Soil is the uppermost layer of the land surface, usually composed of minerals, organic matter, living organisms, air and water. Grains in the soil are of three categories namely, clay, silt, and sand. Soils are generally formed by the weathering of rocks under different conditions. Some soils are formed by the deposition of agents of denudation. Soils can vary greatly from one region to the other.
The Indian Council of Agriculture Research (ICAR) set up in 1953 divides the soils of India into the following eight major groups. They are
1. Alluvial soil
2. Black soils
3. Red soils
4. Laterite soils
5. Forest and mountain soils
6. Arid and desert soils
7. Saline and alkaline soils
8. Peaty and marshy soils
Khadar – light coloured, more siliceous.
Bhangar – the older alluvium composed of lime nodules and has clayey composition. It is dark in colour.
Formation - sediments deposited by streams and rivers when they slowly loose
Chemical properties - rich in potash, phosphoric acid, lime and carbon compounds but poor in nitrogen
Nature –Sandy-loam-silt-clay profile shows no marked differentiation
Formation - Derived from basalts of Deccan trap.
Colour - black colour, due to presence of titanium, iron.
Chemical properties - Consist of calcium and magnesium corbonates, high quantities of iron, aluminium, lime and magnesia.
Rich in potash lime, Aluminium calcium and magnesium poor in Nitrogen Phosphoric acid and humus
Nature - Sticky when wet High degree of moisture retentivity
Formation - decomposition of ancient crystalline rocks like granites and gneisses and from rock type
Chemical properties - rich in minerals such as iron and magnesium.
Deficient in nitrogen, humus, phosphoric acid and lime.
Nature - Light texture, porous friable presence of limited soluble salts Clay fraction of the red soils generally consists of Kaolinitic minerals.
Formation - formed in the regions where alternate wet and hot dry conditions prevail. It is formed by the process of leaching
Chemical properties - Composed mainly of hydrated oxides of iron and aluminium,
Nature - More acidic on higher areas poor in high level, cannot retain moisture while plains they consist of heavy loam and clay and easily retain moisture
Differ from region to region depending on climate.
Formation - due to mechanical weathering caused by snow, rain, temperature variation
Chemical properties - are deficient in potash, Phosphorus and lime.
Nature - light, sandy, thin and found with the pieces of rock. Their character changes with the parent rocks. Very rich in humus. slow decomposition makes it acidic
Formation - Due to prevalence of the dry climate, hightemperature and accelerated evaporation, the soil is dry, it also lacks humus content due to the absence of vegetative cover
Chemical properties - Contain high percentages of soluble salts, alkaline with varying degree of calcium carbonate and are poor in organic matter; rich enough in phosphate though poor in nitrogen
Nature - light in colour, low humus,friable structure, low in moisture
Formation - formed due to ill drainage which causes water logging, injurious salts are transferred from subsurface to the top soil by the capillary action, it causes the salinisation of soils
Chemical properties - liberate sodium, magnesium and calcium salts and sulphurous acid
Nature - Consists of an excess of sodium salts and mineral fragments which are weathering
Formation - formed in humid regions from the organic matter. It is found in the areas of heavy rainfall and high humidity Peaty soils are black, heavyand highly acidic.
Chemical properties - deficient in potash and phosphate.
Nature - Contain considerable amount of Soluble salts and 10-40 per cent of organic matter; and high proportion of vegetable matter.
Soil degradation: Soil degradation is an acute problem in India. According to a 2015 report of the Indian institute of remote sensing (IIRS). The estimated the amount of soil .erosion that occurred in India was 147 million hectares.
The main problems of the Indian soils are i) soil erosion (sheet erosion, Rill erosion, Gully erosion, Ravine and Badland) ii) Degradation of Soil, iii) Water-logging, iv) Saline and Alkaline, and v) Salt Flats, types of soils are different erosion.
Methods of Conservation and Management of Soil
2. Constructing Dams and Barrages
3. Prevention of Overgrazing
4. Improved methods of Agricultural practices
Contour method, Rotation of crops, Contour bunding, Strip cropping, Planting of shelter belts, Adopting the techniques of sustainable agriculture are different conservation methods for better soil management.