Soils

Soil is a mixture of mineral matter such as sand and clay, organic matter, decayed leaves, flowers, minute bacteria, moisture and air. Soil is composed of a complex variety of materials; some of it comes from the actions of weather on rock, and from living sources. Main constituents of soil are sand, clay, chalk, and humus. Different types of soil are sandy soil, clayey soil, and loamy soil. Soil can be classified on the basis of colour, texture like coarse grained or fine grained soils and combination of colour and texture. Soil is formed by the natural processes and changes made on earth's surface over a period of time. Continuous physical, chemical and biological changes in the soil take place in different stages. In Stage 1, there is a weathering of bare rocks. In Stage 2, Organic layer is formed. In stage 3, Water percolates through the material, thus distributing the minerals creating soil. Factors affecting soil formation include climate, weathering, moisture in the soil, vegetation, bio-chemical processes, parent rock, and topography. There are different ways of soil formation, like transported soil is formed by the fragment of rocks carried by stream, waves, winds, glacier, etc., and sedentary soil remains where they are formed. A soil profile is a straight cut into the soil showing the successive layers of the soil. Different layers of soil are Bed Rock, Parent material, Sub-soil, Top soil, and Surface soil. Removal of soil by running water and wind is known as soil erosion. Erosion by water can be of two types: Sheet erosion, and Gully erosion. Wind erosion is common in desert and semi-desert regions. Causes of Soil Erosion are Human Factors, Deforestation, Overgrazing of Land, Flooding and Torrential Rainfall, etc. Soil Conservation is an effort by human beings to prevent soil erosion or at least reduce the rate of erosion. Conservation of Soil can be done by afforestation, restricted grazing, proper farming techniques and flood control.

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