The soil serves as a base for plant growth, a habitat for numerous creatures, a filter for surface water, and a mechanism for maintaining atmospheric gas levels. Soil provides plants, worms, fungi, and bacteria with essential minerals and nutrients, as well as water and air, in order to ensure their survival and growth.
As a result of varying climatic circumstances and extensive agriculture, the soil's health is gradually deteriorating, much to the alarm of the concerned stakeholders. It is essential to use soil restoration practises to ensure soil health, as this will result in increased productivity. Soil restoration is the process of making compacted soils more porous and able to hold on to nutrients. It includes biological (worms and other soil organisms) and mechanical aeration, mechanical loosening (tilling), growing thick vegetation, and the application of soil amendments.
Types of Soils in India
Red and Yellow Soil
In low-rainfall regions of the Deccan Plateau's eastern and southern regions, crystalline igneous rocks transform into red soil. Long stretches of land throughout the piedmont zone of the Western Ghat are occupied by red loamy soil. Yellow and red soils are also present in portions of Odisha, Chattisgarh, and the southern Ganga plain. Due to the widespread dispersion of iron in crystalline and metamorphic rocks, the soil assumes a reddish hue. In its hydrated state, it has a yellow appearance. In general, fine-grained red and yellow soils are productive, but coarse-grained soils in arid upland regions are infertile. They typically lack nitrogen, phosphorus, and humus.
The majority of the Deccan Plateau, which includes portions of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh, and Tamil Nadu, is covered by black soil. In the higher sections of the Godavari and Krishna rivers, as well as the northwest portion of the Deccan Plateau, the black soil is quite deep. These soils are also referred to as "Regur Soil" and "Black Cotton Soil." Generally, the black soils are clayey, deep, and impermeable. When wet, they expand and become sticky, and when dry, they contract. Consequently, during the dry season, these soils develop large fissures. Thus, a form of "self ploughing" happens. Due to its slow absorption and loss of moisture, black soil maintains moisture for a very long time, allowing crops, particularly those dependent on rainfall, to survive even throughout the dry season. The black soils are chemically rich in lime, iron, magnesium, and alumina. They contain potash as well. However, they are deficient in phosphorus, nitrogen, and organic matter. The colour of the soil ranges from deep black to grey.
In the northern plains and river basins, alluvial soils are prevalent. These soils cover around forty percent of the country's entire territory. They are deposited soils, deposited by rivers and streams. They spread over a short corridor in Rajasthan into the plains of Gujarat. In the Peninsular peninsula, they are found in the river deltas and river valleys of the east coast. The nature of the alluvial soils ranges from sandy loam to clay. They are often potash-rich but phosphorus-poor. In the Upper and Middle Ganga plain, two distinct types of alluvial soils, Khadar and Bhangar, have evolved. Khadar is the new alluvium and is deposited regularly by floods, enriching the soil with fine silts. Bhangar is a system of older alluvium that was deposited away from flood areas. Both Khadar and Bhangar soils are composed of calcareous concretions (Kankars). In the lower and middle Ganga plain and Brahamaputra valley, these soils are more sandy and clayey. The amount of sand reduces from west to east.
The alluvial soils range in colour from light grey to ash grey. Its hues are determined by the thickness of the deposition, the texture of the components, and the time required for maturity. Alluvial soils are cultivated intensively.
The term laterite is derived from the Latin word for brick, later. The laterite soils form in regions with high temperatures and precipitation. This is the outcome of strong leaching brought about by tropical rains. Lime and silica are washed away by precipitation, leaving behind iron oxide- and aluminum-rich soils. Bacteria that flourish at high temperatures quickly consume the humus component of the soil. These soils are deficient in organic matter, nitrogen, phosphate, and calcium, but they are rich in iron oxide and potash. Therefore, laterites are not appropriate for cultivation; yet, manures and fertilisers are required to make soils suitable for agriculture. The red laterite soils of Tamil Nadu, Andhra Pradesh, and Kerala are optimal for cashewnut cultivation. Bricks are commonly made from laterite soils for use in home construction. These soils have primarily developed on the peninsular plateau's higher elevations. In Karnataka, Kerala, Tamil Nadu, Madhya Pradesh, and the hilly regions of Odisha and Assam, laterite soils are prevalent.
