Indian Geography / Indian Soils
Indian Council of Agricultural Research ( ICAR ) made the classification of soils in India into 8 major types. They are (i) Alluvial soils, (ii) Black
soils, (iii) Red Soils, (iv) Laterite soils, (v) Forest or Mountainous soils, (vi) Saline and Alkaline soils, (vii) Arid and Desert soils and (viii) Peaty and
Soil can be defined as the topmost layer of the Earth's crust on which flora grows. The Process of formation of the soil is known as Pedogenesis. 1 cm soil
formation takes around 5000-10000 years. Soil is essentially formed from Humus and Regolith, which is nothing but disintegrated rock particles or rubble
material i.e. sediments of erosion. Humus is decayed organic material. Soil provides the nutrients to plants. Whole flora depends on the soil for survival.
- Alluvial soils cover almost one-fourth of the whole area of the country and are most intensely cultivated. These soils are generally poor in Nitrogen, but
rich in Potash. These are generally found in river basins like Great Northern Plains and in East and West Coasts.
- Coastal ( somewhat sandy ) alluvium is somewhat inferior to Riverine alluvium, so productivity is less in coastal alluvium. In between the belts of
alluvial soils, we can find patches of infertile lands. These patches are found in Punjab, Haryana, Western Uttar Pradesh and Kerala.
- These soils are suitable for cultivating rice, cotton, sugarcane, tobacco, wheat, jute, etc.
- The main reasons for high productivity of these soils are
- Loamy texture, with sand, silt and clay in equal proportion and porosity and permeability are optimum here
- Spherical structure, the shape in which the soil particles are held together, because of which these soils are easily tillable
- Wide Ranging Nutrients because of transported soil, which is more suitable for different kinds of crops
- These soils respond quite well for water and manuring
Black or Regur Soils
- Black soils are formed due to the disintegration of Lava sheets. These soils cover most of the Deccan Plateau, mainly Western Madhya Pradesh, Maharashtra,
Gujarat, Karnataka, Telangana and some parts of Rajasthan, Tamil Nadu and Uttar Pradesh.
- They are also called Cotton soils as they are best suited for Cotton production. They are also suitable for tobacco cultivation as well as other dry crops
like chillies, linseeds, Jowar, etc.
- The black soils are chemically rich in Lime, Iron, Magnesia and Alumina. They also contain Potash but they lack Nitrogen, Phosphorus and organic
matter. The colour of the Black soils ranges from deep Black to Grey.
- They have very high moisture retaining capacity as well as high moisture absorption capacity. Because of these features, they are suitable for Dryland
Agriculture. Second crop in winter is possible in Black soil region based on the moisture content.
- If the weather is dry and hot, then cracks are formed in these soils. Under waterlogged conditions, it is sticky and muddy. Plough cannot move freely
because of this stickiness.
- These soils are developed from crystalline Igneous rocks in areas of low rainfall in eastern and southern part of Deccan plateau. They are also found in
Central Highlands, Chotanagpur plateau, parts of East, North and North-East India. These soils are the most extensive soils when compared to other soils.
- The soil develops a reddish texture due to extensive diffusion of iron in metamorphic and crystalline rocks. They cannot hold moisture as these are sandy
soils and hence irrigation is necessary.
- They are poor in lime, humus, Nitrogen and Phosphorous. By supplementing deficient minerals, cultivation can be done in an effective way. They are suitable
for cultivating cotton, pulses, wheat, tobacco, potatoes, fruits, Jowar, etc.
- These soils are formed on summits of hills and plateaus due to laterization process, which takes place in a hot and humid condition. In this process, lime
and silica leaches out of the soil because of high rainfall leaving behind oxides and hydroxides of erosion resistant metals like aluminum and iron.
- These soils are mainly found on the hills and plateaus of Vindhya and Satpura ranges, Eastern Ghat regions Odisha, parts of Assam, Maharashtra, Andhra
Pradesh, Karnataka and Kerala.
- The Laterite soils are poor in Nitrogen, Phosphate, organic matter and Calcium and rich in iron oxide and Potash. Crops like Cashew, Casuarina,
Eucalyptus, rice, ragi, sugarcane, etc. are grown here by supplementing with deficient minerals.
Mountainous or Forest Soils
- These soils occur in the slopes of hills and mountains. They are mainly found in Himalayas, Eastern and Western Ghats.
- They are rich in organic matter and Nitrogen and deficient in Phosphorus, Potash and lime. These soils are more suitable for plantation crops like coffee,
tea, spices and fruits.
Saline and Alkaline soils
- These soils are formed because of excessive irrigation along with poor drainage system as a result of which salt formation is high on the soil surface.
These soils are also called 'Usar', 'Reh' or 'Kallar'.
- These are found in parts of Rajasthan, Punjab, Haryana, Uttar Pradesh and Bihar. They are suitable for salt resistant crops like rice, sugarcane and
Arid or Desert Soils
- These soils are predominantly sandy in structure and are mainly found in Western Rajasthan, Haryana, South Punjab.
- The top soil is made up of Calcium Carbonate, Calcium Sulphate and Sodium Sulphate and are not suitable for cultivation as they lack Nitrogen and Phosphate.
If we flush the soil with water, we can use the soil for Agriculture. Few crops like Jowar, Bajra and other coarse millets are grown here.
Peaty and Marshy Soils
- Peaty soils are formed in humid regions because of accumulation of huge amount of organic matter in soil. They are mainly found in some districts of
Kerala, where they are known as Kari. Paddy is generally grown on these soils.
- Marshy soils originate because of heavy water logging, which in turn prevents crop growth. They are having iron and organic matter. They are found in West
Bengal ( Sundarbans ), coastal tracts of Odisha, some parts of Uttar Pradesh and Bihar.