Agricultural Science

Soil Erosion, Types, Causes and Solutions to Soil Erosion

Olawunmi Omosanya - 12th February, 2019 @ 03:25 AM

What is Soil?

The soil is the top layer of the lithosphere (Lithosphere is the solid part of the earth). The topsoil is a home to many living organisms including bacteria and fungi. It’s also the point on which farming activities occur. It’s important we protect it against soil erosion because this will adversely affect the farmers and everything living on it. According to reports, it takes the soil millions of years for soil to be formed (at a rate of 1cm of growth per 250 years). Also, soil is non-renewable and once lost, it’s gone forever.


Meaning of Soil Erosion

Soil erosion is a process through which the topsoil is removed or moved from one point to another by agents like wind, water, man and animals. Soil erosion occurs naturally (wind and water) or is facilitated by living organisms. Soil erosion is more likely to occur in a sloppy land or a land with no vegetation cover. When this occurs, the nutrient rich layer of the top soil is washed away which ultimately results in fewer plants growing on the soil.


Types of Erosion

  1. Water Erosion: Caused by rainfall and flooding on the top soil. The resultant effect is the removal of this top soil.

  2. Sheet Erosion: When an entire surface of a land becomes eroded at a uniform (equal) level, such is referred to as sheet erosion.

  3. Wind Erosion: Results from the actions of wind on a bare land. This type of soil erosion is often seen in deserts. Overgrazing and lack of vegetation cover also results in wind erosion.

  4. Rill Erosion: Also called channel erosion, rill erosion occurs on a steep land or one that is gently sloped (with irregularities in its path). As a result of these irregularities, water runs through its path bringing about the washing away topsoil along such path. This result in the formation of channels or miniature dongas on such land.

  5. Gully Erosion: They usually occur close to the bottom of a sloppy land and are caused by the removal of the topsoil from the formation of a concentrated runoff that has been caused by water or rainfall. On a hilly land, a gully is likely to be formed when water running downhill creates a channel deep into the soil. As a result, a gully head may be formed at the lower end of the channel as it gently make its way back uphill. While doing this, the gully made on the hill deepens and widens.


Causes of Soil Erosion

  1. Water: Whenever there is a heavy rainfall, the force at which the water drops may cause the breaking of the top soil and a resultant penetration of water into it. This can result in the exposure of the soil’s contents. Runoff water will flush the topmost nutrients of the soil down its path depositing them down the riverbed.

  2. Wind: A strong wind will result in the loss of the top soil especially on those whose soil structure has already been loosened up by erosion. The chances of wind erosion are further enhanced when the land is bare (that is, not covered with plants or vegetation). Wind erosion is common in the desert and the sandy soil is most susceptible to it due to its soil structure.

  3. Lack of crop rotation: The continuous planting of one type of crop on a piece of farmland may result in the loss of nutrients on the soil of such farmlands. As a result, the soil will not be able to support the growth of plants leading to water and wind erosion.

  4. Inappropriate planting techniques: When a land is constantly ploughed, the soil will be exposed to soil erosion.

  5. Sloppiness of the land: The degree of sloppiness of a land will also affect soil erosion. For instance, a land with hill slope is more likely to be eroded from runoff water as it moves down the slope.

  6. Lack of vegetation Cover: Cover crops and plants help to maintain the soil structure, thus reducing soil erosion. They also protect the soil from water and wind erosion.

  7. Overgrazing: Overgrazing is said to occur when cattle, sheep and goats excessively feed on plants over a piece of land. Overgrazing removes the vegetation cover from the top soil, subsequently exposing the top soil to water and wind erosion.

  8. Deforestation: Deforestation occurs when large forest trees are cut down in a large scale. The presence of forest trees on a farmland serves as protection from wind (They act as wind breaks). Also, the roots of these trees firmly hold the soil together thus preventing it from been lost to wind erosion. Deforestation exposes the top soil to water and wind erosion.


Solutions to soil Erosion

The prevention of soil erosion is called conservation of soil. Soil conservation can be achieved via the following ways:

  1. Avoid overgrazing on farmlands.

  2. Encourage planting of trees (act as windbreaks) or Afforestation.

  3. Land tillage should be carefully done. It should also be reduced to its barest minimum.

  4. Practice of strip cropping (that is, leaving grass strips between ploughed lands).

  5. Implement crop rotation on farmlands.

  6. Use of runoff pipes and specialized chutes to direct excess water away from farmlands.

  7. Practice of terrace farming (It can be implemented in hilly areas by cutting steps on the slope of the hills).

  8. Building of dams to prevent flood.

  9. Planting cover crops on bare soil to act as shelterbelts.

  10. Embankments created along the banks of the river can protect fields from the floods.

  11. Educate farmers on soil erosion.

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