60-second revision
- Alluvial soil is the most widespread soil of India; khadar is new alluvium, bhangar old.
- Black (regur) soil: from Deccan lava, moisture-retentive, self-ploughing cracks, best for cotton; poor in phosphorus.
- Red soil is red due to iron oxide; yellow when hydrated.
- Laterite: intense leaching in hot, wet areas; good for cashew; used as bricks.
- Saline soils are reclaimed with gypsum; acidic soils with lime.
- Tropical deciduous (monsoon) forests are the most widespread; evergreen need over 200 cm rain.
- Thorn forests: under ~70 cm rain; mangroves: tidal coasts (Sundari tree in the Sundarbans).
How soils form
Soil is formed from weathered parent rock over long periods, shaped by climate, relief, vegetation and time. Rainfall and temperature are especially important: heavy rain leaches minerals away, while dry climates leave salts behind. The Indian Council of Agricultural Research (ICAR) classifies Indian soils into eight major groups.
| Soil | Where | Properties | Suited crops |
|---|---|---|---|
| Alluvial | Northern plains, river valleys and deltas of the east coast | Most widespread; very fertile; rich in potash, poor in phosphorus; khadar (new) and bhangar (old) | Rice, wheat, sugarcane, pulses |
| Black (regur) | Deccan lava plateau: Maharashtra, Gujarat, MP, parts of Karnataka, Telangana | Clayey, holds moisture, deep cracks when dry (self-ploughing), sticky when wet; rich in lime, iron, magnesia; poor in phosphorus, nitrogen, organic matter | Cotton, also soybean, jowar, sugarcane |
| Red and yellow | Eastern and southern Deccan, Odisha, Chhattisgarh, parts of the Ganga plain fringe | Develops on crystalline rocks in lower rainfall; red due to iron oxide, yellow when hydrated | Millets, pulses, groundnut with fertilisers |
| Laterite | Western Ghats, Kerala, Karnataka, Odisha hills, Meghalaya | Formed by leaching in high temperature and heavy rain; acidic, low fertility; hardens on exposure | Cashew, tea, coffee, rubber; used as building bricks |
| Arid | Western Rajasthan and adjoining areas | Sandy, saline; lower horizons have kankar due to calcium; low humus | Bajra, pulses with irrigation |
| Saline and alkaline (reh, kallar, usar) | Dry areas, over-irrigated parts of Punjab and Haryana, coastal areas | Excess sodium, potassium, magnesium salts; infertile | Reclaimed with gypsum, then salt-tolerant crops |
| Peaty and marshy | Kerala (Kuttanad), Sundarbans, coastal Odisha | High organic matter, waterlogged | Rice in places |
| Forest and mountain | Himalayan and other hill slopes | Vary with altitude; acidic and humus-poor at higher levels | Tea, fruit, spices in places |
Soil erosion and conservation
- Sheet erosion: a thin layer of topsoil washed off evenly over a large area.
- Gully erosion: running water cuts deep channels; land turns into ravines or badlands, as in the Chambal valley.
- Wind erosion: common in arid areas such as Rajasthan.
- Causes: deforestation, overgrazing, faulty farming methods, mining and construction.
| Conservation method | How it helps |
|---|---|
| Contour ploughing | Ploughing along contour lines slows water flowing down slopes |
| Terrace farming | Steps cut into hill slopes reduce run-off |
| Strip cropping | Strips of grass between crops break the force of wind |
| Shelter belts | Rows of trees protect fields in desert margins from wind |
| Plugging gullies, check dams | Stop the spread of gullies |
Forest types of India
| Type | Rainfall | Areas | Typical trees |
|---|---|---|---|
| Tropical evergreen | Above 200 cm | Western Ghats, north-east, Andaman and Nicobar | Ebony, mahogany, rosewood, rubber, cinchona |
| Tropical deciduous (monsoon) — most widespread | About 70 to 200 cm | Moist type in the north-east, foothills, eastern slopes of the Western Ghats, Odisha; dry type in drier interiors | Teak, sal, shisham, sandalwood, khair, arjun |
| Tropical thorn and scrub | Below about 70 cm | Rajasthan, Gujarat, MP, UP, the drier Deccan | Acacia, babool, khejri, cacti, palms |
| Montane | Varies with altitude | Himalaya, and Nilgiri–Anamalai hills (sholas) in the south | Oak, chestnut at middle heights; pine, deodar, fir, spruce higher; alpine meadows above |
| Mangrove (littoral, swamp) | Tidal coasts | Sundarbans, Mahanadi, Godavari and Krishna deltas, Andaman | Sundari, rhizophora; breathing roots |
Deciduous trees shed their leaves for about six to eight weeks in the dry summer to save water. In thorn forests, plants have long roots, thick fleshy stems and small or thorny leaves. In the Himalaya, vegetation changes with altitude much as it changes with latitude from the tropics to the poles.
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