitranspiratnts are also useful for reducing transplantation shock of nursery plants (Horticultural plants) Examples / Different antitranspirants:
1. Metabolic inhibiter like phenyl mercuric acetate, some alkanyl succinic acids.
2. Growth retardant such as A.B.A. Cycocel.
3. Herbicides, fungicides
4. Salicylic acid.
5. Colourless plastics, silicon oil, wax or plastic.
6. White reflecting materials (e.g. Kaolin) emulsions or white wash.
Good features of contranspirant
1. Non toxicity
2. Non permanent damage to stomata mechanism.
3. Specific effects on gard cells and not to other cells.
4. Effect on stomata should persist at least for one week.
5. Chemical or material should be cheap and readily available.
Role of antitranspirants in annual field crops:
In general field crops are highly dependent or current photosynthesis for growth and final yield. Therefore it is unlikely that currently available antitranspirant would increase yield of an annual crop unless crop suffers stressed from inadequate water and or a very high evaporative demand, particularly during a moisture sensitive stage of development.
Fuahring (1973) sprayed stomata inhibiting or film forming anti - Tran spirants on field grown sorghum under limited irrigation conditions, he found that grain yield increases 5 to 17% and application of antitranspirant just before the boot stage was more effective than later sprays.
Water Losses And Their Control In Rainfed Agriculture
A. Use of Mulching:-
1. Mulching like grass, weeds & crop residues applied to the crop@ 5t / ha, reduce the maximum temp, of soil at 10 cm depth by 1 to 70C during monsoon season (July to Sept) by 4 to 100 C during summer season (April to June).
2. Mulches improved soil environment by way of increased moisture availability, reduction in soil temp. To optimum levels & thus higher water use & water use efficiency.
B. Tillage: - Affect soil - water relationships, aeration status, thermal characteristics & the mechanical impedance to the root penetration. Soil acts as mulch & restricts the upward movement of water to the evaporating site by reducing diffusivity gradients.
C. Use of Antitranspirants: - Define as the materials which decrease water loss from the plant leave by reducing the size or number of stomatal opening decreasing thereby the rate of diffusion of water vapour.
Two imp. Points in use of Antitranspirants:-
1. The application or an antitranspirants should restrict the water loss from the leaf surface without reducing photosynthesis, as carbon dioxide diffuse through stomata & is necessary for photosynthesis.
2. Transpiration causes cooling of the leaf surface & the use of antitranspirants should not completely stop transpiration & thus raise the leaf temperature.
Antitranspirants effective in Two ways:-
1. Through films that coat the leaf surface.
2. Chemicals that close the stomata
Examples of antitranspirants:-
1) Phenyl mercuric acetate Inhabits stomatal
2) Alkanyl succinic acids opening
3) Waxy or plastic emulsions - Film forming antitranspirants
4) White wash or kaolinite - Acts directly on wet cell walls & lower leaf temperatures & reduces vapor pressure gradient.
Effect on Photosynthesis of Antitranspirants:-
Antitranspirant result in size & no. of stomata’s of the leaves, however, a supply of carbon - dioxide diffusion into the stomatal cavity is necessary for the occurrence of photosynthesis & it the reduction in opening results in restriction of actual photosynthesis & the yield reduction will be there.
Example of Anti -Tran spirants
Growth retardants
Hydroxylamine hydrochloride
Abscisic acid
Phenyl mercuric acetate (PMA )
a-NAA
Silicon
Phosphon
Cetyl alcohol
Daminozide
Stearic acid
DAMS, TIBA, MH& CMH
Chlormeunat chloride
Methyl ester
Alacholor
Alkenyl succinic adid, 2, 4 - dinitrohenol.
Desiccarts or defoliants
Crop - ripens such as
2, 4 - D
Picloram
Paraquat
Ammonium isobutylate
H2SO4
Ccc, carbanyl urea,
Na - chlorate
Bromacil, Endothal
Diquat
Bacitracin
Minimum Tillage Or No Tillage (Zero tillage) Concept In Rainfed Farming
Tillage may be defined as the practice of modifying the state of soil in order to provide conditions favorable for plant growth.
Tillage can also been defined as the mechanical manipulation of soil with certain implement or tools to provide a suitable environment for seed germination root growth, weed control, soil erosion control and moisture conservation.
In the recent past, minimum tillage concept come into existence reduing time, labour and machine operations as well as conserving moisture and reducing erosion. The modern technology of herbicides & insecticides made it possible to achieve some tillage requirements without using implements.
Any tillage practice in dry lands which does not return more than its cost by increasing yield and improving soil conditions should be eliminated. Soil need to be worked only enough to assure optimum crop production and weed control.
Aims and objectives of tillage in Rainfed farming:
1. Moisture management: - Soil configuration for in situ moisture conservation, to increase infiltration rate to increase moisture storage capacity of soil profile, to increase aeration to reduce evaporation losses through intertillage operations to provide drainage to remove excess water etc.
2. Erosion control: - contour tillage contour cultivation tillage across the slope.
3. Weed control: - check weed growth & avoid moisture competition.
4. Management of crop residues: - Mixing of trash and decomposition of crop residues retention of trash on top layers to reduce erosion.
5. Improvement of tilth: - minimize the resistance to root penetration, improve soil texture & structure etc.
6. Improvement of soil aeration: - For good growth of crop.
7. Providing food seed - soil contact.
8. Preparing fine surface for seeding operation.
9. Incorporation of manures, fertilizers and agro chemicals (weedicide & soil amendments) into the soil.
10. Insect control.
11. Temperature control for seed germination.
Minimum Or Optimum Or Reduced Tillage
It denotes the reduction of number of operation by planting directly after harrowing without any other intervening cultivation which are usually carried out to give a fine seed bed. Or
Minimum tillage is a method aimed at reducing tillage to the minimum necessary for ensuring a good seed bed rapid germination satisfactory stand and favorable growing condition.
Objectives:-
1. Reducing energy input and labour required.
2. Conserving soil moisture and reducing erosion.
3. Increase organic carbon, improve structure of soil, increase hydraulic conductivity of soil, increase infiltration of water.
4. Providing optimum seedbed rather than homogenizing the entire soil surface.
5. Keeping the field compaction to minimum.
Minimum tillage made practicable and economical because of:
1. Development of good equipments for combined tillage & sowing operations.
2. Enormous progress in chemical weed control which has reduced unnecessary many other tillage operations.
3. Minimum tillage frequently gives as good as or even better yields than conventional tillage methods.
Advantages of minimum tillage:-
1. Increases organic carbon.
2. Improves soil structure
3. Increases hydraulic conductivity of soil.
4. Increases infiltration of soil.
5. Reduce soil compaction.
More advantages in coarse & medium soils than heavy soils.
Disadvantage of minimum tillage:-
1. Seed growth / intensity is increased
2. Less decomposition of organic manures & release of nitrogen
3. Less germination of crop seeds.
Minimum tillage can be practiced by different Methods:-
A) Ploughing planting: - In this method only a single trip over field is required. The tractor pulls a plough & planter simultaneously. The seed row is centered on the furrow slice. The area between the rows remains ploughed & weeds do not germinate easily.
This involves in less cost in seed - bed preparation and yields remain some to that of conventional tillage. The disadvantage in this method is that planting is slowed down & sowing is delayed beyond the optimum time.
B) Till planting :- (Special Till planter):- It prepares seed - bed & sows two rows in one operation. The seed - bed is prepared by an implement equipped with a narrow & deep penetrating sweep a wider & shallower sweep and selection of rotary her. The strip between the rows neither is nor disturbed.
C) Wheel track planting: - The field is ploughed as usual. The seedbed a prepared by wheels of the factor. The soil between rows remain rough & loose & absorb better moisture reduces runoff. Weeds seeds he dormant in loose soil until rainfall.
Save 40% villager cost ploughing + planting of seed shout be done at one time to avoid drying of upper soil surface.
Zero tillage
Zero tillage refers to tillage systems in which soil disturbances is reduced to sowing generals and traffic only and where weed country must be achieved by a genital nears. It can be considered as a men extreme form of minimum tillage 2010 tillage maintains more corposiders than any other tillage soil surface and it protect the grout against wind and water evasion.
Primary tillage it commonly avoided and secondary tillage restricted to Seedbed Corporation in the row zone only. It is also known no till and is resorted to who soil are subjected to wind & water erosion Zero tilled soil are homogenous in structure with high population earthworms. Organic matter content increases due to less mineralization.
Control of weeds is the main problem in zero tillage. Incomplete weed control is the main ebstoute to the further adoption. Zero tillage a widely used in humid areas.
Erosion losses and polities are minimized by zero tillage. Zero tillage will be useful concept where than.
i. Soils are subject to wind and water erosion eg. in sloppy bare compacted soils with high gilt fine sand.
ii. Timing of tillage operation 15 foods difficult.
iii. Conventional tillage to not yield more.
iv. Requirement of energy and labour too high.
v. In medium to fine textured soils use of heavy implements can result in formation of hard puncturing wet conditions. Much more research information is needed on cartilage.
Concept of Minimum Tillage is Useful In Rainfed Farming
How the concept of minimum tillage or zero tillage is useful in Rainfed farming:
1. It has been pressed hearing the experimental findings that the conventional tillage practices to not give higher yields over the maximum tillage practices in dry lands & hence the minimum tillage concept is useful in reducing additional cost on unnecessary tillage practices. The practice of harrowing alone may serve the purpose of seedbed preparation.
2. Frequent tillage operations results in loosening the top soil layer frequently which is subjected to more soil erosion due to intense rains. The research findings in dry lands have indicated that the frequent tillage operations lead to higher soil erosion as compared to untilled or less tilled soils. Hence the minimum tillage concept is useful in Dryland framing in reducing soil erosion.
3. The crop residues left over the soil surface acts as a much and helps in minimizing the evaporation losses. These crop residues also reduce the runoff losses, thus help in soil and water conservation in dry land.
4. The organic or crop residues get incorporated in top soil layers in subsequent period and increase the organic mater content of soils increase the infiltration rate of water reduce the bulk density increase the soil aggregation reduce the compaction of top soil layer thus increasing the productivity in dry lands.
5. Frequent tillage operations in dry lands also leads to formation of hard pans in heavy soils when worked under wet conditions & hence frequent tillage operations be avoided in heavy soils of dry lands.
6. The fine textured heavy soils of Dryland posses the self cracking habit extending to the depth of one meter and thus serves the purpose of ploughing Hence such soils should not be ploughed every year. The research findings have indicated that such soils can be ploughed once in three years.
7. The problem of weed control can be avoided by using the effective herbicides for various field crops in Dryland. Thus, the tillage operations required for weeds control can be reduced under Dryland conditions.
8. The concept of zero tillage is not applicable in any kind of Agricultural system including dryfarming at this stage since sufficient research information need to be generated for its successful application.
Harvesting Of Rainfall
(Water harvesting or Run off Farming in Rainfed Agriculture)
About 10 - 20 percent of the total rain goes as runoff in medium deep black soils. This also considerable soil loss by way of erosion. The extent of runoff varies with rainfall intensity and its duration land topography soil type and land use pattern. This runoff otherwise going as waste can be collected in suitable water storage structures such as farm ponds and used further for crop production. This technique of collection of runoff water during the period or excess rainfall and its further use for crop production is called "water harvesting" or "Runoff farming". Such collected water is used to provide supplemental irrigation to the crops at the most critical growth stages or during the prolonged period of drought.
In water harvesting the part of land from which the water is received is called "donor area" or "water producing area" or water harvesting area or watershed area or catchments area and the area in which it is used is called as "Recipient area" or crop production area. The donor area generally is not suitable for crop production.
Method Of Water Harvesting
There are three method of harvesting and recycling of runoff water.
i) Inter plot water harvesting: - In this method harvested water is directed to the crop. This method is suitable for area where rainfall is scanty (< 500 mm) and even there is difficulty of maturing a single crop. In this technique a portion of the area is cultivated & remaining area is used for harvesting water. Usually the uncultivated area is compacted or treated in such a way that runoff would be induced. Surface modification may be required to get runoff. Such method is suitable for arid regions. Runoff may be induced by using cover films (plastic or rubber) preparing hydrophobic layer (wax) compacting surface or spreading sodic soil on surface.
ii) Inter row water harvesting: - There may not be enough rain to support a crop in some areas & therefore by conserving more water in furrows and planting the crop in furrows may give some yields.
iii) Water harvesting in farm Ponds: - A portion of the excess runoff water after allowing maximum in situ moisture conservation is collected in farm ponds. As far as possible the pond should be located in the lower patches of the field to facilitate better storage and less seepage losses. The size of the farm pond should be worked out considering annual rainfall probable runoff and the catchments area. Generally, 10 to 20 per cent of the seasonal rainfall is considered as runoff in medium and deep black soils. A farm pond of 150 m3 capacity with side slopes of 1.5: 1 is sufficient for each hectare of catchments area in black soils. The farm ponds may be circular squared or rectangular. However eared or rectangular ponds are more convenient for harvesting of runoff water.
Under low rainfall situations to increase the runoff from catchments area the soil surface is treated with sodium salt betonies clay hydrophobic compounds like sodium ciliolate sodium rosinate etc. asphalt bitumen and water proofing membranes like paraffin. Some mechanical measures to increase runoff can be adopted such as land surface smoothening reducing surface depressions compacting the soil surface by rollers of spreading the clay blanket before rolling in sandy soils.
There are three important stages involved in water harvesting.
1. Collection of water in form pond.
2. Storage of water & problems
3. Applications of stored water to the crops.
1. Collection of water in form pond: - From the parameters like annual rainfall probable runoff and area of catchments the size of the farm pond can be work out. The location of the farm pond should be such that there v. should be proper storage and facilities to whiles storage and facilities to utilize stored water for crop production e.g. if farm is located in rocky and porous part, it would difficult to use stored water for crop production. Under such circumstances water may be increased and surface area may be required to convey for long distance. As for as possible pond should be located in lower patches of the field to facility better storage and seepage losses. The size of the farm pond should be decided by the quantum of water to be stored and nature of the soil strata. If the stratum is hard, rocky then it would be desirable to have shallow pond. If the structure is clay wool in that case depth may be increased and surface area may be reduced to have minimum evaporation. If the pond is located in upper patches water can be. How gravitationally and may create problems or water logging in low lying areas if proper care is not taken.
2. Storage of water problems: - Seepage and evaporation losses of stored water are the major problems of farm ponds. Nearly 40 to 50% quantity of stored water is lost through seepage and evaporation. When the pond is with murrum strata or under neath the total losses can be to the extent of 72% out at which 80% losses are due to seepage alone. In general the seepage losses in deep black soils are low. For preventing the seepage losses in farm ponds located in coarse textured soils the sealing materials such as natural clay, saling sodic soils, bentonite bituman, soil + cement mixture stones or brick in cement mortar asphalt compounds polyethylene / rubber sheets or plastering with soil + cowdung wheat straw etc. can be used for lining the pond surfaces depending upon the easy availability and cost of the material. However compacting and lining with natural clay soil is most economical.
The evaporation losses from free water surface can be reduced by spreading the materials on water surface such as plant residues oil emulsions long chain fatty alcohols i.e. Cetyl alcohol gum mixtures polyethylene oxides. Floating blocks of wax rubber and plastic floats are more effective in controlling the evaporation to the extent of 80 percent.
