LAND FORMS & SOIL - PART 3
SOILS IN INDIA
SOIL: Soil is the uppermost layer of Earth’s crust. Soil is the medium in which plants grow and thus it supports the lives on earth.
FACTORS THAT CONTROL THE FORMATION OF SOIL
• A number of factors contribute to the soil formation and fertility.
1. PARENT ROCKS : The rock on which the soil is formed decomposes and disintegrates under the processes of weathering. The characteristics of rocks influence the characteristics of soils. For example on lava rocks black soils and iron oxide rich rocks red soils are formed.
SOIL: Soil is the uppermost layer of Earth’s crust. Soil is the medium in which plants grow and thus it supports the lives on earth.
FACTORS THAT CONTROL THE FORMATION OF SOIL
• A number of factors contribute to the soil formation and fertility.
1. PARENT ROCKS : The rock on which the soil is formed decomposes and disintegrates under the processes of weathering. The characteristics of rocks influence the characteristics of soils. For example on lava rocks black soils and iron oxide rich rocks red soils are formed.
2. CLIMATE: Climate influence the rate of weathering of rocks and type of vegetation, thus these influence the characteristics of soils.
3. SLOPE: The nature of relief and slope influence the accumulation of soils. Mountains have thin soil cover but the plains have thick soil cover.
4. TIME: Time provides maturity to the soil.
5. Various forces of nature such as change in temperature, actions of running water, wind and glaciers, activities of decomposers etc. contribute to the formation of soil.
6. Chemical and organic changes which take place in the soil are equally important.
The soils of India on the basis of their formation are divided in the following two broad catagories-
• Residual Soil-which form at the place of their origin. Like – black soils
• Transported Soil-which are transported from place of their formation. Like alluvial soils.
The major soil groups are:
According to ICAR (Indian Council of Agricultural Research) soils are divided into 8 categories. they are:
1) BLACK SOIL
• Black soil is made from lava-solidified rocks and is also 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.
CHARACTERISTICS
• Clayey, deep and impermeable.
• 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 potashLack phosporus, nitrogen and organic matterVery clayey and therefore highly retentive of water.
• Because of high clay content, these soils expand when wet and become difficult to plough.
• During dry season, black soils shrink and develop big cracks which help in air circulation.
• Dark in colour, suitable for cotton cultivation are residual soils.
• Spread over an area of 5.4 sq. km., i.e. 16.6 % of the total land area of the country.
2) RED SOIL
• These soils are found in Chhotanagpur plateau, Telangana, Nilgiris, Tamil Nadu, Karnataka, Andhra Pradesh and periphery areas of Deccan Plateau.
• These soils have been formed due to decomposition of underlying igneous rocks under heavy rainfall.
• These are suitable for the cultivation of millets, pulses, Linseed, tobacco etc.
• These soils are poor in Lime, Nitrogen and humus.
CHARACTERISTICS
• Redsoils 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.
• These are transported type soils.
• Are mostly light to dark colour depending on new or old alluvium.
• Rich in potash and become fertile with the proper use of fertilizers and irrigation.
• Deficient in nitrogen,lime, magnesia, humus and phosphate Red due to its very high iron content.
• Are porous, friable in nature .Loose and aerated.
• Contains soluble salts in small quantities.
3) LATERITE SOIL
• Laterite = brick (Latin word)
• These soils are formed under conditions of high temperature and heavy rainfall with alternate wet and dry periods.
• Thus its formation takes place strictly under monsoon conditions.Residual soils formed by leaching in areas of heavy rain.
• Leaching is a process in which the nutrients get percolated down below the soil due to heavy rainfall; thus leaving the top soil infertile. Also called DESILICATION.
• Laterite soils are found in elevated areas which receive very high rainfallAs a result, top soil gets washed away. This process is called leaching.
• The soil, therefore, loses its fertility to a great extent.
• It covers an area of about 2.4 lakh sq km.
• These soils are found in the north-eastern state of Meghalaya in India. Laterite soils are found on the highland areas of the plateau.
