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Red soils occupy the second largest area of about 61 million hectares or 18.5 per cent of the total reporting area. They are found mainly over the Peninsula from Tamil Nadu in the south to Bundelkhand in the north, and Rajmahal in the east to Kathiawad and Kachchh in the west (Fig. 63).
These soils are also found in tracts in western Tamil Nadu, Karnataka, southern Maharashtra, Andhra Pradesh, Chhattisgarh, Jharkhand, Odisha, and in scattered patches in Bundelkhand, Mirzapur, Sonbhadra (Uttar Pradesh), Banswara, Bhilwara, Udaipur, (Rajasthan).
Developed on Archaean granite, these soils are also known as the omnibus group. Their colour is mainly red because of the presence of ferric oxides. Generally, the top layer is red, while the horizon below is yellowish in colour. The texture of red soils varies from sand to clay and loam. Their other characteristics include porous and friable structure, absence of lime, AanAarand car bonates and small quantity of soluble salts. In general, these soils are deficient in lime, phosphate, magnesia, nitrogen, humus, and potash. Intense leaching is a menace to these soils. In the uplands, they are thin, poor, gravelly, sandy, or stony and porous, light-coloured soils, but in the lower plains and valleys, they are rich, deep, dark coloured fertile loams. In places where irrigation water is available, they are devoted to wheat, cotton, pulses, tobacco, millets, oilseeds (linseed), potato, and orchards.
Black soils, also known as Regur (cotton-soil) and internationally as ‘tropical chernozems’, are the third largest soil group in India. They sprawl over about .50 million hectares accounting for 1,5 per cent of the total reporting area of the country. Getting their parent material from the weathered rocks of Cretaceous lava, they stretch over the greater parts of Gujarat, Maharashtra, western Madhya Pradesh, north-western Andhra Pradesh, Karnataka, Tamil Nadu, Rajasthan, Chhattisgarh, and Jharkhand, up to Rajmahal Hills. They are mature soils. Over the greater parts of the black earth soil, the average annual rainfall varies between .50 and 75 cm.
The colour of these soils varies from deep black to light black. In general, these soils have clayey texture and are rich in iron, lime, calcium, potash, aluminium and magnesium. They are, however, deficient in nitrogen, phosphorous and organic matter. Moreover, these soils have a high water retaining capacity. They are extremely compact and tenacious when wet, and develop wide cracks when dry. In other words, they swell greatly and become sticky when wet in rainy season. When the soil is wet, it becomes difficult to plough the field as the plough gets stuck in mud. In the dry season, the moisture evaporates, the soil shrinks and develops wide cracks, often 10-15 cm deep. These soils are highly productive, and thus well suited for the cultivation of cotton, pulses, millets, linseed, castor, tobacco, sugarcane, vegetables, and citrus fruits.