Water Shed Management – Technology

Along with soil, water is another important factor essential for all life and production. 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 many harms to the soil if proper soil and water conservation methods are followed.

1. Contour bunding

It consists of construction of a series of earthen bunds of suitable sizes along contours at a lateral distance of every 60m or a fall of 1 to 1.5m. The slope of land is thus broken into smaller and more level compartments, which hold soil as well as rain water. The size, cross-section and interbund spacing depend upon the nature of rainfall, soil and slope of the area. The spacing between bunds should not be allowed to exceed 1.5m vertical drop or 67.5m lateral spacing.

Percentage slope	Vertical drop in cm.	Approximate horizontal distance in metres
Upto 1	75	105
1 to 1.5	120	96
1.5 to 2	135	75
2 to 3	150	60

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 7.5cm., per running 33m., to prevent safe disposal of water into the nala.

2. Gully plugging

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.

3. Vegetative bandhara

Mechanical practices like bunding, terracing, gully are costly and also disturb the soil structure. On the other side investing less capital planting of grasses, bushes for stabilizing bunds is very economical as it conserve soil and water and provide pasture for cattle. Vegetative bandhara is nothing but using grasses or vegetation used as bunds. In this technique instead of laying only bund across there is growing vegetation on it and used as vegetative bandhara. For this namely Marvel – 9, Madras anjan, Khas grass and Subabul etc are used. These are sown horizontally across the slope in two rows. Spacing between two rows is 30cm. Between plants spacing is 15 to 20cm and between two vegetative bandhara spacing should be 18 to 22m. Grasses prevent soil erosion and improve soil structure. Soil masses penetrated by countless roots and soil aggregates and particles are enmeshed by the root system. It helps to conserve water in situ. When Subabul is used as vegetative bund it should be cut for forage when it attends 60cm height and cutting up to 30cm from ground level. It is used as green forage as well as green manuring which adds 50kg nitrogen from 60q Subabul. Thus there is saving of chemical fertilizer and by conserving soil and water it helps to increase crop production in water shed area.