Catenary Variations in Properties of Shrink-Swell Soils in Minor 4 of Jayakwadi Irrigation Project in Parbhani District, Maharashtra

A shrink-swell soil sequence developed over Cretaceous-Eocene age basaltic catena was examined for understanding the influence of local relief on morphological, physical and chemical characteristics of soil. The morphology of these clay soils occurring on microhighs and microlows of catena shows that the Vertic Haplustepts on summits have dark grey to brown matrix with subangular to angular blocky aggregates having pressure faces on ped surfaces. There was successive increase in the thickness of Cambic and slickensided horizons in subgroups of Vertisol on the middle and foot slopes having yellowish grey matrix with depth, and of angular blocky structural aggregates with hard and firm consistency when dry. The Fe and Mn concretions in Bssl and Bss2 horizons of Chromic Haplusterts (P3) and Typic Haplusterts (P4) have indicated periodic oxidation and reduction leading to successive mobilisation and precipitation of Fe and Mn as oxides of small nodules along slickensides. The particle size for soils of summits and middle slopes was 'fine' but for soils on foot slopes, the particle size was 'very fine' at family level. These soils are slightly to strongly alkaline with increasing trends of carbonates and decreasing trends of organic carbon content. Exchangeable Ca to Mg ratio decreased with the profile depth and landscape position. The analysis of variance revealed that lateral (between soils) and vertical (within soils) variations in organic carbon and exchangeable Ca to Mg ratio was significant. The study showed that the catena model can be used to predict random variability in soils on landscape and to quantify processes that govern landscape development.