Problem Soils in India

1. Saline Soils (Reh or Kallar Soils)

• Also called Reh / Kallar soils.
• How they look: White salt layer on the surface (like someone sprinkled salt).
• Usually occur in arid and semi-arid climates.
• pH: Less than 8.5 (not very alkaline).
• Crops severely affected at EC > 10 dS/m.
• EC (salinity measure): More than 4 dS/m → means too much salt in water.
• White crust seen on surface due to capillary rise of salts.
• Main problem: Roots cannot take water because of “osmotic stress.” Plants feel thirsty even when water is there.
• Toxic elements: Na⁺, Cl⁻, SO₄²⁻.
• Where found: Rajasthan, Punjab, Haryana, Gujarat, UP, coastal Andhra and Tamil Nadu.

2. Sodic (Alkali) Soils

• Also called Usar soils
• How they look: Hard crusts on surface, black alkali patches, very poor structure.
• pH: 8.5 to 10.5 (sometimes even 11).
• ESP (exchangeable sodium %): More than 15 → means too much sodium in soil particles.
• Sodium Adsorption Ratio (SAR) > 13.
• Black alkali appears due to Na₂CO₃ + organic matter reaction.
• Poor infiltration due to soil dispersion.
• Main problem: Soil becomes hard when dry and sticky when wet. Water cannot enter → poor infiltration. Crops suffer from Zn, Fe, Mn, and Cu deficiency.
• Where found: Indo-Gangetic plains (UP, Bihar, Haryana, Punjab, MP, Maharashtra).

3. Acid Soils

• How they look: Red to yellowish soils, often in high rainfall areas.
• pH: Below 6.5 (can go down to 4.5).
• Found in high rainfall zones (>2000 mm).
• Main problem: Toxic elements like Aluminium (Al³⁺) and Manganese (Mn²⁺) harm root growth. Phosphorus becomes unavailable (gets “fixed”). Calcium, magnesium, and molybdenum are deficient.
• Phosphorus becomes fixed → unavailable to plants.
• Tea, coffee, rubber grow well in acidic soils.
• Where found: North Eastern states (Assam, Meghalaya, Nagaland, etc.), Odisha, Chhattisgarh, Jharkhand, Kerala, Karnataka, West Bengal.

4. Calcareous Soils

• Contain lime nodules (CaCO₃).
• How they look: Grayish with lime nodules (small white lumps).
• Iron deficiency → chlorosis (yellow leaves with green veins).
• pH: More than 7.5.
• Phosphorus gets fixed due to calcium.
• Main problem: Too much calcium carbonate (>10%). Iron, zinc, and manganese deficiency → plants turn yellow (chlorosis). Phosphorus gets tied up with Ca and becomes unavailable.
• Where found: Bihar, UP, Rajasthan, MP, Maharashtra, Andhra Pradesh.

5. Laterite and Lateritic Soils

• Formed by laterization process under high rainfall and leaching.
• How they look: Reddish to yellow due to iron and aluminium oxides.
• How they form: Heavy rainfall washes away silica and bases → only Fe and Al remain.
• pH: 4.5 to 6.0 (acidic).
• Main problem: Very poor in fertility → low N, P, K, Ca, Mg. Poor water-holding capacity.
• Where found: Karnataka, Kerala, Tamil Nadu, Odisha, West Bengal, Assam, Meghalaya.
• Good for tea, coffee, cashew, coconut (with proper management).

6. Peaty and Marshy Soils

• How they look: Black, heavy, full of organic matter. Wet and waterlogged.
• pH: Very acidic (3.5 to 4.5).
• Poorly drained, anaerobic condition.
• Produce greenhouse gases like CH₄ (methane) under flooding.
• Main problem: Too much organic matter (20–40%). Deficient in potassium and phosphorus. Always waterlogged → poor aeration for roots.
• Where found: Kerala, West Bengal, coastal Odisha, Bihar.

7. Desert Soils

• How they look: Light-colored, sandy, loose, blown by wind.
• pH: 7.5 to 9.0.
• Main problem: Very low fertility (almost no organic matter). Cannot hold water (very sandy). Wind erosion is common.
• Where found: Rajasthan (Thar desert), Gujarat, Haryana, Punjab.

Quick Summary Table

• Total problem soils in India: ~100 million hectares.
• Largest area covered by: Acid soils (49 M ha).
• Next major problem soils: Saline–sodic soils (~6–7 M ha each).
• Soil survey & classification of problem soils in India: NBSS & LUP (ICAR), Nagpur.

One-Liner Quick Facts for Exam

• Largest area of problem soil in India → Acid soils (~49 M ha).
• Saline soils limit → EC > 4 dS/m.
• Sodic soils limit → ESP > 15, SAR > 13.
• Peaty soils → High organic matter but acidic (pH 3.5–4.5).
• Calcareous soils → Rich in CaCO₃, cause Fe/Zn deficiency.
• Laterite soils → Product of intense leaching, rich in Fe/Al oxides.
• Desert soils → Found in <400 mm rainfall zones, prone to erosion.
• Black alkali soils → Caused by Na₂CO₃ + organic matter.
• Tea crop grows well in acid soils.
• Salt crust on surface → Sign of saline soils.