Abstract
The development of the profile is mainly the consequence of movement of water in the soil and we may distinguish the following three possibilities:
Firstly under humid condition there is an excess of rainfall over evaporation. Thus, there is a general tendency of downward movement of soil moisture and the soil is subjected to a leaching process, whereby the constituents are carried downwards and are either deposited in the lower horizons or completely removed in drainage water.
Secondly, under arid conditions with an excess of potential evaporation over rainfall, rain moistens the soil to a limited depth. After cessation of rain, the soil moisture rises again to the surface under the influence of evaporation with the result that translocation occurs in both directions, and in final stages of dessication, the deposition of salts from solution may occur throughout an appreciable depth of surface soil.
Thirdly, downward movement may be prevented by the presence of ground water, or the occurrence of impervious sub-soil layer. In such cases water movement can only occur laterally over the horizon of impedence. The impedence may not be complete, but intermediate stages can also be observed.
The development of alkali soil profile is governed either by the second or third or by the combination of both the processes mentioned above.
In India, saline soils, saline-alkali soils and alkali soils are commonly distributed. Leached soils are of very rare occurrence.
