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soils of India:
The process of formation of soils is called Pedogenesis.
The regional variations in soil composition and texture in a vast country like India are an obvious outcome of the variety of landforms and climatic conditions found here.
Classification of Soils:
According to Indian Council of Agricultural Research (ICAR), soils are divided into 8 categories.
1. Alluvial Soils:
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They cover 24% of the land surface and are found in the Indo-Ganga-Brahmaputra plains, coastal plains and river valleys.
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These soils are also found in foothill regions in plenty.
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They contain sand, loam and clay in different proportions.
Types of Alluvial Soils:
(a) Khadar:
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Khadar are newer alluvium soils.
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They are deposited by rivers every year.
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They are more fertile than Bangar soils.
(b) Bangar:
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Bangar are older alluvial soils.
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They contain pebbles and calcium carbonates.
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The colour of alluvial soils can be grey, light brown or yellowish.
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These soils are very rich in chemicals like potash, phosphoric acid, lime and carbon compounds but are deficient in nitrogen and humus.
(c)Bhabar :
The Bhabar region is a narrow belt of land located along the foothills of the Himalayas.
- Found just south of the Shiwalik Hills
- Made up of coarse sediments like pebbles, gravel, and rocks
- Rivers disappear (sink) into the ground due to porous soil
- Land is dry and not suitable for agriculture
- Width: about 8–16 km
(d)Terai :
The Terai region lies immediately south of the Bhabar region.
- Rivers that disappeared in Bhabar reappear here
- Area is marshy, swampy, and waterlogged
- Soil is fertile, good for agriculture
- Thick forests and rich wildlife are common
- Supports crops like rice, sugarcane, wheat
2. Black Cotton Soils:
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The local name of these soils is Regur in Maharashtra.
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They are also known as Cotton Soil.
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These soils are formed by weathering and erosion of volcanic lava rocks and are mainly found in the Deccan Lava Plateau.
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These soils are most suitable for dry farming.
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They are dark black in colour due to the presence of titaniferous magnetite, a compound of iron and aluminium.
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These soils show high swelling when wet and shrinkage when dry due to the presence of Montmorillonite mineral.
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These soils have high moisture-retaining capacity, therefore they are suitable for crops like:
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Cotton
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Coarse grains
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Sunflower
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Citrus fruits
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However, they are not suitable for crops like rice, as they are not suitable for heavy irrigation.
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These soils are deficient in nitrogen, humus and phosphoric acid, but are rich in lime, potash, iron, aluminium, calcium and magnesium.
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Black soils of India are similar to Chernozem soils found in Russia and Ukraine.
3. Red Soils:
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Red soils develop generally from the disintegration of crystalline and metamorphic rocks in areas of heavy rainfall.
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They are rich in ferromagnesium minerals.
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The red colour of these soils is due to the excessive presence of iron oxide (Fe₂O₃).
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These soils are porous and coarse-grained and have low moisture retaining capacity.
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Therefore, they are less fertile and require heavy and frequent irrigation for agriculture.
4. Laterite Soils:
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Laterite soils are formed in areas of heavy rainfall (about 200 cm or more) due to the washing away of lime and silica.
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These soils are mainly found on the tops of hills and mountains in humid climate such as:
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Deccan Plateau
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Western Ghats
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Top of Eastern Ghats
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Assam
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Mysore
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Malabar
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Rajmahal Hills
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These soils are in-situ or residual in nature, formed under typical monsoonal conditions.
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The process of formation is called Leaching.In the leaching process, siliceous compounds of soil are washed away by heavy rainfall in hot climate and sloping terrain.
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Hence, these soils are deficient in siliceous compounds.
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These soils are not very fertile, but are suitable mainly for bushes and pastures.
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With the help of fertilizers, these soils can be used for plantation crops such as:
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Coffee
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Coconut
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Cashew nut
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Ragi
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These soils are rich in oxides of iron and aluminium, but deficient in nitrogen, phosphoric acid, lime and potash.
đ For study materials, follow the previous class and wait for the next class.
5. Mountainous or Forest Soils:
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These soils show variations due to different climatic and ecological conditions.
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They contain kankars, stone pieces and pebbles, and vary from place to place depending on climate.
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These soils are still under the process of formation.
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They are distributed in the mountain regions such as:
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Himalayas
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Vindhyas
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Satpura
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Nilgiri Hills
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Other mountains of India.
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These soils are acidic in nature due to the presence of less decomposed humus.
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They require fertilizers for agriculture.
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In areas of heavy rainfall, these soils contain more humus.
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These soils are suitable for cultivation of:
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Tea
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Coffee
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Spices
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Tropical fruits
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Wheat
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Maize
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Barley
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These soils are rich in organic matter and humus.
6. Arid and Desert Soils:
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These soils are mainly distributed in arid and semi-arid regions of Rajasthan.
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They contain large quantities of sand.
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These soils are suitable for cultivation of crops such as:
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Jowar
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Bajra
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Where irrigation facilities are available, such as in Sri Ganganagar (Rajasthan), crops like wheat and cotton are also grown.
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These soils are light in colour.
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They contain large quantities of soluble salts and phosphorus.
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They are deficient in carbon compounds and nitrogen.
7. Saline and Alkaline Soils:
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These soils are found in arid and semi-arid regions of:
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Rajasthan
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Punjab
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Haryana
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Uttar Pradesh
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Bihar
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Maharashtra
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Tamil Nadu
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They occur in patches and are locally called:
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Reh
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Kallar
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Usar
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These soils are infertile and unsuitable for agriculture.
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They can be treated by:
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Irrigation
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Adding lime and gypsum
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Growing anti-salinity crops such as rice and sugarcane
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After treatment, crops like rice, sugarcane, cotton, wheat and tobacco can be grown.