3. Application of stored water to the crops: - Since available water in the farm pond is a scare commodity its optimum use is the important consideration in entire runoff farming. In the case of application of water for crop production two considerations need to be borne in mind. First is the method of application and second the stage of crop growth.
For efficient application furrow irrigation or alternate furrow irrigation methods should be used than surface irrigation which will increase water use efficiency of stored water. When the stored water is to be used for post rainy season (Rabi) crops the water should be applied at the most critical growth stages.
For example: Rabi sorghum - When 2 irrigations are to be applied
First - stem elongation stage - 30 - 35 DAS.
Second - Flowering 65 - 70 Days. When stored water is limited and only one irrigation is possible in that case water may be applied before flowering to avoid storage losses. Here water should be stored in soil profile rather than in farm pond.
Safflower - 60 - 65 Days - Rosette stage.
Gram - 65 - 70 Days - pod development stage.
The research findings from Solapur have indicated that grain yields of Rabi sorghum safflower and gram can be increased by 100, 40 & 60% respectively by applying single irrigation at boot stage rosette stage & pod development stage respectively to above crops.
All these things discussed above should be combined into a method of management called "watershed based farming system". In this new approach the attempt is made to utilize water in all its stages and then excess water is drained out in to a farm pond connected to the field by protected grass water ways.
Methods Of Controlling Runoff
A. Mechanical Methods:
1. Contour bunding
2. Graded bunding
3. Biological Bunding or live Bunds or vegetative bunding; or Vegetative barriers
4. Water shed management- inter bund management
5. Broad bed furrow
6. Vertical mulching
B. Agronomical practices:-
1. Strip cropping
2. Mulching
3. Contour cultivation
4. Planting of grasses for stabilizing bunds.
5. Intercropping
6. Sequence cropping
7. Relay cropping
Vertical mulching: -
This is the practice followed in dryfarming areas for moisture conservation. The in filtration rate to black soils of dry lands is very low. In the event of high intensity rainfall much more water is lost as runoff instead of infiltrating into the soil profile. This process still accelerated under sloppy lands. Under these conditions the technique of vertical mulch has been found useful in Dryland farming.
This technique consists of digging suitable trenches across the shope and thus making more surface area available for absorption. The open trenches are filled with organic farm wastes like straw stubbles the stalks etc. which is called as filter. The filter should be resistant to decomposition and provide service for 3 - 4 years. The upper portion of filter should be 15 - 20 cm above the soil surface.
The trenun should be of 20 cm width in between two crop rows. The trench depth of 60 to 90 cm is optimum. The interval between trenches should be 4 m. the runoff water is trapped by the filter and allowed to percolate in the trenches the stored water in trenches recharge the soil profile by lateral movement of water. The findings on vertical mulching at Solapur & Mohole indicated 35 to 40% increase in grain yield of Rabi sorghum.
Vegetative or Biological bunding:-
The bushes like Subabul shevri of the grasses like vitiveria i.e. khus grass are planted in between the bunds in the fields across the slope or along the average contours. The system is called as vegetative bunding or biological bunding. The grasses or the bushes are cut close to the ground periodically leaving 20 to 30 cm top portion above the ground. This above ground portion helps to arrest the surface flow of excess water. The water halts temporarily along the vegetative bunds and helps in silting of soil particles. During this time water gets some time to infiltrate into the soil. Then partially clear excess water goes up to the field bunds with non erosive velocity which is further drained into field drains. The interval between two vegetative bunds will depend on the slope of the field. However 10 - 12 m interval between two bunds is convenient for carrying out field operations.
The bushes like Subabul or shevri can also be planted at 15 - 20 m intervals across the wind direction in the fields which acts as wind breaks and useful for checking soil erosion and moisture conservation.
Effective rainfall: -
From crop production point of view it is the portion of rainfall which contributes to the crop water needs is the effective rainfall. In other wounds the and of in tall watch becomes the part of consumptive use of water of a crop. An activicual farmer considers that the effective rainfall whiches that total rainfall which is useful in raising crops planted on his soil. Water which moves out of his field by surface runoff is the portion of total rainfall which is ineffective. Also the water that moves below root zone as deep percolation is ineffective. Any rainfall received after the soil has attained the field capacity up to rot zone depth is ineffective.
Factors Affecting Effective Rainfall
1. Rainfall characteristics:-
i) High intensity of rainfall - less effective rainfall
ii) More duration of rainfall - less effective rainfall
iii) Well distributed rainfall - more effective rainfall
iv) With light showers.
2. Land characteristics:-
i) Leveled land - more effective rainfall
ii) Sloppy land - less effective rainfall more runoff
iii) Ploughed land - More effective rainfall
iv) Vegetative cover - Less runoff, more effective rainfall.
3. Soil characteristics:-
i) Infiltration rate - high infiltration rate - more effective rainfall
ii) Storage capacity - More storage capacity - more effective rainfall
(Depth of soil)
iii) Initial water content - high initial water content then less will be the effective rainfall
4. Crop characteristics:-
More roof zone depth complete ground cover Active stage of growth - More uptake of water more will be effective rainfall.
5. Climate:
More radition High temperature and Low temperature Relative humidity – High crop requirement and more effective rainfall
6. Vegetative cover:-
Surface condition of soil canopy soil cover natures of roots mulches etc. affects the effectiveness of rainfall.
Drought Resistance And Characteristics Of Drought Resistant Crops And Their Varieties
Drought is a hazard to successful production. It occurs due to various combinations of the physical factor of the environment. Internal water stress in crop lands reduces their productivity. This reduction in productivity is brought by
1. Adely or prevention of crop establishment
2. Weakening or distraction of established crops
3. Predisposition of crops to insects & diseases.
4. Predisposition of crops to insects & diseases.
5. Alteration of physiological & bio - logical metabolism in plants & alternation of quality of grain forages fiber etc.
Drought:-
i) "Deficiency of available soil moisture which produces water deficits in the plant sufficient to cause a reduction in plant growth. Or
ii) "Drought is a period of inadequate or no rainfall over extended time creating soil moisture deficit and hydrological imbalances."
Classification of Drought:
A) On the basis of source of
water availability
B) On the basis of
occurrence
C) On the basis of
media
1) Meteorological drought
2) Agril. Drought
3) Hydrological drought
4) Socio - economic drought
1) Permanent drought
2) Seasonal drought
3) Contingent drought
1) Soil through
2) Atmospheric a drought
A) On the basis of water availability:-
1) Meteorological drought: - Ramdas (1960) defined this as actual rainfall is deficient by more than twice the mean deviation.
Indian Metrological Department (IMD) has defined meteorological drought as the situation when actual rainfall is less than 75% of the normal rainfall over an area. This is accepted principally because of its simplicity. The IMD uses two measures to define drought conditions.
i) Rainfall conditions
ii) Drought severity.
Rainfall conditions:-
i) Excess - 20% more than average of 70 - 100 yrs.
ii) Deficient - 20% less than average of 70 - 100 yrs.
iii) Deficient - 20 to 59% less than average of 70 - 100 yrs.
iv) Scanty 60% less than average of 70 - 100 yrs.
Drought severity:-
The IMD classifies droughts as follows from rainfall departures.
i) Slight drought when rainfall departure is 11 to 25% from normal rainfall.
ii) Moderate drought when rainfall departure is 26 to 50% from normal rainfall.
iii) Severe drought when rainfall departure is 50% and more from normal rainfall.
Drought years the year is considered drought when less than 75% of the normal rainfall is received.
2) Hydrological drought: - Definition of hydrological drought is concentrated with the effects of dry speels on surface & sub surfaces hydrology rather than with the meteorological explanation of the event. Linsley et al. (1975) considered hydrological drought as "a period during which stream flows are inadequate to supply established used under given water management system". The frequency and severity of hydrological droughts often defined on the basis of water depletion or shortage in reserve basins, reservoirs lakes wells etc. This drought affects industry and power generation.
3) Agricultural drought:-
Heathcoat (1974) defined agricultural drought as the shortage of water harmful to man's agril. Activities.
This is a situation resulted from inadequate rainfall when soil moisture falls short to meet the water demands of the crop during the growing period. This affects the crop growth or crop may wilt due to moisture stress resulting in yield reduction.
4) Socio - Economic drought:-
The socio - economic effects of drought can also incorporate features of meteorological hydrological and agricultural droughts. They are usually associated with the supply & demand of some economic goods. This drought should be linked hot only to precipitation but also trends of fluctuations in demand.
B) On the basis of time of occurrence:-
Droughts differ in time and period of their occurrence. As per thornithwaite the various droughts are:
1. Permanent drought:-
This is the drought area of permanent dry arid or desert regions. Crop production due to inadequate rainfall is not possible without irrigation in these areas. Vegetation like cactus thorny shrubs, xerophytes etc are generally observed.
2. Seasonal drought:-
In the regions with clearly defined rainy (wet) and dry climates seasonal droughts may result due to large scale seasonal circulation. This happens in monsoon area.
3. Contingent drought:-
This results due to irregular & variability in rainfall especially in humid & sub humid regions. The occurrence of drought may coincide with critical crop growth stages resulting in severe yield reduction.
C) On the basis of medium: - Maximov (1929) has defined into 2 types.
1. Soil drought: - It is the condition when soil moisture depletes & falls short to meet the potential Evapotranspiration (PET) of crop.
2. Atmospheric drought: - This results from low humidity dry and hot winds & causes desiccations of plants. This may happen even when rainfall & moisture supply is adequate.
Drought Prone Area
A drought prone area is defined as one in which "the probability of drought year is greater than 20%
Cronic drought prone area: A cronic drought prone area is defined as one in which the probability of a drought year is greater than 40%.
The criterion described above is useful for a continuous monitoring of the monsoon season. The sum of the seasons rainfall becomes the basis for describing a region under moderate or severe drought. When more than 50% of the area in the country is affected is described as severely affected by drought & when the area of 26 - 50% of the country is affected it is described as an incidence of moderate drought.
What is Drought Resistance?
It is the ability of a plant to maintain favorable water balance and turgidity even exposed to drought conditions there by avoiding stress and its consequences. Stress avoidance due to morphological anatomical characteristics which themselves are the consequences of the physiological processes induced by drought these zerophytic characteristics are quantitative and vary according to environmental conditions.
A favorable water balance under drought conditions can be achieved by transpiration before as soon as stress is experienced. These are called "water savers" or.
Accelerating water uptake sufficiently so as to replenish the lost water called as "water spenders"
A) The mechanism for conserving water:-
1. Stomatal mechanism: -Stomata of different species vary widely in their normal behaviour and range. In some species stomata remain open continuously or remain closed continuously. Many cereals open their stomata only during a short time in the early morning and remain closed during rest of the day. There is a difference in this respect between varieties of the same crop as shown by the example in two varieties of oat one is more resistant to drought open its stomata more rapidly in the early morning when moisture stress is at its minimum and photosynthesis can precede with the least loss of water (stocker 1960).
However mechanism of conserving water based on the closure of stomata will inevitable load to reduce photosynthesis and may lead to drought induced starvation injury (Leavitt, 1972).
2. Increased / Photosynthetic efficiency :- On possibility for overcoming limitations on photosynthesis, imposed bicoastal closure as means for increasing resistance to loss of water by transpiration there by transpiration there by accumulations of CO2 would be at higher rate for a given stomatal opening (Hatch & stack, 1970). A number of imperfect crop plants (maize, sugarcane sorghum prose, fox tail & finger millets) (Hatch et. al. 1987) as well as certain forage species Bermuda grass (Cynodon dactyl on) Sudan grass Bahia grass (Paspalum notatum) Rhodes grass (chloris Guyana) (Murata lyama 1963) and certain A triplex sp. fixed most of CO2 into the C4 of molic and aspartic acids so called C4 dicarboxylic acid (C4) pathway.
3. Low rate of cuticular transpiration: - The typical example is the cacturs. Thick cuticle results in low rate of transpiration.
4. Decreasing transpiration by a deposit of lipids layers on the surface of the leaves on exposure to moderate drought e.g. soybean (Levitt 1972).
5. Reduce leaf area: - The principal means of reducing water loss of xenomorphic plants is their ability to reduce their transpiring surface. Apart from the common means of keeping the aerial parts small perhaps the simplest form of this reduction of the transpiring surface is the sealing or of leaves at the time of water stress a characteristic phenomenon exhibited by many grasses. The rolling of leaves has been shown to reduce transpiration by almost 55 percent in semi conditions and by 75 percent in desert xerophytes (Stalfect - 1956).
6. Leaf surface: - Various morphological characteristics of leaves he reduce the transpiration rate and may affect survival of plants drought conditions. Leaves with thick cuticle waxy surface and the presence of spines etc. are common and effective.
7. Stomatal frequency and location: - A smaller number of stomata retard the development of water deficits. In certain species, the stom are located in depression or cavity in the leaves which is feature can further reduce transpiration by limiting the impingement of currents.
8. Effect of awns: - Awned varieties of wheat predominate in the drier at warmer regions and have been found to yield better than awnless one especially under drought conditions though there are exceptions (Gurandhacher 1963). Awns have chloroplasts stomata and so as photosynthesized. It has been found that the contribution of the away to the total dry weight matter of the kernels was 12% of that the entire plant.
B) To Improving water uptake (MC - Donough & Gauch 1959) :-
1. Efficient root system:-
The root systems of drought resistant plants are characterized by wide variety of apparent adaptations. These responded to such predominant soil conditions as the duration of soil dryness and the depth that is normally wet. Plants become adapted to dry conditions mainly by developing an extensive root system rather that structural modification of the roots (shields - 1958). The conceres "extensive root system" includes additional growth of secondary hair roots.
2. High root to top ratio (R/T):-
A high root to top ratio is very effective mean to adoption of plants to dry conditions of the growth rate of the roots considerably exceeds that of the shoots. The transpiring surface is there by reduced while root system of the individual plant obtains it's water from a large volume of soil (Simonis 1992) has shown that an increased root top ratio may actually result in greater amount of total dry matter of plants grown under dry conditions as compared a similar ones grown with full moisture.
3. Difference in osmotic potential of plants :-
Levitt (1958) has calculated a difference of 0.5% in soil moisture content that includes per manual wilting could supply a plant with enough water to keep it alive for 6 days. This could mean in certain cases the difference between survival and death.
4. Conservation of water spenders to water stress:-
Because of increased water absorption water spenders are characterized by very high rate transpiration. However as soon as the absorption rate becomes insufficient to keep up with water loss the water spenders generally develop some of the characteristics of the water savers (Cevitts - 1972).
C) Mitigating stress:-
1. Mitigating stress:-
Adoptions a drought basis mitigating effects of stress permit the plant to maintain a high internal water potential inspite of drought conditions. They therefore able to maintain cell tartar and growth avoid direct or indirect metabolic injury due to dehydration (Levit 1972).
D) Drought tolerance:-
When plant is actually submitted to low water potential it can show drought tolerance by either mitigating the actual stress induced by the moisture deficiencies or by showing high degree of tolerance to stresses.