• These are found in Karnataka, Kerala, Tamil Nadu and hilly regions of Assam, Rajmahal hills and Chhotanagpur plateau.
• These are shallow, acidic and less fertile soils. These soils are poor in lime but rich in iron.
• So these are suitable for plantation of crops like tea, rubber, coffee etc.
• Is of coarse texture, soft and friable.Is red due to the presence of iron oxide which is formed by leaching.
• The soluble plant foods like potash are removed from the top soil leaving alumina and iron oxide.
• Is a porus soil, silica is removed from it by chemical action.Is poor in lime and magnesium, and deficient in nitrogen.
4) ALLUVIAL SOIL
• (Riverine soil)It covers about 40 percent of land area of the country.
• They are depositional soils, transported and deposited by rivers and streams.
• These soils are formed by the deposition of fine sediments and silt by the rivers along their banks.
• 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 the rivers.
• They represent the ‘riverine alluvium’ brought down by Sutlej, Yamuna, Ghagra and other rivers of Indo-Gangetic Plains.
• These soils are the most widespread soils covering an area of 8 lakh sq. km from Punjab to Assam.
• These are found in the river basin, flood plains and coastal areas.
• These soils are covering 22.16 per cent of total area of India.
• Alluvial soils though differ greatly in texture, are very fertile on whole.
• They:Respond well to irrigation and manuring.
• Good for both rabi and kharif crops.
• Suitable for wheat, sugarcane, rice, cotton and oilseeds.In delta region, they are ideal for jute cultivation.
• Useful for agriculture since it is fertile.
• Soil is rich in potash and lime but poor in nitrogen and humus.
Other Soils: The other soils in the category of the Indian soils are as follows:
MOUNTAIN SOILS:
• Mountain soils are found in, as the name suggests, in mountainous regions.
• They are quite prone to soil erosion as a result of the top soil getting washed away due to the steep slopes of the mountains after a period of heavy rainfall.
• These soils are mostly thin and infertile.
• These include peat, meadow and forest hill soils.
The major characteristics of this soil are:
• They are rich in humus-Are coarse and infertile.
• They are deficient in potash, phosphorous and lime.-Tea, coffee, spices and tropical fruits
• The states of Jammu and Kashmir, Himachal Pradesh and Uttaranchal, Assam, Sikkim as well as higher reaches of Arunachal Pradesh have mountain soil.
ARID AND DESERT SOILS
• Large part of arid and semi-arid region of Rajasthan and adjoining areas of Punjab and HaryanaDesert soils are found in arid regions which receive very little rainfall.
• Low rainfall and high temperature are reasons for the formation of this soil.
• Having less than 50 cm rainfall.
• The high temperature adds to the loss of any remaining moisture in the soil.
• The soil is therefore sandy in nature.
• Thar Desert in Rajasthan has sandy soil.-Covers an area of about 1.4 lakh sq km-Originated from the mechanical disintegration of the ground rock of by deposition by wind-Desert soil contain 90% of sand and 5% of clay.
• It contains rich percentage of soluble salts, but lack in organic matter.-Are porus and coarse .-They respond well to irrigation and manuring , especially phosphate and nitrate.-it can improve the soil fertility as it is seen in the case of Indira Gandhi Canal in Rajasthan.
• Only suitable for drought resistance crops like millets, barley, cotton, maize and pulses.
SALINE AND ALKALINE SOILS
• Soils with high proportion of salts and alkalis are called saline and alkaline soils .
• They are formed due to accumulation of tidal water in adjoining coasts where drainage is poor.
• They are found in drier parts of Bihar, Rajasthan, U.P., Punjab, Haryana, Maharashtra.
• These soils contain many salts like sodium, magnesium and calcium which make them infertile and render unfit for agriculture.
MARSHY SOIL
• Found in continuously water
• Logged areas, or marshy areas especially in the coastal regions near the sea or near the deltas.
• It covers about56,000 sq km.
• They are formed as a result of water-logging.
