1) Alluvial Soil
2) Black Soils
3) Red Soil
4) Laterite Soil
5) Forest Soil
6) Arid and Desert Soils
7) Saline and Alkaline Soils
1. Alluvial Soil:
- Alluvial soils are mostly found in Northern plains running from Punjab in the west to West Bengal and Assam in the East.
- It is also found in Narmada and Tapti valleys in Madhya Pradesh and Gujarat, Mahanadi valley in Chhattisgarh and Odisha, Godavari valley in Andhra Pradesh and Cauvery valley in Tamil Nadu.
- Alluvial soils are the largest soil group covering about 15 lakh sq km or about 6 per cent of the total area.
- Alluvial soils are deficient in nitrogen and humus therefore it requires fertilisation.
- The fine particles of sand, silt and clay are called alluvium.
- The alluvial soil can be divided into old alluvium (bangar) and new alluvium (khadar).
- Alluvial soils are suitable for production of crops of rice, wheat, maize, sugar cane, tobacco, cotton, jute, oilseeds, etc.
- They are mostly flat and regular soils and are best suited for agriculture.
- They are best suited to irrigation and respond well to canal and well/tube-well irrigation.
Geologically, the alluvium of the Great plain of India is divided into newer or younger khadar and older bhangar soils.
The Bhangar is the older alluvium along the river beds forming terraces higher than the flood plain (about 30 metres above the flood level).
It is of a more clayey composition and is generally dark colored.
The Khadar is composed of newer alluvium and forms the flood plains along the river banks.
The banks are flooded almost every year and a new layer of alluvium is deposited with every flood. This makes them the most fertile soils of Ganges.
They are sandy clays and loams, more dry and leached, less calcareous and carbonaceous (less kankary).
A new layer of alluvium is deposited by river flood almost every year.
Note: The khadar soil is sandy and light in colour, while the bhangar soil is clayey and dark.
The khadar soil is more fertile than the bangar soil.
2. Black Soil:
- Black soil is found largely in the Deccan Plateau covering large areas of Maharashtra, Gujarat and western Madhya Pradesh. It is also found in Karnataka, Andhra Pradesh and Tamil Nadu.
- These are the region of high temperature and low rainfall. It is, therefore, a soil group typical to the dry and hot regions of the Peninsula.
- The colour of the soil is black due to the presence of compound of iron and aluminium.
- This soil is rich in calcium carbonate, magnesium carbonate, potash and lime, but deficient in nitrogen.
- Black soil is best suited for cotton crop. Hence these soils are called as regur and black cotton soils.
- Other major crops grown on the black soils include wheat, jowar, linseed, virginia tobacco, castor, sunflower and millets.
- This soil has been used for growing a variety of crops for centuries without adding fertilizers and manures, with little or no evidence of exhaustion.
- Red Soils occupy about 3.5 lakh sq km (10.6 per cent) of the total area of the country.
- The red soil occurs mostly in the south-eastern peninsula. It is mainly found in Tamil Nadu, parts of Karnataka, south-east Maharashtra, parts of Andhra Pradesh, Madhya Pradesh, Orissa and Jharkhand.
- The soil is made up of crystalline and metamorphic rocks.
- It is rich in ferromanganese minerals and soluble salts but is deficient in nitrogen and humus and hence needs fertilisation.
- They are acidic mainly due to the nature of the parent rocks. The alkali content is fair.
- The colour of the soil is red due to the high percentage of iron contents.
- Red soil has a light texture and a porous structure.
- The red soils are mostly loamy and hence cannot retain water like the black soils.
- The red soils, with the proper use of fertilizers and irrigation techniques, give good yield of wheat, rice, pulses, millets, tobacco, oil seeds, potatoes and fruits.
- Laterite soil is found in areas of high rainfall and temperature with alternate dry and wet periods.
- The laterite soil is widely spread in India and is mainly found in the high reaches of the Western Ghats, Eastern Ghats, Rajmahal Hill s, Vindhyas, Satpuras and Malwa plateau. It is also found in parts of Karnataka, Andhra Pradesh, Kerala, Odisha and West Bengal.
- It contains high content of iron oxides but is deficient in nitrogen.
- ‘Laterite’ means brick in Latin. They harden greatly on loosing moisture.
- Laterite soils are red in colour due to little clay and more gravel of red sand-stones.
- Laterite soils lack fertility due to intensive leaching.
- When manured and irrigated, some laterites are suitable for growing plantation crops like tea, coffee, rubber, cinchona, coconut, arecanut, etc.
- In some areas, these soils support grazing grounds and scrub forests.
- Forest soils are found in the Himalayas and other mountain regions of the north.
- These soils occupy about 2.85 lakh sq km or 8.67% of the total land area of India.
- These are mainly heterogeneous soils found on the hill slopes covered by forests.
- These soils are very shallow, stony, and infertile for the production of field crops.
- This type of soil is useful for forest produce such as timber, tropical fruits and fuel.
- These are deficient in potash, phosphorus and lime and require good deal of fertilizers for high yields.
- The desert soils consist of Aeolian sand (90 to 95 per cent) and clay (5 to 10 per cent).
- These cover a total area of 1.42 lakh sq km (4.32%).
- The arid and semi-arid regions of north-west India receiving less than 50 cm of annual rainfall have this type of soil.
- It is largely found in Rajasthan, parts of Haryana and Punjab and extends up to the Rann of Kutch in Gujarat.
- These types of soils are deficient in nitrogen but have high content of phosphates. It is unfertile but its fertility can be improved by adding lime or gypsum.
- These are usually poor in organic matter.
- Some desert soils are alkaline with varying degree of soluble salts like calcium carbonate.
- Phosphates and nitrates make these soil fertile wherever moisture is available.
- In large areas, only the drought resistant and salt tolerant crops such as barley, cotton, millets, maize and pulses are grown.
- Saline and Alkaline soils are found in the arid and semi-arid parts of Rajasthan, Punjab, Haryana, Uttar Pradesh and Bihar.
- These soils are characterised by white incrustation of salts of calcium, magnesium and sodium on the surface.
- These soils are known by different names such as 'reh', 'usar', 'kallar', 'chopan', etc.
- Accumulation of salt make this soil unfertile and unsuitable for agricultural production.
- This soil is suitable for production of crops such as wheat, tobacco, millets, barley, maize, pulses, cotton, etc.
- Along the coastline, saline sea waters infiltrate into coastal regions during storm surges (when cyclones make landfall) and makes the soil unfit for cultivation.
- The low lying regions of coastal Andhra Pradesh and Tamil Nadu face this kind of soil degradation.