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SOIL MOISTURE CONSERVATION

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RamnathPotai

This document discusses various techniques for soil moisture conservation. It explains that soil moisture conservation aims to minimize water loss from soil through evaporation and transpiration. It then discusses different agronomic measures like conservation tillage, deep tillage, contour farming, mulching, crop rotation, and use of cover crops and anti-transpirants to conserve soil moisture. The document also discusses mechanical measures like bunding, terracing, trenching etc. that are used for soil moisture conservation, especially on lands with slopes greater than 2%.

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Soil moisture conservation Presented by Ramnath Potai Ph. D Scholar Dept. of Agronomy COLLEGE OF AGRICULTURE , RAIPUR INDIRA GANDHI KRISHI VISHWAVIDYALAYA, RAIPUR CHHATTISGARH
 Soil moisture conservation is to minimize the amount of water lost from the soils through evaporation (water loss directly from the soil) and transpiration (water loss occurring through the plants) or combined, the evapotranspiration.  Soil is one of the most important water storage in nature.  Water content in the soil is very significant parameter of water regime of the country which significantly depends on soil area and quality of soil. Lower acreage of soil and lower soil quality lead to less water content in the country and vice versa.  Human activities (Agriculture, forest management, soil sealing) are still important factors of water regimes of land. INTRODUCTION 1
 Drought is primarily an agricultural phenomenon that refers to conditions where plants face certain levels of moisture stress that affect both vegetative growth and yield of the crops.  Decrease in rainfall and shortage of surface water and ground water recharge causes depletion in soil moisture.  Changes in such factors develop due to changes in local, regional and global weather and climate. 2
The earth has a limited amount of water. That water keeps going around and around and around and around and (well, you get the idea) in what we call the "Water Cycle". 3
4
Average moisture availability of soils under different textural classes Soil moisture (up to 100cm) Average moisture content (mm) Silt loam Silty clay loam Clay loam clay Available mosture 240 155 152 165 Readly available moisture 135 60 90 80 SRDI 2019 5
Soil moisture characteristic curve  A curve showing relationship between the energy statuses of water i.e. tension and amount of moisture in soil.  A Soil water characteristic curve describes the amount of water retained in a soil under equilibrium at a given matric potential  Sandy soil = L shaped  Clay soil = I shaped (almost a strainght line) 6
Soil Moisture depletion  Soil moisture depletion is the amount of water required to raise the soil water content of the crop root zone to field capacity. D= FC-PWP X D.Db Where D = Depletion FC = Field capacity PWP = Permanent wilting point D = Depth Dp = Bulk density 7
Ground water Scenario of Chhattisgarh 8 Annual replenishable ground water 14.93 BCM Net Annual ground water availability 13.68 BCM Annual ground water draft 2.80 BCM Artificial Recharge to ground water 258 MCM CGWB 2021
Techniques of soil moisture conservation The principle behind the recommendation of different practices is to increase the infiltration by reducing the rate of runoff, temporarily. Agronomic measures Mechanical/Engineering measures 9
Agronomic measures are adopted Where land slope is <2 percent, which are followings Conservation Tillage Deep tillage Contour farming Mulching Growing of cover crops Strip cropping Crop rotation Anti-transpirants 10
Conservation tillage  This umbrella term can include reduced tillage, minimum tillage, no-till, direct drill, mulch tillage, trash farming, strip tillage, plough-plant.  The principles are equally effective in any conditions - to maximize cover by returning crop residues and not inverting the top soil, and by using a high crop density of vigorous crops.  Conservation tillage also has the advantage of reducing the need for terraces or other permanent structures. Advantages - Control of soil erosion - Water holding capacity of soil increases - Availability of nutrient increases 11
Deep tillage  One of the reasons for low yields in semi-arid areas is the limited amount of moisture available to crop roots. The available moisture will be increased if the rooting depth is increased and it has been shown that in some cases deep tillage can help, for example on the dense sandy soils.  Deep tillage is beneficial for some crops but not all, and on some soils but not all. It requires greater draught power which is usually in short supply in semi-arid areas.  Ripping or sub soiling can be beneficial, either to increase the porosity of the soil, or to break a pan which is reducing permeability. 12
