Black Cotton Soil Ecology and Deccan Trap Landscape of Raichur

Raichur district sits on the Deccan Traps — a vast volcanic basalt plateau formed by massive lava flows 65 million years ago. The basalt weathers into a distinctive black cotton soil (regur) — deep, vertisol soil with exceptional water-holding capacity and shrink-swell properties. This soil cracks deeply in summer, sealing itself to retain moisture — a natural slow-release water mechanism that supports dryland cotton and paddy cultivation without heavy irrigation. The district's flat floodplain ecology along the Krishna supports significant wetland bird populations, including migratory waders and waterbirds. Traditional communities understand the soil's seasonal behaviour precisely, knowing when black cotton soil fields are workable (a narrow window after sufficient drying) and when they will become impassable.