Soil is an essential natural resource that supports a majority of plant and animal life on the earth. It is a renewable resource.
The loss of soil cover due to natural agents like wind and running water is called soil erosion. The roots of plants and trees keep the soil moist and hold the soil particles together. Humans destroy vegetation cover by deforestation, overgrazing, construction and mining activities.
Without vegetation cover, soil becomes dry and loose, and gets easily eroded. Defective farming methods, like ploughing up and down a slope, increase the speed of water flowing down the slope increase the rate of soil erosion.
Running water carves deep channels through clayey soils, called gully erosion, which converts the land into bad-land making it unsuitable for cultivation.
When flowing water washes away the entire sheet of top soil in a region, it is called sheet erosion. Wind erosion occurs generally in areas of little or no vegetation. It happens in places that receive scanty rainfall.
The prevention of soil erosion is called soil conservation and the ways can be:
- Terrace farming is one way to do so and involves cutting terraces along a slope. These terraces reduce the speed of water flowing down the slope and help in soil conservation.
- Contour ploughing is also beneficial in reducing the flow of water down the slope and involves ploughing at right angles to the natural slope of land.
- Effective farming techniques further help in soil erosion. In plain areas, strip cropping can be used for soil conservation where strips of grass are allowed to stand between crops in large fields. These strips of grass reduce the force of wind and thus prevent soil erosion.
Planting rows of trees along farmland also help break the force of wind and help in soil conservation. Shelter belts of trees, when planted along sand dunes, help stabilise them and prevent the desert from extending into land available for cultivation.