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Soil As A Resource

Soils are renewable natural resource. They serve as the medium of plant growth and support a number of living organisms. Soil consists of organic (humus) and inorganic materials.

Factors which contribute to soil formation are as follows:

  • Relief of the land
  • Parent rock of the area
  • Climate
  • Vegetation
  • Time

Classification of Soils in India

The soil types found in India are classified on the basis of factors responsible for soil formation, colour, thickness, texture, age, physical and chemical properties.

  1. Alluvial soils
  • These are most widespread and very fertile.
  • These soils are found in river valleys. North Indian plains are formed by alluvium deposited by the rivers Indus, Ganga and Brahmaputra.
  • These are found in the eastern coastal plain in the delta regions of Mahanadi, Godavari, Krishna and Cauveri.
  • These soils consist of varying proportions of sand, silt and clay. The size varies from very fine silt and clay in the delta regions to coarse soils in the upper reaches, e.g. piedmont plains of Terai and Duars in the foothills of the Himalayas.
  • According to the size of grains, alluvial soils are classified as:
  1. Bhangar—This is old alluvium. It is less fertile. Bhangar has a higher concentration of Kankar nodules.
  2. Khadar—This is new alluvium. This consists of fine particles and has higher fertility. It is usually found closer to the river valleys.
  • Major crops—These include paddy, wheat and cereals, pulses, sugarcane.


  1. Black soil
  • Black in colour, it is also called regur soil. This soil is ideal for cultivation of cotton; hence, it is also called black cotton soil.
  • It is formed from weathering of basaltic rocks, in places made up of horizontal sheets of lava.
  • It is found in Deccan Trap region in the northwestern part of the Deccan Plateau. It is found in the plateaus of Maharashtra, parts of Saurashtra, Madhya Pradesh, Chattisgarh and parts of Godavari and Krishna valleys.
  • The soil is made of very fine clayey material and has a high capacity to hold moisture.
  • The soil develops cracks during the hot dry season. This helps in the proper aeration of the soil. It becomes sticky when wet; its difficulty to work during such times.
  • Soils are rich in nutrients such as calcium carbonate, magnesium, potash and lime.
  1. Red and Yellow Soils
  • Red soils develop on crystalline igneous rocks in areas of low rainfall in eastern and southern parts of the Deccan Plateau.
  • Reddish colour develops due to diffusion of iron in crystalline igneous and metamorphic rocks. In its hydrated form, the soil looks yellow.
  • These soils are found in parts of Orissa, Chattisgarh, southern parts of the middle Ganga plain and foothills of the Western Ghats.



  1. Laterite soils
  • Laterite is derived from the Latin word later which means bricks.
  • These soils are found in areas of high temperature and heavy rainfall and are formed due to intense leaching caused by heavy rainfall.
  • Soil is poor in humus, as the soil microbes get destroyed by the high temperature.
  • With the application of manure and fertilisers, the soil becomes suitable for cultivation. Tea, coffee, cashewnuts are grown in laterites along hilly areas.
  • It is mainly found in Kerala, Karnataka, Tamil Nadu, Madhya Pradesh and hilly areas of Orissa and Assam

  1. Arid Soils
  • These are red to brown in colour, sandy in texture and saline in nature.
  • These are found in dry climate with high temperature. Soil lacks humus and moisture. Increased concentration of calcium in the lower horizons of the soil gives rise to kankar nodules. The kankar nodules limit the infiltration of water.
  • With irrigation, the soil can be cultivated.



  1. Forest soils
  • These are found in hilly mountainous areas with sufficient rainfall.
  • These soils vary from fertile loamy and silty soils along river valleys and river terraces to coarse-grained in the mountain slopes. In higher altitudes, the soils are acidic with low humus content.

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