Spatial Variability of Available Soil Nutrients in the Shekhawati Region of Thar Desert, India

Abstract

Based on soil samples collected from 814 geo-coded sites in the rainfed croplands, irrigated croplands, rangelands and protected forests within the Shekhawati region of Thar Desert, Rajasthan, India, a spatial analysis of the distribution pattern of organic carbon (OC) and macronutrients i.e., available phosphorus (P) and available potassium (K) and micronutrients viz., DTPA extractable zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn) was carried out in GIS environment. It revealed that OC is deficient almost throughout the region, while P is deficient in large parts of the dune-covered west. Among others, K, Cu and Mn are adequately supplied in most areas, but Zn and Fe are inadequate in large parts. Irrigated croplands are better endowed than other land uses in respect of OC, P, Zn and Cu; forests in respect of K and Fe, and rainfed croplands in respect of Mn. The distribution pattern of the organic C and nutrients appears to be controlled by both natural and anthropogenic processes. Among the natural processes, fluvial processes appear to control the distribution in the hills and plains in the wetter east, while aeolian processes appear to control the distribution in the drier dune-covered west. Anthropogenic processes, especially through land use decisions and fertilizers input in irrigated tracts, have also influenced the sufficiency or otherwise of the soil nutrients.