Soils of India
Soil is the topmost layer of the continental crust, made up of worn rock fragments. The soils of India are the result of both physical and human causes.
Simply said, soil is a mixture of small rock particles/debris and organic materials/humus that forms on the earth’s surface and supports plant growth.
Factors affecting soil formation –
- Material for Parents
- Biological Factors & Natural Vegetation
Types of Soil in India
Related Links: https://scores100.tech/2021/11/types-of-grasslands-in-the-world.html
Vasily Dokuchaev created the first scientific classification of soil. Soils in India are divided into eight categories by the Indian Council of Agricultural Research (ICAR).
- Alluvial Soil
- Red Soil
- Laterite Soil
- Mountains or Forests Soil
- Arid or Desert Soil
- Saline or Alkaline Soil
- Peaty and Marshy Soil
Classification of India Soil
- The silt deposited by the Indo-Gangetic and Brahmaputra rivers is primarily responsible for the formation of alluvial soils. Wave activity in coastal areas causes some alluvial deposits to form.
- The source material is made up of Himalayan rocks. As a result, the parent material of these soils has been moved.
- They are the largest soil group, encompassing over 15 lakh sq km or 46% of the entire land area.
- They provide the most fertile agricultural lands to more than 40 percent of India’s population.
Alluvial Soil Characteristics
- Because of their recent origin, they are immature and have weak profiles.
- The soil is mostly sandy, but clayey soils do exist.
- In drier areas, they range from loamy to sandy-loam, with clayey loam near the delta.
- Soils that are pebbly or gravelly are uncommon. Some areas along the river terraces have kankar (calcareous concretions) beds.
- Because of its loamy (equal proportions of sand and clay) composition, the soil is porous.
- Porosity and texture provide for good drainage and other agricultural conditions.
- The repeated floods replace these soils on a regular basis.
Alluvial soil chemical properties
- The nitrogen content is normally low.
- Potash, phosphoric acid, and alkalies are in proper proportions.
- The proportions of iron oxide and lime might vary a lot.
India’s Alluvial Soil Distribution
Except in a few areas where the top layer is covered by desert sand, they may be found all over the Indo-Gangetic-Brahmaputra plains.
They also exist in the Mahanadi, Godavari, Krishna, and Cauvery deltas, where they are known as deltaic alluvium (coastal alluvium)
The Narmada and Tapi valleys, as well as the northern regions of Gujarat, have some alluvial soils.
Crops that Grow in Alluvial Soils
- They are best suited for agriculture because they are mostly flat and consistent soils.
- Irrigation is beneficial for them, and they respond well to canal and well/tube-well irrigation.
- Rice, wheat, sugarcane, tobacco, cotton, jute, maize, oilseeds, vegetables, and fruits are all abundant.
- The Great Plain of India’s alluvium is split geologically between newer or younger khadar and older bhangar soils.
- The bhabar belt stretches for 8-16 kilometers along the Shiwalik foothills. It’s a porous region of Indo-Gangetic plain in the far north.
- Rivers descending from the Himalayas deposit their burden in the shape of alluvial fans along the foothills. The bhabar belt is made up of alluvial fans (typically pebbly soils) that have melded together.
- The porosity of bhabar is its most distinguishing characteristic. The porosity is caused by a large amount of pebbles and rock debris being deposited across the alluvial fans.
- Because of the porosity, the streams vanish once they reach the bhabar zone. As a result, save during the rainy season, the land is defined by dry river courses.
- This belt is unsuitable for cultivation, and only giant trees with deep roots flourish here.
- To the south of Bhabar, the Terai is a narrow, ill-drained, moist (marshy) and densely forested region (15-30 km wide) that runs parallel to it.
- The Bhabar belt’s subsurface streams resurface in this belt. It’s a lowland marsh with silty soils.
- The soils of the Terai are high in nitrogen and organic matter, but low in phosphate.
- Tall grasses and woodlands cover these soils, yet they are good for a variety of crops such as wheat, rice, sugarcane, jute, and others.
- A variety of species can be seen in this densely forested area.
- The Bhangar is the ancient alluvium that forms terraces above the flood plain along river banks (about 30 meters above the flood level).
- It has a more clayey texture and is often black in hue.
- Beds of lime nodules known as “Kankar” may be seen a few meters below the bhangar’s terrace.
- The flood plains along the river banks are formed by the Khadar, which is made up of recent alluvium.
- Almost every year, the banks are flooded, and each flood deposits a new layer of alluvium. As a result, they are the Ganges’ most fertile soils.
- They are sandy clays and loams that are drier and more leached, with less calcareous and carbonaceous content (less kankary). River floods produce a new layer of alluvium practically every year.
Rainfall-prone alluvial zones
- Above 100cm – ideal for paddy; between 50 and 100cm – ideal for wheat, sugarcane, tobacco, and cotton
Course grains below 50cm (millets)
- Weathering of these basaltic rocks that erupted during the Cretaceous period’s fissure eruption resulted in the formation of this formation.
