6. Land and Soil Degradation and Remedial Measures

Most published research on soil degradation in general emphasizes the role of anthropogenic factors. Even among the natural soil degradation processes the regressive pedogenic processes that lead to the formation of CaCO₃ and concomitant development of subsoil sodicity and the adverse effects of palygorskite mineral on the soils of the semi-arid tropics (SAT), have received little global attention as the natural processes of chemical degradation of soils. Pedogenic calcium carbonate, soil sodicity and palygorskite mineral impair the hydraulic properties of the SAT soils, which reduce their crop productivity. This type of unfavourable soil health triggered by the tectonic-climate linked regressive pedogenic processes (formation of pedogenic calcium carbonate and development of sub soil sodicity) needs to be globally considered as the natural soil degradation process. The regressive pedogenic processes that are inherently connected to the development of natural soil degradation, expands the basic knowledge in pedology and thus it may have relevance in soils of other SAT areas of the world. Research efforts made in the Indian subcontinent explains the cause-effect relationship of the degradation and provides enough insights as to how the remedial measures are to be invented including the role of pedogenic CaCO₃ and geogenic Ca-zeolites as soil modifiers along with gypsum, in making naturally degraded soils resilient and healthy.