Soils in India
Soil Groups: 8 Major Soil Groups available in India
major soil groups available in India are: 1. Alluvial Soils 2. Black Soils 3. Red Soils 4. Laterite and Lateritic Soils 5. Forest and Mountain Soils 6. Arid and Desert Soils 7. Saline and Alkaline Soils 8. Peaty and Marshy Soils
India is a country of vast dimensions with varied conditions of geology, relief, climate and vegetation. Therefore, India has a large variety of soil groups, distinctly different from one another. Different criteria have been applied to classify Indian soils, the outstanding being geology, relief, fertility, chemical composition and physical structure, etc.
The earlier studies of Indian soils were made by foreign scholars like Volckar (1893), Leather (1898), Schokalskaya (1932), Champion (1936), etc. Indian scholars including Wadia (1935), Basu (1937), Vishwanath and Ukil (1944), Chatterjee, Krishnan, Roychaudhary (1954) made strenuous efforts to classify soils of India.
Geologically, Indian soils can broadly be divided into two main types: (a) Soils of peninsular India and (b) Soils of extra-peninsular India.
The soils of Peninsular India are those which have been formed by the deomposition of rocks in situ, i.e. directly from the underlying rocks. They are transported and redeposited to a limited extent and are known as sedentary soils.
On the other hand, the soils of the Extra-Peninsula are formed due to the depositional work of rivers and wind. They are mainly found in the river valleys and deltas. They are very deep and constitute some of the most fertile tracts of the country. They are often referred to as transported or azonal soils.
The Indian Council of Agricultural Research (ICAR) set up an All India Soil Survey Committee in 1953 which divided the Indian soils into eight major groups. They are (1) Alluvial soils, (2) Black soils, (3) Red soils, (4) Laterite and Lateritic soils, (5) Forest and Mountain soils, (6) Arid and Desert soils, (7) Saline and Alkaline soils and (8) Peaty and Marshy soils
Alluvial soils are by far the largest and the most important soil group of India. Covering about 15 lakh sq km or about 45.6 per cent of the total land area of the country, these soils contribute the largest share of our agricultural wealth and support the bulk of India’s population. They are depositional soils, transported and deposited byrivers and streams. These soils are formed by the deposition of fine sediments and silt by the rivers along theirbanks. In India, alluvial soils are mostly found in the Great Northern Plains, the coastal plains and river deltas.
They can be divided into two types:
1. Young Khadar soils: these are newer alluvium of sandy, pale brown composition, found in lower areas of valley
bottom which are flooded almost every year. It is non phorous, clayey and loamy.
2. Old Bhangar soils: these consist of older alluvium of clayey composition and are dark in colour.
They are coarse in nature, contain kankar (lime nodules), pebbles, gravels. They are found 30 m above flood level of
They represent the ‘riverine alluvium’ brought down by Sutlej, Yamuna, Ghagra and other rivers of Indo-Gangetic
. These soils are covering 22.16 per cent of total area of India.
The black soils are also called regur (from the Telugu word Reguda) and black cotton soils because cotton is the most important crop grown on these soils. Several theories have been put forward regarding the origin of this group of soils but most pedologists believe that these soils have been formed due to the solidifaction of lava spread over large areas during volcanic activity in the Deccan Plateau, thousands of years ago.
– Black soil is called as ‘Black Cotton Soil’ or ‘Regur Soil’.
The black colour of regur soil is due to its iron content, deriving from plutonic lava materials.
Mainly found in the Deccan region which includes the major part of Maharashtra, Gujarat and part of Tamil Nadu, Andhra Pradesh and Madhya Pradesh.
Cotton is most important crop grown on this soil.
They swell and become sticky when wet and shrink when dried During dry season, these soils develop wide cracks.
Rich in lime and iron, magnesia and alumina Also contain potash
Lack phosporus, nitrogen and organic matter
Spread over an area of 5.4 sq. km., i.e. 16.6 % of the total land area of the country.
Red Soil in IndiaRed Soil in India comprises of more drainage properties than other types of soils as it is formed of clay, created by wearing and tearing of limestone and formed by the breakdown of igneous rocks and metamorphic rocks. When limestone erodes, the clay enclosed within the rocks remains intact with other forms of non-soluble materials. In oxidizing conditions, rust or iron oxide develops in the clay, when the soil is present above the water table giving the soil a characteristic red colour. Red soil in India lacks nitrogenous material, phosphoric acid, organic matter and is rich in iron. Some of the major crops grown in the red soil in India include groundnut, millets, ragi, rice, potato, sugarcane, wheat, tobacco etc.
The red soils occupy a vast area of about 3.5 lakh sq km which is about 10.6 per cent of the total geographical area of the country. These soils are spread on almost the whole of Tamil Nadu, parts of Karnataka, south-east of Maharashtra, eastern parts of Andhra Pradesh and Madhya Pradesh, Chhattisgarh, Orissa and Chota Nagpur in Jharkhand.
poor in Lime, Nitrogen and humus.
Red soils are reddish in colour due to the presence of iron.
Formed due to weathering of ancient crystalline and metamorphic rocks.
Parent rocks are acid granites and gneisses.
Occupy an whi area of about 3.5 lakh sq km – 10.6% of the total land area of the country .
Laterite soil is rich in aluminium and iron, formed in wet and hot tropical areas. Almost all laterite soils are red due to the presence of iron oxides. It is prepared by the prolonged and rigorous weathering of the parent rock. Laterisation or tropical weathering is a long-drawn-out process of chemical and mechanical weathering which results in a large variety in the chemistry, grade, thickness and ore mineralogy of the ensuing soils. Laterite soils are pregnant with aluminium and iron oxides, but are deficient in potash, phosphoric acid, lime and nitrogen.