The colour of arid soils ranges from red to brown. They are often composed of sand and have a salty nature. In some areas, the salt content is so high that common salt is obtained by evaporating the saline water. They lack moisture and humus because to the dry climate, high temperature, and fast evaporation. The nitrogen content is inadequate while the phosphate value is average. Due to the rising calcium concentration downhill, the soil's lower horizons are filled by 'kankar' layers. The creation of the 'Kankar' layer in the lower horizons prevents the infiltration of water; hence, when irrigation is provided, the soil moisture is easily available for plant growth. The western region of Rajasthan is characterised by the development of dry soils and arid topography. These soils are deficient in humus and organic material.
Additionally known as Usara soils. The higher concentrations of salt, potassium, and magnesium in saline soils render them infertile and incapable of supporting plant life. They contain higher salts, primarily due to their arid climate and poor drainage. They inhabit dry and semiarid locations, as well as flooded and swampy regions. Their composition varies between sandy and loamy. They are nitrogen and calcium deficient. Saline soils are more prevalent in western Gujarat, coastal deltas, and Sunderban regions of West Bengal. The Southwest Monsoon transports salt particles to the Rann of Kuchchh, where they form a crust. Infiltrations of seawater into deltas promote the formation of salty soils. The fertile alluvial soils are getting salinized in places of intense farming with excessive use of irrigation, notably in areas of green revolution. Excessive irrigation in dry climatic circumstances stimulates capillary action, resulting in the deposition of salt on the soil's uppermost layer. In such regions, particularly Punjab and Haryana, farmers are encouraged to add gypsum to the soil to combat salt.
They inhabit regions with considerable precipitation and high humidity, where vegetation flourishes. Thus, a considerable amount of dead organic matter accumulates in these places, enriching the soil with humus and organic matter. The organic matter content of these soils may reach 40 to 50 percent. Typically, these soils are dense and dark in colour. In numerous locations, they are also alkaline. It occurs widely in the northern part of Bihar, southern section of Uttaranchal and the coastal areas of West Bengal, Orissa and Tamil Nadu.
Factors Contributing to Soil Degradation
The variables that contribute to soil deterioration and are distinguished by how they alter the soil's inherent composition and structure.
These factors include human and plant activities that tend to diminish soil quality. Some bacteria and fungi overgrowth in a region has the potential to significantly alter the microbial activity of the soil via biochemical reactions, hence diminishing crop production and the soil's suitability for productivity.
The chemical components of soil deterioration include the depletion of soil nutrients due to alkalinity, acidity, or waterlogging. It comprises, in the broadest sense, changes in the soil's chemical properties that impact nutrient availability. It is mostly caused by salt accumulation and nutrient leaching, which diminishes soil quality by causing unwanted changes in the important soil chemical components.
Soil Health Card Program
It is a Government of India scheme offered by the Ministry of Agriculture's Department of Agriculture . Each state and union territory government's Department of Agriculture will carry it out. A SHC is meant to give each farmer with the soil nutrient status of his/her land and to advise on the fertiliser dose as well as the soil amendments needed to sustain soil health over time.
This programme, in addition to supporting ecologically beneficial practises, has the potential to save India's agricultural sector. Farmers have abandoned traditional knowledge in favour of modern inputs such as chemical-based fertilisers. This is mindless adoption, which will not last in the long run. It initially increased yield, but misuse and poor management have permanently harmed soil health. Farmers can use this technology to learn more about the soil profile and apply the right inputs. To begin, it may aid in the restoration of deteriorated soils. It may also help farmers identify which crops are most suited to their specific soil profile, enhancing yields and earnings.