Variations in morphometric characteristics of vertisols in Rajasthan

Range, mode and coefficient of variation (CV) have been reported for crack indices and attributes of slickensides within and between seven soils series of Vertisols. The factors for the variation have also been analyzed. Width, depth, spacing and volume among the crack indices ranged from 2 to 9.2 cm, 30 to 100 cm, 84 to 100 cm and 9100 to 74400 cm3 m−3, respectively with moderate (15 to 36%) to high (>36%) CV. Upper and lower arms of slickensides were situated between the soil depths of 32 to 76 and 51 to 150 cm with moderate CV. The thickness of slickenside varied from 6 to 84 cm with high CV. Mode of crack width and thickness of slickensides were higher in Aklera, Bhatewar and Patan series, while Chambal and Kota series registered higher mode values for crack depth. Crack volume, a product of width, depth and spacing was higher in former than latter. Taswaria and Taswaria sodic series were the intermediate between the two with respect to these attributes. Upper and lower arms of slickensides were closer to the surface in shallow Vertisols, as compared to their deeper counterparts. The CV with respect to crack width and depth and thickness of slickensides was low (<15%) and was moderate for crack volume, within the soil series. Proportion of fine to total clay, smectite content, soil depth and hydraulic conductivity alone or in combination accounted for the variations. COLE and free Fe2O3 to clay ratio were the mirror image of the variations.