write an essay on various causes of soil erosion and the ways to prevent it.
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Answer:
Explanation:
The Latin word erodere,meaning “to gnaw away” is the origin of the word erosion (Roose, 1996). Soil Erosion is the physical removal of topsoil by various agents, including falling raindrops, water flowing over the soil profile and gravitational pull (Lal 1990). The Soil Science Society of America defines erosion as ” the wearing away of the land surface by running water, wind, ice or other geological agents, including such processes as gravitational creep” (SCSA, 1982). Physical erosion involves the detachment and transportation of insoluble soil particles (sand, silt and organic matter). Removal of soluble material as dissolved substances is called chemical erosion and this maybe caused by surface runoff or subsurface flow where the water moves from one layer to another within the soil profile (Lal 1990).
According to ASCE, 1975, the physical processes in soil erosion include detachment of soil particles, their transportation and subsequent deposition of soil sediments downslope by raindrop impact and runoff over the soil surface. Rainfall is the most important detaching agent (Morgan and Davidson 1986; Lal, 1990) followed by overland flow in entraining soil particles (Lal 1990).
The process of soil erosion occurs in three main steps, detachment of soil particles, transportation and deposition of soil particles downslope by raindrop impact and runoff over the soil surface (ASCE 1975; Morgan and Davidson, 1986, Lal 1990) followed by overland flow in entraining soil particles (Lal, 1990). Soil erosion reduces soil productivity by physical loss of topsoil, reduction in rooting depth and loss of water. In contrast soil, soil depletion means loss or decline of soil fertility due to crop removal or removal of nutrients by eluviations from water passing through the soil profile (Lal, 1990). Sedimentation however, causes off site effects like degradation of basins, accumulation of silts in water reservoirs and burial of low-lying productive areas and other problems (Lal, 1990). Sediments is the main cause of pollution and eutrophication (Lal, 1990). According to Lal 1990, soil degradation may be caused by accelerated soil erosion, depletion through intensive land use, deterioration in soil structure, changes in soil pH, leaching, salt accumulation, build up of toxic elelments such as aluminum or zinc, excessive inundation leading to reduced soil conditions and poor aeration.
Soil Erosion is the most serious and least reversible form of land degradation (Lal, 1977; El-Swaify, Dangler and Amstrong, 1982). Soil erosion and soil loss , according to Lal (1990) have adverse effects on agriculture because they deplete the soil’s productivity and diminish the resourse base.