What is soil erosion? What are the conservaton methods to prevent the soil erosion? Information about soil erosion.
Soil consist of 2 layers. The upper layer is top soil and the lower layer is subsoil. Top soil is the layer in which plants grow. Top soil may be removed by the process of erosion (water-wind erosion). Rain water washes it away while winds dry it out and blow it away. When the top soil is eroded away the subsoil is exposed. Subsoil is not suitable for the growing of plants since it contains rock particles.
Sometimes top soil loses its fertility due to leaching when water passes down through it. The water dissolves minerals in the soil and carries them de ep into the subsoil. This removal of mineral stop soil by water is called leaching.
The top soil is important for us. So it must be conserved. There are different ways to conserve the soil.
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Conservation of soil
soil can be conserved by :
1- preventing erosion using various methods
a- covering the soil with plants.
b- reducing the rate of running water using contour farΔ±ning, strip farming and terracing.
2- adding minerals and organic matter to the top son to increase son richness.
3- using crop rotation.
4- leaving fields empty for a period of time.
Here is an explanation of the steps in each of the above methods:
1- a- Covering the soil with plants.
Plants are the best protection against soil erosion. Grass stems and leaves which cover the soil surface cause little erosion. Also the roots ofplants hold the soil partides together. Which root system is this? in a forest the drops ofwater don’t hit the ground with much force because they strike the leaves and branches of trees and gradually drop to the ground or run down the trunk. Roots of plants hold the soil in place and humus collects under them. This acts like a sponge holding water in the soil and prevents erosion.
Plants also prevent wind erosion. Shelter belts are effective against wind erosion. Shelter belts are thick rows of evergreen trees that break the wind. They reduce wind erosion by slowing down the speed of the wind. Another way to conserve the soil from wind erosion is to plant cover crops like clover and alfa alfa. These remain on the land during the winter and help to keep the soil in the field. Theyare also used as food for animals during the winter months.
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b- Reducing the rate of running water.
Erosion is greatest in hilly farm lands. One way of preventing excessive erosion on hilly farm land is to use contour farming in which the land is ploughed horizontally instead of vertically. This reduces soil loss.
Another way of preventing wasteful erosion is to use strip farming. This is to grow alternate rows of crops such as corn and grass, to check the downhill running off of water.
Another method is to use terracing but this is rather expensive.
2- Adding minerals and organic matter (Fertilizer)
Fertilizers contain many minerals which make the soil rich.
3- By crop rotation:
Growing the same plant year af ter year removes minerals from the soiL. The removal of mineral s decreases the richness of soil. This is called depletion. To keep the soil rich these minerals must be returned to the soil. This is often done by crop rotation. One crop is grown one year and a different crop is grown the next year. For example, corn one year, wheat or oats the next and clover the third year. The series is then repeated. Legume crops, such as clover, alfa alfa, bean and pea add nitrates to the soil. Usually at least one legume crop is included in the rotation.
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4- Leaving fields empty for a period of time:
The field is left empty of crops for one or two years to give the soil a chance to regain the lost elements and minerals. Land left uncultivated like this is called fallow.
