Genesis of associated red and black shrink-swell soils of Maharashtra

Two associated shrink - swell soils (red and gray coloured) occurring in a catena in the Hingoli district of Maharashtra were taken for this study. Detailed study of the morpho logical, physical and chemical properties indicated that both the soils have Vertisol characteristics. The low hydraulic conductivity of red Vertisols is due to high Mg2+ and Na+ in the exchange complex. Mineralogical properties indicate that smectite is the dominant mineral in both the soils. The presence of kaolin in the gray Vertisols indicate that the transformation of smectite to kaolin in the past humid climate. The absence of kaolin in red Vertisol indicates that the parent material (red bole) was not exposed to the earlier humid climate. They have been formed from the red boles observed in the vicinity of the study area containing high amount of smectite along with palygorskite mineral. The presence ofpalygorskite mineral with smectite in red shrink-swell soils and its absence in other associated soils in a catena indicate that this mineral cannot be considered as an index mineral for arid climate. The release of Mg2* from paly gorskite mineral disperses the clay and clogs the pores resulting impeded drainage which adversely affected the crop production.