Shrink–swell soils on shale geology of Chhattisgarh Basin, India: its formation and significance

We present the formation of shrink–swell (SS) soils on the shale geology of Chhattisgarh basin (CB), India, and its implications on sustainable agriculture management. In this study, four pedons (P1, P2, P3, and P4) were studied in a 10 km transact for their morphological, physical, chemical and mineralogical properties. Pedons P1 and P3 have more than 50 % clay, developed from shale and have both di- and tri-octahedral smectite in their fine clay fractions, and classified as Vertic Inceptisols. The pedons P2 and P4 with 65 % clay were developed from basaltic alluvium, with well-developed slickenside horizons and classified as Typic/Sodic Haplusterts. Based on the drainage line analysis, we attribute the formation of these SS soils to the riverine deposits of Deccan basalt (DB) from the higher elevation to valley portions, transported from the Maikal range of Central India. The presence of low-charge di-octahedral smectite of Vertisols and di- and trioctahedral nature of smectite in Inceptisols combinations are rare, but this possibility arises from mica (biotite) in the shale. These clays play a vital role in edaphological aspects, specifically rice-based agro-management (particularly in potassium and nitrogen) practices in this basin. High exchangeable magnesium per cent (EMP) and low exchangeable sodium per cent (ESP) in subsoil enhance the water storage in subsoils and its utilization during dry spell by the rice crop. Such kind of edaphological studies with decoding the pedological data is minimum. This research decodes the current information and paves a role in rationalizing the rice production system using the scientific methods of input usage.