Give geographical reasons —

1. Red soil is not suitable for cultivation.
2. Laterite soils are used as building material.
3. Black soils are black in colour.
4. Alluvial soils of Coastal region are black in colour.

1. Red soils are generally low in nutrients and have poor water-holding capacity. They lack lime, magnesia, phosphate, nitrogen and humus. This makes red soils unsuitable for cultivation.
2. Laterite soils are used as building material because they harden like iron when exposed to air.
3. Black soils are black in colour because they are formed from weathered lava rocks like black crystalline schists and basic gneisses.
4. The Alluvial soils of the coastal regions are formed due to the deposition of sediments brought mainly from the Deccan Trap region. The Deccan Trap region is volcanic in origin so the sediments are black in colour. This imparts black colour to the Alluvial soils of Coastal region.