Soil Groups Of India
1. Red soils: Derived from crystalline, metamorphic rocks, which consist of granites, gneisses and schist’s, red or reddish brown, either in situ or from the decomposed rock materials washed down to lower level by rain, light textured with porous and friable structure. They have neutral to acid reaction and are deficient in N, humus, P2O5 and lime.
Cover large parts of TN, Karnataka, N-E AP, eastern part of MP to Chota Nagpur and Orissa, noticed in Up, Bihar, WB and Rajasthan.
2. Laterites and laterite soils: Formed in situ condition under conditions of high rainfall with alternating wet and dry periods, to reddish yellow, low in N, P, K, lime and magnesia. Formed due to the process of laterization in which silica is removed while Fe and Al remain behind in the upper layers.
Soils are common on the low hills in eastern AP, K, Kerala, eastern MP, Orissa, Assam and Ratnagiri district of MS.
3. Black soils: Highly clayey, 35 to 60% even up to 80% in valleys or depressions dark colored, from deep cracks during dry seasons, characterized by swelling and low permeability, neutral to slightly alkaline, High CEC, high content of K, exchangeable Ca and Mg poor in org. matter, N, P. The clay is mainly montmorillonite type, hence soft on wetting and contract on drying. These are called as regures or black cotton soils which are divided into: Very deep (More than 90 cm depth), Deep (45 – 90 cm), moderately deep (22.5 to 45 cm), Shallow (7.5 to 22.5 cm) and very shallow (below 7.5 cm depth). Black colour is not due to org. matter but due to presence of titaniferrous magnetite compounds and/or clay complexes. Major areas of black soils are in MS, MP and parts of AP, Gujarat and TN.
4. Alluvial soils: Develop from water deposited sediments. Do not show any prominent profile development. Varies in nature and properties which depends on sediments from which they develop the percent material in the respective catchments area and the place of deposition in valleys. Mostly poor drained, grayish colour, acidic but develop into saline and alkali soils in dry regions.
Occur in all states along rivers, for example, Indo-gangeric plains, Brahmaputra valley, Coastal areas of Gujarat, Ms, K, Kerala, TN, AP, Orissa, WB and Goa.
Sub-divided into: Old, Recent, Lacustrine, Coastal and Deltaic alluviums.
5. Desert soils: Formed in arid regions, as a result of physical weathering, sandy. Both wind and water erosion is severe in such soils, well supplied with soluble salts. Low in N and org. matter has a high pH.
Soils form a major part of Rajasthan, Southern part of Haryana and Punjab, northern part of Gujarat and receive 50 cm to less than 10 cm rainfall with high evaporation
6. Saline and alkaline soils: Soils show white crustation of salts of Ca, Mg and Na on the surface, poor drained and infertile. Occur in semi-arid areas of Bihar, UP, Punjab, Rajasthan Coastal and Deccan Canal Tract of MS.
7. Peaty and marshy soils: Soils are black, clayey, highly acidic (pH3.5) and contain 10 to 40% org. matter, poorly drained, high ground water table. Found in Kerala, Coastal tracts of Orissa, Sunder ban area of WB, SE and Coast of TN and in parts of Bihar and UP.