Assessment of Soil Erodibility under Different Land Use/Land Covers in Western Himalayas

Soil erodibility refers to soil’s inherent susceptibility to erosion by rainwater and runoff. In this study, soil erodibility was estimated by using modified nomograph equation model (M-NOMO), and compared with various soil-based erodibility indices such as dispersion ratio, erosion ratio, erosion index, structural stability index, suspension ratio, critical level of soil organic matter, clay ratio, plasticity index etc. The study was conducted in a catchment of Nauni, Solan district, Himachal Pradesh, which falls under Ga3a micro-watershed. The study dealt with soil erodibility assessment by employing different indices under five land use/land covers, i.e., chir pine forest, oak forest, mixed forest, grassland and barren land. A total of 60 composite soil samples were collected from two slope categories, i.e., ≤ 30% and > 30% at two depths viz., 0-15 cm and 15-30 cm with three replications. The soil texture was found to be loam, sandy loam and sandy clay loam. The soil pH was slightly acidic to neutral in nature among all land use/land covers. The study highlighted that measurement of soil erosion in field practices is difficult, time consuming and expensive whereas, the approach of estimating soil erosion through soil erodibility indices on basis of soil conditions is relatively advantageous. The indices further prioritize the sub-watersheds for suggesting appropriate conservation measures. The highest values of erodibility factor (0.31 -0.37), dispersion ratio (19.55 - 23.58), erosion ratio (27.42 - 31.88), erosion index (18.31 - 21.48), suspension ratio (40.56 - 43.21) and lowest values of critical level of soil organic matter (1.79-2.45), plasticity index (12.22-13.10) and structural stability index (42.98-55.86) in barren land revealed that the barren land use is most susceptible to erosion in comparison to other land use/land covers in the study area.