1. High degree tolerance; Resistance to dehydration:-
The simplest method of avoiding drought induced damage is by resisting dehydration, preferably tot he extent .of maintaining turgur and at least by avoiding cell collapse after loss of turgur (Levit 1972) retain their turgur and therefore can continue to grow when exposed to drought stress. When plants are grown in their natural environment their osmotic potentials tend to be characteristic for each ecological group.
Characteristics Of Drought Resistant Plants
1. Early closure or stomata:
Opening stomata for short time in easy morning & remained closed during rest of day when moisture stress is minimum with photosynthesis with the least loss of water e.g. varieties of wheat, oats.
2. Increased photosynthetic efficiency:
The plant species using the pathways have a high rate or carbohydrate assimilation for given stomatal opening higher temperature & light optimum e.g. maize sorghum.
3. Low rate of cuticular transpiration:
Thick cuticle results in low rate in transpiration e.g. cactus.
4. Deposits of lipid layers:
On exposure to moderate drought conditions the lipids are deposited on leaf surface which in reduction transpiration losses e.g. soybean
5. Reduction in leaf area:
Rolling or curling of the leaves reduces the leaf surface exposed to sunlight thus helps in reducing the transpiration loss under stress conditions. E.g. Maize, Sorghum, grasses etc.
6. Waxy leaf surface:
The leaf surface becomes waxy forming thick cuticle and develops spines on leaves which help in reducing transpiration losses. Eg. Safflower.
7. Stomatal frequency and location:
Location of stomata in cavity or in depressions of leaves reduces the direct contact of stomata with wind currents & reduces the transpiration losses. In drought resistant plants, the number of stomata found more a lower leaf surface. Similarly, the number of stomata is also reduced which helps in reducing transpiration losses.
8. Effect of awns:
The Awned varieties of wheat barley etc. can thrive well under stress conditions as the awns contain chloroplasts & stomata & can continue photosynthetic activities even when the stomata on leaves get closed during day time.
9. Accelerating water uptake:
The water uptake by plants in increased efficiently due to following plant characteristics.
i) Efficient root system:
i) Extensive root system
ii) Deeper root system
iii) Secondary root etc.
iv) Ability of roots to go towards available water
v) Ability of roots to penetrate in soil
ii) High root to top ratio:
1. Transpiring surface is reduced.
2. Water absorbing surface is increased.
3. High osmotic pressure: Under stress conditions the osmotic (Low osmotic potential) potential in roots and aboveground plant parts in reduced resulting increased water movement through soil and plant.
10. Nature of varieties suitable for Rainfed farming:
1. Varieties should have medium height with early grand growth period. e.g. rabi sorghum varieties - Selection - 3. SFV - 86, M -35 - 1.
2. Varieties should have medium tillering habit, bigger ear head size & bold grain size. E.g. bajara variety - shraddha.
3. The variety should have deep and extensive root system.
4. The variety should be of shorter duration.
5. The variety should have High Harvest Index.
6. The intercrop varieties should be of longer duration with differentiation growth habit. E.g. Red gram varieties BDN - 2, No. 148.
7. Varieties should be resistant to moisture stress.
8. Varieties should have coating either with wax or other material which prevent the loss of moisture through evaporation from stem and leaves. E.g. Rabi sorghum varieties - white glumes on stem & leaf sheath. Safflower varieties - waxy surface & spines on leaves.
9. The varieties should be photo and thermo insensitive e.g. Gr. nut variety - TAG - 24.
Package Of Practices Of Crops Under Rainfed Conditions
Choice Of Crop And Varieties For Rainfed Agriculture
Dryland constitutes about 75 per cent of cultivatable lands in the country. The contribute about 42 per cent of off grains, almost all the coarse grains and 75 percent pulses and oilseeds. More than 90% of sorghum, Pearl millet, groundnut and pulses are grown in arid and semi arid areas.
At present, the cultivable area under Dryland agriculture in the state is 87% and only 13% area is under irrigation. After harvesting all available water resources, it is possible to bring it to 30%. It means 70% of the cultivable area will remain as Rainfed in the state. Under this situation the state will have to depend upon for its major share of food production on Dryland. However, the Dryland agriculture suffers from two problems viz. low productivity and high in stability.
The reasons for low productivity in Rainfed area are:
1. Lack of moisture conservation practices.
2. Low rate of fertilizer use.
3. Lack of timely farm operations.
4. Improper crop planning as per land capability.
5. Inadequate efforts to increase water resources.
6. Unpredictable rainfall situations.
7.Lack of improved Technology
The adoption of improved Dryland technology will be the only answer to mitigate above situation. Considerable research efforts are being made in the state to develop the improved the improved Dryland technologies since early seventies which will help to improve the crop production in Rainfed agriculture.
The important improved Dryland technologies are given below:
1. Selection of efficient crops and their varieties:
2. Crop planning as per length of cropping season:
3. Developing suitable varieties for dry lands.
4. Seeding time for Dryland crops
5. Timely seeding for pest avoidance
6. Planting pattern and plant densities
7. Intercropping
8. Fertilizer use in Dryland
9. Weed Management
10. Use of minimal irrigation
11. Crop planning as per land use capability
12. Crop planning for aberrant weather situation in dry lands
13. mid - season correction practices
14. Soil and water conservation practices
Improved Dryland Technologies
Selection of efficient crops and their varieties, Crop planning as per length of cropping season
1. Selection of efficient crops and their varieties:
Improved varieties and hybrids of Kharif and Rabi crops have higher moisture use efficiency as compared to local varieties. Hence improved varieties are adopted for efficient moisture use.
Kharif crops: Bajara - Shraddha (RHRBH - 8609, Saburi (RHRBH - 9824)
Sunflower - Modern, SS- 56, EC - 68414, KBSH - 11, APSH - 11)
Gr. Nut - SB X 1, K - 4 - 11, ICGS - 11, TG - 26, Koyana (B - 95)
Red gram - No. 148, BDN - 2, ICPL - 87; TT - 6, T - Vishakha - 1.
Cowpea - Konkan Sada bahar.
Soybean - MACS - 13 Pk - 472, Monetta, JS - 335.
Setaria - Arjun
Horse gram - Sina, Man (Kulthi or Hulga)
Green gram - PM - 2, S-8, Jalgaon - 781, BM - 4, THRM - 18.
Black gram - T - 9 TPU - 4, TAU - 1, TAU - 2.
Castor - Aruna, VL - 9, Girija
Kidneybean - MBS - 27 (Matki),
Grasses - Marvel - 8; Stylo, Siratro.
In general, the use of improved varieties increases the grain yields by 20 to 25 percent over local varieties. Hence sowing of these varieties should be carried out in Rainfed Agriculture.
Rabi Crops:
Rabi sorghum - M - 35 - 1 (Maldandi), Selection - 3, Swati (SPV - 504), CSV - 14 - R.
Gram - PG - 12, Vijay, Vishal, N - 59, Chaffa, Bharati,
Safflower - Bhima, Girana
2) Crop planning as per length of cropping season:
A) Cropping season with less than 20 weeks:
Single crop either in Kharif or Rabi.
Kharif - Bajara, Green gram, Gr. nut, black gram sunflower.
Rabi - Jowar, Safflower, gram.
B) Cropping season with more that 30 weeks:
Two crops with short duration Kharif crops following by 100 - 120 days rabi crops.
E.g. Bajra / Green gram - R. Jowar, Safflower, Gram.
C) Cropping season with 20 - 30 weeks:
Suitable for intercropping e.g. Pearl millet + Red gram (2: 1)
Developing Suitable Varieties For Dry Lands
The varieties or hybrids suitable for dry lands should have flowing characteristics.
i) Short duration, medium height, high yielding ability.
ii) Big ear head size with bold grains.
iii) Resistant to water stress conditions.
iv) Strong penetrating root system.
v) High Harvest Indes
Eg. Grunt JL - 24, TAG - 24, Bajra - Shraddha - Safflower - Bhima
Horse gram - Sina, Man etc.
Seeding time for dryland crops:
Proper time of seeding is important in dry lands as the let growing season is likely to be shortened. For this rainfall probabilities.
Eg. Cotton, red gram, horse gram dry seeding in 24th Meteorologist week at Solapur found optimum.
For this the off season tillage to be practiced to shorten the time aces between first rain and actual seeding time. It also helps to increases moisture.
Timely seeding of Rabi crops is also important eg. Sorgurti & Safflower - Traditional practice - end of September. Improved practice - first fortnight of September. This helps in better utilize of soil moisture and nutrients.
Timely seeding for pest avoidance:
Timely seeding of Kharif crops found useful in avoiding cest incidence.
E.g. Kharif sorghum should be sown before early. July to seed shoofly incidence at seeding stage and midge fly incidence at flowering to grain formation stage.
Planting pattern and plant densities:
Under adequate soil moisture conditions change in planting pattern has no advantage. However, it is necessary while adopting intercropping systems to accommodate intercrop rows.
E.g. Kharif - Bajra + Tur in paired planting in 2: 1 row proportion (30 - 15cm.). Under limited soil moisture paired planting is useful during the season for efficient moisture paired planting is useful during Rabi season by efficient moisture use.
E.g. Rabi sorghum 30 - 30 - 60 cm. or 45 - 45 - 90 cm spacing. This is due to deeper & more root growth and convenience in inter culture operations.
Plant density - While deciding the plant density, the availability of stored soil moisture needs to be considered.
Gram - Low soil moisture - wider planting - 60cm.
high soil moisture - closer planting - 30 cm.
Sorghum - Low soil moisture - 5 - 10 plants / M2.
High soil moisture - 5 -10 plants / m2.
Safflower - Not affected by plant density
Bajra - 10 - 15 plants / m2 optimum.
Safflower - 1 to 1.25 Lakhs plants / ha optimum.
The optimum plant population leads to higher production per unit area.
Sr.No.
Crop
Spacing (Cm)
Plant population in lakhs / ha
1.
Bajra
45 x 15
1.5
2.
Groundnut
30 x 15
2.5
3.
Red gram
60 x 20
0.75
4.
Horse gram
30 x 10
3.30
5.
Moth bean
30 x 10
3.30
6.
Setaria
30 x 5
6.0
7.
Sunflower
60 x 20
1 to 1.25
8.
Gram
30 x 10
3.3
Developing suitable varieties for dry lands, Seeding time for dryland crops, timely seeding for pest avoidance and Planting pattern and plant densities
Improved Dryland Technologies
Improved Dryland Technologies
Selection of efficient crops and their varieties, Crop planning as per length of cropping season
1. Selection of efficient crops and their varieties:
Improved varieties and hybrids of Kharif and Rabi crops have higher moisture use efficiency as compared to local varieties. Hence improved varieties are adopted for efficient moisture use.
Kharif crops: Bajara - Shraddha (RHRBH - 8609, Saburi (RHRBH - 9824)
Sunflower - Modern, SS- 56, EC - 68414, KBSH - 11, APSH - 11)
Gr. Nut - SB X 1, K - 4 - 11, ICGS - 11, TG - 26, Koyana (B - 95)
Red gram - No. 148, BDN - 2, ICPL - 87; TT - 6, T - Vishakha - 1.
Cowpea - Konkan Sada bahar.
Soybean - MACS - 13 Pk - 472, Monetta, JS - 335.
Setaria - Arjun
Horse gram - Sina, Man (Kulthi or Hulga)
Green gram - PM - 2, S-8, Jalgaon - 781, BM - 4, THRM - 18.
Black gram - T - 9 TPU - 4, TAU - 1, TAU - 2.
Castor - Aruna, VL - 9, Girija
Kidneybean - MBS - 27 (Matki),
Grasses - Marvel - 8; Stylo, Siratro.
In general, the use of improved varieties increases the grain yields by 20 to 25 percent over local varieties. Hence sowing of these varieties should be carried out in Rainfed Agriculture.
Rabi Crops:
Rabi sorghum - M - 35 - 1 (Maldandi), Selection - 3, Swati (SPV - 504), CSV - 14 - R.
Gram - PG - 12, Vijay, Vishal, N - 59, Chaffa, Bharati,
Safflower - Bhima, Girana
2) Crop planning as per length of cropping season:
A) Cropping season with less than 20 weeks:
Single crop either in Kharif or Rabi.
Kharif - Bajara, Green gram, Gr. nut, black gram sunflower.
Rabi - Jowar, Safflower, gram.
B) Cropping season with more that 30 weeks:
Two crops with short duration Kharif crops following by 100 - 120 days rabi crops.
E.g. Bajra / Green gram - R. Jowar, Safflower, Gram.
C) Cropping season with 20 - 30 weeks:
Suitable for intercropping e.g. Pearl millet + Red gram (2: 1)
Crop planning as per land use capability, Crop planning for aberrant weather situation in dry lands.
Use of minimal irrigation: Moisture due to low rainfall and limited soil moisture due to soil depth are the situations normally experienced in dryland agriculture. Mid season droughts and soil moisture deficiency could be mitigated by applying protective irrigations to the crops alermn growth stages. The harvested water in farm ponds or from seam functioning wells can be utilized for the purwabcdefghi~ X }hT5/as indicated that the grain yields of Rabi Jowar, Safflows a gram can be increased by 100, 40 - and 60% respective by arrive single irrigation at most critical growth stages. For this, the irrigation should be applied at boot stage rosette stage and pod development stage to jawar, safflower and gram respectively.
Crop planning as per land use capability: The cultivable land in wear has different depths ranging from few cm to several meters. Available so moisture depends on the soil depth. The water requirement of different crops varies from crop to crop. Therefore, crop planning as per vate storage capacity of the soil helps in increasing and stabilizing crop avoid with higher economic returns. Following crop planning is suggested to dryland farming in Maharashtra for different soil depths.
Soil type
Soil depth (cm)
Available
Crop planning
Soil moisture (mm)
1
2
3
4
1. Very shallow
<7.5
15.2
Dry land horticultural crops, grasses
2. Shallow
7.5 to 22.5
30 - 35
Horse gram, Kidney bean, castor,
grasses, agro - forestry, dryland
Horticultural crops. Bajra + Matki
3. Medium deep
22.5 to 45
40 - 65
Pearl millet, Red gram, sunflower
groundnut, Castor, Pearl millet +
Red gram (2 : 1), Sunflower & Red gum
(2: 1) intercropping systems.
4. Medium deep
45 to 60
65 - 90
Rabi jawar, sunflower, safflower, gram
Pearl millet + Red gram (2 : 1) in
Intercropping systems.
5. Medium deep
60 to 90
90 - 150
Double cropping Kharif green gram back
gram, Rabi sorghum, safflower or Sade
crops in rabi i.e. sorghum safflower and
Gram.
6. Deep
> 90
> 150
As above
Crop Planning For Aberrant Weather Situation In Dryland
The following common weather aberrations are observed in Solapur region of dryfarming area in Maharashtra.
1) Delayed onset of monsoon.
2) Good start of monsoon followed by dry spells.
3) Good start of monsoon followed by dry spells.
3) Early withdrawal of monsoon.
4) Extended monsoon.
The following crop management practices can be followed under different aberrant weather situations.
Delayed onset of monsoon: Onset of delayed monsoon is a common feature of the dryland agriculture. If the Kharif soils (< 45 cms) are diverted for rabi sorghum under such delayed rains, it not only affect the production of Kharif crops especially pulses and oilseeds but also results in poor production of rabi sorghum. Hence such shallow soils must be put under Kharif crops. Substantial research efforts were made at dryland centre. Solapur in this regards and following cropping pattern has been suggested depending on the lateness of monsoon during Kharif season.
