Classification of Indian soils | IBPS PO Prelims & Mains Preparation - Bank Exams PDF Download

• The different types of soil found in India show the variety created by the country's unique geography and climate.
• Knowing about these soil types is essential for improving farming methods and promoting responsible use of land.
• This article will explore the various types of soilsin India, including:
  • Characteristics of each soil type
  • Chemical properties associated with them
  • The crops that grow best in each type of soil

What is Soil?

• Soil is made up of a mix of rock fragments and organic material that forms on the Earth's surface.
• The main components of soil include mineral particles, humus (which is decomposed organic matter), water, and air.
• Soil formationis a gradual process influenced by various natural forces such as:
  • Changes in temperature
  • The actions of running water
  • Wind
  • Glaciers
  • The activities of decomposers
• These forces break down rocks and organic material over time.
• It can take millions of years to develop soil that is just a few centimeters deep.

Types of Soils in India

• The varied relief features, landforms, climatic realms, and vegetation types of India have contributed to the development of various soil types in India.
• Based on this, the Indian Council of Agriculture Research (ICAR)classified soils into eight types:
  • Alluvial Soils,
  • Red Soils,
  • Black Soils (Regur),
  • Desert Soils,
  • Laterite Soils,
  • Mountain Soils,
  • Alkaline Soils, and
  • Peaty and Marshy Soils.

All these soils of India have been discussed in detail in the following section.

Alluvial Soil in India

• Alluvial soilin India are found primarily in the Indo-Ganga-Brahmaputra Plains, the valleys of the Narmada and Tapi, as well as the Eastern and Western Coastal Plains.
• These soils are mainly formed from debris from the Himalayas or from the silt deposited by the retreating sea.
• Alluvial soils represent the largest soil group in India, covering approximately 46% of the total land area.
• They are vital for agriculture, as they support over 40% of the Indian population.

Characteristics of Alluvial Soil

• The color of alluvial soils ranges from light grey to ash grey.
• The texture of these soils can be sandy to silty loam.
• Alluvial soils can be classified as well-drained or poorly drained.
• In undulating areas, these soils typically have an immature profile.
• In contrast, in flat areas, they exhibit a well-developed and mature profile.

Chemical Properties of Alluvial Soil

• The soil has a low nitrogen content.
• However, it has enough potash, phosphoric acid, and alkaline present.

Types of Alluvial Soil in India

The alluvial soils in India may be divided into the following:

Khadar Soil

• The Khadar soils are found in low-lying areas that often get flooded during the rainy season.
• These soils are located in the flood plains of rivers and receive fresh layers of silt every year, which enriches them.
• In drier regions, Khadar soils may also show areas with saline and alkaline deposits that are locally referred to as reh, kallar, or thur.

Bhangar Soil

• Elevation: The area is above the flood level.
• Drainage: The land is generally well-drained.
• Soil Composition: Contains concretions of impure calcium carbonate known as kankars.
• Soil Texture: Varies from loamy to clayey loam.
• Agricultural Suitability:The soil is well-suited for growing:
  • Wheat
  • Rice
  • Maize
  • Sugarcane
  • Pulses
  • Oilseeds
  • Barseem (fodder)
  • Fruits
  • Vegetables
• Nutrient Content:Alluvial soils are rich in:
  • Humus
  • Phosphoric acid
  • Lime
  • Organic matter
• However, they lack potash.

These are the best agricultural soil due to the following reasons:

• They consist of various salts that come from Himalayan rocks.
• The soils are light and porous, making them easy to work with.
• Due to a high water table and a layer that allows easy water movement, these soils are good for canal irrigation.
• However, since the water is found very deep, these soils are not suitable for plants that need water close to their roots.
• These soils are rich in potash, but they have low levels of nitrogen and organic matter.

Red and Yellow Soil in India

• They are mainly located across the Peninsula from Tamil Nadu in the south to Bundelkhand in the north, and from Rajmahal in the east to Kathiawad and Kutch in the west. 
• These soils can also be found in areas of western Tamil Nadu, Karnataka, southern Maharashtra, Andhra Pradesh, Chhattisgarh, Jharkhand, and Orissa. 
• Additionally, they exist in scattered areas of Bundelkhand, Mirzapur, Sonbhadra (in Uttar Pradesh), Banswara, Bhilwara, and Udaipur (in Rajasthan). 

