Explanation: Regur soils:

• Black soils are essentially mature and fertile soils which have been produced by relief and climate, rather than by a particular type of rock. Chemically, the black soils are rich in lime, iron, magnesia, and alumina. Owing to their iron-rich granular structure makes them resistant to wind and water erosion. They are poor in humus yet highly moisture-retentive, thus responding well to irrigation. They also contain potash.
• This soil has been used for growing a variety of crops for centuries without adding fertilizers and manures, with little or no evidence of exhaustion. These soils are best suited for cotton crops. Hence these soils are called regur and black cotton soils. Other major crops grown on the black soils include leguminous crops, wheat, jowar, linseed, Virginia tobacco, castor, sunflower and millets.
• Rice and sugarcane are equally important where irrigation facilities are available. Large varieties of vegetables and fruits including citrus fruits are also successfully grown on the black soils.
• A typical black soil is highly argillaceous with a large clay factor, 62 percent or more. In general, black soils of uplands are of low fertility while those in the valleys are very fertile.

Sources: NCERT