Previous Year Question

1. Terrace cultivation—Incorrect

In terrace cultivation, a hill slope is converted into a series of level steps. This shortens the slope, reduces the velocity of surface runoff, increases infiltration and allows transported soil to settle on the terraces. Therefore, terrace cultivation is not a cause of soil erosion; it is a soil-conservation method.

2. Deforestation—Correct

A forest canopy intercepts raindrops, leaf litter absorbs water and tree roots bind soil particles together. Following deforestation:

• raindrops strike the ground directly;

• infiltration decreases and surface runoff increases;

• the root network no longer binds the soil;

• sheet, rill and gully erosion may intensify.

Thus, the problem of soil erosion in India is directly associated with deforestation.

3. Tropical climate—Incorrect

Intense rainfall can increase erosive power, but a tropical climate alone is not a sufficient cause of soil erosion. Erosion depends on rainfall intensity as well as slope, soil characteristics, vegetation cover and land use. In an undisturbed tropical forest, the dense canopy, leaf litter and root network protect the soil. Therefore, tropical climate is not treated as an independent cause in the context of this question.

Additional facts

• Sheet erosion: Uniform removal of a thin layer of topsoil.

• Rill erosion: Running water produces numerous small channels on the surface.

• Gully erosion: Rills deepen and widen into gullies, sometimes making the land unsuitable for cultivation.

• Loss of topsoil reduces humus, nutrients and water-holding capacity, while the eroded material causes siltation of rivers and reservoirs.

• Afforestation, contour ploughing, terrace cultivation, strip cropping and controlled grazing are important conservation measures.

Therefore, statement 2 alone is correct.