Major Soil Types of India: Classification and Characteristics for UPSC SSC

Alluvial Soils

Alluvial soils are the most widespread and fertile soils in India, covering about 40% of the total land area. They are formed by the deposition of silt, sand, and clay brought by rivers originating from the Himalayas and the Peninsular region. These soils are found extensively in the Northern Plains, from Punjab to Assam, and also in the deltas of major rivers like the Mahanadi, Godavari, Krishna, and Kaveri. They are rich in potash, phosphoric acid, and lime, making them ideal for crops like wheat, rice, sugarcane, and pulses.

Alluvial soils are generally deficient in nitrogen and humus. They are categorized into two types: Khadar (new alluvium) and Bhangar (old alluvium). Khadar soils are found in the floodplains and are renewed every year by floods, making them more fertile. Bhangar soils are found away from the floodplains, are coarser in texture, and contain calcareous concretions called 'kankars'. Their high fertility supports a large population and intensive agriculture.

Black Soils

Black soils, also known as Regur soils or Black Cotton soils, are characteristic of the Deccan Trap region. They cover large areas of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh, and parts of Tamil Nadu. These soils are formed from the weathering of basaltic rocks and are rich in clay content, giving them excellent moisture-retentive capacity. This property makes them highly suitable for growing cotton, hence the name Black Cotton Soil.

Black soils are rich in lime, iron, magnesia, and alumina, and also contain potash. However, they are generally deficient in phosphoric content, nitrogen, and organic matter. They develop deep cracks during hot, dry weather, which helps in aeration. When wet, they become sticky and difficult to work, requiring tillage immediately after the first monsoon shower. Their self-ploughing characteristic is a unique feature.

Red and Yellow Soils

Red soils develop on crystalline igneous rocks in areas of low rainfall in the eastern and southern parts of the Deccan Plateau. They are found in parts of Odisha, Chhattisgarh, the southern parts of the Middle Ganga Plain, and along the piedmont zone of the Western Ghats. The red color is due to the diffusion of iron in crystalline and metamorphic rocks. When these soils are hydrated, they appear yellow.

These soils are generally poor in nitrogen, phosphorus, and humus content. They are typically sandy to loamy in texture and are less fertile than alluvial or black soils. With proper irrigation and use of fertilizers, they can support crops like groundnuts, potatoes, rice, ragi, tobacco, and pulses. Their fertility varies greatly depending on their location and the parent rock material.

Laterite Soils

Laterite soils develop in areas with high temperature and heavy rainfall, which leads to intensive leaching. This process removes silica, leaving behind iron and aluminum oxides. These soils are mainly found in the Western Ghats, Eastern Ghats, North-Eastern Region, and parts of Odisha and West Bengal. They are generally deficient in organic matter, nitrogen, phosphate, and calcium, making them less fertile for cultivation.

Laterite soils are coarse and crumbly in texture. They are suitable for plantation crops like tea, coffee, cashew nuts, and rubber, especially after applying manures and fertilizers. The high iron oxide content makes them hard when dry, and they are often used as building materials, particularly laterite bricks. Their characteristic brick-like hardness is a key identifier.

Arid and Saline Soils

Arid soils, also known as desert soils, are found in arid and semi-arid regions, primarily in Western Rajasthan, parts of Gujarat, and Haryana. They are characterized by a dry climate, high temperatures, and lack of humus and moisture. The soil texture ranges from sandy to gravelly, and they are generally saline in nature. Due to high evaporation, the salt content is very high, and in some areas, the salt is even extracted for commercial use.

These soils are poor in organic matter and nitrogen but rich in phosphate. The lower horizons of these soils are often marked by the presence of 'kankar' layers due to increasing calcium content downwards, which restricts water infiltration. With proper irrigation, these soils can be made cultivable for drought-resistant crops like bajra, jowar, and some pulses. Saline soils are also found in coastal areas and deltas where tidal waters ingress.

Important Keywords Explained

Khadarconcept

Khadar refers to the new alluvium soil found in the floodplains of rivers. These soils are renewed annually by floodwaters, making them highly fertile and suitable for intensive agriculture. They are finer in texture and generally more productive than Bhangar soils.

Bhangarconcept

Bhangar denotes the old alluvium soil, found away from the floodplains and above the level of floodwaters. These soils are coarser in texture and contain calcareous concretions known as 'kankars'. They are less fertile than Khadar soils as they are not renewed annually.

Regur Soilconcept

Regur soil is another name for Black Soil, predominantly found in the Deccan Trap region of India. It is known for its high clay content and excellent moisture-retentive capacity, making it highly suitable for cotton cultivation. These soils are formed from the weathering of basaltic rocks.

Lateritizationconcept

Lateritization is a soil-forming process that occurs in tropical and subtropical regions with high temperatures and heavy rainfall. It involves the intense leaching of silica, leaving behind a high concentration of iron and aluminum oxides, which gives laterite soils their characteristic red color and hardness.

Additional Facts & Context

• The Indian Council of Agricultural Research (ICAR) classified Indian soils into 8 major types in 1956.
• Black soils cover approximately 15% of India's total geographical area.
• Red and Yellow soils cover about 18.5% of India's land area.
• Laterite soils are found in areas receiving more than 200 cm of annual rainfall.
• Saline and Alkaline soils are also known as Reh, Kallar, or Usar soils in local dialects.