Rainfall situation
Suggested crops
Remarks
1. Normal onset of
Monsoon. Rains during Ist fortnight of July
All Kharif crops Bajra,
Setaria, sorghum, grunt, castor, Red gram, Horse gram, Black gram, sunflower
Adopt intercropping of
Bajra + red gram in 2 : 1 preparation
2. Late onset of
monsoon Rains during 2nd
fortnight of July (Rains delayed by 15 days_
Setaria, Sunflower, castor, Red gram, Horse gram (delate Bajra, sorghum, gr. nut, black gram)
Intercropping of Red gram + Setaria in 2 : 2
Proportion.
3. Very late onset of
monsoon Rains during Ist
fortnight of august (Rains
delayed b 7 y 30 days)
Sunflower, red gram,
castor, castor, horse gram
(delese Setaria from above set)
Intercropping sunflower +
Red gram in 2 : 1 proportion
4. Very very late onset of monsoon Rains during 2nd fortnight of august (Rain delayed by 45 days)
Castor, sunflower red gram
(Delete horse gram from above set.)
Red gram in 2:1
proportion
5. Extremely late onset
of monsoon Rains during
Ist week of September (Rains delayed by 50 days)
Rabi jawar for fodder
i) Controlling plant population for conserving and effective are of available moisture.
ii) Checking weed growth to reduce moisture loss.
iii) Increasing interculturing to prevent evaporation.
iv) Choice of crops like red gram and castor which can sustain longer breaks.
Early withdrawal of monsoon: This situation creates two problems in rabi.
a) Sowing of Rabi crops may be suspended.
b) When crop is sown, requires moisture conservation practices such as :
i) Reduced plant density: Rabi jawar sown at early September with 1 to 1.35 lakh / ha require 50% reduction. This plant population needs to be adjusted before plants go for their grand period of growth (30 - 35 DAS)
ii) Use of surface mulch: Moisture can be conserved by using organic surface mulches. For this purpose apply mulch @ 5 t/ha.
iii) Protective irrigation: If possible protective irrigation may be given. Usually, protective irrigation is given at 55 - 56 days growth. However, due to early withdrawal of monsoon, the same may be applied at 35 - 40 days growth.
iv) Increase frequency of Intercultivation: Early stoppage of monsoon results in early cracking in soil. To prevent cracking and loss of moisture, frequency of Intercultivation may be increased. Untimely, 3 interculturing are recommended. Same can be increased to 5 or 6 which acts as a dust mulch.
v) Stripping of leaves: Upper 3 - 4 leaves are retained & lower leaves are removed to reduce transpiration.
Extended monsoon: Such situation is rarely experienced. Double cropping is possible in medium deep soils. Sowings of Rabi crops are extended. In certain areas sorghum may be replaced by gram and what as the sorghum may suffer due to cool speel.
Crop Planning For Aberrant Weather Situation In Dryland
The following common weather aberrations are observed in Solapur region of dryfarming area in Maharashtra.
1) Delayed onset of monsoon.
2) Good start of monsoon followed by dry spells.
3) Good start of monsoon followed by dry spells.
3) Early withdrawal of monsoon.
4) Extended monsoon.
The following crop management practices can be followed under different aberrant weather situations.
Delayed onset of monsoon: Onset of delayed monsoon is a common feature of the dryland agriculture. If the Kharif soils (< 45 cms) are diverted for rabi sorghum under such delayed rains, it not only affect the production of Kharif crops especially pulses and oilseeds but also results in poor production of rabi sorghum. Hence such shallow soils must be put under Kharif crops. Substantial research efforts were made at dryland centre. Solapur in this regards and following cropping pattern has been suggested depending on the lateness of monsoon during Kharif season.
Rainfall situation
Suggested crops
Remarks
1. Normal onset of
Monsoon. Rains during Ist fortnight of July
All Kharif crops Bajra,
Setaria, sorghum, grunt, castor, Red gram, Horse gram, Black gram, sunflower
Adopt intercropping of
Bajra + red gram in 2 : 1 preparation
2. Late onset of
monsoon Rains during 2nd
fortnight of July (Rains delayed by 15 days_
Setaria, Sunflower, castor, Red gram, Horse gram (delate Bajra, sorghum, gr. nut, black gram)
Intercropping of Red gram + Setaria in 2 : 2
Proportion.
3. Very late onset of
monsoon Rains during Ist
fortnight of august (Rains
delayed b 7 y 30 days)
Sunflower, red gram,
castor, castor, horse gram
(delese Setaria from above set)
Intercropping sunflower +
Red gram in 2 : 1 proportion
4. Very very late onset of monsoon Rains during 2nd fortnight of august (Rain delayed by 45 days)
Castor, sunflower red gram
(Delete horse gram from above set.)
Red gram in 2:1
proportion
5. Extremely late onset
of monsoon Rains during
Ist week of September (Rains delayed by 50 days)
Rabi jawar for fodder
i) Controlling plant population for conserving and effective are of available moisture.
ii) Checking weed growth to reduce moisture loss.
iii) Increasing interculturing to prevent evaporation.
iv) Choice of crops like red gram and castor which can sustain longer breaks.
Early withdrawal of monsoon: This situation creates two problems in rabi.
a) Sowing of Rabi crops may be suspended.
b) When crop is sown, requires moisture conservation practices such as :
i) Reduced plant density: Rabi jawar sown at early September with 1 to 1.35 lakh / ha require 50% reduction. This plant population needs to be adjusted before plants go for their grand period of growth (30 - 35 DAS)
ii) Use of surface mulch: Moisture can be conserved by using organic surface mulches. For this purpose apply mulch @ 5 t/ha.
iii) Protective irrigation: If possible protective irrigation may be given. Usually, protective irrigation is given at 55 - 56 days growth. However, due to early withdrawal of monsoon, the same may be applied at 35 - 40 days growth.
iv) Increase frequency of Intercultivation: Early stoppage of monsoon results in early cracking in soil. To prevent cracking and loss of moisture, frequency of Intercultivation may be increased. Untimely, 3 interculturing are recommended. Same can be increased to 5 or 6 which acts as a dust mulch.
v) Stripping of leaves: Upper 3 - 4 leaves are retained & lower leaves are removed to reduce transpiration.
Extended monsoon: Such situation is rarely experienced. Double cropping is possible in medium deep soils. Sowings of Rabi crops are extended. In certain areas sorghum may be replaced by gram and what as the sorghum may suffer due to cool speel.
Climatologically Approach For Crop Planning In Rained Areas
Agriculture production in India is closely related with rainfall India. About 75% of total cropped area is rained. Crop product on area is very uncertain due to erratic behavior of rainfall. The main for very low and highly unstable yields in these areas is unavailability adequate soil moisture occurring active growth period of crops. The moisture stress can be mitigated if it is followed by good rainfall. How prolonged stress period affects the rinal crop production. There are reasons for low productivity but primary constraint to this is lacs suitable tautology for soil and water management.
A sustainable farming system needs management strategies with respect varietals selection soil fertility programs and pest management agricultures order to reduce the input cost and provide a sustained avel of production profit from farming.
For planning an efficient agricultural production system information weather and climate is vital and also a major resource for agriculture productivity and sustainability especially in a stressed environment considering the complete macroclimate system. It is necessary to develop farming systems that are sensitive to climate and weather sustainable and to susceptible to degradation on account of climate.
In some areas the total rainfall is sufficient for one good crop and the some cases for two good crops in a year. However the rainfall distribution in root profiles some times exceeds and percolation of water to deeper layer or ground water recharge takes place. Because of the uncertainties and ever present risk of droughts the farmers are generally reluctant to adopt the use of available high yielding varieties, fertilizers and other input management which will effectively conserve and utilize soil and water.
Weather plays an important role in crop production, more so in India where 75% of the cultivated area is rained. The effective cropping season in rainy season is restricted by both rainfall quantity and distribution, thereby setting limits on choice of crops, cultivars and cropping systems. For post rainy season crops grown on conserved soil moisture, it is moisture storage at sowing time that determines the choice of crops and cultivars.
Crop growth rate at different ptenophases, length of growing season, efficiency of PAR interception, efficiency of solar energy conversion, efficiency in biomass conversion are explained to quantity the impact of evicemental parameters on growth and development of crops. However in arid and semi - arid areas water use plays a dominant role in crop production.
In many arid and semi arid areas crop production problems follow a familiar sequence:
i) Unfavorable crop growth environment:-
i) Limited choice of crops and cultivars, particularly in water deficit environments and aberrant weather situation.
iii) Low crop intensity.
iii) Low and onstable productivity.
Water deficits are responsible for low and unstable crop yields in both arid and semi arid areas. In addition, environment stresses / or nutrient stress may make the water deficit environment more unfavorable for the growth. The crops and cultivars currently popular in dryland areas are in necessarily the most stable and efficient in terms of moisture use. Many the existing cultivars of sorghum, pearl millet, pigeon pea, groundnut sunflower, castor and other crops are not adapted to rainfall pattern when they are grown for effective cropping season. The usually experience drogue stress at the most critical stages of their life cycle, which leads to low at unecrowic yield. In order to achieve yield stability it is necessary to ground crops and cultivars with water requirement patterns that watch the effective growing season
Climatic Variability In Rainfed Agriculture
In India about 70% of cultivated area is rained which contribute to about 40% of the country's food production. Appa Rao and Bhide, 1980). The main climatic parameters controlling crop growth are rainfall followed the temperature, adiation day length, humidity and wind speed. The inter seasonal and inter a variability in these climatic parameters play a major role in deciding the proper agronomic management options and subsequent realization of the yield. The major characteristics associated with the south west rainfall are high variability in its distribution in time and space in its onset and withdrawal and frequent and prolonged dry spells as a result of break in the monsoon. The uncertainty in rainfall received ouring the growth of crop become a major limitation factor in deciding about the final yield.
In the day sew arid areas the men annual rainfall exceeds potential
These areas suffer from one or more or a combination of factors such as moisture deficits. Limit of nutrients soil version and physical conditions, resulting in low infiltrations and poor crop establishment and subsequently larger yield gap. Thus crop yields in semi - arid India have remained low and variable because of aberrant weather and soil related constraint such as poor management of soil fertility and rain water.
Time and Length of Growing season - Tropical Regions
In tropical regions where low temperature does not limit growth, the time and length of the growing season for sorghum is determined by the seasonal precipitation pattern. Kassam et.al. (1978) and Kassam (1979) used precipitation data and computations of potential Evapotranspiration (PET) (Thorntwaite, 1948) to determine the growing seasons for crops in tropical Africa. This procedure is illustrated in Figure 1 and was used to determine the time and length of growing season for sorghum.
The first day (a) wren the normal precipitation becomes equal to or greater than half the normal PET is the beginning of the growing season and earliest planting time. The last day of the growing season (c) is the day when the normal daily precipitation becomes less than half normal PET plus time required to evaporate 100 mm of stored moisture from the period when precipitation exceeds PET.
The sorghum growing seasons for different tropical areas in eastern end western Mexico are shown is Table 1. The growing season at Villahermosa which receives 1902 mm. of rainfall is 333 days. At Apatzingan (716 mm rainfall) the season is only 125 days. A study by Kassm (1979) shows that a creed relationship exists between the amount of annual rainfall and the length as growing season in Africa.
Table: Growing season as related to precipitation at two locations to tropical Mexico.
Location
Rainfall
Growing season
Villahermosa (170 59 N 920 55 W)
1902
15-Apr
Apatzingan 190 05 N 1020 15 W)
716
4 Nov.
Growing Period Or Moisture Availability Periods
Length of the growing period is defined as the period during which the availability of moisture in the root zone of a crop is adequate to meet the water needs. Because the amount and distribution of rainfall varies considerably from year to year so does the effective growing period. The length also depends on the type of soil interacting with a given quantity on rainfall. In areas receiving rainfall for 2 months, the growing season may the 8 days in a coarse textured soils or 100 days in soils of clayey or day texture. Similarly in areas with 5 rainy months, the growing from 180 to 210 days depending upon soil texture and moisture tolding capacity (Virman - 1991).
Therefore, at a given location, the amount and distribution of rainfall, moisture storage capacity and the rate of Evapotranspiration determines the length and characteristics of the growing period. Soil moisture reserves have the ability a extend the growing period by as much as one to three months spending upon the soil texture and depth.
The soil moisture availability period determines effective cropping season. Based on the analysis of long term data in the arid and semi - arid areas of India effective cropping period have been delineated for a number of locations (Table 2). In arid areas, the effective cropping season is normally 11 - 17 weeks, which restricts the choice of crops and limits the farmer to a single crop in the rainy season. In semi - arid regions, the effective cropping season is normally longer (22 - 32 weeks) with exceptions of 8 weeks in Bellary (Karnataka) and 17 weeks in Bijapur (Karnataka) regions. Rainy season crops are grown on shallow to medium Vertisols at Bijapur, while post - rainy season
Table 2. Effective cropping season at various locations in arid and semi arid areas of India.
Zone
Location
Growing Season (Weeks)
Monsoon (23 - 39 mm)
Rainfall (mm) Post - monsoon
Arid
Jodhpur
11
353
8
Hissar
13
395
19
Anantapur
13
305
149
Rajkot
17
572
36
Semi
Hyderabad
22
603
108
Arid
Bangalore
32
400
226
Bijapur
17
381
130
Solapur
23
494
101
(Source: Single and Sebba Reddy, 1988)
crops are commonly grown on deep Vertisols at Bellary. The rainfall pattern and soil depth together determines the choice or crops and cropping systems. On shallow to medium Alfisols and related soils, only single season cropping mostly during the rainy season is possible. The amount of pre-monscore ram received in May determines whether or not double cropping is possible on demo Alfisols.
The water balance for different dryland research stations of SAI. The India has been calculated (Sing - 1993) and water availability periods haven been worked cut. The water availability period ranges between as low as 105 days at Bijapur and Bejary and as high as 210 days at Bangalore (Table 3).
Table 3. Water availability period at different dryland research centers of the SAT in India.
Soil type
Rainfall (mm)
Water availability
Total duration
& centre
Total Dependable
Period
(weeks)
Day
Range (mm)
1. Vertisols and related black soils :
Rajkot
674
532
134
25 - 44
20
Udaipur
661
572
164
25 - 48
24
Akola
878
702
196
25 - 52
28
Indore
1054
858
196
25 - 52
28
Jhansi
999
809
196
25 - 52
28
Solapur
743
584
168
23 - 46
24
Bijapur
537
434
105
33 - 47
15
Bellary
519
387
105
33 - 47
15
Kovilpatti
724
622
135
39 - 05
19
(Source: Singh, 1993)
Rainfall at 75% probability on long term basis Based on the information of water availability seriods potential cropping system have been suggested for different situations. The selection of efficient cropping system is also influenced by selection of suitable crops and their cultivers passed on duration and water use efficiency besides.
Climate, Soils And Socio Economic Factors (Singh, 1993)
Farmers have to adjust the cropping systems and crop management practices to the limitations imposed by the environment. The farming system which they have practiced has been developed by experience of generations without proper knowledge of agro climatic conditions, effective cropping pattern and schedule of supplemental irrigation can not be planned. For this study of moisture availability index (M.A.I.) is very important.
