2. Black soils (Vertisols)
- A typical black soil has a high clay content of 62% or more.
- The black soils have high moisture retention capacity, and are generally neutral to slightly alkaline.
- When dry, soil shrinks and develops deep cracks permitting oxygenation of the soil to sufficient depths and thus enhancing fertility.
- The black colour is due to the presence of a small proportion of Titaniferous Magnetite or Iron and black constituents of the parent rock.
- They generally contain 10% Alumina, 9-10% Iron Oxide, 6-8% lime and Magnesium Carbonates, less than 0.5% Potash and are low in Phosphates, Nitrogen and humus.
- This soil has been used for growing a variety of crops for centuries without adding fertilizers and manures.