Strip cropping  Strip cropping is the system of growing alternate strips of erosion permitting crops (row crop such as maize, jowar, bajra, cotton etc) and erosion resisting crops (close growing crops such as green gram, black gram, moth, groundnut etc.) in the same field. This practice reduces the velocity of runoff and checks the eroded soil from being washed away. 13
 Strip cropping is essentially for controlling the run-off erosion and there by maintaining the fertility of the soil is now universally recognized. Strip cropping, in effect, employs several good farming practices, including crop rotation, contour cultivation, proper tillage stubble mulching, cover cropping, etc. Strip cropping is of the following different forms:  Contour strip cropping  Field strip cropping  Wind strip cropping 14
Contour-farming  During intense rain storms, the soil cannot absorb all the rain as it falls. The excess water flows down the slope under the influence of gravity.  A simple practice of farming across the slope, keeping the same level, as far as possible is technically called contour- farming.  Contour-farming reduces run-off and prevents soil erosion as Compared with the up and down cultivation in the major groups of soils in India, viz. Alluvial soils, black soils and deep lateritic soils. 15
MULCHING  Any material used (spread) at surface or vertically in soil to assist soil and water conservation and soil productivity is called mulch. And process of applying mulches to soil is known as mulching.  Mulching helps in conserving moisture, lowering soil temperatures around plant roots, reducing weed growth, etc thus helps crops during moisture stress conditions. 16
Types of mulches 1.Plastic 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. Examples-Polythene, polyvinyl 17
2.Crop residues or stubble mulch: Crop residues and other plant waste products 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. Mulch tinge is a practice where at least 30% of the soil surface remains covered with crop residues after tillage. Examples- Straw, cloves, leaves. 18
3. Saw dust mulch: Mulching with sawdust is a common practice. Sawdust is acidic, making it a good mulch choice for acid-loving plants. They have high water absorption capacity. 19
4.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. Inter-culturing creates soil mulch in growing crops and helps in closing deep cracks in vertisols. 20
5. Vertical mulch 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. 21
Growing of cover crops  Cover crops can increase soil moisture by as mulching as 10 percent  Cover crop can uptake excessive water after winter rainfall, enhance water infiltration (as well as soil aeration) with their root, and retain moisture for the subsequent cash crop. 22
Crop rotation Growing different types of crops every season helps improve soil structure and thus water holding capacity. Examples include rotating deep-rooted and shallow rooted crops that make use of previously unused soil moisture, as plants draw water from different depth levels within the soil. Crop rotation may also improve soil fertility and help control pests and diseases. 23
Anti-transpirants  Anti-transpirants are the materials or chemicals that applied to transpiring plant surfaces for reducing water loss from the plant. The purpose of ATS is to maintain the growth and productivity under stress conditions and it is never recommended for high productivity / unit area.  The severity of intermittent drought of 6-10 days during critical stages of the crop can reasonably be avoided by the use of anti transpirants and thus crops can be save ❖ Mainly four types of anti-transpirants: 1. Stomatal closing type 2. Film forming type 3. Reflectance type 4. Growth retardant 24
1.Stomatal closing type: Most of the transpiration occur through the stomata on the leaf surface. They induce stomatal closing or decrease size and number of stomata which subsequently reduce the photosynthesis. Examples: Phenyl Mercuric Acetate (PMA), Atrazine 2.Film forming type: Waxy material which form a thin colour less film over the leaf surface and result in a physical barrier. These glossy films then reduce water loss on plants while at the same time allow them to breathe normally. Examples: Hexadecanol, Cetyl alcohol, Methanol. 25
3.Reflecting 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. Examples: Kaoline(5%), Calcium bicarbonate, Lime water 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. Examples: cycocel 26
