Soil erosion is the degradation of the soil, which is a natural occurring process occurring on the land cover. This process is caused by several agents including: water, wind, human beings activities animals. The degree of soil erosion is determined by the intensity of the force of the causative agent and the nature of the soil cover. The end result is loss of the top rich soil in nutrients, low quality of crops, damaged networks of water drainage and reduced quality of the surface water. This paper will discuss only the major agents of soil erosion which are water, wind and human activities. It is hoped that through this purpose the identified factors will guide to enable this paper identify the best methods of correcting the soil erosion.
Water is a major factor that causes soil erosion in almost every part of the globe. The rate and the degree to which soil erosion happens is determined by several factors. First, the intensity of rainfall and surface runoff are to be considered when evaluating the magnitude of soil erosion. The impact of falling raindrops on the loose surface soil breaks the soil aggregates and disperses them to another position on the ground. The light particles of soil on the surface are carried away by the surface runoff of water down the gradient of the slope. Other factors include the type and quantity of vegetation cover on the soil which is able to reduce the impact of the raindrops and the speed of the surface runoff. Another factor is the gradient of the slope which determines the speed of the surface runoff. Lastly, the ability of the soil to resist erosion determines the ability of the soil to be carried away by water depending on its physical characteristics.
Several factors determine the rate and the extent to which the soil is carried away by the force of wind. First, the ability of the soil to resist being suspended by wind and get moved to a distant position or great distances. Fine particles will be easily carried away whereas large heavier particles are hard to be lifted by the force of the wind current. The roughness of the ground also determines the magnitude of the soil to resist erosion since the level and plain grounds are not able to resist wind erosion. The climate of the area also determines the season of winds and its prevalence in that geographical climate. The vegetative cover also determines the intensity of the destructive effects of the wind on the soil.
The activities of human beings on the ground such as farming, rearing of animals, deforestation among others causes to a large extent cause soil erosion. First, crop farming involves digging of the soil loosening the top soil which reduces the resistance of the soil to other agents of erosion such as water and wind. The processes of digging also remove the soil top cover exposing it to the other agents of soil erosion. The grazing of animals also loosens the soil top layer and also animals eat the grass cover on the soil exposing it to erosion agents. The cutting of trees, which act as protection on the soil top layers from impact of wind and impact of raindrops, increases soil erosion by other agents of erosion. The activities of machines on the ground also loosen the soil particles as well as transporting them to other places.
Correcting Soil Erosion
1. Increasing the vegetative cover on the ground reduces the effect of the agents of erosion on the soil. This also helps on reducing the flow of water on the ground, increases the resistance of soil aggregates to the actions of agents of erosion; the falling leaves of plants also increase the humus on the top soil layers which enriches it.
2. The activity of human beings on land such as tilling the soil and other crop farming activities, animal farming directly affect by either reducing the soil cover or exposing the soil to agents of erosion. To correct soil; erosion by water:
a. Contour plowing which is digging contours across the slope of the land controls erosion. They trap the surface runoff allowing the soil to decant and settle on the contours.
b. Strip cropping is another method of control since the crops are planted across the slope which goes against the current of the runoff and also reduces the impact of raindrops.
c. Terracing is another control method whereby the terraces trap large quantities of surface runoff water
3. The third correcting measure is practicing soil rotation which keeps the soil covered and enriched with nutrients.
4. Reforestation is the planting trees on areas where deforestation had been going on. This reduces the ability of the erosion agents to act on the soil and carry it away. Trees act as wind breakers and they also slope the force of falling water drops.
5. Controlled grazing and management of grazing fields also protect the soil from adverse effects of animals on the soil top layers. The soil is not left exposed and also the grass cover prevents the loosening of the soil. Lands should be set aside for grazing and grass and other plants should be planted to ensure the soil is always covered.
6. Building of gabions and dams control the adverse effects of soil erosion by surface water runoff. The river bank erosion is controlled as well as water running down the slope carrying away the top fertile soils from the farming lands.
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