India is one of the major agricultural countries with more than 65% of the population depending on agriculture. Indian agriculture is dependent on monsoon which is not uniform over the years. Nearly three fourth of the cultivable land in India is dependent on monsoon. According to estimates of 2008 the agriculture sector contributed 17.2% of India’s GDP and providing employment to around 58.2% of the work force.
The productivity of any crop mainly depends on two natural resources- land and water in addition to management practices. Therefore the conservation, up gradation and utilization of these two natural resources on scientific principles is essential for the sustainability of rainfed agriculture. The watershed concept for development of rainfed agriculture is gaining importance over the years and it amply demonstrated that watershed developmental tools are very effective in meeting the objectives and mission.
Soil loss apart from removing fertile top soil, reduce the rooting depth and adversely affect moisture storage and thereby the crop yields. The large quantity of eroded soil deposited in tanks, reservoirs, streams and river beds,reduce their storage and carrying capacities. Soil erosion depends on various factors like rainfall, soil type, vegetation and land use. Mechanical as well as vegetative measures are used for soil and water conservation.
Soil and Water Conservation Activities
Arable Land Treatment
Non Arable Land Treatment
Drainage Line Treatment
1. Contour Bunds
2. Waste Weir
3. Boulder Waste Weir
4. Trench cum Bund
5. Boulder Bund
6. Farm Pond
7. Water ways
8. Zing Terracing
9. Recharging of failed wells/Borewells
10. Vegetative Bund
11. Land Levelling
12. Graded Bund
13. Shallow Well
14. Reclamation of Problematic Soils
15. Bench terrace
16. Conservation Ditch
17. Contour Bund Strips
1. Diversion Channel
2. Recharge Pond
3. Staggered Contour Trench
4. Contour Trench
5. Graded Trench
7. Vegetative Filter strips
I. Upper Reach Treatment
1. Sod Strip
2. Sodded Earthen check
3. Shrub Check
4. Boulder Check
5. Rubble Check
7. Sunken Pond
9. Mini percolation Tank
10. Water Recharge Pit
II. Middle Reach Treatment
1. Dugout Pond
2. Loose Rock Ravine Reclamation Structure (LRRS)
3. Ravine Reclamation Structure (RRS)
4. Sand Bag Check
III. Lower Reach Treatment
1. Nala Bund
2. Check Dam
3. Percolation Tank
4. Vented Dam
5. Underground Dykes
6. Nala Revetment
Land Management Practices
These are trapezoidal earthen or loose-boulder embankments constructed on contour. These bunds intercept runoff and hold the water for subsequent absorption and there by conserve soil and moisture.
Waste weirs are normally provided by using loose stones properly embedded in soil to avoid scouring / under cutting and to drain the excess water accumulated against bund.
It is a newly evolved bunding type, where in the earthen embankments constructed with a 5 mtr length x 1 mtr width x 0.6 mtr depth trenches & by leaving 0.6 mtr berm in between each trenches. More runoff water can be stored, there by more water is infiltrates into the soil and provides moisture for more periods to the development of vegetation.
These are the earthen embankments constructed along the boundary lines of the individual farmers plot to conserve the soil and moisture in his plot itself
Contour strip formed in the areas where rainfall is less, gentle slope with less infiltration. This is to increase the moisture infiltration rate. Within the two contour strips small size bunds with bund former are also made.
This is a bund across the slope constructed by using locally available stones / boulders in the sand mixed soils and in the shallow soils. This is an alternative to the contour bund, when enough soil is not there to form bunds.
These are trapezoidal earthen embankments constructed on grade across the major slope. These bunds are taken up in areas receiving annual rainfall of more than 750 mm, where runoff is high & surplusing is essential.
Vegetative bund/ Vegetative check :
A live vegetative barrier on the contours is made which will decrease the velocity of rain water in turn soil erosion is controlled. These checks could also be formed in between the contour bunds.
Water ways :
These are formed along the slope for safe disposal of excess rain water from cultivable areas to nalas. Grass is also grown in the water ways to avoid further scoring.
Farm ponds are opened across the water ways by digging the soil. The excess rain water is harvested and the harvested water is used for various activities like giving protective irrigation to vegetables & orchards including drinking water to animals and birds.
INTERBUND MANAGEMENT PRACTICES
- Fall ploughing after each harvest.
- Land smoothening to avoid local stagnation
- Vegetative barriers - Khus/Subabul/Dicanthium Sp. across slope at 10 to15m interval
- Deep tillage
- Adoption of ridges and furrows, Beds across slope
- Small bund (0.18 sq. m) or (0.09 Sq.m) at 10m / 15m interval across slope
- Vertical mulching
Treatment of non-arable land has been inevitable to reduce the runoff and to create water storage at field level. They help to distribute moisture uniformly on sloping land so that natural vegetation grows successfully and restores the bio-diversity.