Mechanical /Engineering measures. Mechanical/Engineering measures are construction of mechanical barriers across the direction of the flow of water to retain the runoff for reducing soil and water loss. They are generally adopted where land slope is >2 per cent and to supplement the agronomical practices When the later alone are not adequately effective. These measures include: 1. Bunding 2. Terracing 3. Trenching 4. Sub soiling 5. Check dam 6. Ridges and furrows 7. Broad bed furrows (BBF) 8. Dead furrows: 27
BUNDING Bund is an earthen embankment constructed to control runoff and minimize soil erosion by reducing the length of slope. Contour Bunding  Contour bunding is most popular mechanical measure to control soil erosion and conserve moisture in arid and semi- arid areas with high infiltration and permeability.  This practice consists in making a comparatively narrow- based embankment at intervals across the slope of the land on a level that is along the contour.  It is commonly adopted on agricultural land up to a slope of about 6 per cent and in areas where average annual rainfall is < 600 mm 28
Graded Bunding  In graded bunding water flows in graded channels constructed on up-stream side of bunds and leads to safe outlet on grassed water ways.  Graded bunds may be narrow-based or broad-based. A broad-based graded terrace consists of a wide-low embankment constructed on the lower edge of the channel from which the soil is excavated. The channel is excavated at suitable intervals on a falling contour with a suitable longitudinal grade. It is adopted at about 2-10 per cent land slope and in areas where average annual rainfall is > 600 mm. 29
Compartmental bunding:  Small bunds of 15 cm width and 15 cm height are formed in both directions to divide the field into small basins or compartments of square or rectangular shape of 6 x 6 m to 10 x 10 m size using bund former  They are useful for temporary impounding of rain water which facilitates high infiltration resulting in high moisture storage in the soil. Recommended for black soils with a slope of 0.5 to 1%. Maize sunflower sorghum perform well in this type of bunding 30
Grass waterways  Grass waterways are natural or constructed watercourses covered with erosion resistant grasses and are used to dispose surface water from the crop land. They are constructed along the slope of the land.  Grassed waterways are associated with channel terraces for the safe disposal of concentrated runoff, thereby protecting the land against rills and gullies.  The suitability of a grass was based on the cover it gave, the ease with which it was established and the forage yield obtained from it.  Panicum repens was the best suited grass, followed by Brachiara mutica, Cynodon dactylon and Paspalum notatum. 13
2) TERRACING A terracing is a combination of ridge and channels built across the slope. This is generally practiced in steep hill slope. (a) Bench Terracing: Bench terrace consists of construction of step like fields along the contour by half cutting and half filling. Original slope of the land is converted into level fields and thus all hazards of erosion are eliminated. (b)The vertical drop may vary from 60 to 180 cm, depending upon the slope and soil conditions, as also on the economic width required for easy cultural operations. 32
 The material excavated from the upper part of the terrace is used in filling the lower part.  A small shoulder bund of about 30 cm in height is also constructed along the outer edge of the terrace.  It is generally practiced on steep sloping (16-33 per cent) and undulated land.  Bench terraces may be table top or sloping outward or inward with or without a slight longitudinal grade, according to the rainfall of the tract - medium, poor or heavy, and the soil and the subsoil are fairly absorptive or poorly permeable 33
3) TRENCHING Trenching is made along the contour for soil & moisture conservation and afforestation purpose.  The size of trenches - 60cm x 48cm  Spacing between trenches-10-30 meter  Trenches are half refilled with excavated materials and remaining half of the soil forms the spoil bank.  The remaining water in the trenches help in conserving the moisture and provides benefits for sowing and planting. 34
4) SUBSOILING  This method consists of breaking the hard and impermeable subsoil with a sub soiler to conserve more rainwater by improving the physical conditions of a soil.  This operation, which does not involve soil inversion and promotes greater moisture penetration into the soil, reduces both run-off and soil erosion.  The subsoiler is worked through the soil at a depth of 30-60 cm at a spacing of 90-180 cm. Sub soling by tractor drawn chisel plough at 2 m horizontal interval is the most effective insitu soil and water conservation practice for early establishment and improving the pasture. 35