• It contain iron and varying amount of decayed organic matter.
• Found in southern parts of Siwaliks, Jammu and Kashmir, U.P.
MAJOR CLASSIFICATION OF INDIAN SOILS
1) Alluvial soil:
Mostly available soil in India (about 43%) which covers an area of 143 sq.km. Widespread in northern plains and river valleys.In peninsular-India, they are mostly found in deltas and estuaries. New alluvium is termed as Khadarand old alluvium is termed as Bhangar.
Colour: Light Grey to Ash Grey.
Texture: Sandy to silty loam or clay.
2) Red soil:
Seen mainly in low rainfall area. Also known as Omnibus group..
Colour: Red because of Ferric oxide. The lower layer is reddish yellow or yellow.
Texture: Sandy to clay and loamy.
3) Black soil / regur soil:
Regur means cotton – best soil for cotton cultivation. Most of the Deccan is occupied by Black soil.It is Mature soil.It has High water retaining capacity.Soils are Swells and will become sticky when wet and shrink when dried. Self-ploughing is a characteristic of the black soil as it develops wide cracks when dried.
Colour: Deep black to light black.
4) Laterite soil:
Name from Latin word ‘Later’ which means Brick.It becomes so soft when wet and so hard when dried. In the areas of high temperature and high rainfall.
Colour: Red colour due to iron oxide.
5) Desert / arid soil:
Seen under Arid and Semi-Arid conditions.
Colour:Red to Brown.
Texture:Sandy
6) Peaty / marshy soil:
Areas of heavy rainfall and high humidity.Growth of vegetation is very less.A large quantity of dead organic matter/humus which makes the soil alkaline.
7) Forest soil:
Regions of high rainfall. Humus content is less and thus the soil is acidic.
8) Mountain soil:
In the mountain regions of the country. Immature soil with low humus and acidic.
4. TIME: Time provides maturity to the soil.
5. Various forces of nature such as change in temperature, actions of running water, wind and glaciers, activities of decomposers etc. contribute to the formation of soil.
6. Chemical and organic changes which take place in the soil are equally important.
The soils of India on the basis of their formation are divided in the following two broad catagories-
• Residual Soil-which form at the place of their origin. Like – black soils
• Transported Soil-which are transported from place of their formation. Like alluvial soils.
The major soil groups are:
According to ICAR (Indian Council of Agricultural Research) soils are divided into 8 categories. they are:
1) BLACK SOIL
• Black soil is made from lava-solidified rocks and is also 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.
CHARACTERISTICS
• Clayey, deep and impermeable.
• 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 potashLack phosporus, nitrogen and organic matterVery clayey and therefore highly retentive of water.
• Because of high clay content, these soils expand when wet and become difficult to plough.
• During dry season, black soils shrink and develop big cracks which help in air circulation.
• Dark in colour, suitable for cotton cultivation are residual soils.
• Spread over an area of 5.4 sq. km., i.e. 16.6 % of the total land area of the country.
2) RED SOIL
• These soils are found in Chhotanagpur plateau, Telangana, Nilgiris, Tamil Nadu, Karnataka, Andhra Pradesh and periphery areas of Deccan Plateau.
• These soils have been formed due to decomposition of underlying igneous rocks under heavy rainfall.
• These are suitable for the cultivation of millets, pulses, Linseed, tobacco etc.
• These soils are poor in Lime, Nitrogen and humus.
CHARACTERISTICS
• Redsoils 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.
• These are transported type soils.
• Are mostly light to dark colour depending on new or old alluvium.
• Rich in potash and become fertile with the proper use of fertilizers and irrigation.
• Deficient in nitrogen,lime, magnesia, humus and phosphate Red due to its very high iron content.
• Are porous, friable in nature .Loose and aerated.
• Contains soluble salts in small quantities.
3) LATERITE SOIL
• Laterite = brick (Latin word)
• These soils are formed under conditions of high temperature and heavy rainfall with alternate wet and dry periods.
• Thus its formation takes place strictly under monsoon conditions.Residual soils formed by leaching in areas of heavy rain.
