India faces an acute problem of soil erosion. On an average, the country is losing soil at a rate of 16 tonnes per hectare (ha) annually, which is more than three times the acceptable limit of 4-5 tonnes. Even the Union agriculture minister, Sharad Pawar, had raised concern over the problem at the first Krishi Vigyan Kendra Conference, held in Delhi recently.

Soil erosion is the loss of topsoil, for which rain is the biggest cause. Water is about 800 times heavier than air and about as heavy as loose topsoil. A drop of rain hits the ground hard enough to dislodge the soil, which is then carried away by flowing water. In India, wind is the major agent of erosion only in the Thar desert. Other factors influencing erosion include soil structure, vegetation cover, slope, land and water use patterns.

Worse in Shivalik
In a study published in the Journal of Soil and Water Conservation (Vol 47, No 1, 1992), Gurmel Singh and colleagues from the Central Soil and Water Conservation Research and Training Institute, Dehradun, classified soil erosion into six categories