5) CHECK DAM  A low weir normally constructed across the gullies.  Constructed on small streams and long gullies formed by erosive activity of flood water.  It cuts the velocity and reduces erosive activity.  The stored water improves soil moisture of the adjoining area and allows percolation to recharge the aquifers. Spacing between the check dams water spread of one should be beyond the water spread of the other.  Height depends on the bank height, varies from a 1 meter to 3 meter and length varies from less than 3m to 10m. 36
6) Ridges and furrows:  The field must be formed into ridges and furrows. Furrows of 30-45 cm width and 15-20 cm height are formed across the slope. The furrows guide runoff water safely when rainfall intensity is high and avoid water stagnation. They collect and store water when rainfall intensity is less.  It is suitable for medium deep to deep black soils and deep red soils. It can be practiced in wide row spaced crops like cotton, maize, chillies, tomato etc. 37
(7) Broad bed furrows (BBF)  This practice has been recommended by ICRISAT for vertisols or black soils in high rainfall areas (> 750 mm). Here beds of 90-120cm width, 15 cm height and convenient length are formed, separated by furrows of 60 cm width and 15 cm depth.  When runoff occurs, its velocity will be reduced by beds and infiltration opportunity time is increased. The furrows have a gradient of 0.6%. Crops are sown on the broad beds and excess water is drained through number of small furrows which may be connected to farm ponds. 38
To encourage moisture storage in the soil profile .Deep vertisols may have soil moisture storage up to 250 mm , which is sufficient to support plants mid- season or late- season spells of drought. 39
(8) Dead furrows: At the time of sowing or immediately after sowing, deep furrows of 20 cm depth are formed at intervals of 6 to 8 rows of crops. No crop is raised in the furrow. The dead furrows can also be formed between two rows of the crop, before the start of heavy rains (Sep-Oct). It can be done with wooden plough mostly in red soils. The dead furrows increase the infiltration opportunity time. 40
- Soil moisture conservation depending on the material used, may also include better control of weeds, provision of additional nutrients to the soil, soil temperature control and protection of soil surface from the impacts of heavy rain and wind. - Active reuse of waste organic materials also reduces waste management needs, returning the residue crops and plants to the soil through decomposition. Socio economic Benefits. - Potential to reduce water irrigation needs, increase crop productivity and improve soil quality. - By extension, reduced irrigation needs may also reduce the costs and energy requirements of water pumping for irrigation. Conclusion 41
Thank you

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SOIL MOISTURE CONSERVATION

  • 1. Soil moisture conservation Presented by Ramnath Potai Ph. D Scholar Dept. of Agronomy COLLEGE OF AGRICULTURE , RAIPUR INDIRA GANDHI KRISHI VISHWAVIDYALAYA, RAIPUR CHHATTISGARH
  • 2.  Soil moisture conservation is to minimize the amount of water lost from the soils through evaporation (water loss directly from the soil) and transpiration (water loss occurring through the plants) or combined, the evapotranspiration.  Soil is one of the most important water storage in nature.  Water content in the soil is very significant parameter of water regime of the country which significantly depends on soil area and quality of soil. Lower acreage of soil and lower soil quality lead to less water content in the country and vice versa.  Human activities (Agriculture, forest management, soil sealing) are still important factors of water regimes of land. INTRODUCTION 1
  • 3.  Drought is primarily an agricultural phenomenon that refers to conditions where plants face certain levels of moisture stress that affect both vegetative growth and yield of the crops.  Decrease in rainfall and shortage of surface water and ground water recharge causes depletion in soil moisture.  Changes in such factors develop due to changes in local, regional and global weather and climate. 2
  • 4. The earth has a limited amount of water. That water keeps going around and around and around and around and (well, you get the idea) in what we call the "Water Cycle". 3
  • 5. 4
  • 6. Average moisture availability of soils under different textural classes Soil moisture (up to 100cm) Average moisture content (mm) Silt loam Silty clay loam Clay loam clay Available mosture 240 155 152 165 Readly available moisture 135 60 90 80 SRDI 2019 5
  • 7. Soil moisture characteristic curve  A curve showing relationship between the energy statuses of water i.e. tension and amount of moisture in soil.  A Soil water characteristic curve describes the amount of water retained in a soil under equilibrium at a given matric potential  Sandy soil = L shaped  Clay soil = I shaped (almost a strainght line) 6