The cropping patterns are basically dependent on moisture availability index (M.A.I.). Hargreaves (1971) defined M.A.I. as there ratio of assured rainfall expected at 75% probability and estimated potential Evapotranspiration for the concerned period. However, Thormathwite and Mather (1965) calculated MAI by using water balance equation. Bistroni (1980) has defined M.A.I. as:
AE
MAI = ----
PE
Whereses,
AE = Actual Evapotranspiration
PE = Potential Evapotranspiration
For determining actual, Evapotranspiration (AE) following two conditions nave to be considered.
1) If P > PE, then PE = PE
2) IF P < PE, then ae = p + s
Where,
P = Precipitation
S = Change in soil moisture
Rainfall distribution over the country is highly erratic and tooth in time and space and there by Moisture Availability Index (M.A.I.) also becomes very underlain.
Moisture Availability Index the prime factor for especially in tropics waries both in time and space. The MAI on the basis of average monthly rainfall (Roman and Marth, 1971 and planning was done. However, in such system the monthly MAI values where truly representative as month is a longer period for planning any operation,. Moreover, If there are dry spells in between causing failure, the monthly MAI may not represent it. Hence, there is need is weekly MAI for agriculture planning. For planning of majority of crops the weekly MAI values would be most available.
Raskar (1994) determined crop growing period on the cases of availability index (MAI) of different rainguage stations of Pune, Ahmednagar districts of Maharashtra. In rainfall zone 1 to 3 of scarcity of these districts, the crop growing period at 0.3 MAI ranged between 18 a 19 weeks and at 0.5 MAI between 13 and 17 weeks during that season and 0.3 MAI between 9 and 11 weeks and at 0.5 MAI between 7 and 9 weeks during rabi season (Table 4). The dry spells of 3 to 6 weeks duration were observed.
Table 4. Weekly moisture availability period at 0.3 and 0.5 MAI in different soil type in various rainfall zone of scarcity tract of Pune and Ahmednagar districts.
Rainfall
Kharif
Rabi
Zone
Shallow
Medium
Deep
Shallow
Medium
Deep
0.3
0.5
0.3
0.5
0.3
0.5
0.3
0.5
0.3
0.5
0.3
0.5
1*
18
13
18
13
18
13
10
9
10
9
10
9
2**
19
16
19
16
19
16
11
7
11
8
11
8
3***
19
17
19
17
19
17
9
7
9
7
9
7
(Source: Rasker 1994)
Main of 5 iccation ** Mean of 8 locations *** Mean of locations at different locations. Drop planning on the basis of MAI was suggested sorghum grown on conserved soil moisture is sown in 39 the week but analysis suggests that it is quite possible to sow the crop well ahead of the present practice i.e. by 39 mm, preferably by 35 mm itself, when the assured amount of soil moisture is available for sowing as indicated by MAI more than 0.5. This will help the crop to have sufficient moisture in latter active growth stages such as elongation, flowering and grain filling.
Importance Of Rainfall Distribution
The average annual or seasonal rainfall at a place does not give sufficient information regarding its capacity to support crop production. Rainfall distribution pattern is the most important. This is illustrated by taking examples of Hyderabad and Solapur. These two locations are 500 km apart but have very similar amount of total rainfall (742 mm at Solapur, 764 mm at Hyderabad). At both the places, more than 75% of total rainfall is received September. However the distribution of rainfall at Solapur is highly erratic during Kharif. In comparison, Hyderabad has more dependable rainfall distribution pattern and thus more favorable for Kharif cropping than Solapur (Virmani et.al. 1982).
Field experiments at these two locations have shown that at Hyderabad, it is rossible to produce more that 500 kg grain ha-1 on deep Vertisols by adopting pigeon pea + maize intercropping C- maize - chickpea sequence cropping under good agronomic management. At Solapur Kharif cropping is undependable for a long duration crops but short duration crops of pearl millet sunflower or grain legume in Kharif followed by rabi Sorghum or gram is successful.
Some Practical Application Of Weather Data
Prostitution of rainfall within a season and the frequency of occurrence of dry speels of different durations can help to select the optimum time of planting and fertilizer application. If the probable dates of such saving irrigation, under taking or wittroiming of a nitrogen top dressing car also be made with greater confidence.
Temperature and humidity:
Temperature as the dominate factor controlling rate of development. The diurnal temperature cycle is more important than either the seasonal cycle or random effects of weather in the SAT (Monteeith, 1977) Even more important for plant growth processes and incidence of pests and diseases are the effects of microclimate. Humidity is also an important agro climatic factor because it is a major determinant of evaporation and incidence of pests and diseases. Nair et al. (1995) studied the influence of meteorological parameters on the incidence of shoot fly on Kharif sorghum order field conditions. They closer that egg laying and population dynamics stowed highly significant corretation with meteorological parameters like temperature, relative humidity, bright moisture tours and rainfall intensity while dead heart formation was not correlated
The incidence of powdery mildew on grape appeared early and more vigorously where relative humidity was high due to irrigation at shorter intervals (Chavan et. al., 1995). The temperature in the range of 11.8 to 32.42 C and relative humdity) 58.4% favored the development of powdery mildew. Wereas, temperature below 8.6 and above 34.09 C and relative humidity below 47.4% showed zero rate of multiplication indicating that disease did not multiply though, it existed. The incidence and multiplication was rapid in the months of December and Jawary when the climate was cool and humid.
Management Option In Relation To Weather Adjustment
While in irrigated condition timeliness of irrigation is important for higher production, a number of options such as choice of suitable crops and varieties, alternate crop strategies, mid season correction, crop life saving measures, alternate land use systems etc. are to be adopted in rained agriculture to adjust to aberrant weather conditions.
Cropping systems:
Suitable cropping systems aiming to adjust or reduce the intra - seasonal impact of climatic variability should be based on inter - seasonal variability of rainfall the water deficiency and the length and characteristics of growing season.
Intercropping:
In arid and semi - arid region of Hyderabad, the length of growing season varies from 15 to 30 weeks with variation in rainfall and soil moisture storage capacity (Table 6). In soils having medium available water storage capacity (150 mm in the soil profile) a crop with a 19 weeks growing season is likely to have adequate moisture only coce in 4 years. Under such conditions.
Table 6 Length of the growing season (week) for three soil conditions Hyderabad.
Rainfall Probability
Growing Season (weeks)
Available water storage capacity (mm)
Low (50 mm)
Medium (150 mm)
High (300 mm)
Mean
18
21
26
75%
15
19
23
25%
20
24
30
(Source : Virmani - 1989)
From seed germinating rains 25 June to put of season (time when profile moisture reduces AET / PET ratio of Actual evaportanspiration to potential evapotranspration to 0.5 )
* Low : shallow Altisol : medium : shallow to medium - deep Vertisols : high deep vertisoils.
intercropping of a short duration sorghum (105 - 110 days) with a long our at lon pigeonpa (150 - 180 days) yielded a land equivalent ratio of 1966. Pan and willey 1981). Thus, in case of random variability of rainfall, intercropping increases crop yield as well as provides stability. Based on 89 sorghum pigeonpea intercrop experiments conducted in diverse environments. It was been observed that on an average intercropping yielded equivalent of 90 mm solv sorghum yield and about 25% of sole pigeonpea yield.
Choice of the right intercropping will depend of the awards distribution pattern and soil moisture storage. In areas having be ental rainfall in the early part of the growing season drought tolent be (pigeonpea) may be useful. If rainfall is undertain is the later part of the growing season, then intercrop spould be storter in than the base crop Considering the high valves of pulses and outseeds and their soil restoring ability, these crops shouln find a place in any probulable intercropping programme.
Intercropping of pearl millet + pigeonpea (2:1) and sunflower + pigeonpea (2: 1) on medium deep soils are ideally suited for dryland conditions (Jadhav et.al., 1991) due to large difference in maturity periods of component crops which useful for harvesting the natural resources like solar rediation, soil moisture and nutrients more efficiently.
Table 7. Mean grain yield kg. ha-1, LER and gross monetary returns (Rs. ha-1) as influenced by treatements (Pooled data of 3 years : 1985 - 1988).
Treatments
Grain yield
LER
Gross monetary
Main crop
Intercrop
returns
Pearl millet + pigeonpea
1082
250
1.58
3564
Sunilower + pigeonpea
639
224
1.42
4049
Sole pearl millet
1053
-
1.00
2350
Soil sunflower
700
-
1.00
3222
Sole pigeonpes
442
-
1.00
2339
S.E.
-
-
-
390
C.D. (p 0.05)
-
-
-
1125
(Source : Jadhav et. al., 1991)
Proportionate Cropping
In this system land area allocated to crops of different growing duration on the basis of long term probabilities of soil moisture. Research conducted at OCS Haryana Agricultural University, Hisar allocating 40% of land to guar U 20 d durational. 40% to pearl millet (70 days) and 20% to mungbeen (50 days) enabled to harvest all three crops in good rainfall years and at least two crops in all but severe drought years (Virmani, 1989). Thus, proportionate cropping can help to decrease the risk of loss and increase over all productivity.
Moisture deliverinacy and cropping system:
In covered and rained regions because of combined effect of variable rainfall. High Evapotranspiration rates and poor water tolding capacity of soils crops are often exposed to suhoptimal moisture availability our mg our or more capital plenological stages of crop growth. The adverse effect of moisture deficiency can be minimized by choosing crop or crop varieties with duration appropriately fitting to moisture availability periods (Table B).
Table8. Potential cropping systems in relation to rainfall and soil type.
Rainfall (mm)
Soil type
Water availability
Potential clopping
period (week)
systems
350 - 600
Alfisols and shallow
20
Single Water if crop
Vertisols
350 - 600
Aridisols and Entisols
20
Single crop enther
water if or ran
350 - 600
Deep Vertisols
20
Single ran crop
600 - 750
Alfisols and entisols
20 - 30
Intercropping
750 - 900
Entisols, deep Vertisols
20
Double cropping with
Alfisols, Inceptisols
monitoring
0 - 900
Entisols, deep Vertisols.
20
Double cropping
deep Inceptisols
(Source: Katyal et al., 1994)
Contingent crop planning:
Weather aberrations are important features of deyland agriculture. One season seldom matches with another. As such every year poses a new situation. It if therefore, not enough to develop the tectrology for normal weather conditions but strategy needs to be developed for aberrant weather suitability. In fact these aberrations are the part of the propping situations.
Analysis of weather data and crop conditions at Solapur reveals that out of a years, 3 years are normal and ? Years are abserval in scar rate tract. Water delayed onset of monsoon 20 - 30% of the total cropped area team.
Table 9. Contingent crop planning on shallow and medium deep sols (45 cm depth) of scarcity zone of Maharashtra.
On set of monsoon
Crops suggested
(Fortnight)
June II
Pearl millet, sorghum, pigeanpea, sunflower, green
gram black gram, proundnut, horse gram, kindney bean,
castor, etc. and intercroppings.
July I
Pearl millet, sorghum, horsegram, kidney bean, pigeon pea,
groundnut, sunflower, castor etc. & intercroppings
July II
Pigeonpea, sunflower, horse gram, kindney bean castor
August I
Pigeonpea, sunflower, horsegram, castor.
August II
Pigeonpea, sunflower, castor
September I
Rabi sorghum (M - 35 - 1) for fodder or selection 3 for
grain
(Source : Patil et al., 1981)
monson for shallow to medium deep soils of scarcity tract of Maharashtra (Table 9).
Management Strategies Under Different Draught Conditions
Depending upon time and intensity of moisture stress, management strategies have to be adopted. Moisture stress periods are usually classified be (i) parly season moisture stress (ii) mid - season moisture stress (iii) terminal stress.
Early season stress:
Early season moisture stress occurs due to the failure of rains after sowing of crops /cropping systems or delayed start of rainy season. If produced dey spell occur immediately after sowing the seedlings may water.
Mid reserve stress may occur due to the period of monsoon after mateblislwent of crops. Under these situations adoption of frequent interculturing aerations use of organic mulches, lop dressing of outrage after rained of moisture steps formation of dead furrow red such dry spells in the same season, the likelihood is quite high Bhavanisagar (77%), while it is les at Solapur (15% once in 7 years) and the chance at Hyderabad is zero.
Extension advisors, field agronomists and district agriculture officials can use such information by using the data from their regional metrological stations in order to time tune the blanket recommendations to suit particular conditions.
Table 10. Probabilities of selected events at three locations.
Event or opportunities
Probability (%)
Solapur
Hyderabad
Bhavanisagar
Possibility of at least one off season
38
54
92
tillage in May
Success in early panting
77
92
15
Occurrence of one 21 day dry spell during
June to September rainy season
92
54
100
Occurrence of three 21 day dry speel in
one rainy season
15
0
77
Occurrence of three 14 - day dry spell in
the rainy season
62
38
100
(Source: Huda et al., 1988)
Management Strategies Under Different Draught Conditions
Depending upon time and intensity of moisture stress, management strategies have to be adopted. Moisture stress periods are usually classified be (i) parly season moisture stress (ii) mid - season moisture stress (iii) terminal stress.
Early season stress:
Early season moisture stress occurs due to the failure of rains after sowing of crops /cropping systems or delayed start of rainy season. If produced dey spell occur immediately after sowing the seedlings may water.
Mid reserve stress may occur due to the period of monsoon after mateblislwent of crops. Under these situations adoption of frequent interculturing aerations use of organic mulches, lop dressing of outrage after rained of moisture steps formation of dead furrow red such dry spells in the same season, the likelihood is quite high Bhavanisagar (77%), while it is les at Solapur (15% once in 7 years) and the chance at Hyderabad is zero.
Extension advisors, field agronomists and district agriculture officials can use such information by using the data from their regional metrological stations in order to time tune the blanket recommendations to suit particular conditions.
Table 10. Probabilities of selected events at three locations.
Event or opportunities
Probability (%)
Solapur
Hyderabad
Bhavanisagar
Possibility of at least one off season
38
54
92
tillage in May
Success in early panting
77
92
15
Occurrence of one 21 day dry spell during
June to September rainy season
92
54
100
Occurrence of three 21 day dry speel in
one rainy season
15
0
77
Occurrence of three 14 - day dry spell in
the rainy season
62
38
100
(Source: Huda et al., 1988)
Interaction Of Sowing Date And Climatic Variability
The effect of sowing wheat at different dates was simulated for all 138 locations (Das and Karla, 1995). It was apparent that as potential yield increased. The reduction in yield per day delay in sowing also increased. In general, the yield decrease was between 0.25% and 0.75% of potential yield when the latter was less than 4% hari, between 0.5 to 1.00% for yield potential between A and 6% hart and between 0.75 to 1.00% for yield potentials greater than 6. It is interesting first irrespective of potential yield, a few location showed a small yield reduction (less than 0.25%) with delayed sowing. For New Delhi environment, the maximum grain yield was obtained for sowings done between 1 and 15 November.