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Excess sodium and magnesium cause salinity in soil.
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High calcium causes alkalinity.
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These soils are deficient in nitrogen and have poor water holding capacity.
8. Peaty and Marshy Soils:
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These soils are formed due to accumulation of large quantities of organic matter under water-logged conditions for long periods.
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They are mainly found in coastal areas such as:
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Odisha
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West Bengal
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Tamil Nadu
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Kerala
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In Kerala, these soils are also called Kari soils.
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These soils are highly saline and deficient in phosphate and potash.
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Therefore, they are generally unsuitable for agriculture.
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The colour of these soils is dark grey or black due to high organic matter content.
The Reasons of Soil Infertility:
1. Nutrient Deficiency:
One of the main reasons for soil infertility is the lack of essential nutrients required for plant growth. Important nutrients such as nitrogen, phosphorus and potassium are necessary for healthy crop development. When these nutrients are absent or present in very small amounts, the soil becomes less productive and crops cannot grow properly.2. Soil Erosion:
Soil erosion is another major cause of infertility. The top layer of soil, which contains most of the nutrients and organic matter, is removed by natural forces such as wind and running water. When this fertile topsoil is lost, the remaining soil becomes poor in nutrients and unsuitable for agriculture.3. Excessive Leaching:
In regions of heavy rainfall, important minerals and nutrients present in the soil are washed away by water. This process is known as leaching. Due to leaching, nutrients like lime, silica and potash are removed from the soil, reducing its fertility and making it less suitable for crop cultivation.4. Lack of Humus:
Humus is the decomposed organic matter formed from plants and animals. It helps in improving soil structure, increasing water retention and providing nutrients to plants. When soil contains very little humus, it becomes dry, less fertile and unable to support good crop growth.5. Salinity and Alkalinity:
The presence of excessive salts such as sodium and magnesium in soil leads to salinity, while high calcium content causes alkalinity. Such soils are not suitable for agriculture because they reduce the ability of plants to absorb water and nutrients, making the soil infertile.6. Improper Irrigation:
Poor irrigation practices can also reduce soil fertility. Excess irrigation may cause waterlogging and salt accumulation in the soil. These conditions affect plant roots and reduce the productive capacity of the soil.7. Continuous Cropping:
Growing crops repeatedly on the same land without giving the soil time to recover or without adding fertilizers leads to depletion of nutrients. Over time, the soil loses its natural fertility and crop yields decrease.8. Excessive Use of Chemicals:
The overuse of chemical fertilizers and pesticides harms beneficial microorganisms present in the soil. These microorganisms play an important role in maintaining soil health. When they are destroyed, soil quality declines and fertility decreases.Results (effects) of Soil Erosion :
1. Loss of Fertile Topsoil:
Soil erosion removes the top layer of soil, which is the most fertile part containing humus and essential nutrients. When this layer is washed or blown away, the remaining soil becomes less productive and unsuitable for agriculture. This leads to a decrease in crop yields.2. Decline in Agricultural Productivity:
As nutrients and organic matter are lost due to erosion, the soil becomes weak and less capable of supporting plant growth. Farmers may experience poor crop production, which can affect food supply and farmers’ income.3. Formation of Deserts (Desertification):
Continuous soil erosion can convert fertile land into barren land. Over time, productive agricultural land may turn into desert-like conditions, especially in dry and semi-arid regions.4. Siltation of Rivers and Reservoirs:
The eroded soil particles are carried by water and get deposited in rivers, lakes, and dams. This process is called siltation. It reduces the water storage capacity of reservoirs and increases the risk of floods.5. Flooding:
When rivers and drainage channels get filled with silt, water cannot flow properly. As a result, during heavy rainfall, rivers overflow and cause floods in nearby areas.6. Environmental Degradation:
Soil erosion damages natural vegetation and reduces soil quality. This affects ecosystems, wildlife habitats, and overall environmental balanceđ For study materials, follow the previous class and wait for the next class.
ways to conserve soils :
1. Afforestation:
Planting more trees helps in conserving soil because the roots of trees hold the soil firmly and prevent it from being washed away by water or blown away by wind. Forest cover also reduces the impact of rainfall on the soil surface and maintains soil fertility.2. Contour Ploughing:
Contour ploughing is the practice of ploughing the land along the natural contours of the slope rather than up and down the slope. This method slows down the flow of water and reduces soil erosion on hilly lands.3. Terrace Farming:
In hilly and mountainous regions, terraces or step-like fields are made on slopes. These terraces reduce the speed of flowing water and prevent soil from being carried away, thereby conserving soil.4. Strip Cropping:
In this method, crops are grown in alternating strips along the slope of the land. The strips of crops help to slow down the wind and water movement, which prevents soil erosion.5. Shelter Belts:
Rows of trees and shrubs are planted along the boundaries of agricultural fields. These are called shelter belts. They act as barriers against strong winds and prevent wind erosion of soil.6. Crop Rotation:
Growing different types of crops in a sequence on the same land helps maintain soil fertility. Some crops restore nutrients in the soil, which prevents the soil from becoming infertile.7. Proper Irrigation Practices:
Controlled and proper irrigation helps prevent waterlogging and salinity in the soil. Efficient irrigation methods help maintain soil health and conserve soil.8. Construction of Dams and Check Dams:
Small dams or barriers built across streams slow down the flow of water and reduce soil erosion. They also help in storing water for agricultural purposesDisclaimer:
This content is prepared for educational and informational purposes only. The notes are simplified for better understanding and exam preparation (UPSC and State Exams). Readers are advised to refer to standard textbooks and official sources for detailed study
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