  • 8. Soil Moisture depletion  Soil moisture depletion is the amount of water required to raise the soil water content of the crop root zone to field capacity. D= FC-PWP X D.Db Where D = Depletion FC = Field capacity PWP = Permanent wilting point D = Depth Dp = Bulk density 7
  • 9. Ground water Scenario of Chhattisgarh 8 Annual replenishable ground water 14.93 BCM Net Annual ground water availability 13.68 BCM Annual ground water draft 2.80 BCM Artificial Recharge to ground water 258 MCM CGWB 2021
  • 10. Techniques of soil moisture conservation The principle behind the recommendation of different practices is to increase the infiltration by reducing the rate of runoff, temporarily. Agronomic measures Mechanical/Engineering measures 9
  • 11. Agronomic measures are adopted Where land slope is <2 percent, which are followings Conservation Tillage Deep tillage Contour farming Mulching Growing of cover crops Strip cropping Crop rotation Anti-transpirants 10
  • 12. Conservation tillage  This umbrella term can include reduced tillage, minimum tillage, no-till, direct drill, mulch tillage, trash farming, strip tillage, plough-plant.  The principles are equally effective in any conditions - to maximize cover by returning crop residues and not inverting the top soil, and by using a high crop density of vigorous crops.  Conservation tillage also has the advantage of reducing the need for terraces or other permanent structures. Advantages - Control of soil erosion - Water holding capacity of soil increases - Availability of nutrient increases 11
  • 13. Deep tillage  One of the reasons for low yields in semi-arid areas is the limited amount of moisture available to crop roots. The available moisture will be increased if the rooting depth is increased and it has been shown that in some cases deep tillage can help, for example on the dense sandy soils.  Deep tillage is beneficial for some crops but not all, and on some soils but not all. It requires greater draught power which is usually in short supply in semi-arid areas.  Ripping or sub soiling can be beneficial, either to increase the porosity of the soil, or to break a pan which is reducing permeability. 12
  • 14. Strip cropping  Strip cropping is the system of growing alternate strips of erosion permitting crops (row crop such as maize, jowar, bajra, cotton etc) and erosion resisting crops (close growing crops such as green gram, black gram, moth, groundnut etc.) in the same field. This practice reduces the velocity of runoff and checks the eroded soil from being washed away. 13
  • 15.  Strip cropping is essentially for controlling the run-off erosion and there by maintaining the fertility of the soil is now universally recognized. Strip cropping, in effect, employs several good farming practices, including crop rotation, contour cultivation, proper tillage stubble mulching, cover cropping, etc. Strip cropping is of the following different forms:  Contour strip cropping  Field strip cropping  Wind strip cropping 14
  • 16. Contour-farming  During intense rain storms, the soil cannot absorb all the rain as it falls. The excess water flows down the slope under the influence of gravity.  A simple practice of farming across the slope, keeping the same level, as far as possible is technically called contour- farming.  Contour-farming reduces run-off and prevents soil erosion as Compared with the up and down cultivation in the major groups of soils in India, viz. Alluvial soils, black soils and deep lateritic soils. 15
  • 17. MULCHING  Any material used (spread) at surface or vertically in soil to assist soil and water conservation and soil productivity is called mulch. And process of applying mulches to soil is known as mulching.  Mulching helps in conserving moisture, lowering soil temperatures around plant roots, reducing weed growth, etc thus helps crops during moisture stress conditions. 16
  • 18. Types of mulches 1.Plastic 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. Examples-Polythene, polyvinyl 17
  • 19. 2.Crop residues or stubble mulch: Crop residues and other plant waste products 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. Mulch tinge is a practice where at least 30% of the soil surface remains covered with crop residues after tillage. Examples- Straw, cloves, leaves. 18
  • 20. 3. Saw dust mulch: Mulching with sawdust is a common practice. Sawdust is acidic, making it a good mulch choice for acid-loving plants. They have high water absorption capacity. 19
  • 21. 4.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. Inter-culturing creates soil mulch in growing crops and helps in closing deep cracks in vertisols. 20
  • 22. 5. Vertical mulch 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. 21
  • 23. Growing of cover crops  Cover crops can increase soil moisture by as mulching as 10 percent  Cover crop can uptake excessive water after winter rainfall, enhance water infiltration (as well as soil aeration) with their root, and retain moisture for the subsequent cash crop. 22
