Pedogenic Processes and Variability in Soil Properties of Red-ferruginous Soils of Southern Karnataka, India

Abstract

Climatic and landform diversity left its footprints on Indian Peninsula, offers an opportunity to inspect the impact of climate and related changes on key pedogenic soil qualities. To understand different pedogenic processes, we studied eight pedons from five major agro-climatic zones with varying morphology and physiography associated with similar land use. Depending on morphology and physio-chemical soil variables, soils were classified as Rhodic Kandiustults, Rhodic Kandiustalfs, Kandic Paleustalfs, Rhodic Paleustalfs, Typic Rhodustalfs, Aquic Haplustalfs, Typic Haplustepts at sub group level. Given that horizon differentiation is the basic unit of pedogenesis, numerical hierarchical cluster analysis was used to compare and construct the quantifiable soil qualities within horizons for better comprehension of pedogenic processes. The main pedogenic processes were desilication, clay illuviation, base leaching, ferralitization, rubrifaction, ferrugination and braunification. Principal component analysis (PCA) was used to identify the key soil characteristics that affect the pedogenic processes and they were correlated with elevation and climatic factors. Indicating the impact of dryness and climate change on clay mineralogy, potential evapotranspiration (PET) and length of dry period (LDP) showed a significant negative correlation with clay type and soil exchangeability, leading to an accumulation of clays with more sub-active to semi-active CEC/clay ratio classes in sub-surface soils in semi-arid tropical regions of southern Karnataka. In contrast, the horizon sequence of P4 showed a limited effect of time on profile development, due to cyclical variations in erosion and deposition cycles