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Current Category » Rainfed Agriculture

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.

Current Category » Rainfed Agriculture