  • 24. Crop rotation Growing different types of crops every season helps improve soil structure and thus water holding capacity. Examples include rotating deep-rooted and shallow rooted crops that make use of previously unused soil moisture, as plants draw water from different depth levels within the soil. Crop rotation may also improve soil fertility and help control pests and diseases. 23
  • 25. Anti-transpirants  Anti-transpirants are the materials or chemicals that applied to transpiring plant surfaces for reducing water loss from the plant. The purpose of ATS is to maintain the growth and productivity under stress conditions and it is never recommended for high productivity / unit area.  The severity of intermittent drought of 6-10 days during critical stages of the crop can reasonably be avoided by the use of anti transpirants and thus crops can be save ❖ Mainly four types of anti-transpirants: 1. Stomatal closing type 2. Film forming type 3. Reflectance type 4. Growth retardant 24
  • 26. 1.Stomatal closing type: Most of the transpiration occur through the stomata on the leaf surface. They induce stomatal closing or decrease size and number of stomata which subsequently reduce the photosynthesis. Examples: Phenyl Mercuric Acetate (PMA), Atrazine 2.Film forming type: Waxy material which form a thin colour less film over the leaf surface and result in a physical barrier. These glossy films then reduce water loss on plants while at the same time allow them to breathe normally. Examples: Hexadecanol, Cetyl alcohol, Methanol. 25
  • 27. 3.Reflecting 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. Examples: Kaoline(5%), Calcium bicarbonate, Lime water 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. Examples: cycocel 26
  • 28. Mechanical /Engineering measures. Mechanical/Engineering measures are construction of mechanical barriers across the direction of the flow of water to retain the runoff for reducing soil and water loss. They are generally adopted where land slope is >2 per cent and to supplement the agronomical practices When the later alone are not adequately effective. These measures include: 1. Bunding 2. Terracing 3. Trenching 4. Sub soiling 5. Check dam 6. Ridges and furrows 7. Broad bed furrows (BBF) 8. Dead furrows: 27
  • 29. BUNDING Bund is an earthen embankment constructed to control runoff and minimize soil erosion by reducing the length of slope. Contour Bunding  Contour bunding is most popular mechanical measure to control soil erosion and conserve moisture in arid and semi- arid areas with high infiltration and permeability.  This practice consists in making a comparatively narrow- based embankment at intervals across the slope of the land on a level that is along the contour.  It is commonly adopted on agricultural land up to a slope of about 6 per cent and in areas where average annual rainfall is < 600 mm 28
  • 30. Graded Bunding  In graded bunding water flows in graded channels constructed on up-stream side of bunds and leads to safe outlet on grassed water ways.  Graded bunds may be narrow-based or broad-based. A broad-based graded terrace consists of a wide-low embankment constructed on the lower edge of the channel from which the soil is excavated. The channel is excavated at suitable intervals on a falling contour with a suitable longitudinal grade. It is adopted at about 2-10 per cent land slope and in areas where average annual rainfall is > 600 mm. 29
  • 31. Compartmental bunding:  Small bunds of 15 cm width and 15 cm height are formed in both directions to divide the field into small basins or compartments of square or rectangular shape of 6 x 6 m to 10 x 10 m size using bund former  They are useful for temporary impounding of rain water which facilitates high infiltration resulting in high moisture storage in the soil. Recommended for black soils with a slope of 0.5 to 1%. Maize sunflower sorghum perform well in this type of bunding 30
  • 32. Grass waterways  Grass waterways are natural or constructed watercourses covered with erosion resistant grasses and are used to dispose surface water from the crop land. They are constructed along the slope of the land.  Grassed waterways are associated with channel terraces for the safe disposal of concentrated runoff, thereby protecting the land against rills and gullies.  The suitability of a grass was based on the cover it gave, the ease with which it was established and the forage yield obtained from it.  Panicum repens was the best suited grass, followed by Brachiara mutica, Cynodon dactylon and Paspalum notatum. 13