- The volcanic rocks that originated in the Deccan Plateau are the parent material for the majority of the black soil (Deccan and the Rajmahal trap).
Gneisses and schists are the parent materials of Tamil Nadu. The former is appropriately deep, whilst the latter is mostly shallow.
- These are the areas with the highest temperatures and the least amount of rainfall. As a result, it is a soil type found in the Peninsula’s arid and hot parts 15 percent of the region is affected.
- Titani-ferrous magnetic chemicals present in basalt give it its black color.
Black Soil Characteristics
- A typical black soil has a high clay factor of 62 percent or more and is highly argillaceous [Geology (of rocks or sediment) consisting of or containing clay].
- In general, upland black soils are poor in fertility, but valley black soils are quite fertile.
- The black dirt is extremely water-retentive. When moisture accumulates, it swells dramatically. Working on such soil during the rainy season necessitates a lot of effort since it becomes quite sticky.
- When the moisture in the soil evaporates in the summer, the earth shrinks and becomes seamed with broad and deep fractures. Moisture can still be retained in the bottom layers.
- The fissures allow the soil to be oxygenated to a suitable depth, and the soil is extremely fertile.
- It fractures and has a blocky form when dry. (Capacity for Self-Ploughing)
Soil Color in Black
- The parent rock’s black color is owing to the presence of a minor fraction of titaniferous magnetite or iron, as well as black components.
- The dark color comes from crystalline schists and basic gneisses in Tamil Nadu and parts of Andhra Pradesh.
- This group of soils contains several shades of black, including deep black, medium black, shallow black, and a blend of red and black.
Black Soil Chemical Composition
- Alumina is 10%, iron oxide is 9-10%, lime is 6-8%, and magnesium carbonates are 6-8%. Phosphates, nitrogen, and humus are all low, and potash is variable (less than 0.5 percent).
- Iron and lime are abundant, while humus, nitrogen, and phosphorus are in short supply.
Black Soil Distribution
- It can be found in India’s Deccan lava plateau.
- Maharashtra, Madhya Pradesh, parts of Karnataka, Telangana, Andhra Pradesh, Gujarat, and Tamil Nadu make up the 46 lakh sq km (16.6 percent of the total area).
Crops Grown in Dark Soils
- Cotton crops thrive on these types of soils. Regur and black cotton soils are the names given to these soils.
- Wheat, jowar, linseed, virginia tobacco, castor, sunflower, and millets are among the other significant crops produced on the black soils.
- Rice and sugarcane are both major crops in areas where irrigation is available.
- On the dark soils, a wide range of vegetables and fruits can be cultivated effectively.
- For millennia, this soil has been utilized to grow a variety of crops without the addition of fertilizers or manures, with little or no signs of depletion.
- This Archean granite-derived soil covers the second-largest area of the country.
- The presence of ferric oxides, which appear as thin coatings on soil particles, causes the soil to be red.
- The soil’s top layer is red, while the horizon beneath it is yellowish.
- 18.5 percent of the total area
- Sandy to clayey and loamy texture.
- The omnibus group is another name for this soil.
Red Soil Characteristics
- The amount of rain that falls is quite varied. As a result, three sorts of soil have emerged.
- Red and yellow soil – 200cm rainfall – NE India – Nagaland, Mizoram, the Manipur Hills, and sections of the Malabar coast require immediate drainage.
- Drier plateaus such as Karnataka, TN, Telangana, and Rayalseema have red sandy soil with rainfall ranging from 40 to 60 cm.
- The soil along river valleys, known as red alluvial soil, is rich in fertility.
- The soil is well-drained, and the structure is sandy.
- Iron and potassium are abundant, but other minerals are scarce.
Red Soil Chemical Composition
Phosphate, lime, magnesia, humus, and nitrogen are all deficient in these soils.
The Red Soil’s Distribution
- From Tamil Nadu in the south to Bundelkhand in the north, and Raj Mahal in the east to Kathiawad in the west, they are mostly found in the Peninsula.
- Because the mineral foundation is rich, it produces a high yield when irrigated and supplemented with humus.
- Rice, sugarcane, and cotton farming are also supported.
- Millets and pulses are cultivated in drier climates.
- The Kaveri and Vaigai basins are known for their crimson alluvium, which can be used for paddy if well watered.
- For rubber and coffee plantation production, large areas of Karnataka and Kerala have created Red soil regions.
- This soil has appeared in areas where the following conditions have been met:
- There must be laterite rock or a structure made of laterite (Laterites are rich in iron and aluminium content)
- The growth of laterite soils is better suited to alternating dry and wet periods.
- Brown in color, it is mostly made up of hydrated aluminium and iron oxides.
- Iron oxides are present in the form of nodules.
- Iron and aluminum are abundant, but nitrogen, phosphorus, potassium, lime, and magnesium are in little supply.
- It has a moderate humus and water-holding capacity.
- Bacterial activity has been quite strong, and excessive precipitation causes humus leaching, resulting in moderate to low humus levels.
