A History of Agriculture in India v1.c8.s1.1

v1.c8.s1.1

A mature soil is the handiwork of geoclimatic and geobiological forces operating jointly. How do these forces operate? Soils are formed by the weathering and disintegration of rocks. Soils are either sedentary, i.e. those formed out of the underlying rock, or are transported, i.e. those formed out of the disintegrated parts of rocks, brought down by the action of rivers from a distance. The process of breaking down of rock masses and their gradual development into soil is called weathering. The agencies of weathering are physical, i.e. those that break the rock into smaller pieces, and chemical, i.e. those that change the composition of the minerals forming the rock and, in so doing, exert a marked influence upon its physical character. The work of the physical agencies is called decomposition. Both these processes are complementary to each other.