The effect of varying amounts of post sown irrigation for wheat was tested for New Delhi environment with WIGROWS model in relation to the seasonal climatic variability (using 20 years runs from 1971 - 93). The amount of moisture at the time of sowing was assumed to be 75% of the field capacity. The amount of water applied at each irrigation was assumed to be 60 mm. Nitrogen application at the rate of 150 kg hart was applied at the time of sowing. The result showed increased yield with increase in number of post sown irrigations and stabilizing beyond three irrigation. Variability width seemed to be dependent of the amount of post - son water received. It is decreased with increase in post - son water received. It is decreased with increase in post - son water received by the crop, indicating the reduced effect of climatic variability on yields under increment moisture availability condition. The variability index values ranged from about 0.59 up to one irrigation to around 0.135 (beyond for irrigations) with intermediate values of 0.42 (Two irrigations) and 0.20 Three
Fertilizer Use In Rained Farming, Levels And Methods Or Fertilizer Application
One of the important management practices to increase the crop production. In dry lands is the use of fertilizers. Fertilizer is next important component to moisture in dry lands. Therefore, it is said that the soils of dryland are not only thirsty but hungry also. Soils of this zone are generally poor in nitrogen content (Total nitrogen content 0.03 to 0.05%) and they respond to nitrogen application. Available phosphate status is low to medium (10 to 30 kg P2O5/ha.) Response to phosphate application is noticed only during Kharif on sallow soils, which are poor in phosphate. However, there has not response to the phosphate on medium deep and deep soils (rabi soils). The reason may be that these soils are medium in phosphate and the drop requirements like jawar (M - 35 - 1) are not very high. Potash content of the soils are quite high (300 to 750 kg available K2O/ha) than usually required for dry land crops. Potash is abundant and it would be difficult to expect any response to dry crops due to application of potash.
Experiment ants on use of inorganic fertilizers are in progress since 1957 at Solapur and other locations. The fertilizer use has done much progress in dry lands.
Kharif Crops:
1. Bajra: Bajra is an important Kharif crop. During last 15 to 20 years hybrid varieties are becoming popular in dryland areas. Bajra crop responded to nitrogen application very well. Response to P2O5 was very small. On shallow and malin help, there is likely to get reapions P2O5.It is recommended to apply 50 kg N + 25 kg P2O5/ ha. The whole does of N & P should be applied at sowing. There is no interaction between N and P. If money is short P2O5 application may be deleted.
2. Setaria: Setaria is a Kharif crop in dry lands for shallow and medium deep soils. It is particularly suited under delayed sowing conditions. From the results of experiments on Setaria it is observed that nitrogen application helped to increase production significantly and substantially. In case of P2O5 the response was very small. It is therefore, recommended to apply 50 kgN to Setaria crop at sowing.
3. Rabi Jowar : Rabi Jowar is the most important and major crop of the region. Earlier work on the fertilizer requirement revealed that there was only response to nitrogen application and as such 25 kg N for medium deep soils and 50 kg N for deep about 7 to 8 kg. The experiments were conducted to see the efficiency of fertilizer by applying part of nitrogen by foliar sprays. But in this experiment it was observed that foliar application and no advantage over soil application. With the use of new dry farming technology such as high yielding varieties and early September sowing, experiment on nitrogen requirements was started during 1973 - 74. The results of this experiment showed that in early sowing, the nitrogen utilization was proper which resulted in better response to the fertilizer. As high as 17 kg. grain and 36 kg. Fodder is prepuce per kg. of nitrogen applied. The optimum level of nitro in for different varieties tried was around 85 kg/in
Effect of despite application on rabi Jowar:
Studies of varieties conducted on the phosphate requirement of Rabi Jowar (M - 35 - 1) and it was observed that the phosphate application did not affect the grain production. Lack of response to phosphate may be attributed to two reasons. Firsts the soils on which the crop was grown contained medium level of phosphate (20 kg P2O5/ha). Secondly the requirement of the phosphate for M - 35 - 1 variety may be very low which might be supplied through native phosphate alone. On an average, M - 35 - 1 removes 25 to 28 kg P2O5/ha.
Safflower: Safflower is another important rabi crop in dry farming zone. It is, usually taken as mix crop. Studies at Solapur proved that mixing safflower along with jawar is harmiture. As a result, it has been recommended to cultivate this crop at a sole crop. This crop was found to respond extremely well to nitrogen application. Response to phosphate is small, erratic and noticed only in shallow soils in some years. Response to nitrogen is very good under good soil moisture conditions. Application of 50 kg N/ha is sufficient to get good and economic returns.
Methods Of Fertilizer Application
For dry land crops fertilizers are usually applied at the sowing time. For drilling the seeds and fertilizers together Jyoti ferti - seed - drill can be used. This implement can be drawn by a pair of bullocks. It is suitable for all crops except groundnut. The row to row spacing can be adjusted from 22.5 cm to 45 cm. The fertilizers are drilled 5 cm. away at proper depth developed by providing a traditional bowl rand tubes on locally available seed drills. Fertilizer needs to be placed at 10 cm. Depth and as close as possible to the seed row. The fertilizer is placed about 2 to 4 cm. deeper than seed in the same row. Locally used 3 or 4 countered seed drill can be converted to ferti - seed - drill by local carpenters.
Manure and fertilizer application schedule for dry land crops (Kharif)
Crop
Manure
T/ha
Fertilizers
Time of application
N
P
K
1
2
3
4
5
6
1.
Kharif Jowar
(Local, improved )
6-7.5
50
25
-
Whole quantity of N,P, applied at sowing.
2.
Rainfed Kharif
Hybrids of Jowar with assured rainfall.
6 - 7.5
75
62
62
1/2 N-at sowing 1/2 N at top dressing. Full dose of P and K and sowing.
3.
Maize Rainfed with assured rainfall.
12-15
90
40
40
1/2 N at sowing, 1/2 N at Knee high stage. Whole of P2O5 and K2o at sowing.
4.
Pearl millets
(Hybrids)
5-6
50
25
-
Whole of N and P at sowing.
5.
Pearl millet
(Local and improved varieties)
5-6
25
25
-
Whole of N and P at sowing
6.
Setaria
(Rala)
3-5
50
--
--
Whole quantity of N at sowing.
7.
Hill millet
5-6
50
25
25
Whole quantity of N,P,K, at sowing.
8.
Groundnut
5
12.5
25
-
Whole quantity of N and P at sowing.
9.
Sunflower
5-6
25
25
-
--do--
10.
Niger
5
25
25
-
--do--
11.
5
25
25
-
--do--
12.
5
25
25
-
--do--
13.
5
12.5
25
-
--do--
14.
5
12.5
25
-
--do--
15.
Kidney bean
5
12.5
25
-
16.
Red gram
5
25
50
-
Manures and fertilizers application schedule for Rabi crops
1.
2
3
4
5
6
1.
Rabi Jowar on
deep soils
6-8
50
25
--
Entire quantity of N & P at sowing.
2.
Rabi Jowar on
medium deep soils
6-8
25
12/2
--
Entire quantity of N & P at sowing.
3.
Safflower
5-6
50
25
--
Entire dose of N & P at sowing.
4.
Gram
6-7
12.5
25
--
--do--
5.
Linseed
3-5
30
15
--
--do--
6.
Sunflower
3-5
50
25
--
--do--
Concept Of Watershed Management
Introduction:
Out of the 20.1 million hectares of cultivable land in the state about 17.5 million hectares are under rained agriculture. At presents nearly 13 percent of the cultivated area is irrigated. After harvesting all the available water resources at the most 30 per cent of the cultivated area can be brought under irrigation. Thus, 70 per cent area would remain as rained in the state. The crop production under rained agriculture is most unstable due to inadequate, uncertain and ill - distributed rainfall. Besides. Non adoption of improved agricultural practices in rained agriculture has further deteriorated the socio - economic status of the farmers.
The major food grain requirement of the state is net from the rained areas which contain mostly all grains pulses and oilseeds while in many areas heavy soils are utilized only for rabi cropping. Crop production under rained agriculture is mostly subsistence oriented producing food grains for home consumption including cash crops and fodder for livestock. The cropping patterns vary according to soils, climate, and farmer preference and to a limited extent market demands. Sorghum, cotton, pearl millet, groundnut, pigeon pea, green gram, black gram, sunflower, wheat, gram and safflower are among the important crops grown in rained agriculture. However, the productivity of the crops is extremely low due to improper crop management practices including land management treatments adopted in rained agriculture.
Most of the community lands and privately owned marginal lands which are unsuitable for arable farming remain uncultivated and serve as grazing grounds for village livestock and source of fuel supply. The Government lands are normally located at higher elevations and are badly eroded and deprived off any vegetation. The communal grazing lands are also severely denuded and eroded leaving thin vegetative cover. As a result, these areas serve as an origin of erosion.
It is estimated that out of 30.6 million hectares of the geographical area of the state, nearly 13.8 million hectares suffers from moderate to heavy soil erosion. The detailed crosion studies made in Solapur district indicated that the percentage of deep soils (depth > 45 cm) came down from 46 to 29 in a period of 75 years indicating the severity of erosion hazard. From the studies, it is observed that the soil loss was in the range of 60 to 90 tonnes / ha per annum. With this rate is estimated that 20 cm of fertile soil may be lost within a pan of 24 years. However, under natural conditions of weathering process the process the formatting of 1 cm top soil layer will require more than 100 years.
Agricultural development of such rained areas has remained neglected compared to irrigated agriculture. The integrated development efforts in these areas initiated in most parts in the country under the name. "Water shed Development in Rainfed Areas" since 1984 - 85.
Definition of watershed:
i) Watershed is an area above a given drainage point on a stream that contributes water to the flow at that point.
ii) Watershed is a natural unit draining runoff water to common point of outlet.
iii) The watershed is geohydrological unit or a piece of land that drains at common point. Catchments basin or drainage basin are synonymous of watershed.
Broad Objectives of watershed Development
In general, the watershed development fulfills the following objectives.
1.To bring about increased productivity.
2.To make yields less subject to the effect of erratic rains.
3.To improve resource conservation (soil & water) and land use.
4.To create additional employment potential for the small / marginal farmers and agricultural labourers.
Principles or objectives of watershed management:
1. Utilizing the land according to its capability.
2. Putting adequate vegetal cover on the soil during the rainy season.
3. Conserving as much water as possible at the place where it falls. i.e. In situ conservation of rain water.
4. Draining out excess water with a safe velocity and diverting it to storage ponds avoiding situation hazards and store it for further sue for supplemental irrigation during stress periods.
5. Avoiding gully formation and putting checks at suitable intervals to control soil erosion and recharge ground water.
6. Maximizing productivity per unit area, per unit time and per unit of water.
7. Increasing cropping intensity and land equivalent ratio through intercropping and sequence cropping.
8. Safe utilization of marginal lands through alternate land use system such as horticulture, Agro forestry, silvipasture etc.
9. Ensuring sustainability of the eco - system benefiting the man - animal - animal - plant - land, water complex in the water complex in the watershed.
10 Maximum the combined income from the inter related and dynamic crop - livestock - tree - labour complex over years.
11. Stabilizing total income and cut down risks during aberrant water situation.
12. Improving infrastructural facilities with regards to storage, transportation and marketing.
13. Improving the socio - economic status of the farmers.
Classification Of Watershed
Classification of watershed:
1. Macro watershed: 400 to 2000 ha.
2. Micro watershed: Less than 400 ha.
Agricultural watersheds:
i) Sub watershed: 10,000 to 50,000 ha.
ii)Multiwatershed : 1000 to 10,000 ha.
iii) Micro watershed: 100 to 1000 ha.
iv) Miniwatershed: 1 to 100 ha.
Water shed Development Concept:
Watershed development refers to the conservation, regeneration and judicious utilization of all the resources viz. land, water, vegetation, animal and human within a particular watershed in integrated manner. Watershed development seeks to bring about an optimum equilibrium in the ecosystem between natural resources man and animals.
In the past, watershed development programme was aimed at mainly on the treatment of catchments for preventing situation in reservoirs. 8Xthe aim of the watershed development in present contest is quite different. It includes the improvement in productivity of dry lands through the components like
i) Crop management
ii) Soil and moisture conservation
iii) Water harvesting &
iv) Alternate land use system.
In the past full potential of new technology could not be exploited as these components were implemented in piece meal. Now, this is possible due to implementation of all there components in integrated manner in each hydrological unit of watershed.
Components of watershed development:
Following are the general items of watershed development which are required to be excuted in the catchments area depending upon the prevailing situation.
1. Soil and land management
i) Interceptor drains.
iii) Graded bunding
iv) Bench terracing
v) Interbund vegetative barriers
vi) Grass Waterways.
vii) Improvement of ill drained soils
viii) Nala training / improvement.
2. Water Harvesting Structures:
i) Nala bunding
ii) Farm ponds
iii) Percolation tanks
iv) Minor irrigation tanks
v) Stop dams in nalas
vi) Underground diaphragms.
3. Afforestation cum pasture development for rural energy and forage for animals:
i) On private marginal and culturable waste lands.
ii) On community and Government forest lands.
4. Agricultural development:
i) Selection of crops and their varieties suitable for local soil and climatic situation.
ii) Adoption of appropriate cropping system.
iii) Contour farming.
iv) Strip cropping.
v) Mulching and crop residue management.
vi) Adoption of alternate land use system depending on land capability such as Alley Cropping, Agro - horticulture, silvipastural management, dryland horticulture, tree farming, and pasture management.
Significant Gains From Watershed Development Programme
1. Soil and moisture conservation:
Soil and moisture conservation is the basic need in rained agriculture. Top soil is the most fertile part of the soil profile. This layer is lost due to erosion causing decrease in yield. Agronomic and mechanical measures for soil and moisture conservation are adopted in the watershed such as contour farming, strip cropping, mixed cropping, inter - cropping, contour / graded bunding, vegetative barriers etc.
2. Increase in water storage:
Due to construction of surface water storage structures like minor irrigation tanks, percolation tanks, nala bunds, farm ponds etc. the excess runoff water is collected in these storage structures which in turn is used either for supplement irrigation for field crops, horticultural crops or for drinking water to animals. Thus, additional area can be brought under irrigation.
3. Increase in number of wells:
Due to considerable improvement in ground water recharge, the numbers of dugout wells or tube wells are increased. The farmer can apply protective irrigation to various field crops whenever necessary. Thus the area under well irrigation is increased.
4. Increase in cropping intensity:
Due to increase in water resources and adoption of appropriate crop management practices, and area under double cropping is increased, which results in increasing cropping intensity.
5. Increase in fertilizer use:
Due to increase in water potential and moisture conservation measures, the fertilizer use by the farmers is increased.
6. Improvement in crop production and productivity:
Adoption of vegetative and mechanical conservator measures, results in considerable reduction in soil, water and nutrient losses from the watershed area. Further adoption of improved crop management practices results in appreciable increase in crop productivity and total crop production from these areas.
7. Animal and milk production:
Appropriate management of marginal lands with productive grasses and pastures, the total forage resources are increased which reflects in increasing animal component resulting increase in meat and milk production.
8. Increase in afforestation and alternate land use:
For producing fuel, fodder and timber, alternate land use programme is implemented in watersheds. Dryland horticultural species in addition to fuel and fodder tree species have shown promise in the watersheds.
9. Employment generation and increase in per capita income:
Due to optimization of available resources, there is increase in employment generation to farm families throughout the year. Due to overall increase in production and productivity in the entire watershed, there is considerable increase in per capita income.
