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| Soil Erosion |
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| Land is also a precious resource. Land is needed for agriculture and occupation. Land is under pressure due to increasing population. Land for agriculture has to be fertile in order to be able to support a good crop. The fertility of land lies in the quality of the soil. |
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| Soil is formed as a result of weathering of rocks. There are also many living organisms in the soil. Soil is, in fact a product of the interaction of living organisms with rocks. Soil has many layers. The topmost layer is called the topsoil and is the most fertile. The removal of this topsoil is called soil erosion. |
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 Soil erosion results in the loss of soil fertility and makes the land barren. There are more than 25 million hectares of barren lands in the world now. |
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Soil erosion also leads to desertification. Desertification refers to increase of desert areas. |
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| The main cause of soil erosion is the removal of vegetation. Vegetation removal takes place due to removal of forest covers. Unscientific farming has also led to barren lands. |
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| The removal of vegetation exposes the topsoil to water and wind. Water and wind cause the topsoil to be removed. |
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| Removal of topsoil by water is called water erosion. It takes place in the following ways: |
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Sheet erosion |
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Rill erosion |
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Gully erosion |
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Riparian erosion |
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Wind erosion |
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| Sheet Erosion |
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| The removal of the entire topsoil as a result of heavy rains is called sheet erosion. |
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| Rill Erosion |
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| Runoff water moves across the soil forming small streams. The topsoil is removed only in these rills formed by the water streams. |
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| Gully Erosion |
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| Deep depressions called the gullies are formed by swiftly moving waters causing soil erosion by them. |
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| Riparian Erosion |
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| The banks of rivers lose top soil due to the action of the fast moving rivers waters. These waters remove the underlying soil and this results in the loss of topsoil. |
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| Soil Leaching |
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| The topsoil is fertile due to rich presence of minerals. Sometimes the rain water dissolves these minerals which go down into the soil along with the water. This results in the loss of fertility of the topsoil. |
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| Wind Erosion |
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| The other cause for erosion is wind. It is more in areas where there is less or no vegetation covering the land. The fast moving wind moves the fine particles to other places. The deserts are encroaching the fertile areas in this manner. The wind laden with fine sand deposits the latter and forms sand dunes. Shifting sand dunes are common in dry areas of Rajasthan, Gujarat and Madhya Pradesh. Expansion of deserts in this manner is called desertification. |
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| Increase of Vegetation |
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| When the land is covered with vegetation, the roots of the plants and trees interlock and interlace to bind the soil particles. This helps in two ways: |
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does not allow the soil particles to be carried away by wind or water |
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does not allow free flow of water over the soil which prevent erosion of soil by flowing water |
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the falling leaves of the plants get converted to humus by decomposing action of the soil microbes. This enriches the soil. |
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| Several methods can be employed to increase the vegetation cover of land. Some of them are as follows: |
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| Crop Rotation |
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| The practice of growing different crops at different times on the same land is called crop rotation. This keeps the topsoil covered with vegetation. Rotation of cereal crops with legumes also keeps the soil enriched with nitrogen (from the legumes). |
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| Reforestation |
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| Slopes are more subject to soil erosion by running water. Growing trees on lands which have lost their vegetation is called reforestation. Trees like Albizia, Cassia, Butia, etc. are suitable for this. |
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| Strip Cropping |
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| It involves growing of crops in strips. The most common method followed is the contour farming where the strips of crop are at right angles to the slope. Wind-strip cropping is when the strips of crop are place at right angles to the direction of wind. |
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| Restoring Soil Fertility |
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| Fertile soil supports vegetation. Loss of fertility results in loss of vegetation and this exposes the land to erosion. Fertility of soil can be increased by addition of natural and synthetic fertilizers. |
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| Control of Grazing |
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| Covering the land with small plants and grasses helps the topsoil to remain in place as the roots of these plants bind with the soil particles. Cattle graze on these plants and expose the topsoil Thus, grazing should be allowed only on the land meant for the purpose and other areas should be protected from grazing. |
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| Terracing |
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| Fields are cut at right angles to the slope. This slows down the flowing water and allows it to irrigate the crops, as well. |
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| Dam Building |
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| With the dams the speed and amount of water flowing can be controlled. This will control the soil erosion of the river banks. |
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| Wind Breakers |
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| Trees are planted across the wind direction to protect against the high velocity winds. These rows of trees are called shelter belts or wind breakers. |
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