Clay Mineralogical Composition of Some Soil Orders from Himachal Pradesh

The clay fractions of A and B horizons of seven soil profiles collected from various locations of Himachal Pradesh have been studied. These profiles have developed under four different agro-climatic zones and classified as Alfisol, Inceptisol and Mollisol orders. Profiles belonging to Alfisol and Mollisol orders have similar mineralogical composition with mica, a complex of 14Å minerals, kaolinite, quartz and feldspars. The complex of 14 Å minerals, has always a fraction that is heat resistant (trioctahedral chlorite), a portion that collapses on K⁺ saturation and does not expand with glycol (vermiculite) and a small amount swelling with glycol (smectite). Some of these soils also show presence of interstratified minerals. The same minerals are present in profiles of Inceptisol but with dominance of smectite. The transformation of mica and chlorite into interstratified and swelling minerals generally increased toward the upper horizons of the profiles.