Soil erosion and the causes of its occurrence
Soil erosion is a common process, withwhich is the destruction of soil and soil by streams and streams of melt, rain, rain and irrigation waters or winds. The damage from such an impact is enormous. Soil erosion has already removed 2 billion hectares of agricultural land, including arable land (50 million hectares).
The soil is a self-healing system, however, 300-1000 years will be required to repair a damaged 2.5 cm layer.
Types of soil erosion - is water and air (deflation).
Erosion forms rills that hinder processingsoil; creates gullies, while reducing the area of land for crops; destroys roads, agricultural lands are flooded. On the upper surface of short slopes, the chernozem layer is significantly reduced or completely washed away, which affects the yield.
Causes of erosion
On the intensity of erosionprocesses is very influenced by climate, terrain, erosion resistance of the soil, vegetation in these areas, people's economic activities and other factors.
Soil erosion depends on the climate, becauseerosion processes are intensified as a result of sudden temperature fluctuations, the amount and intensity of precipitation, wind speed and force. From low temperatures the soil freezes deeply, and the intensity of its thawing and melting of snow affects the rate of water absorption into the soil, which is reflected in water runoff, washout and erosion.
Water erosion of soils is ravine (streamlike, linear), planar and irrigation (irrigation).
If in the winter from the slopes the snow is carried away by strong winds, the soil is bare, freezes, and prevents the meltwater from being absorbed. This causes an intense runoff of water.
The wind also affects the process of water erosion, because it redistributes the snow along the relief, blows it off the slopes into ravines, beams, etc.
Deflation depends on the erosive force of the wind, starting to appear at a speed of about 12 m / s at an altitude of about 10 m above the soil surface.
The speed of the wind depends on the vegetation cover. On treeless expanses, in the steppe, wind speed sometimes reaches 30 m / s, and in the forest zone and forest-steppe it is less.
Precipitation can significantly weaken wind erosion, but their abundance contributes to the development of water.
The intensity of destruction is affected by the relief, steepness and length of the slopes, the width of the watershed. The longer and steeper the slope, the larger the area is damaged by erosion and the more serious its consequences.
The condition and characteristics of soils are reflected in the degree of destruction. So, qualitatively structured, chernozem are distinguished by their friability, water permeability, and therefore the erosion and washout on them is much less.
Soil erosion depends on the mechanical compositionof the soil. In natural conditions of air erosion, a light soil is more susceptible - sandy and sandy loamy. Clay soils undergo deflation only in the loosened, dusty state. The carbonate soils are easily destroyed by the wind - chestnut and chernozem soils. Solonets soils and solonetzes are wind-resistant.
Thanks to the vegetation cover,the process of soil erosion is reduced or completely eliminated. The impact of raindrops is mitigated by dense vegetation, some of the liquid is retained on the leaves of plants, and the grass drastically slows the flow of water.
Erosion of soils is reduced if the ground is covered with perennial grasses, which protect the soil from the effects of raindrops and winds, increasing water permeability.
The economic activity of people has a great impact on erosive processes. With an increase in the proportion of areas sown with tilled crops, the intensity of soil erosion increases.
With excessive mechanical tillageit is sprayed, which increases both wind and water erosion. Sealing the soil causes a passage through the field of heavy agricultural machinery, which reduces its water permeability, increases the flow of water, blurs and flushes.
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