📌 Topic 03 of 6 · Chapter 04 · Soils of India
Red & Yellow Soil of India
Distribution, properties, crops — complete notes for UPSC & PSC exams.
🌱 Red Soil — Overview
| Feature | Details |
|---|---|
| Formation | Weathering of ancient crystalline and metamorphic rocks (granite, gneiss) |
| Area covered | ~18% of India’s land area — 3rd most widespread |
| Distribution | Tamil Nadu, AP, Telangana, Karnataka, Odisha, Jharkhand, Chhattisgarh, MP, Rajasthan |
| Colour | Red due to iron oxide (Fe₂O₃); yellow when hydrated |
| Texture | Sandy to loamy; porous; friable |
| Fertility | Less fertile; deficient in nitrogen, phosphorus, humus, lime |
| pH | Acidic to neutral |
🌱 Why Red and Yellow?
- Red colour = presence of iron oxide (Fe₂O₃) — ferric iron in anhydrous form
- Yellow colour = iron in hydrated form (Fe₂O₃·H₂O) — in lower layers or wetter areas
- The soil looks red on the surface but yellow in the lower horizons
🌾 Crops Grown in Red Soil
- Wheat, rice, cotton, sugarcane, pulses, millets (jowar, bajra, ragi)
- Groundnut, potato, tobacco
- With irrigation and fertilizers, red soil can be made productive
- Ragi (finger millet) grows well in red soil — important crop of Karnataka, Tamil Nadu
⭐ Key Facts — Red & Yellow Soil:
• Red colour = iron oxide (Fe₂O₃) = ferric iron
• Formed from crystalline and metamorphic rocks (granite, gneiss)
• 3rd most widespread soil in India (~18%)
• Deficient in: Nitrogen, phosphorus, humus, lime
• Tamil Nadu has the largest area under red soil
• Responds well to irrigation and fertilizers
• Red colour = iron oxide (Fe₂O₃) = ferric iron
• Formed from crystalline and metamorphic rocks (granite, gneiss)
• 3rd most widespread soil in India (~18%)
• Deficient in: Nitrogen, phosphorus, humus, lime
• Tamil Nadu has the largest area under red soil
• Responds well to irrigation and fertilizers
📌 Red Soil vs Black Soil:
• Red soil = crystalline rocks = less fertile = porous = acidic
• Black soil = basaltic lava = more fertile = sticky = alkaline
• Red soil = eastern/southern Deccan; Black soil = western/central Deccan
• Red soil = crystalline rocks = less fertile = porous = acidic
• Black soil = basaltic lava = more fertile = sticky = alkaline
• Red soil = eastern/southern Deccan; Black soil = western/central Deccan