Cropping Patterns
Cropping Pattern: The selection of crops and their varieties is to be made depending on the soil and rain fail situation in the rained areas. The photo insensitive crops and varieties with shorter duration should be chosen to escape drought of different intensities. There are wide variations, location to location in water availability periods in dryland areas. Thus depending upon water availability following are the different crops and cropping patterns to suit different climatic situations.
For rained areas:
Monoculture
Scarcity zone
Pearl millet, red gram, green gram, black
gram, Horse gram, groundnut
Rabi : Jowar Safflower
Assured rainfall
Cotton, sorghum, red gram, black gram,
green gram, soybean, sunflower
Double cropping
Scarcity zone
Kharif crops Mung /
Urid Mung / Urid
Sunflower
Bajra
Bajra
Rabi crops Safflower
Jowar
Gram
Gram
Safflower
Assured rainfall zone
Paddy
Soybean
Mung/Urid
Mung/Urid
Sunflower
Gram
Safflower
Jowar
Safflower
Gram
Irrigated areas
Jowar
Jowar
Maize
Grunt
Grunt
Wheat
Gram
Wheat
Jowar
Sunflower
Stable intercropping systems for rained areas:
Scarcity zone Bajra + Tur in 2: 1 row proportion
Assured rain Sorghum + Mung / Urid in 2: 1 row proportion fall zone.
Cotton + Mung / Urid in 1: 1 row proportion
Cotton + Tur in 8: 2 row proportion
Sorghum + Tur in 2: 1 row proportion.
Tur + Mung / Urid in 1: 3 row proportion.
Grassland or pasture management:
Most of the marginal lands are not able to sustain arable crops particularly during the drought years. Such lands can be developed into dependable pastures by following soil and water conservation measures like contour trenches and contour furrows. Controlled grazing may also help in building the forage resource.
At times, native pastures are stocked with low productive and less palatable species. These pastures lack legume component, thus, making the pasture lands nutritionally deficient. Artificial renovation of such pastures is likely to provide forage of good quality as well as sufficient quantity. In rained areas, different legumes from the genera Dolichos, Leucaena, Clitoria, Cassia and Stylosanthes have been found to do well with or without grasses like Cenchrus ciliaris. But Stylosanthes has been found to be excellent in all situations with regard to persistence, nutritive value and palatability. Different grasses from the genera Dichanthium, Cenchrus, Lasiurus, Chloris, Urochloa, Panicum, and Pennisetum etc. have been observed doing well. Cenchrus ciliaris has been found to be good in most of the situations.
The pastures are easily established if they are seeded at the beginning of rainy season. Seeds of Cenchrus ciliaris @ 1.0 Kg. Stylosanthes hamata @ 4.0 Kg and Stylosanthes scabra @ 1.0 Kg per hectare may be used as seed moistures. The seed moisture may be broadcasted on a drizzling day. After that, light raking of the soil may improve germination chances considerably.
Research investigations have revealed that application of 20 - 25 Kg N increases dry matter yield of grass species considerably. Similarly, 30 - 40 Kg. of P205 gives good response of legume component. For the establishment of pasture as well as for getting increased forage production the access of livestock to pastures should be controlled so that grazing pressure could be minimized.
Planning And Implementation Of Watershed Management Programme
The planning and implementation of watershed management programme should be carried out in systematic way with the active participation of farmers including constitution of co-operative watershed management societies. During implementation of the programme, following guidelines may followed.
1. The implementation programme should start from the ridge line of the watershed to the valley, not on piecemeal basis in isolated patches.
2. Development of arable and non - arable lands should be done together.
3. Forest, pasture, cultivable land and water lands should be treated as inter linked units of hydrological entity. The condition of all lands has to be improved to meet the demands of increasing man and animal population.
4. Essentially, all developmental activities are to be carried out on watershed basis. Whole watershed area needs to be covered, may be in planned phases.
The following points to be considered while preparing the master plan for watershed development.
Out line of master plan of Watershed:
For preparing of master plans of the watershed, specific formats are prescribed by the Central Research Institute for Dry Land Agril., Hyderabad. The out line for preparation of master plan for development of dry lands on watershed basis are given below -
I. Introductions: General description regarding aims & objectives of the watershed approach for Dry land Agril.
II. Characteristics of watershed:
1. General information i.e. the general description of its characteristics name of watershed, general special problems on use of natural resources like soil & water.
2. Climate: Annual of monthly rainfall in mm & no. of rainy days from the harvest, rainguage station, special problems of watershed.
3. Soils: Geological features: type of soils, series, physical & chemical properties; soil survey map & report.
4. Natural vegetation: General description of the type of vegetation & the level of management.
5. Present land use & capability of classification: Detailed land capability classification under each category. Area under each class of soil Existing cropping pattern through systematic survey of the farm.
6. Socio - Economic condition: Existing land holding pattern, irrigation facilities; available draft power; labour; credit & other facilities like marketing, transport, roads etc.
III. Analysis of Problems & Potentials:
1. Existing level of crop management & reasons for non adoption of technology.
2. Existing level of Erosion control measures & suggested control measures.
3. Present level of main water use efficiency & methods of insitu moisture conservation.
IV. Improved Technology:
1. Proposed land use: Management of practices of the alternate land use system.
2. Crop management: Description of the main features of the new technology i.e. use of different production inputs, proposals to tackle aberrant weather situations.
3. Soil & water management: Specification of the engineering measures e.g. diversion drains, bunds, terracing etc.
4. Pasture management: Silvi - Horti - Agril. Pasture development details.
V. Schedule of operation: Defining the sequence of operation keeping in view with weather & available resources.
VI. Cost benefit Analysis & budget :
a) Cost benefit ratio for each component.
b) Description of subsidy pattern under each item of work.
c) Year wise - budget.
d) Likely overall benefits from the plan.
VI. Supplemental information:
a) Soil survey reports.
b) Summery of formers survey report.
c) Design; Drawing & details of major structure.
d) Agencies involved & their responsibilities.
VIII. Maps
a) Soil survey reports
b) Land capability classification
c) Existing land use
d) Existing measures for erosion control, rills, gullies etc.
e) Proposed land use
f) Contour map
g) Proposed soil & water management measures.
IX) Provision of staff, farmers training, monitoring & evaluation of the project should also be made in the master plan.
X) Involvement of farmers in planning & executions of programme through formation of co-operative watershed development societies at village levels be considered.
Plant Population, Distribution Pattern And Weed Control In Rainfed Agriculture
Cropping pattern in dryland in dependent on quantity and distribution of rainfall, soil type and its depth. In general, cropping intensity in dryland is only 100 percent. It is observed in the farmers field that plant density is low ranging 50 to 60 thousand / ha in dryland. It is possible to increase density of population with early sowing and use of fertilizers. In fact, in may be said that in case of rabi sorghum it would be difficult to get higher production without change in plant density to higher side to about one lakh per ha is desirable for variety M - 35. In case of high yielding varieties it is advisable to go in still higher side. In case of safflower there is remarkable adjusting capacity to plant density. However it is desirable to have plant density between 50 to 100 thousands ha. It is advisable to adjust plant density towards higher side from practical point gives.
Plant geometrical studies revealed that paired planting for Rabi jawar found suitable for maintaining plant density. In case of sunflower planting in square or reciangular had little advantage. A plant density of about 74000/ha with 60 x 22.5 cm spacing is desirable. In subnormal season alternate plant could be removed to reduce density to half is desirable. Density of 1 lakh / ha (30 x 30 cm) give same yield but 1000 grain weight gets reduced. The object of keeping optimum plant population is to get higher production & grain / fodder / ha.
Crop Planning For Aberrant Weather
Crop production in dryland suffers from in stability due to aberrant weather condition from time to time. Delayed monsoon results in non sowing of traditional kharif crops which accounts for nearly 25 to 30% of the total area under crops. So also early withdrawal of monsoon interferes sowing of Rabi a crop which is main constraint of crop production in the region. Similarly, breaks in monsoon also after crop production adversely year 1972 was the lowest rainfall year which resulted in total failure of both Kharif and rabi crops under dry lands.
Mid - Season correction: Crop planning under aberrant weather condition in dry land.
Sr.No.
Nature of rainfall
Crops to be grown
1.
Delayed on set of Monsoon
2.
Rains during July & sowing of kharif crops by end of July or early August.
Setaria (Arjun) Red gram (No. 148) Sunflower (EC 68414), caster () Horse gram (Mans, Sinha)
3.
Rains during August & Sowing up to end of August
Red gram (No. 148) Sunflower (EC 68414) Caster (Aruna)
4.
Rains during late August &
sowing up to Early Sept.
Castor (Aruna). Jowar for fodder
5.
Good onset of monsoon
Sowing of all kharif crops
Common situation usually one or
two dry spells are noticed
6.
If dry spell exceeds tow weeks
Corrective measures
a) Control of plant population
b) Checking weed growth
c) Increasing interculturing
serious situation in drought
prone area
7.
Early withdrawal of monsoon
a) Reducing of plant population from lakh to 50 thousand as in case of rabi Jowar in 35 -1 before grand growth.
b) Use of surface mulch
c) Protective irrigation 30 - 45 days drought.
d) Increase frequently of inter culturing
e) Stripping of leaves
8.
Extended monsoon
It is rarely experienced
a) Sowing of grown and wheat instead of rabi sorghum.
b) Double cropping would be possible in medium deep soils.
c) Postponement of sowing of rabi crops.
Weed Control In Rainfed Agriculture
Weed cause considerable damage to the crops in general and in dryland particular. The weeds complete with crop plants in respect of moisture and nutrients. The moisture as such is already in short supply in dryland. In fact one of the measures of moisture conservation is to control weeds. The extent damage varies from 35 to 97% Pretillage perations usually deep ploughing reduces weed intensity control of annual weeds is not problem in rabi soils but control of perennial weeds like.
Hanjalic, Kunda is the problem in dry lands weeds are found in patches. Weeds in kharif lands are the problem. The cost involved in weed control is not likely to be compensated by the production. The major composition of the weed flora is celosia (Kurdu) comeliness (Kena) and cyanotis (Echaka).
Weed control methods:
1. Mechanical weed control: Hand weeding or hoeing carried out at 30 to 35 days of sowing at grand growth period. Competition is serious during first 30 days period. During this period plant growth is slow and there is set back to crop growth affecting tillers, panicle size and poor stand in general.
2. Chemical weed control: Under certain situations like shortage of labour, inaccessibility of fields due to rains and mechanical weed control is with great difficulty the chemical weed control has place in dry lands. In this regards reemergence of application of weedicide has a place. Use Atrazine @ 0.5 kg al / ha as a re emergence and 2.4 - D as post emergence.
Crop rotation And Its Factors and Advantages
Growing of set of crops in a regular succession over a same piece of land (field with) in a specific period of time.
In crop rotation soil improving crops should be rotated in time over the entire farm in a regular sequence as permissible by soil, climatic and economic factors. In general cropping intensity in dryland is only 100 per cent. At few places on partial lands occasionally two crops are taken in favorable season (Monoculture is the rule in dryland agriculture) Increasing the cropping intensity is one of the methods for increasing crop production. Cropping intensity is increased by sequence cropping and double cropping but intercropping may also prove effective measure for increasing production per unit area.
Factors to be considered for planning of crop rotation:
1. Soil type crop and its duration.
2. Livestock on the farm
3. Occurrence of pests and diseases
4. Price and availability of Agricultural produce
5. Cost of labour.
Advantages of crop rotation:
1. Crop rotation maintains and improves soil fertility.
2. Prevent - build up of pests, weeds & soil diseases.
3. Control of soil erosion.
4. Ensures balanced programme of work through out the year.
5. Prevent or limit periods of peak (requirements of irrigation water)
6. Conserve moisture from one season to next.
Characteristics of good rotation:
1. It should be adoptable to the existing soil climate and economical factor.
2. It should be based on proper land utilization.
3. It should contain a sufficient number of soil improving crops to maintain and build up organic matter content of the soil.
4. It should provide sufficient fodder for live stock reared on farm.
5. It should be so arranged so as to make economy in production and labour utilization.
6. It should be so arranged as to help in control of weeds, plant diseases and pests.
7. It should provide maximum area under most profitable cash crop adopted in the area.
Effect of crop rotation so soil:
1. On runoff and soil loss: Crop rotation of Bajra - red gram or groundnut recorded minimum runoff and soil less (82 to 90%) followed by Bajra red gram - horse gram.
2. On bio - logical yield: Legumes cereals or cereals legumes rotations are not only beneficial for runoff but also increase biological yields.
3. Use of crop rotations according to soil moisture:
a) Kharif season: (Shallow and poor moisture retention capacity soils.)
Crop: Bajra, Sorghum, pulses, groundnut followed by follow.
b) Rabi season: (Medium to deep soils fairly good moisture retention capacity soils)
Crop: Sorghum, safflower, gram are rotted with Kharif Bajra sorghum etc.
Monoculture growing of a crop on the same piece of land year after year is known as monoculture or single crop system. Fallow - Jowar
(R) Or safflower fallow in rotation. In scarcity areas only two crops are taken in three years as against one crop every year. Experiments at Dry farming Research Station Shown the variability in benefits of fallow in rotation in increasing the yield of crop in the succeeding year.
Intercrop system:
By following intercropping system risk is reduced (shared) cropping intensity is increased. Crop selected for intercropping (intercrop) should not compete for moisture quick growing and short duration. The medium soils, depth uptown 45 cm do not provide sufficient moisture to support two crops in sequence (double cropping) even in normal year. These soils are therefore ideal for intercropping. A base crop and intercrop should have different duration of life and growth rhythms. At the same time crops should be cooperative. Bajra + Red gram are ideally suited for this purpose. Red gram gets of benefits from Sept showers and gives high yields. In the events of failure of later rains in Sept bajara already sown gives good yields. In the even of failure of early rains red gram compensates the production. In normal and above normal seasons both these crops boost up total production. For very shallow soils (up to 20 cm depth) Gross like Marvels planted 60 cm apart and established and horse gram is sown as intercrop was found to be most profitable. Intercropping is uneconomic and undesirable during Rabi season because Rabi crops are cultivated mainly on receding soil moisture and thus, it creates Competition for moisture. Gram and Safflower consume more moisture during early period there will be moisture stress at ear head emergence for Rabi sorghum resulting in low yields, Sequence or double cropping. In normal your (normal rainfall) there is possibility of two cops in dry land area giving increased production ranging from 100 to 300 percent over single cropping.
At Solapur seq. Viz.
Green gram / black (gram (k) - Jowar (R) and Bajra (K) - Gram (R) was found beneficial -
Mixed cropping is extensively followed for Kharif crops. Usually 4 - 5 crops are mixed. The proportion of crops varies from place to place. Seeds of bajara, red gram, horse gram, moth bean and Sesamum are mixed. The practice is common because of shortage of labour for sowing separate rows. For Rabi season sorghum safflower is a common mixture. Usually 12 - 15 rows of sorghum followed by there rows of safflower. The proportion of rows changes as per the sowing implements in practice.
Crop mixture And Its Advantages
It is similar to inter cropping the difference that crops are either broadcasted seeds are mixed and sown or grown as mixture with in a row.
Types:
1. Cereals - legumes
2. Cereals - oilseeds
3. Fiber crops - oilseeds
4. Fiber crops - cereals
A) For Vidarbha - Khandesh tract
Jowar - black gram
Bajra - kidney beam / Green gram
Cotton 10 - 15 rows - Red gram 2 lines.
