Spatial Variation of Soil Available Phosphorous in the Dal Lake Catchment of Lesser Himalayas

The study attempts to evaluate the spatial pattern of soil available phosphorus, and its availability with respect to various factors including elevation, slope and landuse using statistical methods and GIS spatial analysis techniques. The results showed that the Ordinary Kriging Spherical method performed the best in the prediction of soil available phosphorus in the Dal Lake catchment. The spatial variation of soil available phosphorus was high in Dal Lake catchment and the upstream regions around Dal Lake, including the north of Dal Lake, had the highest soil available phosphorus content. The mean and standard deviation of soil available phosphorus content gradually decreased as the slope increased. The cultivated land comprised 24.36% of the catchment and out of that land 50.81% belonged to the medium to very high SAP level classes, and it played a major role in SAP availability within the catchment and a potential source of phosphorus to Dal Lake resulting in eutrophication. Among land use types, paddy fields have some of the highest maximum values and variation of coefficients. Sub watershed scale soil available phosphorus was significantly affected by elevation, slope and landuse and was decided by not only these environmental factors but also some other factors such as artificial phosphorus fertilizer application.