Laterite soil is primarily found in the tropical regions which receive heavy seasonal rainfall. High rainfall encourages the leaching of soil where lime and silica are leached away and a soil rich in oxides of aluminium predominate and abundance laterite is called bauxite. Due to the presence of iron oxides the colour of laterite soil is basically red. This soil is poor in lime content and hence it is acidic. Laterite soils are found on the high level plateau and hilly areas that receive high rainfall and are specifically well developed on the Eastern Ghats in Orissa. It is also found in the southern regions of the Western Ghats including the adjoining coastal regions in Ratnagiri District and Malabar.
Humus is almost absent in this type of soil. However, in the laterite soil developed in the forested areas in the western part of Karnataka state, humus is present. Further, laterite soils of high level areas are very poor and least retentive of moisture and at times barren. But, in the low lying areas, regular addition of soils that are washed down from the adjacent higher areas affects lateritisation. In those areas, the lateritic soil being either mud or loam is useful and is regularly ploughed. For the continuous cultivation of crops, regular application of fertilizers is required. Laterite soil is found in different parts of India including the Eastern Ghats, Rajmahal hill, Western Ghats, Maharashtra, Kerala, Orissa, Karnataka, West Bengal, Tamil Nadu, Assam, etc. Laterite soil is also widely found around the Satpura, Vindhyan Plateau, Maikal and Mahadeo ranges in Madhya Pradesh.
soils are mainly found on the hill slopes covered by forests. These soils occupy about 2.85 lakh sq km which is about 8.67 per cent of the total land area of India. The formation of these soils is mainly governed by the characteristic deposition of organic matter derived from forest growth.
These soils are heterogeneous in nature and their character changes with parent rocks, ground-configuration and climate. Consequently, they differ greatly even if they occur in close proximity to one another. In the Himalayan region, such soils are mainly found in valley basins, depressions, and less steeply inclined slopes. Generally, it is the north facing slopes which support soil cover; the southern slopes being too precipitous and exposed to denudation to be covered with soil.
Apart from the Himalayan region, the forest soils occur on Western and Eastern Ghats as well as in some parts of the Peninsular plateau.The forest soils are very rich in humus but are deficient in potash, phosphorus and lime. Therefore, they require good deal of fertilizers for high yields. They are especially suitable for plantations of tea, coffee, spices and tropical fruits in Karnataka, Tamil Nadu and Kerala and wheat, maize, barley and temperate fruits in Jammu and Kashmir, Himachal Pradesh and Uttaranchal.
ARID AND DESERT SOILS
Desert Soils in IndiaDesert soils are basically of sandy texture. This type of soil has poor clay content and also lacks in moisture content. Desert soils are generally of brown, light brown or reddish colour. Due to the arid conditions, leaching of soil is almost absent in the desert soils and thus evaporation is quite rapid Deserts are defined as areas with an average annual precipitation of less than 250 millimetres (10 in) per year. Desert soils are basically poor in nitrogen, which is an important nutrient required for the plantation purpose. These soils when irrigated properly produce rich crops. The soils of the arid zone actually are sandy to sandy loamy in texture. The depth and consistency vary according to the topographical features. The low lying loams are heavy and have a hard pan. Some of the desert soils contain high percentage of soluble salts in the lower horizons turning water in the wells poisonous.
Rajasthan Desert is covered with sand at most of the places. Moreover, small mounds of sand and fine dust particles also occur in some districts of states like Punjab and Haryana that are very close to Rajasthan. The desert soils or sandy soils are also called as ‘bhur’. They also grow along the river courses and coast. In Rajasthan Desert, south-west monsoon is relatively strong during summer season. These strong dust storms and winds carry fine dust and leave behind bigger sand particles. As a result, the soils in the west of the Aravalli Mountain Ranges become more and more sandy and thus are infertile..
-Covers an area of about 1.4 lakh sq km
SALINE AND ALKALINE SOILS
These soils are found in Andhra Pradesh and Karnataka. In the drier parts of Bihar, Uttar Pradesh, Haryana, Punjab, Rajasthan and Maharashtra, there are salt-impregnated or alkaline soils occupying 68,000 sq km of area. These soils are liable to saline and alkaline efflorescences and are known by different names such as reh, kallar, usar, thur, rakar, karl and chopan.
There are many undecomposed rock and mineral fragments which on weathering liberate sodium, magnesium and calcium salts and sulphurous acid. Some of the salts are transported in solution by the rivers, which percolate in the sub-soils of the plains.
In canal irrigated areas and in areas of high sub-soil water table, the injurious salts are transferred from below to the top soil by the capillary action as a result of evaporation in dry season. The accumulation of these salts makes the soil infertile and renders it unfit for agriculture.
It has been estimated that about 1.25 million hectares of land in Uttar Pradesh and 1.21 million hectares in Punjab has been affected by usar. In Gujarat, the area round the Gulf of Khambhat is affected by the sea tides carrying salt-laden deposits. Vast areas comprising the estuaries of the Narmada, the Tapi, the Mahi and the Sabarmati have thus become infertile.
Peaty and Marshy Soils:
Peaty soils originate in humid regions as a result of accumulation of large amounts of organic matter in the soils. These soils contain considerable amount of soluble salts and 10-40 per cent of organic matter. Soils belonging to this group are found in Kottayam and Alappuzha districts of Kerala where it is called kari.
Marshy soils with a high proportion of vegetable matter also occur in the coastal areas of Orissa and Tamil Nadu, Sunderbans of West Bengal, in Bihar and Almora district of Uttaranchal. The peaty soils are black, heavy and highly acidic. They are deficient in potash and phosphate. Most of the peaty soils are under water during the rainy season but as soon the rains cease, they are put under paddy cultivation.