Soil Resources of India

4.1 Major Soil Types

India's soils are classified by the National Bureau of Soil Survey and Land Use Planning (NBSS&LUP) into 8 orders (following USDA system) and broadly into 6 major types for exam purposes.

Alluvial Soil — Most Widespread and Fertile

Alluvial Soil covers ~43% of India's cultivated area (~7.5 lakh sq km). It spans the entire Indo-Gangetic Plain (Punjab, Haryana, UP, Bihar, WB, Assam) and the deltas of Mahanadi, Godavari, Krishna, and Kaveri.

Key characteristics:

• Types: New alluvium (Khadar) — light coloured, sandy; Old alluvium (Bangar) — darker, with Kankar nodules
• Nutrients: Rich in potash and lime; deficient in nitrogen, phosphorus, and humus
• Crops: Wheat, rice, sugarcane, jute, cotton, oilseeds — virtually any crop

Black/Regur Soil — Cotton Soil

Black/Regur Soil covers ~5.46 lakh sq km (~15% of cultivated area). It is found across the Deccan Trap plateau — Maharashtra, MP, Gujarat, parts of Karnataka, AP, and Tamil Nadu.

Key characteristics:

• Origin: Weathering of Deccan basaltic lava (Deccan Trap)
• Texture: Fine-grained; high clay content (montmorillonite); self-ploughing (cracks in dry season)
• Nutrients: Rich in iron, magnesia, lime, and calcium; deficient in phosphorus, nitrogen, and organic matter
• Crops: Cotton (ideal — hence "cotton soil"), soybean, jowar, wheat, sunflower, sugarcane, citrus fruits

Red and Laterite Soil

Red and Laterite Soil covers ~18% of India's cultivated area. Red soil is found in eastern MP, Chhattisgarh, Odisha, Jharkhand, Tamil Nadu, and Karnataka plateau. Laterite soil occurs in high-rainfall areas of Kerala, Karnataka, Odisha, and parts of Tamil Nadu.

Key characteristics:

• Origin: Iron oxide (Fe₂O₃) from weathered crystalline Archaean rocks
• Texture: Sandy to gravelly; low fertility (poor in nitrogen, phosphorus, humus); well-drained; friable
• Crops: Rice (with irrigation), millets, groundnut, cotton, tobacco, cashew (laterite); tea, coffee, rubber (red/laterite slopes)

Arid/Desert Soil

Arid/Desert Soil is found in Western Rajasthan (Thar Desert), Gujarat (Rann of Kutch border areas), and parts of Punjab-Haryana near the Thar. It is sandy with low organic matter, high salt content in places, and very low moisture retention. Poor for crops; millet (bajra) and drought-resistant crops grown; Indira Gandhi Nahar has converted some areas to irrigated agriculture (wheat, cotton).

Forest/Mountain Soil

Forest/Mountain Soil occurs on Himalayan slopes (J&K, HP, Uttarakhand, NE states) and Western Ghats slopes. It is thin, acidic, organic matter-rich, and immature (shallow profile) with rocky outcrops. Crops: tea (Darjeeling, Assam), apple, potato; mainly forestry use.

Saline/Alkaline Soil

Saline/Alkaline Soil affects canal-irrigated areas of Punjab, Haryana, and Rajasthan (waterlogged, salt accumulation) and coastal areas (saltwater intrusion). Types include:

• Usar/Reh — alkaline, UP
• Thur — saline, Gujarat
• Sar — coastal salt marshes

This soil degradation affects ~7.5 million ha nationally. Reclamation methods: gypsum application, leaching (heavy irrigation + drainage), growing salt-tolerant crops (rice).

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