A History of Agriculture in India v1.c8.s2.t2.3

v1.c8.s2.t2.3

Black soils are highly argillaceous, fine-grained, and dark with a high proportion of calcium and magnesium carbonates. They are very tenacious of moisture, and are exceedingly sticky when wet. Owing to considerable contraction on drying, large and deep cracks are formed. They contain much iron and fairly high quantities of lime, magnesia, alumina, and potash. However, they are poor in phosphorus, nitrogen and organic matter. In all regur soils, in general, and in those derived from ferromanganesian schists, in particular, there is a layer rich in kankar nodules formed by the segregation of calcium carbonate at some depth below the surface and above the weathered rocks. The soils are generally rich in montmorillonitic and beidellitic groups of minerals.