Properties for coarse, fine and very fine clays were evaluated in two Vertisol pedons, namely, Karanpur and Keshavi. The molecular weight and charge density in both the soils increased with reduction in particle size and depth of the pedon. For all particle fractions, Keshavi soil had higher CEC. Specific surface area was more in Karanpur soil, whereas surface charge density was more in Keshavi soils. Kaolinte and Ca-montmorillonite under Ca-system, K-beidelite and kaolinite in K-system and Na-beidelite and kaolinite in Na-system were the stable phases in both the soils. The negative ΔGr values indicated that smectite and vermiculite are more stable under the prevailing soil environment.
Vertisol, clay properties, mineral stability, clay minerals
