November 28, 2009

Soils of India & Their Classification

Classification of Indian Soils
  • There are 8 major group of soils in India which are furnished below
Red Soils
  • Red colour is due to various oxides of iron. They are poor in N, P, K and with pH varying 7 to 7.5. These soils are light textured with porous structure. Lime is absent with low soluble salts.
  • Red soils occurs extensively in Andhra Pradesh , Assam, Bihar, Goa, Parts of kerala, Maharastra, Karnataka, Tamilnadu and West Bengal. Most of the red soils have been classified in the order ' Alfisols'.
Lateritic Soils
  • Seen in high rainfall areas, under high rainfall conditions silica is released and leached down wards and the upper horizons of soils become rich in oxides of iron and alluminium. The texture is light with free drainage structure.
  • Clay is predominant and lime is deficient. pH 5 to 6 with low in base exchange capacity, contained more humus and are well drained. They are distributed in summits of hills of Daccan karnataka, Kerala, Madhyapradesh, Ghat regions of Orissa, Andhra pradesh, Maharastra and also in West Bengal, Tamilnadu and Assam.
  • Most of the laterite soils have bee classified in the order ' ultisols' and a few under ' oxisols'.
Alluvial Soils
  • These are the most important soils from the agriculture point of view. The soils are sandy loam to clay loam with light grey colour to dark colour, structure is loose and more fertile. But the soils are low in NPK and humus.
  • They are well supplied with lime; base exchange capacity is low, pH ranges from 7 to 8. These soils are distributed in Indo-Gangetic plains, Brahmaputra valley and all most all states of North and South. Most of the alluvial soils have been classified in the orders ' Entisols', ' Inceptisols' and ' Alfisols'.
Black Soils
  • This is well known group of soils characterised by dark grey to black colour with high clay content.
  • They are neutral to slightly alkaline in reaction. Deep cracks develop during summer, the depth of the soil varies from less than a meter to several meters. Poor free drainage results in the soils, base exchange is high with high pH and rich in lime and potash. Major black soils are found in Maharastra, Madhyapradesh, Gujarat and Tamilnadu.
  • Cotton is most favourable crop to be grown in these soils. These soils are classified in the order 'Entisols', ' Inceptisols' and ' vertisols'.
Forest Soils
  • This group of soils occur in Himalayas. Soils are dark brown with more sub-soil humus content. They are more acidic.
Desert Soils
  • These soils are mostly sandy to loamy fine sand with brown to yellow brown colour, contains large amounts of soluble salts and lime with pH ranging 8.0 to 8.5. Nitrogen content is very low.
  • The presence of Phosphate and Nitrate make the desert soils fertile and productive under water supply. They are distributed in Haryana, Punjab, Rajasthan. They are classified in the order ' Aridisols' and ' Entisols'.
Peaty and Marshy Soils
  • These soils occur in humid regions with accumulation of high organic matter. During monsoons the soils get submerged in water and the water receipts after the monsoon during which period rice is cultivated. Soils are black clay and highly acidic with pH of 3.5. Free alluminium and ferrous sulphate are present.
  • The depressions formed by dried rivers and lakes in alluvial and coastal areas some times give rise to water logged soils and such soils are blue in colour due to the presence of ferrous iron.
  • Peaty soils are found more in Kerala and marshy soils are found more in coastal tracks of Orissa, West Bengal and South - East coast of Tamilnadu.
Saline - Sodic Soils
  • Saline soils contain excess of natural soluble salts dominated by chlorides and sulphates which affects plant growth. Sodic or alkali soils contain high exchangeable sodium salts.
  • Both kinds of salt effected soils occur in different parts of India like Uttarpradesh, Haryana, Punjab, Maharastra, Tamilnadu, Gujarat, Rajastan and Andhra pradesh. These soils are classified under ' Aridisols', ' Entisols' and ' Vertisols'.


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