Assessing aggregate stability of soils under various land use/land cover in a watershed of Mid-Himalayan Landscape

Abstract

Soil aggregate stability is considered as an important indicator of soil quality in thelandscapes witnessing land degradation due to soil erosion by water. An increase inanthropogenic activities over the period of time has accelerated soil erosion thatnecessitated need to assess soil aggregate stability in various land use/land cover in thehilly and mountainous landscape. The study investigated the soil aggregate stability ofsurface soils in different land use/ land cover classes, hillslope unites as well as in respectto terrain parameters in the watershed. The watershed located in mid- Himalayan regionof Tehri Garhwal district, Uttarakhand, India covering an area of 196 ha. The elevation ofthe watershed ranges from 1200 m to 1927 m. CartoDEM was used to derive terrainparameters i.e., aspect, slope and terrain indices like Terrain Wetness Index (TWI) andStream Power Index (SPI) of the watershed. Among the various land use /land coverclasses, aggregate stability in crop land was found to be in the range of 0.16 (lowerhillslope) to 0.28 (mid hillslope), in forest ranged from 0.18 (mid hillslope) to 0.28 (upperhillslope) and in dense scrub ranged from 0.16 (middle slope) to 0.32 (upper/lowerhillslope). The aggregate stability was further analyzed in relation with various soil(carbon, nitrogen, sand, silt, clay and pH) and terrain (slope, elevation, TWI and SPI)variables. Among these variables soil carbon, nitrogen, elevation, TWI and SPI were foundto have moderate to high degree of correlation with soil aggregate stability. Predictionmodel developed by using the various significant soil and terrain parameters were foundto be more effective (r2 = 0.50) than the models developed using only soil parameters(r2= 0.36) or only terrain parameters (r2= 0.37).