Red Soil

Definition

A reddish soil formed by the weathering of old crystalline and metamorphic rocks in the low-rainfall areas of the Peninsular plateau, owing its colour to iron oxide.

Key points

• Develops on the ancient crystalline and metamorphic rocks of the Peninsula in areas of relatively low rainfall, especially eastern and southern Tamil Nadu, Karnataka, Andhra Pradesh, Chhattisgarh, Odisha, and parts of the middle Ganga plain.
• The red colour comes from a high content of iron oxide (ferric oxide); the soil looks yellow when hydrated.
• Generally porous, friable, and poor in nitrogen, phosphorus, and humus, but fertile in the lower areas with proper manuring and irrigation.
• Suited to crops such as cotton, wheat, pulses, millets, groundnut, potato, and, in irrigated patches, rice and oilseeds.
• The second most widespread soil group in India after alluvial soil, covering much of the Peninsular plateau.

Why it matters for CAPF

The crystalline-rock origin, the iron-oxide colour, the low fertility (improved by inputs), and the Peninsular low-rainfall distribution are recurring soils facts and matching items.

Common confusion

Red soil (weathered crystalline rock, iron-oxide colour, low rainfall areas) is different from laterite soil (intense leaching, high rainfall, infertile, hardens into brick) and from black cotton soil (basalt weathering, moisture-retentive). All three occur in the Peninsula.

Parent note

soils and natural vegetation of india