Correct Option
Red soil derives its characteristic red colour primarily from the presence of ferric oxides (Fe₂O₃). These iron oxides are formed due to the chemical weathering of ancient crystalline and metamorphic rocks under conditions of high temperature and moderate rainfall. Red soils are generally porous, acidic, and deficient in nitrogen, phosphorus, and humus, but rich in iron. They are predominantly found in regions such as the Deccan Plateau, parts of Tamil Nadu, Chhattisgarh, Odisha, and southern Bihar.
Incorrect Options
- Abundance of magnesium: Magnesium does not impart a red colour to soil. It is often associated with dark-coloured rocks and soils.
- Accumulated humus: Humus, which is decomposed organic matter, typically gives soil a dark brown to black colour, not red.
- Abundance of phosphates: Phosphates are essential plant nutrients but do not play a role in determining the red coloration of soil.