Deccan hemp - Sesamum - seeds mixed
B) For Deccan Dists:
Bajra - 5 - 6 rows - Red gram of row
Bajra - 2 - 1 rows - one row of tur.
R. Jowar - 8 rows - Safflower 4 rows
Sunflower - 2 rows - one row of tur.
Advantages:
1. To utilize available space and nutrients to the maximum extent.
2. To secure daily requirements like pulses and oilseeds.
3. To safeguard against hazards of weather, diseases and pests.
4. To provide balanced cattle feed.
5. To avail distribution of labour through out the year.
6. To get handy installments of cash returns.
Limitation: In Rabi this system is uneconomical as rabi crops are grown on recording moisture.
The growth rhythmus and duration of life cycle of the mixture is different. In this main crop get harvested earlier than mixed crop by which the mix crop produces high yield with benefit of September showers. Bajra + red gram where the duration of life cycle of bajara is less than that of red gram.
Inter Cropping And Its Advantages
Intercropping: Growing of two or more crops simultaneously on the same piece of land (field). There is a crop intensification in both time and space dimensions. There is intercrop competition during all or part of crop growth.
Type of intercropping:
1. Mixed intercropping
2. Row intercropping
2. Strip intercropping
4. Relay intercropping
Definitions of Intercropping system:
1. Mixed Intercropping: Growing two or more crops simultaneously with no district row arrangement.
2. Row Intercropping: Growing two or more crops simultaneously where one or more crops are planted in rows.
3. Strip Intercropping: Growing soil conserving and soil depleting crops in alternate strips running perpendicular to the slope of the land or to the direction of prevailing winds for the purpose of reducing errosion.
4. Relay Intercropping: Seeding planting two or more succeeding crops after flowering and before the harvest of the standing crop.
Advantages:
1. Intercropping gives higher income per unit area than sole cropping.
2. It acts as an insurance against failure of crop in abnormal year.
3. Intercrops maintain soil fertility as the nutrient uptake is made from both layers.
4. Reduce soil runoff.
Limitations: Intercropping system is uneconomical and undesirable during rabi.
Crops to be considered for intercropping.
A) Kharif crops:
1. Medium black soils:
a) Pearl millet + Red gram 2: 1
b) Pearl millet + Horse gram / Kidney bean / cow pea Inter row of pearl millet.
3. Soils up to 20 cm depth
a) Pearl millet + red gram (30 - 60 - 30 cm)
B) Rabi crops:
Safflower + Gram (2: 1)
D) Fodder for milch animals: Sorghum bajara + Cowpea or horse gram or kidney bean.
In rained areas of Maharashtra:
1. Sorghum / pearl millet / cotton + red gram / black gram or kidney bean or cowpea or groundnut.
2. Groundnut + Sunflower.
Cotton + soybean, cotton + Black gram
Safflower + gram
How intercropping economizes water use:
Selection of intercrop is one the basis of duration of crop and growth rethyms. The short duration crop gets harvested and long duration crop gets the benefits of September showers and produces more yields. E.g. Pearl millet + red grams.
LER: It is observed that under the rainfall situation deviating from 2090 to 50 percent, the intercropping system of bajara + red gram is more stable as cowpea to the pure crops tried. On an average, the land equivalent ratio (LER) comes to 77 percent compared to pure crop.
Alternate Land Use Like Agro Forestry Horticulture
Pasture, Diversified Farming Systems In Rainfed Agriculture
Introduction : Crop production on dry lands in general and marginal rained lands in particular results in low and unstable and often times in low and unstable, and often times, uneconomic yields, Marginal lands because of poor management are often subjected to the processes of degradation. It is estimated that nearly 70 m hectare out of a total 100 m ha under Rainfed cultivation are facing some kind of land degradation or the other. These marginal lands are not able to sustain arable crops particularly during the drought years. The Govt. of India is deeply concerned about the improvement of degraded / marginal lands. We have, therefore to think of developing some alternate land use systems for these lands.
The alternate land use systems are surer means of stabilizing both productivity of dryland and incomes of dryland farmers, besides generating more complement potential.
Day by day demand for food fodder and fuel is growing, which could be solved by selecting suitable land use system. One of the areas of research for Rainfed agriculture is improvement of degraded, marginal and sub - marginal lands by introduction of suitable. Alternate Land Use systems like alley cropping lay farming tree farming, dryland horticulture etc. Alternate land use systems not only help in generating much needed off season employment in monocropped dryland but also minimize risk tallies off - season rains which may otherwise go waste as runoff prevent degradation of soils and restore balance in the ecosystem.
Alley – Cropping And Its Advantages
Alley cropping is a system in which food crops are grown in alleys formed by hedge rows of trees or shrubs.
The essential feature of the system is that hedge rows are cut back at planting and kept pruned during cropping to prevent shading and to reduce competition with food crops.
Advantages:
1. It provides higher total biomass per unit area than arable crops alone.
2. It utilizes off - season precipitation which otherwise would go waste,.
3. It provides green fodder during the lean period of fodder availability.
4. It provides additional employment opportunities during the off season.
5. When planted along the contours on a sloppy land, it provides a barrier to run off water holds the silt and conserves moisture. Or
Alley cropping is a farming system in which arable crops are grown in alleys formed by trees or shrubs established mainly to hasten soil fertility restoration and enhance soil productivity.
Objectives of Alley - cropping:
The main objective of alley cropping is to get green and palatable fodder from hedge rows in the dry season and produce reasonable quantum of grain and Stover in the alleys during the rainy / cropping season.
Alley - cropping - a version of agro - forestry system, could meet the multiple requirements of food, fodder, fuel and fertilizers etc.
Three Versions (Types) of Alley cropping:
Three versions of alley cropping system, based on different objectives are.
1. Forage alley cropping.
2. Forage - cum - mulch alley cropping
3. Forage - cum - pole alley cropping
In all the three systems crops are grown in the alleys and forage is obtained from lopping of hedge rows. Two components from an essential part of the system these are at the hedge rows b) the crop grown in the alley.
Need - Based Alternate Land use System And Its Advantages
1. Among the several needs of a farmer Food always remains the first priority item, although fodder requirement is more as compared to food. Some of the need - based alternate land use systems matching the land. Capability classes are discussed below Alternate land use systems.
Sr.No.
Food (Arable Land)
II and III
Fodder
(Non - arable land)
IV and V
Fuel / Timber / Fiber
(Marginal degraded land)
VI and VII
1.
Alley cropping
Agro horticulture
Horti - pastoral silvi
pastoral
Tree farming Timber
cumfibre (TIMFIB)
2.
Agro - horticulture
Silvi - pastoral
3.
Intercropping with NFTs
Ley farming
Pasture management
2. Ley Farming: a rotation of arable crops requiring annual cultivation and artificial pasture occupying field for two years or longer.
3. A rotation is a cropping system in which two or more crops are grown in a fixed sequence. If the rotation includes a period of pasture (a lay) which is used for grazing and conservation the system is sometimes called "Alternate husbandry" or mixed farming. The term Ley - farming denotes a system where a farm or a group of fields is cropped entirely with leys which are reseeded at regular intervals some people described any cropping system which includes leys as "Lay Farming".
Types of Ley Farming:
1. Unregulated ley systems :
These are characterized by natural fallow vegetation of various grass species a certain amount of bust growth on the pasture, community grazing and lack of pasture management all of which make such systems often more short term fallow systems.
2. Regulated ley system:
Individual grazing fencing pasture management and rotational use of the grassland are the usuall characteristics of regulated ley system.
Advantages of Ley Farming:
1. It helps in soil conservation, improvement in structure and fertility. It acts as a self fertility regentrating system especially with respect to nitrogen.
2. With lay farming system the other important requirement I the farmer i.e. fodder for his cattle in addition to his food is easily met.
3. For rained farming it is a low risk system as they need not invest on the costly fertilizer input for the food grain crops but by the pasture legume.
4. Labour economy during the years under ley is yet another advantage. Some of the weeds which will be vigorous during the arable cropping years would be suppressed and eliminated and as such the weeding requirements of the crop would be reduced.
5. No tillage during the ley years would have other advantages like no compaction due to farm machinery more of earthworm and soil microbial activity. It will also have the other benefits like better soil sanitation less hibernation of pests and diseases of the crop plants.
Example of ley farming:
If a farmer has say 4 hectares land in which he want to grow sorghum and caston then he can plan four year rotation as follows.
Unit
Year 1
Year 2
Year 3
Year 4
A
Stylo
Stylo
Sorghum
Castor
B
Stylo
Sorghum
Castor
Stylo
C
Sorghum
Castor
Stylo
Stylo
D
Castor
Stylo
Stylo
Sorghum
Three Alternate Land Use In Dryland Ecosystems
Consistent with the policy of conservation and desirability of preserving the integrity of the ecosystem, the alternate land use systems could be classified into
i) agro forestry
ii) pastoralism and
iii) tourism which includes wild life.
Agro forestry systems of land use:
Agro forestry is a collective term for a land use system in which woody perennials (trees and / or shrubs) are eliberately mixed on the same land management unit as crop and / or animals either in some forms of spatial arrangement or in time sequence. An ideal agro forestry system should result in a sustainable increase in overall production using management practices compatible with social cultural and economic of the local population.
In agro forestry land use systems, there are three basic sets of elements of components that are managed by man viz. tree, the herb (agricultural crops including pasture species) and the animal. This leads to a simple classification of agro forestry systems as given below.
Agri silvi cultural - Crops and trees including shrubs / vines / tress.
Silvi pastorl - Pastures / animals and trees.
Agro silvopastoral - Crops / pastures / animals / trees
Agrihorticulture - Crops / fruits species
Silvi - horticulture - Trees / fruit species
Silvi Horti pastoral - Trees / fruit species / animal / pastures.
Agri Silvi system:
Agri silvi cultural system could be practiced in areas where wood lands can be created. The planting consists of both annual crops and perennial trees. This type of approach is most commonly observed in the cultivated areas. The perennial tree species are planted in a single row or multiple of rows in a strip at a interspaces distance of 15 - 40 m between two strips. The interspaces are utilized for growing annual / seasonal crops. The preference of choice for tree selection may lie in Acacia spp. Azadirachta indica, Dalbergia sissoo; Eucalyptus spp; Casuarinas spp; Albizzia spp; and Leucaena leucocephala, prosopis spp and caliandra spp. Growing of perennial tree species on bunds / strips may also act as wind breaks in areas where high wind velocity is a problem resulting in wind erosion and desiccation of soil moisture. Certain tree species offer the possibility of providing at least a portion of optimum crop nutrients by natural leaf drop or by lopping for purposes of green leaf manuring. This includes both fixed nitrogen as well as other nutrients recycled from the deeper soil depth. This is especially true with Acacia albida which when matures (after 3 years) is said to be deciduous in the Kharif season. As such it offers less competition for light and moisture at the time when crops need them most.
In India agriculture and forestry have co - existed for many years in close proximity. Agro - forestry systems of land use are not new to our rich heritage. Farmers from time immemorial have been growing useful tree species with agricultural crops which used to supply fodder, fuel and small timber for himself and his live stock. The best examples available are ; growing of Prosopis cineraria (Khajri) with agricultural crops in Rajasthan and in black soils of Northern Karnataka and the other parts of the country. The other practices then prevailing where growing of perennial tree species such as Acacia’s neem mango tamarind on farm boundaries.
Agro forestry offers a good scope for more efficient use of land; water, other natural and human resources. The main advantages of this system would be:
i) Progressive land improvement by providing vegetation cover and brief to bring about soil and water conservation and production of organic material for enrichment of soil.
ii) Recycling of plant nutrients is possible due to roots of perennial tree species penetrating deep into the soil and absorbing the plant nutrients and depositing on the soil surface through leaf litter.
iii) Perennial tree species are photosysnthetically active through out the year and hence produce large quantities of biomass.
iv) Legumes plants may provide for fixation of atmospheric nitrogen and thereby enrich the site conditions and
v) Provide employment opportunities to the people.
Structural basis of classification of agro forestry systems:
Structure of the system can be defined in terms its components (constituents) and the expected roles (functions) of each (manifested in terms of outputs). It is not only the nature of components that is important but also their arrangement.
Silvi - Horti / agro - Horti system:
The concept of silvi - Horti / agro - Horti or combination of agricultural crops, perennial tree and fruit species could profitably be adopted in both arable and non arable marginal and sub - marginal lands.
Semi wild but useful fruit species such as cashew, Ber, annonaceas fruit species, Chiranji, phalsa carrisa, mango, sapota, guava, tamarind and jack fruit trees are planted in regular strips or inter planted with silvi component. In areas receiving higher rainfall of 1000 m and above coconut can be planted as in being practiced in coastal Karnataka and Kerala. In the agro Horti - silvi system of land use the distance between the two horticultural plants within the strip may be quite apart to avoid competition. The inters trip space between the two horticultural plants can be used for planting fast growing economic silvi - cultural species such as leucaena casuarinas, Dalbergia teak and albizza. The tree plants are cut for wood after 4 - 6 years so that the competion could be minimized. The idea behind planting tree species as an intercrop with horticultural plants is to obtain biomass production before horticultural plants attain full growth, and later to obtain fodder or green manure material by frequent cutting and create thicker vegetation for better soil dwater conservation.
Many plant species of different heights and architecture, planted in an orderly manner form a multi stored and close cover vegetation with different biological cycles in agro - Horti / agro - Horti - silvi system. In coconut and areca nut plantations other perennial or semi perennial and / or annual crops like tapioca, elephant foot yam, dioscrea, turmeric, ginger, colocasia, sweet potato, groundnut, vegetables and pulses, pineapple, bana, papaya can possible by grown. High density multi species systems are capable of generating high biomass; high income and can meet various needs of the farmer.
Silvi pastoral system of land use:
The fodder requirement for the growing cattle population in the country by 2000 - AD is expected to be around 700 mit against the present supply of 540 m.t. The gap will be of the order of 250 m.t. and to meet this demand the country will require 10 m ha of additional area. To achieve this every demanding increase of fodder the area under soil erosion problems, marginal and sub marginal lands waste lands village grazing areas need to planted with suitable forage species or in combination with economic perennial tree species preferably tree species yielding fodder.
In such land use systems, ideal species of woody perennials should be fast growing, hardy, with wide ecological aptitude, tight crown with multilayer branching and leaf orientation and of multiple use to the rural population. The forage component need to be very hard, easily colonising, palatable, nutritious and with strong establishment through roots or self sown seeds. For arid and semiarid areas species like Acacia tortillas. Albizzia amara, Hardiwickia binata, ledcaena leucocephala with Cenchrus ciliaris, Cenchrus setigerus, Dichanthium annufatum chresopogon fulvus sehima nervosum etc find greater adaptability. Legume species such as stylosanthes spp., have been found very versatile. On difficult sites Desmodium, Alcidcarpus and sesbania would promise as primary colonisers. Tourism and wild life system of land use.
Tourism as a means of expoiting and developing the potential of arid and semiarid areas needs careful consideration. The wildlife fauna of the arid region is unique resource and need attention for their conservation. It would help to develop more and more desert parks which attract the tourism and provide employment opportunities.
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