Major types of Soil - Indian Geography
Several attempts have been made to classify the soils of India during the last century. The first scientific classification of Indian soils was made by Voelker (1893) and Leather (1898). According to them, the Indian soils may be classified into four (4) categories:
- Alluvial
- Regur (black-earth)
- Red soil
- Lateritic soil
Subsequently, based on texture, structure, color, pH value, and porosity, All India Soil and Land Use Survey Organisation attempted a classification of the soil of India in 1956. In 1957, the National Atlas and Thematic Mapping Organisation published a soil map of India in which Indian soils were classified into six (6) major groups and eleven (11) sub-groups.
In 1963, the Indian Council of Agricultural Research (ICAR), under the supervision of S.P. Ray Chaudhary, published a soil map of India in which the soils have been divided into seven (7) groups.
More recently, the ICAR, based on texture, structure, color, pH value, and location porosity and location has identified the following types of soil groups:
- Alluvial- a.) Khadar, b.) Bangar
Alluvial Soil:
The alluvial soil covers about 143.1 million sq km accounting for about 43.2% of the total reporting area. These soils are mainly derived from the debris brought down from the Himalayans or from the silt left out by the retreating sea. The solar of the alluvial soil varies from light grey to ash grey and texture is from sandy to silty loam. These soils are both well-drained and poorly drained. In general, they have an immature profile in undulating areas, while in the level areas they have a well-developed and mature profile.
These soils may be divided into:
- Khadar soil: These are low-lying frequently inundated by floods during the rainy season. Thus, the khadar occupies the flood plains of the rivers and is enriched by fresh silt deposits every year. In the drier areas, it also exhibits stretches of saline and alkaline efflorescence locally known as reh, kallar, or thur.
- Bangar soil: These are above the flood level. It is generally well-drained but concertion of impure calcium carbonate. The soil texture varies from loamy soil to clayey loam. It is well-drained.
Red Soils:
Red soils occupy the second largest area of about 61 million hectares or 18.5% of the total reporting area. They are found mainly over the area of Penisula from Tamilnadu in the south to Bundelkhand in the north, and Rajmahal in the east to Kathiawad and Kutch in the west. Developed on Archian granite these soils are also known as an omnibus group. Their color is mainly red because of the presence of ferric oxides. In places, where irrigation water is available, they are devoted to wheat, cotton, pulses, tobacco, millets, oilseeds, potato, and orchards.
Black or Regur Soils:
It is also known as cotton soil and internationally a tropical chernozems, is the third-largest soil in India. They sprawl over about 50 million hectares accounting for 15% of the total reporting area of the country. They get their parent material from the weathered rock of Createceous lava. They are mature soils. Over the greater parts of the black earth soil, the average annual rainfall varies between 50 and 70 cm. The soils have a clayey texture. Moreover, these soils have a high retention capacity of water. They are extremely compact and tenacious when wet, and develop wide cracks when dry.
Mountain Soils:
Covering an area of about 18.2 million hectares or about 5.5% of the total reporting area of the country. These soils are found in the valley and hill slopes of the Himalayas between 200 cm and 300 m. These soils are generally immature and are still to be probed systematically. In structure and texture, they vary from silt-loam to loam. Their color is dark brown. These soils can be divided into loamy podzols and high-altitude soils. The high altitude soils, depending on the forest cover, slope, and rainfall are classified as brown earth-type and red-loam. The sub-soil surface of these soils remains frozen under snow. Their soil profile is generally less developed.
Desert Soils:
Sprawling over about 15 million hectares, desert soil accounts for over 4.42% of the total reporting area of the country. These soils are developed under arid and semi-arid conditions and deposited mainly by wind action. The desert soils are sandy to gravelly in texture organic matter, but have low content and low water retention capacity. If irrigated, they give high agricultural returns. The availability of water from the Indira Gandhi Canal has transformed the agricultural landscape of the desert soil of Western Rajasthan.
Laterite Soils:
Their name has been derived from the Latin word Later which means brick. These soils, when wet, are soft as butter, but become quite hard and cloddy on drying. These are the typical soils of the monsoon climate which is characterized by seasonal rainfall. The alternating dry season leads to leaching away of the alkalis and siliceous matter than iron and aluminium of the rock leading to the formation of such soil. Laterite soil hardness rapidly and irreversibly on exposure to the air, a property leads to its use as building bricks. These soils developed mainly in the highland areas of the plate. Though they have low fertility, they respond well to manuring.
Submontane Soils:
These soils are found in the Tarai region of the sub-montane stretching from Jammu & Kashmir to Assam in the form of a narrow belt. These soils have been formed by the deposition of eroded material from the Shiwaliks and the Lesser Himalayas. The soil is fertile and supports the luxuriant growth of the forest. The clearing of forest for agricultural purposes had made this area highly susceptible to soil erosion.
Snowfields:
The areas and snow and glaciers are about 4 million hectares. The soil in these areas is immature generally without soil erosion.
Grey and Brown Soils:
These soils have been formed by the weathering of granite, gneiss, and quartzite. These are loose friable soils. Due to the presence of iron oxide, these soils vary from red to black and brown in color. These soils are found in Gujarat and Rajasthan.
Saline and Alkaline Soils:
The saline soils are characterized by the presence of sodium chloride and sodium sulfate. In these soils, the saline and alkaline efflorescence appear on the surface as a layer of white salt through capillary action. These soils are known by different names in different parts of the country. They are called reh, kallar, usar, rakar, thru, karl, and chopan. These soils are found in Rajasthan, Haryana, Punjab, Uttar Pradesh, Bihar, and Maharashtra. They are deficient in nitrogen, calcium and have low water-bearing capacity. These soils can be reclaimed by improving drainage by applying gypsum and/or lime and cultivating salt-resistant crops like berseem, and leguminous crops.
Peaty and Marshy Soils:
Peaty soils originate in areas of heavy rainfall where adequate drainage is not available. These are generally submerged during the rainy season and utilized for the cultivation of rice.
Karewa Soils:
These are the flat-topped mounds of lacustrine deposits that border the Kashmir valley and all sides. They are composed of fine silt, clay, sand, and bouldery gravel. They are characterized by fossils of mammals and at places by peat. The karewas of Palampur, Pulwama, and Kulgam are well known for their production of superior quality saffron.
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