ABSTRACT
The physical causes and mechanisms of soil erosion have only been understood for the 50 years out of humankind's 7,000-year-long efforts to grow food crops. To reduce the damage from overland flow, the US Soil Conservation Service developed systems of contour plowing with the organization of surface drainage into grassed channels on a sub-watershed basis. In order to protect the soil from direct assault by raindrops, the farmer achieve a complete crop canopy. In India attempts have been made to allot coefficients for soils, crop cover, and rainfall intensity. The direct action that the subsistence farmer can take to maintain soil structure during the weeks before the crop provides cover is to replace lost organic matter with farmyard manure or compost. A narrow lip or soil bund along the outer edge is a valuable addition to rainfed terraces because it protects the terrace edge from damage by draft animals, it stops storm water from spilling over and starting a gully.