Contour Trench / 'V' ditches:
These are trenches / V-ditches dug on contour in non-arable lands of more than 3% slope to hold run off for conservation and reducing erosion. They are established for development of trees and grass species and are adoptable in areas with annual rainfall of up to 950 mm.
Pits with Crescent - shaped bunds:
These consists of staggered rows of pits with crescent-shaped bunds for planting trees and are adoptable in non-arable lands having less than 3% slope in areas with annual rainfall of less than 950 mm.
These are large pits dug at rill points and in waterways to trap runoff water. They are adoptable in hilly lands with rock outcrops.
Continued contour trenches:
Trenches are opened at a distance of 5 to 10 meters with 0.45 meter depth and 0.6 meters width in the areas where annual rainfall is less than 750 mm. The rain water is collected in the trenches and then the plants could be planted.
Staggered contour trenches:
These are opened where there is undue soil slope with humps.
Graded contour trenches:
These trenches are made in the black soil areas where rainfall is more than 750 mm, for safe disposal of excess water and forest plants are planted.
Vegetative filter strips:
These are made to reduce the velocity of rain water coming from hills, forest area across the slope at intercepting areas where cultivable and uncultivable areas joins. Once the vegetative strips are grown fully it will act as a barrier to check the flow of water from slopes and soil erosion is controlled. The locally available Agaves, lavancha, Jatropia, Pongamiaetc could be used as veg checks.
Water recharge pit:
The pit is opened in the uncultivable area in the direction of diversion channels / water ways or nearby areas where there is flat lands. Dry stone pitching on the three sides of upstream side also be done.
Diversion channel is formed to avoid the rain water that flows form pasture lands, hills areas, and forest areas into t he cultivable area. A drain across the slope is opened for safe disposal of water.
1. Upper reaches treatment
Sod-forming grasses like Cynodon dactylon, Digitaria & Dicanthium are planted. In some cases trees and shrubs such as Ipomoea cornea, Vitex nigundo, Agave, Saccharum munja & bamboo are also recommended.
Vegetative filter strips:
These are made to reduce the velocity of rain water coming from hills, forest area across the slope at intercepting areas where cultivable and uncultivable areas joins. Once the vegetative strips are grown fully it will act as a barrier to check the flow of water from slopes and soil erosion is controlled. The different types of filter strips are sod strips, sodded earthen strips & shrub checks. The locally available Agaves, lavancha, Jatropia, Pongamiaetc could be used as vegetative checks.
These are porous checks across the nala constructed using boulders to check water velocity and to arrest silt.
Rubble check is constructed where the gully width is upto 10 meter and depth is 1 to 3 meters with a vertical interval of 2-2.5 meters. The catchments area considered is from 8 to 15 hectares. This should also serve to control soil erosion and silt flow. Agaves row could also be planted on up stream and down stream side at a distance of 0.3 meters.
Brush wood checks:
These are porous checks constructed across the gully with wooden pegs and brush wood and are adoptable in all areas.
These are dams made of wire-woven baskets filled with stones placed in trench of suitable size across steep-sloped gullies to trap erosion debris during rains. They are adoptable in all areas of high slopes and high rainfall.
Water recharge pit:
Pit is opened in the soils where there is less water infiltration rate. The pit is opened in the gentle slope nalas / gullies where the upper reaches are already treated and so there is less scope of siltation. These should be opened preferably adjacent to open / bore wells.
2. Middle reaches treatment:
Dry stone checks/ Rock filled dam:
These structures are constructed where there is no necessity of impounding more water and to avoid further scoring. There are constructed at the points where gullies join and gullies of serious nature. The availability of stones should be within 40kms distance.
Small sunken ponds:
The rain water that would have flown in gullies will be sorted so that the moisture percentage around the cropped area is increased. The excavated soil is put as bund so that water storage is increased.
Ravine Reclamation structure (RRS):
RRS is a masonry structure consisting of a body wall, apron and header. The banks are protected by stone revetment to further scouring. They are constructed to control head movement of gullies, avoid further widening and deepening ravine. Reduce sedimentation of tanks/reservoirs to provide protective irrigation, drinking water for the cattle and wild life, increase moisture regime and recharge underground waier table. They are constructed in ravines with depth of 2.5 to 3.5m width 8 to 15m and catchment area 15 - 25ha
3. Lower reaches treatment:
These are stone masonry structures constructed across deep nala with the objective of controlling runoff water, reducing sedimentation of tanks/ reservoirs, providing protective irrigation, drinking water for the cattle and wild life & to recharge underground water table.
Vented dam: Cement
Missionary work taken up in the high rainfall area. The vents are provided to allow the water flow during the rainy season and store water after the decrease in rainfall. Wooden Flanks are provided to close the vents. The stored water is used for irrigation.
This structure consists of homogenous earthen embankment constructed across the nalas / valleys in arable & non arable lands to store run-off for recharging ground water & make water available for social & agricultural use at surface level.
This is also Nala bund but with stone, cement masonary out let to drain the excess water. This is opted where there is less scope for cut-out let.