Characteristics of Red and Yellow Soil

• Geographical Coverage: Red soils make up about 18.5% of India's total land area.
• Color: The primary color of red soil is red due to the presence of ferric oxides.
• Layers: Typically, the top layer of this soil is red, while the layer beneath has a yellowish hue.
• Hydration: When the soil is wet, it takes on a yellow appearance.
• Texture: The texture of red soils can range from sand to clay and loam.
• Structure: Red soils have a porous and friable structure.
• Composition: They lack lime, kankar, and carbonates, and contain a small amount of soluble salts.
• Location: These soils are mainly found in areas with low rainfall.

Chemical Properties of Red and Yellow Soil

• Soil Deficiencies: These soils usually lack essential nutrients such as lime, phosphate, magnesia, nitrogen, humus, and potash. 
• Leaching Risks: Heavy leaching is a major risk for these soils, affecting their overall health and fertility. 
• Soil Types: In higher areas, the soils are generally thin, poor-quality, and consist of gravel, sandy, or stony materials, making them porous and light in color. 
• Lower Plains and Valleys: Conversely, in the lower regions and valleys, the soils are much richer, deeper, and have a dark color, constituting fertile loams. 
• Crops Grown: In areas where there is access to irrigation water, the main crops include: 
  • wheat
  • cotton
  • pulses
  • tobacco
  • millets
  • oilseeds (like linseed)
  • potatoes
  • orchards

Black Soil in India

• Black soils, commonly referred to as Regur or cotton soil, are formed from the weathered remains of Cretaceous lava rocks.
• These soils are found widely across several states in India, including: 
  • Gujarat
  • Maharashtra
  • Western Madhya Pradesh
  • North-western Andhra Pradesh
  • Karnataka
  • Tamil Nadu
  • Rajasthan
  • Chhattisgarh
  • Jharkhand
  • Extending up to the Rajmahal Hills
• These soils are considered mature soils.
• The average annual rainfall in regions with black soil typically ranges from 50 to 75 cm.
• The color of black soils can vary, typically ranging from deep black to light black.

Characteristics of Black Soil

• Black soils cover about 15% of India's total land area.
• These soils are known for their high water-retaining ability.
• When wet, they are compact and sticky, but they form wide cracks when they dry out.
• During the rainy season, they swell significantly, making them difficult to work with.
• When the soil is wet, it can be hard to plow the fields because the plow tends to get stuck in the mud.
• In the dry season, moisture evaporates, causing the soil to shrink and create cracks that can be 10-15 cm deep.
• This shrinking leads to a natural self-ploughing effect.
• Black soil has a slow rate of moisture absorption and gradual moisture loss, which helps it retain water for a long time.
• This quality is beneficial for crops, especially those that rely on rain, allowing them to survive even during dry spells.

Chemical Properties of Black Soil

• These soils usually have a clay-like texture and are abundant in iron, lime, calcium, potash, aluminium, and magnesium.
• However, they lack sufficient nitrogen, phosphorus, and organic matter.

Important Crops

• These soils are very productiveand are ideal for growing:
  • Cotton
  • Pulses
  • Millets
  • Linseed
  • Castor
  • Tobacco
  • Sugarcane
  • Vegetables
  • Citrus fruits

Desert Soil in India

• These soils are formed in dry and semi-dry areas.
• They are mainly created by wind deposits.
• These soils can be found primarily in:
  • Rajasthan, located to the west of the Aravalli mountains.
  • Northern Gujarat.
  • Saurashtra.
  • Kutch.
  • Western regions of Haryana.
  • South-western parts of Punjab.

Chemical Properties of Desert Soil

• The desert covers about 4.4% of the total land area. 
• Desert soils are primarily sandy or gravelly, with low organic matter, low nitrogen, and varying amounts of calcium carbonate. 
• These soils have a high level of soluble salts, but they retain little moisture and have a low capacity to hold water. 
• When irrigated, desert soils can lead to high agricultural yields. 
• Important crops grown in these areas include bajra, pulses, guar, and fodder, which require less water. 
• The availability of water from the Indira Gandhi Canal has significantly changed farming in the desert regions of western Rajasthan. 

