Soils and Natural Vegetation of India

Soil is the thin skin of the Earth on which almost all our food grows. It is a mixture of broken rock particles, humus (rotted plant and animal matter), water and air. It forms very slowly: it can take hundreds of years to make just a few centimetres, but a single bad monsoon can wash it away. That is why soil is called a renewable resource that renews extremely slowly. The study of soil is pedology, which is another name for soil geography.

Soil texture depends on the share of three particle sizes: sand (largest), silt, and clay (smallest). Loam, a balanced mix, is the best for farming. Black soil is clayey (holds water), desert soil is sandy (drains fast), and alluvium is sandy loam to clay. Weathering by temperature change, frost, water, wind and living things is what breaks rock down into soil in the first place.

Every soil type in India is a signature of three things: the rock it came from, the climate that worked on it, and the crops it supports. If you remember that black soil = basalt (lava) = cotton, red soil = granite = iron oxide, laterite = heavy rain + leaching = tea, coffee and cashew, alluvium = rivers = the great plain, then the whole table below is only a matter of putting the places beside the names.

Why black soil is "self-ploughing". It is rich in clay. In the hot dry season it shrinks and develops deep, wide cracks, and the surface material falls into the cracks. In the monsoon it swells and turns sticky, so the soil keeps getting turned over naturally. That is also why black soil holds more water than any other Indian soil, and why it is called black cotton soil. Its black colour comes from iron and titanium-bearing minerals, not from humus.

Soil erosion is the removal of the topsoil faster than nature can rebuild it. Natural erosion is slow and balanced by soil formation. Accelerated erosion is the dangerous kind, and it is mostly man-made: deforestation, overgrazing, ploughing up and down the slope, shifting cultivation, mining and construction. When trees are cut, the roots no longer bind the soil and the raindrops hit bare ground directly. A long period of erosion and deforestation can turn good arable land into a wasteland.

Legumes enrich the soil. Pulses such as gram, lentil, pea and bean carry bacteria (Rhizobium) in their root nodules that turn atmospheric nitrogen into a form the plant can use. So growing pulses in rotation with cereals raises the natural fertility of the soil and cuts the need for nitrogen fertiliser. This is why mixed cropping and crop rotation with pulses are classic soil-conservation practices.

Soil Health Card Scheme was launched on 19 February 2015 (at Suratgarh, Rajasthan). Each farmer receives a card that reports the nutrient status of the soil of his or her field and advises the right dose of fertiliser. Its primary aim is to assess the nutrient status of the soil. Reclamation of bad soils: gypsum and drainage for saline-alkaline soils, green manure and compost for poor soils, and afforestation or check dams for ravines.

Natural vegetation is the plant cover that grows on its own, without human help. In India it follows rainfall first, then temperature, soil and altitude. As the rainfall falls, the forest changes in a clear order: tall evergreen forest, then deciduous forest, then thorny scrub, then desert. In the mountains the same change happens with height instead of distance. Champion and Seth (1968) grouped Indian forests into 16 major types; for exams we use the five-fold list below.

Forests are our soil-binders, rain-makers and carbon stores, and the country measures them regularly. The Forest Survey of India (FSI), Dehradun publishes the India State of Forest Report (ISFR) every two years. In ISFR 2023 (released in December 2024), forest cover was about 21.76 per cent of the country's area and forest plus tree cover about 25.17 per cent. The National Forest Policy 1988 set the goal of keeping one-third (33 per cent) of the land under forest and tree cover, and two-thirds in hill areas. Madhya Pradesh has the largest forest cover by area, and Mizoram is among the states with the highest share of its own area under forest.

The Sundarbans form the world's largest mangrove forest, spread over the delta of the Ganga, Brahmaputra and Meghna, and shared by India (West Bengal) and Bangladesh. The name comes from the Sundari tree (Heritiera fomes). It is the home of the Royal Bengal Tiger and was inscribed as a UNESCO World Heritage Site (the Indian part) in 1987. West Bengal has the largest mangrove cover among Indian states (as of ISFR 2023), followed by Gujarat. The "Sundarbans Honey" of West Bengal has a GI tag.