The wearing away (due to the action of winds) and washing down of soil cover (due to running water) is known as soil erosion.
Causes of Soil Erosion
Soil Erosion by Water
- Gully Erosion: This occurs during heavy rainfall when running water cuts through the soil making deep channels. The land thus becomes unsuitable for cultivation and is known as bad land.
- Rill Erosion: It occurs when runoff water forms small channels running down the slope. It is an intermediate stage between sheet and gully erosion.
- Sheet Erosion: The washing away of the topsoil because of the flowing of water as a sheet over large areas is known as sheet erosion.
- Leaching: When soil is bare of any vegetation, nutrients present in the soil percolate below the soil because of heavy rainfall. It makes soil infertile.
- Stream Bank Erosion: It occurs when streams of rivers change their course by cutting one bank and depositing the silt on the other bank of the river.
- Sea or Shore Erosion: The powerful waves of the sea dash against the coast and break the cliff rocks. The fragmented material is then removed by the retreating sea waves. Eastern and western coasts have experienced this kind of soil erosion.
Soil Erosion Due to Human Action
- Deforestation has resulted in soil erosion. The absence of any vegetation on the land leads to the washing away of the soil.
- Overgrazing by domestic animals also leads to soil erosion.
Soil Erosion by Winds
- When the wind blows away the topsoil, it is known as wind erosion.
- When bare land is exposed to high-speed winds, smaller soil particles are removed in a bouncing and hopping manner along the surface of the ground. This is known as saltation.
- The rolling and sliding of larger soil particles along the ground surface are known as soil creep.
Regions Affected by Soil Erosion
In India, the following regions are affected by soil erosion:
- Badlands of Chambal and Yamuna rivers
- Western Himalayan region
- Chotanagpur Plateau region
- Tapti Sabarmati valley region in Gujarat
- Regur soil area of Maharashtra
- Dry areas of Rajasthan, Gujarat and Haryana
Methods to Prevent Soil Erosion
- Contour Ploughing: When one ploughs along the contour lines, it is called contour ploughing. It decreases the flow of water down the slopes and thus helps in soil conservation.
- Terrace Farming: When steps are cut out on the slopes of the hills making terraces, it reduces soil erosion.
- Strip Cropping: When strips of grass are grown between the strips of crops, they are known as strip cropping. It breaks down the speed of winds.
- Shelter Belts: When trees are planted in a row, it breaks the force of the winds. This method has proved very useful in the station of dunes in the deserts of western India.
- Plugging of Gullies: The gullies made in the soil are plugged with deposition of silt during heavy rainfall. Soil conservation is required to prevent the loss of soil fertility and agricultural productivity. Soil erosion may also increase the risks of droughts and floods. Landslides also occur because of deforestation and soil erosion.
Soil conservation programmes in India
In India, many programmes have been undertaken to prevent soil erosion.
- An integrated watershed management programme was launched during the Sixth Plan in flood-prone rivers. The programme enhances the ability of the catchment by absorbing rainwater and reducing erosion.
- A scheme for reclamation and development of the ravine areas was launched in 1987–88 in Madhya Pradesh, Uttar Pradesh, and Rajasthan. The scheme included afforestation and reclamation of ravines.
- The scheme was also launched for controlling shifting cultivation in the states of Arunachal Pradesh, Mizoram, Nagaland, Tripura, and Assam.
- National Project on Development and Use of Bio fertilizers and National Project on Quality Control were implemented during the Seventh Five Year Plan. It aimed at balancing the use of fertilizers.
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