• Leaching is a process in which the nutrients get percolated down below the soil due to heavy rainfall; thus leaving the top soil infertile. Also called DESILICATION.
• Laterite soils are found in elevated areas which receive very high rainfallAs a result, top soil gets washed away. This process is called leaching.
• The soil, therefore, loses its fertility to a great extent.
• It covers an area of about 2.4 lakh sq km.
• These soils are found in the north-eastern state of Meghalaya in India. Laterite soils are found on the highland areas of the plateau.
• These are found in Karnataka, Kerala, Tamil Nadu and hilly regions of Assam, Rajmahal hills and Chhotanagpur plateau.
• These are shallow, acidic and less fertile soils. These soils are poor in lime but rich in iron.
• So these are suitable for plantation of crops like tea, rubber, coffee etc.
• Is of coarse texture, soft and friable.Is red due to the presence of iron oxide which is formed by leaching.
• The soluble plant foods like potash are removed from the top soil leaving alumina and iron oxide.
• Is a porus soil, silica is removed from it by chemical action.Is poor in lime and magnesium, and deficient in nitrogen.
4) ALLUVIAL SOIL
• (Riverine soil)It covers about 40 percent of land area of the country.
• They are depositional soils, transported and deposited by rivers and streams.
• These soils are formed by the deposition of fine sediments and silt by the rivers along their banks.
• 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 the rivers.
• They represent the ‘riverine alluvium’ brought down by Sutlej, Yamuna, Ghagra and other rivers of Indo-Gangetic Plains.
• These soils are the most widespread soils covering an area of 8 lakh sq. km from Punjab to Assam.
• These are found in the river basin, flood plains and coastal areas.
• These soils are covering 22.16 per cent of total area of India.
• Alluvial soils though differ greatly in texture, are very fertile on whole.
• They:Respond well to irrigation and manuring.
• Good for both rabi and kharif crops.
• Suitable for wheat, sugarcane, rice, cotton and oilseeds.In delta region, they are ideal for jute cultivation.
• Useful for agriculture since it is fertile.
• Soil is rich in potash and lime but poor in nitrogen and humus.
Other Soils: The other soils in the category of the Indian soils are as follows:
MOUNTAIN SOILS:
• Mountain soils are found in, as the name suggests, in mountainous regions.
• They are quite prone to soil erosion as a result of the top soil getting washed away due to the steep slopes of the mountains after a period of heavy rainfall.
• These soils are mostly thin and infertile.
• These include peat, meadow and forest hill soils.
The major characteristics of this soil are:
• They are rich in humus-Are coarse and infertile.
• They are deficient in potash, phosphorous and lime.-Tea, coffee, spices and tropical fruits
• The states of Jammu and Kashmir, Himachal Pradesh and Uttaranchal, Assam, Sikkim as well as higher reaches of Arunachal Pradesh have mountain soil.
ARID AND DESERT SOILS
• Large part of arid and semi-arid region of Rajasthan and adjoining areas of Punjab and HaryanaDesert soils are found in arid regions which receive very little rainfall.
• Low rainfall and high temperature are reasons for the formation of this soil.
• Having less than 50 cm rainfall.
• The high temperature adds to the loss of any remaining moisture in the soil.
• The soil is therefore sandy in nature.
• Thar Desert in Rajasthan has sandy soil.-Covers an area of about 1.4 lakh sq km-Originated from the mechanical disintegration of the ground rock of by deposition by wind-Desert soil contain 90% of sand and 5% of clay.
• It contains rich percentage of soluble salts, but lack in organic matter.-Are porus and coarse .-They respond well to irrigation and manuring , especially phosphate and nitrate.-it can improve the soil fertility as it is seen in the case of Indira Gandhi Canal in Rajasthan.
• Only suitable for drought resistance crops like millets, barley, cotton, maize and pulses.
SALINE AND ALKALINE SOILS
• Soils with high proportion of salts and alkalis are called saline and alkaline soils .