  • 33. 2) TERRACING A terracing is a combination of ridge and channels built across the slope. This is generally practiced in steep hill slope. (a) Bench Terracing: Bench terrace consists of construction of step like fields along the contour by half cutting and half filling. Original slope of the land is converted into level fields and thus all hazards of erosion are eliminated. (b)The vertical drop may vary from 60 to 180 cm, depending upon the slope and soil conditions, as also on the economic width required for easy cultural operations. 32
  • 34.  The material excavated from the upper part of the terrace is used in filling the lower part.  A small shoulder bund of about 30 cm in height is also constructed along the outer edge of the terrace.  It is generally practiced on steep sloping (16-33 per cent) and undulated land.  Bench terraces may be table top or sloping outward or inward with or without a slight longitudinal grade, according to the rainfall of the tract - medium, poor or heavy, and the soil and the subsoil are fairly absorptive or poorly permeable 33
  • 35. 3) TRENCHING Trenching is made along the contour for soil & moisture conservation and afforestation purpose.  The size of trenches - 60cm x 48cm  Spacing between trenches-10-30 meter  Trenches are half refilled with excavated materials and remaining half of the soil forms the spoil bank.  The remaining water in the trenches help in conserving the moisture and provides benefits for sowing and planting. 34
  • 36. 4) SUBSOILING  This method consists of breaking the hard and impermeable subsoil with a sub soiler to conserve more rainwater by improving the physical conditions of a soil.  This operation, which does not involve soil inversion and promotes greater moisture penetration into the soil, reduces both run-off and soil erosion.  The subsoiler is worked through the soil at a depth of 30-60 cm at a spacing of 90-180 cm. Sub soling by tractor drawn chisel plough at 2 m horizontal interval is the most effective insitu soil and water conservation practice for early establishment and improving the pasture. 35
  • 37. 5) CHECK DAM  A low weir normally constructed across the gullies.  Constructed on small streams and long gullies formed by erosive activity of flood water.  It cuts the velocity and reduces erosive activity.  The stored water improves soil moisture of the adjoining area and allows percolation to recharge the aquifers. Spacing between the check dams water spread of one should be beyond the water spread of the other.  Height depends on the bank height, varies from a 1 meter to 3 meter and length varies from less than 3m to 10m. 36
  • 38. 6) Ridges and furrows:  The field must be formed into ridges and furrows. Furrows of 30-45 cm width and 15-20 cm height are formed across the slope. The furrows guide runoff water safely when rainfall intensity is high and avoid water stagnation. They collect and store water when rainfall intensity is less.  It is suitable for medium deep to deep black soils and deep red soils. It can be practiced in wide row spaced crops like cotton, maize, chillies, tomato etc. 37
  • 39. (7) Broad bed furrows (BBF)  This practice has been recommended by ICRISAT for vertisols or black soils in high rainfall areas (> 750 mm). Here beds of 90-120cm width, 15 cm height and convenient length are formed, separated by furrows of 60 cm width and 15 cm depth.  When runoff occurs, its velocity will be reduced by beds and infiltration opportunity time is increased. The furrows have a gradient of 0.6%. Crops are sown on the broad beds and excess water is drained through number of small furrows which may be connected to farm ponds. 38
  • 40. To encourage moisture storage in the soil profile .Deep vertisols may have soil moisture storage up to 250 mm , which is sufficient to support plants mid- season or late- season spells of drought. 39
  • 41. (8) Dead furrows: At the time of sowing or immediately after sowing, deep furrows of 20 cm depth are formed at intervals of 6 to 8 rows of crops. No crop is raised in the furrow. The dead furrows can also be formed between two rows of the crop, before the start of heavy rains (Sep-Oct). It can be done with wooden plough mostly in red soils. The dead furrows increase the infiltration opportunity time. 40
  • 42. - Soil moisture conservation depending on the material used, may also include better control of weeds, provision of additional nutrients to the soil, soil temperature control and protection of soil surface from the impacts of heavy rain and wind. - Active reuse of waste organic materials also reduces waste management needs, returning the residue crops and plants to the soil through decomposition. Socio economic Benefits. - Potential to reduce water irrigation needs, increase crop productivity and improve soil quality. - By extension, reduced irrigation needs may also reduce the costs and energy requirements of water pumping for irrigation. Conclusion 41