- The following are the laterite soil regions in the country:
- Patches of it can be found in the Western Ghats ( Goa and Maharashtra).
- Karnataka’s Belgam district and Kerala’s laterite plateau
- Amarkantak plateau region of MP- Panchmahal district of Gujarat; Santhal Pangana divisions of Jharkhand are all located in the state of Orissa, in the Eastern Ghats.
- It is known for crops like as groundnut, cashew nut, and others.
- Coffee, rubber, and spices are grown on Karnataka’s laterite soil.
Forest Soil/ Mountain Soil
Formation – It is principally found on mountains with steeper slopes, high relief, shallow profiles.
- It is thinly stratified, with poorly defined profiles and vistas.
- It has been prone to soil erosion due to rapid drainage.
- It has a high organic content and a good humus content, but it lacks other nutrients.
- When sand, silt, and clay are mixed together, it is called a loamy soil.
- These are usually found over 900 meters.
- Himalayan foothills, Western Ghats mountain slopes, Nilgiri, Annamalai, and Cardamom hills
- It is highly beneficial to those crops that require good air and water drainage, which this soil provides due to its location on slopes.
- Rubber plantations, bamboo plantations, as well as tea, coffee, and fruit farming, are all common uses.
- A large area has also been set aside for shifting agriculture, in which soil fertility deteriorates after two to three years.
- Silvi pastoral farming (forest+grasses) can be sustained due to the limited reach of agriculture.
This soil is deposited by wind activity deposits this soil in dry and semi-arid places such as Rajasthan, West of the Aravallis, Northern Gujarat, Saurashtra, Kachchh, Western Haryana, and the southern portion of Punjab.
It is deficient in moisture. The humus level is lower, and nitrogen content is initially low, but part of it is available as nitrates.
They’re sandy and devoid of biological substances. The content of living microorganisms is minimal.
It contains a lot of iron. The phosphorus amount is practically adequate, thanks to the abundance of lime and bases.
It has a low soluble salt content and a low moisture retention capability.
This soil has a high agricultural return when watered.
These are ideal for crops that require less water, such as Bajra, pulses, fodder, and guar.
Western Rajasthan, the Rann of Kachchh, and portions of south Haryana and south Punjab are also part of the distribution.
Saline or Alkaline Soil
- The amount of NaCl in alkali soil is high.
- The soil is barren.
- Reh, Usar, Kallar, Rakar, Thur, and Chopan are some of the other names for these.
- Rajasthan, Haryana, Punjab, Uttar Pradesh, Bihar, and Maharashtra are the most common locations.
- This soil contains sodium chloride and sodium sulphate. It works well with leguminous crops.
- It is both natural and manmade in its formation and dissemination.
- Natural — Includes Rajasthan’s dried-up lakes and the Kuchchh Rann.
- It has made its appearance in the Palaya basin ( a clay basin in the midst of the desert)
- Anthropogenic — It has emerged in western Uttar Pradesh and Punjab as a result of poor agricultural practices.
- Identifying Features – Humus formation is almost non-existent due to a lack of moisture, humus, and live microbes.
Peaty and Marshy Soil
- This dirt comes from places where proper drainage isn’t possible. It is high in salinity and contains a lot of organic debris. Potash and phosphate are inadequate in their diet.
- Clay and mud predominate, making it heavy.
- It has a high moisture content, but a high salt content and daily flooding by high tide have rendered it barren soil.
- Because of the high moisture level, there is no organic activity.
- Its distribution is typified by the delta region of India.
- It can also be found in Alleppey (Kerala) in addition to the delta region (known as Karri along the backwaters or Kayals of Kerala)
- Almora is a town in the province of Almor (Uttaranchal)
- It is suitable for jute and rice across the Bengal delta, while it is suitable for spices, rubber, and large-sized rice over Malabar.
- It has been beneficial to India’s Mangrove forests to some extent.
Related Links: https://scores100.tech/2021/11/highest-mountain-ranges-in-india.html
Characteristic of Indian Soils
- The majority of soils are mature and ancient. The peninsular plateau’s soils are substantially older than the huge northern plain’s.
- Nitrogen, mineral salts, humus, and other organic elements are all in short supply in Indian soils.
- The soil layers in plains and valleys are thick, but hilly and plateau locations have sparse soil cover.
- Some soils, such as alluvial and black soils, are fruitful, while others, such as laterite, desert, and alkaline soils, are infertile and produce poor yields.
- For hundreds of years, Indian soils have been utilized for agriculture, and much of their fertility has been lost.
Soil Problems in India
Soil erosion (Himalayan region, Chambal Ravines, etc. ), fertility deficiency (Red, lateritic, and other soils), desertification (around Thar desert, rain-shadow regions like parts of Karnataka, Telangana, etc. ), waterlogging (Punjab-Haryana plain), salinity, and alkalinity (excessively irrigated regions of Punjab, Haryana, Karnataka, etc.)