Classification of Soil in India - Alluvial Soil, Black & Red Soil [UPSC Geography Notes]

Classification of Soil in India includes Alluvial soils, Black soils, Red soils, Laterite and Lateritic soils, and Forest and Mountain soils. The topmost layer of the continental crust is made up of soil, which contains weathered sand particles. India's soils are the result of both natural and human-made influences. Soil is a mixture of small rock fragments/debris and organic materials/humus that forms on the earth's surface and supports plant growth. The soil is the topmost layer of the Earth's crust. It develops due to rock weathering under the influence of the environment, flora, relief, and parent rock. The vast nation of India has a variety of geology, relief, climate, and vegetation. India, hence, has many different soil types that are unique from one another.

Classification of Soil in India is among the most important topics for the UPSC IAS exam. It covers a significant part of the geography subject in the Mains General Studies Paper-1 syllabus and General Studies Paper-1 of the UPSC Prelims Syllabus.

In this article, we shall study in detail the features and classification of soil in India.

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What is Soil?

Soil is a naturally occurring mixture of mineral and organic components, as well as living organisms, that together support the growth of plants. It is a vital natural resource that is essential for human survival and plays a critical role in sustaining life on Earth.

Soil formation is a complex process that involves the breakdown of rocks and organic matter by physical, chemical, and biological processes. Over time, the gradual decomposition of rocks and organic matter forms a mixture of minerals, organic compounds, and living organisms that we call soil.

Classification of Soil in India 

Soils of India are divided into eight categories by the Indian Council of Agricultural Research (ICAR). The All India Soil Survey Committee was founded by the Indian Council of Agricultural Research (ICAR) in 1963, and it categorized Indian soils into eight broad types. This is a highly reasonable classification of Indian soils and has a lot of support. ICAR divided India into the following groups:

• Alluvial soils,
• Black soils,
• Red soils,
• Laterite and Lateritic soils,
• Forest and Mountain soils,
• Arid and Desert soils,
• Saline and Alkaline soils,
• Saline and Alkaline soils

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Also, read NCERT Notes For Geography on Volcanoes here.

Distribution of Soil in India Map

Different Types of Soil in India

The major soil types in India include the following:

Alluvial Soil

Alluvial soils are created by silt carried by rivers like the Indo-Gangetic-Brahmaputra and coastal wave action. They cover around 46% of India's land, supporting over 40% of its population.

Characteristics of Alluvial Soil

These soils are young and not fully developed, with mostly sandy texture and some clay. They vary from loamy to sandy loam in drier areas and clayey loam near the delta.

Types of Allluvial Soil

Chemical Properties of Alluvial Soil

They are low in nitrogen but have sufficient levels of potash, phosphoric acid, and alkalies. Iron oxide and lime content can vary.

Distribution of Alluvial Soil in India

It is found throughout the Indo-Gangetic-Brahmaputra plains, except for areas covered in desert sand. Also, deltas like Mahanadi, Godavari, Krishna, and Cauvery are known as deltaic alluvium. Some regions in Narmada, Tapi valleys, and parts of Gujarat have alluvial soils.

Crops in Alluvial Soil

Well-suited for agriculture, especially rice, wheat, sugarcane, tobacco, cotton, jute, maize, oilseeds, vegetables, and fruits.

Geological Divisions of Alluvial Soil

Alluvium in India's Great Plain is divided into newer khadar and older bhangar soils.

Alluvial Regions with Rainfall

Rainfall above 100cm is suitable for paddy, 50-100cm for wheat, sugarcane, tobacco, and cotton, and below 50cm for coarse grains.

Alluvial Soil

Red Soil

Red soils develop on Archean granite and cover a significant portion of India.

Characteristics of Red Soil

Their characteristics vary based on rainfall, with some types suitable for quick drainage. They are rich in iron and potash but deficient in other minerals.

Features of Red Soil

Chemical Composition of Red Soil

Generally low in phosphate, lime, magnesia, humus, and nitrogen.

Distribution of Red Soil

It is found in the Peninsula from Tamil Nadu to Bundelkhand, Raj Mahal to Kathiawad.

Crops in Red Soil

Supports rice, sugarcane, cotton, millet, and pulses. Kaveri and Vaigai basins are famous for red alluvium and are suitable for paddy.

Also, read NCERT Notes for Geography on Endogenic Process here.

Black or Regur Soil

Formation of Black soil

These soils are formed from the weathering of basaltic rocks that emerged during fissure eruptions in the Cretaceous period. They are typical in dry and hot regions.

Characteristics of Black Soils

Black soils are highly clayey, making them fertile. They retain moisture well, swell when moist, and crack in summer, allowing for oxygenation.

Features of Black Soil 

Chemical Composition of Black Soils

They are rich in iron and lime but lack humus, nitrogen, and phosphorus.

Distribution of Black Soil in India

It is found in the Deccan lava plateau region. It covers parts of Maharashtra, Madhya Pradesh, Karnataka, Telangana, Andhra Pradesh, Gujarat, and Tamil Nadu.

Crops in Black Soil

Ideal for cotton, hence called regur and black cotton soil. Also suitable for wheat, jowar, linseed, tobacco, castor, sunflower, millets, rice, sugarcane, vegetables, and fruits.

Regular Soil/Black Soil

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Desert Soil

Desert soil is primarily found in arid and semi-arid regions. It includes Rajasthan, West of the Aravallis, Northern Gujarat, Saurashtra, Kachchh, Western parts of Haryana, and southern Punjab.

Characteristics of Desert Soil

• This soil lacks moisture. It has low humus content, low organic matter, and a low population of living microorganisms.
• It's rich in iron but has nearly adequate phosphorus and high lime content. It has low soluble salts and low moisture retention capacity.
• If irrigated, desert soil can yield high agricultural returns. It is suitable for less water-intensive crops like bajra, pulses, fodder, and guar.