Laterite Soil in India

• Monsoon climate soils are typically found in areas with seasonal rainfall. 
• When it rains, substances like lime and silica are washed away, resulting in soil that is rich in iron oxide and aluminium. 
• This process leads to the creation of laterite soil. 
• The term "laterite" comes from the Latin word “later”, which means brick. 
• The red laterite soil found in places like Kerala, Tamil Nadu, and Andhra Pradesh is ideal for growing tree crops such as cashew nuts. 
• One important feature of laterite soil is that it hardens quickly and permanently when exposed to air. 
• This characteristic makes it useful for making building bricks in southern India. 

Chemical Properties of Laterite Soil

• These soils cover about 3.7% of India's total land area.
• The red color of the soil is caused by the presence of iron oxide.
• Soils in the higher regions tend to be more acidic compared to those in the lower areas.
• These soils are high in iron and aluminium but low in nitrogen, potash, potassium, lime, and organic matter.
• Even though they are not very fertile, they respond well to manuring.
• These soils are primarily located in the highlands of the plateau, including the hills of:
  • Western Ghats
  • Eastern Ghats
  • Rajmahal Hills
  • Satpura
  • Vindhya
  • Orissa
  • Chhattisgarh
  • Jharkhand
  • West Bengal
  • North Cachar Hills of Assam
  • Garo Hills of Meghalaya
• Important crops grown in these soils include:
  • Rice
  • Ragi
  • Sugarcane
  • Cashew nuts

Mountain Soil in India

• They cover about 3.7% of the total land area of India. 
• The soil appears red because of the presence of iron oxide. 
• Soils found in higher regions tend to be more acidic compared to those in lower areas. 
• These soils are high in iron and aluminium, but they are low in nitrogen, potash, potassium, lime, and organic matter. 
• Even though they are not very fertile, they respond positively to manuring. 
• These soils can mainly be found in the highlands of plateaus, as well as in the hills of the Western Ghats, Eastern Ghats, Rajmahal Hills, Satpura, Vindhya, Orissa, Chhattisgarh, Jharkhand, West Bengal, North Cachar Hills of Assam, and the Garo Hills of Meghalaya. 

Saline and Alkaline Soils

• The saline soils are defined by the presence of sodium chloride and sodium sulphate.
• These soils often show a white layer of salt on the surface, which forms through capillary action.
• This saline and alkaline efflorescence indicates the accumulation of salts at the top layer of the soil.

Chemical Properties of Saline and Alkaline Soils

• These soils range from sandy to sandy loam textures.
• They lack nitrogen and calcium and have a very low ability to hold water.
• Improving drainage, using gypsum and/or lime, and growing salt-resistant crops like barseem, dhaincha, and other leguminous crops can help reclaim these soils.
• These soils are known by various names in different regions, including reh, kallar, usar, rakar, thur, karl, and chopan.
• They are found in the states of Rajasthan, Haryana, Punjab, Uttar Pradesh, Bihar, and Maharashtra.

Peaty and Marshy Soils in India

• Peaty soils form in regions that experience a lot of rain and where there is not enough drainage.
• These soils are usually underwater during the rainy season.
• They are commonly used for growing rice.

Chemical Properties of Peaty and Marshy Soils

• The soils are rich in organic matter but have a high level of salinity. 
• They lack phosphate and potash. 
• These soils are mainly found in parts of the Kottayam and Alappuzha districts of Kerala. 
• They can also be seen in the Sundarban delta. 
• Other locations where these soils exist include the deltas of the Mahanadi, Godavari, Krishna, Kaveri, and the Rann of Kutch. 

Conclusion

The different types of soil in India show the country’s wide range of geographical and climatic conditions. Each soil type has its own special features and qualities that affect how well it can support various crops and farming methods. The ICAR classification offers a detailed system to help understand these differences. This system assists farmers, policymakers, and researchers in making smart choices for improving crop yields and protecting the soil. As India progresses in agricultural science and technology, keeping the soil healthy and fertile will be essential for its farming plans.