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Describe the formation of soils

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Soil forms the thin surface layer to the earth’s crust. It provides the foundation for plant and, consequently, animal life on land. Soil results from the interrelationship between and interaction of, several physical, chemical and biological processes all of which vary according to different natural environments. The study of the soil, its origin, characteristics and utilisation is known as pedology.
The first stage in the formation of soil the weathering of parent rock to give a layer of loose, broken material known as regolith. Regolith may also be derived from the deposition of alluvium, drift, loess and volcanic material. The second stage, the formation of true soil or topsoil, results from the addition of water, gases (air), living organisms (biota) and decayed organic matter (humus). Five main factors are involved in soil formation namely parent rock, climate, topography, organisms and time. These same factors affect the rate of weathering.
When a soil develops from an underlying rock, its supply of minerals is largely dependent on the parent rock. These minerals are susceptible to different rates and processes of weathering. Parent rock contributes to control of depth, texture, drainage or permeability and quality (nutrient content) of a soil and also influences its colour.
Climate determines the type of soil at a global scale. The distribution and location of world soils corresponds closely to patterns of climate and vegetation. Climate affects the rate of parent rock weathering with the most rapid breakdown being in hot humid environments. Precipitation affects the type of vegetation, which grows in an area, and this in turn provides humus. In areas of heavy rainfall, the downward movement of water through the soil transports mineral salts with it, a process known as leaching.
Where rainfall is light or where evaporation exceeds precipitation water and mineral salts are drawn upwards towards the surface, a process known as capillary action. Leaching tends to produce acidic soils, while capillary action results in alkaline soils. Temperatures determine the length of the growing season and affect the supply of humus. Vegetation decays more quickly in hot, wet climates as temperature further
influences the activity and number of organisms and the rate of evaporation.

francis1897 answered the question on October 11, 2022 at 07:46

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Describe the formation of soils

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