• They are formed due to accumulation of tidal water in adjoining coasts where drainage is poor.
• They are found in drier parts of Bihar, Rajasthan, U.P., Punjab, Haryana, Maharashtra.
• These soils contain many salts like sodium, magnesium and calcium which make them infertile and render unfit for agriculture.
MARSHY SOIL
• Found in continuously water
• Logged areas, or marshy areas especially in the coastal regions near the sea or near the deltas.
• It covers about56,000 sq km.
• They are formed as a result of water-logging.
• It contain iron and varying amount of decayed organic matter.
• Found in southern parts of Siwaliks, Jammu and Kashmir, U.P.
MAJOR CLASSIFICATION OF INDIAN SOILS
1) Alluvial soil:
Mostly available soil in India (about 43%) which covers an area of 143 sq.km. Widespread in northern plains and river valleys.In peninsular-India, they are mostly found in deltas and estuaries. New alluvium is termed as Khadarand old alluvium is termed as Bhangar.
Colour: Light Grey to Ash Grey.
Texture: Sandy to silty loam or clay.
2) Red soil:
Seen mainly in low rainfall area. Also known as Omnibus group..
Colour: Red because of Ferric oxide. The lower layer is reddish yellow or yellow.
Texture: Sandy to clay and loamy.
3) Black soil / regur soil:
Regur means cotton – best soil for cotton cultivation. Most of the Deccan is occupied by Black soil.It is Mature soil.It has High water retaining capacity.Soils are Swells and will become sticky when wet and shrink when dried. Self-ploughing is a characteristic of the black soil as it develops wide cracks when dried.
Colour: Deep black to light black.
4) Laterite soil:
Name from Latin word ‘Later’ which means Brick.It becomes so soft when wet and so hard when dried. In the areas of high temperature and high rainfall.
Colour: Red colour due to iron oxide.
5) Desert / arid soil:
Seen under Arid and Semi-Arid conditions.
Colour:Red to Brown.
Texture:Sandy
6) Peaty / marshy soil:
Areas of heavy rainfall and high humidity.Growth of vegetation is very less.A large quantity of dead organic matter/humus which makes the soil alkaline.
7) Forest soil:
Regions of high rainfall. Humus content is less and thus the soil is acidic.
8) Mountain soil:
In the mountain regions of the country. Immature soil with low humus and acidic.
| Types of Soils | States where found | Rich in | Lacks in | Crops grown |
| Alluvial | Mainly found in the plains of Gujarat, Punjab, Haryana, UP, Bihar, Jharkhand etc. | Potash and Lime | LimeNitrogen and Phosphorous | Large variety of rabi and kharif crops such as wheat, rice, sugarcane, cotton, jute etc |
| Black (Regur soil) | Deccan plateau- Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh,Tamil Nadu, Valleys of Krishna and Godavari.Lime | Lime, Iron, Magnesia and Alumina, Potash | Phosphorous, Nitrogen and organic matter | Cotton, sugarcane, jowar, tobacco, wheat, rice etc. |
| Red | Eastern and southern part of the deccan plateau, Orissa, Chattisgarh and southern parts of the middle Ganga plain. | Iron and Potash | Nitrogen, Phosphorous and humus. | Wheat, rice, cotton, sugarcane and pulses |
| Laterite | Karnataka, Kerala, Tamilnadu, Madhya Pradesh, Assam and Orissa hills. | Western Rajastan, north Gujarat and southern Punjab | Organic matter, Nitrogen, Phosphate and Calcium | Cashewnuts, tea, coffee, rubber |
| Arid and Desert | Western Rajastan, north Gujarat and southern Punjab | Soluble salts, phosphate | Humus, Nitrogen | Only drought resistant and salt tolerant crops such as barley, rape, cotton, millets maize and pulses |
| Saline and Alkaline | Western Gujarat, deltas of eastern coast, Sunderban areas of West Bengal, Punjab and Haryana | Sodium, Potassium, Magnesium | Nitrogen and Calcium | Unfit for agriculture |
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