Distribution of Desert Soil

Desert soil is found in western Rajasthan, the Rann of Kachchh. It is found in patches in southern Haryana and southern Punjab.

Desert Soil 

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Laterite Soil

Formation of Laterite Soil

Develops where laterite rock or structure exists, with alternating dry and wet periods.

Characteristics of Laterite Soil

Brown in color, composed of hydrated oxides of aluminum and iron. Rich in iron and aluminum but poor in other nutrients.

Distribution of Laterite Soil

• Laterite soil is found in specific regions of India.
• It occurs in patches in the Western Ghats, including Goa and Maharashtra.
• It's also present in the Belgaum district of Karnataka and the laterite plateau of Kerala.
• Other areas include: 
  • parts of Orissa in the Eastern Ghats, 
  • the Amarkantak plateau region of Madhya Pradesh, 
  • Panchmahal district in Gujarat, and 
  • Santhal Pangana divisions of Jharkhand.

Significance of Laterite Soil

• Laterite soil is well-known for growing crops like groundnuts and cashew nuts.
• Karnataka's laterite soil is used for cultivating coffee, rubber, and spices.

Laterite Soil

Mountain Soil

This soil is primarily found on mountains with steep slopes, high relief, and shallow profiles.

Characteristics of Mountain soil 

The characteristics of mountain soil include:

• thin layers, 
• poorly developed profiles and horizons, 
• vulnerability to soil erosion, 
• richness in organic content (with adequate humus but deficient in other nutrients), and 
• a loamy composition when sand, silt, and clay are mixed.

Distribution of mountain soil

Mountain soil is typically found at altitudes above 900 meters. These soils occur in regions like:

• the Himalayas, 
• Himalayan foothills, 
• mountain slopes of the Western Ghats, Nilgiri, Annamalai, and Cardamom hills.

Significance of Mountain soil

• Forest soil is beneficial for crops that need good air and water drainage due to its location on slopes.
• It's commonly used for rubber, bamboo, tea, coffee, and fruit plantations.
• Some areas practice shifting agriculture, but soil fertility may decline after 2-3 years.
• Silvi-pastoral farming, combining forest and grassland for animal husbandry, is also sustained due to limited agricultural opportunities.

Mountain Soil

Alkaline and Saline Soils

Saline and alkaline soils contain a high content of sodium chloride (NaCl). They are generally infertile. These soils are also known as Reh, Usar, Kallar, Rakar, Thur, and Chopan.

Formation of Alkaline soil

Saline and alkaline soil can form naturally, such as in dried-up lakes of Rajasthan and the Rann of Kutch. They also form due to anthropogenic factors like faulty agriculture in western UP and Punjab.

Characteristics of Alkaline soils 

This soil lacks moisture and living microorganisms, leading to almost absent humus formation.

Distribution of Alkaline soil

They are mainly found in regions like Rajasthan, Haryana, Punjab, Uttar Pradesh, Bihar, and Maharashtra.

Alkaline and Saline Soil

Peaty and Marshy Soils

This soil originates in areas with poor drainage and is rich in organic matter but has high salinity. It is deficient in potash and phosphate.

Characteristics of Marshy Soil

• Peaty and marshy soil is heavy due to the dominance of clay and mud.
• It has a high moisture content. It also contains a significant amount of salt, making it infertile.
• Excessive moisture inhibits organic activity in these soils.

Distribution of Marshy Soil

• This soil is characteristic of delta regions in India, including the Bengal delta.
• It is also found in places like Alleppey (Kerala). It is known as Karri along the backwaters or Kayals of Kerala and Almora (Uttaranchal).

Significance of Marshy Soil

• In the Bengal delta, it is suitable for jute and rice cultivation. In the Malabar region, it is used for spices, rubber, and large-sized rice.
• Peaty and marshy soil has also been favorable for the mangrove forests of India.

Peaty Soil

Overview of Classification of Soils of India

Type of Soil	Feature	Color	Texture
Alluvial soil	The alluvium is made up of finer rock particles formed by sea waves, Rivers.	Light Grey to Ash Grey.	Sandy to silty loam or clay
Red soil	It is formed by weathering granites, gneisses, crystalline rocks, Ragi, groundnuts, millets, and tobacco grown well in these soils.	Reddish to Brownish	Sandy to clay and loamy.
Black soil	Get its name black coloration of the Basalt rock, suited for cotton production.	Deep black to light black.	Clayey
Arid and Desert soils	low in nitrogen, humus, phosphates, and nitrates – making them unsuitable for cultivation	Red to Brown	Sandy
Laterite and Lateritic soils	Acidic in higher elevations, low in calcium and magnesium – useful in growing rice as well as plantation crops such as cashew, rubber	Red color due to iron oxide	thick loam to clayey
Mountain soils	Ideal for growing plantation crops such as tea, coffee, spices, and tropical fruits	dark brown color	clayey silt to loamy texture
Saline and Alkaline soils	These soils are infertile and uncultivable	white alkali or brown alkali	sandy to loamy
Peaty Soils	forms in hot, humid conditions	dark, almost black in hue	spongy

Also, read NCERT Notes For Geography on Earthquakes here.

Classification of Indian Soil as per USDA

According to the United States Department of Agriculture's (USDA) Soil Taxonomy, the Indian Council of Agricultural Research (ICAR) has classified Indian soil based on its order and percentage.

S.No	Order	Percentage
1.	Inceptisols	39.74
2.	Entisols	28.08
3.	Alfisols	13.55
4.	Vertisols	8.52
5.	Aridisols	4.28
6.	Ultisols	2.51
7.	Mollisols	0.40
8.	Others	2.92

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