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Alluvial Soils of India
Alluvial soils cover the largest area (about 40%) of India’s land surface. They are formed by the deposition of sediments by rivers and are most extensive in the Indo-Gangetic-Brahmaputra plains.
Formation
- Deposited by rivers as silt, sand, and clay over millions of years
- Derived from weathering of Himalayan rocks and transported by river systems
- Renewed annually during floods — naturally fertile
Distribution
- Indo-Gangetic plains: Punjab, Haryana, UP, Bihar, West Bengal, Assam
- Coastal alluvium: River deltas of Mahanadi, Godavari, Krishna, Kaveri
- Peninsular river valleys: Narmada, Tapti valleys in Gujarat and MP
Classification
| Type | Characteristics | Location |
|---|---|---|
| Bhangar | Old alluvium; higher elevation; less fertile; contains calcareous concretions (kankar) | Interfluves in Gangetic plains |
| Khadar | New alluvium; lower elevation; renewed annually; very fertile | Active floodplains of rivers |
| Deltaic alluvium | Fine silt and clay; extremely fertile | Ganga-Brahmaputra delta, Mahanadi, Godavari deltas |
| Coastal alluvium | Mixed origin; some sand content | Eastern and western coastal plains |
Characteristics
- Texture ranges from sandy loam to clay loam
- Rich in potash, lime, and phosphoric acid
- Deficient in nitrogen and humus
- Porous and well-drained in upper reaches; poorly drained in deltaic regions
Major Crops
Alluvial soils are the most agriculturally productive soils of India, supporting:
- Rice (khadar of West Bengal, Bihar, coastal deltas)
- Wheat (bhangar of Punjab, Haryana, UP)
- Sugarcane (UP, Bihar)
- Jute (deltaic alluvium of West Bengal)
- Maize, pulses, oilseeds (well-drained alluvial areas)
Agricultural Issues
- Increasing salinity in irrigated areas
- Waterlogging in poorly drained deltaic regions
- Depletion of soil fertility due to continuous monocropping
- Need for nitrogenous fertilizers to supplement deficiency