Evaluating the Soil Properties of Different Land Use Types in the Deviskel Watershed in the Hilly Region of Northeast Türkiye

Land use is a remarkable human-induced change that has redesigned the Earth’s surface since the beginning of civilization. Due to the combination of rugged terrain and low-income levels in rural areas, people in watershed regions often resort to overexploiting forests, agricultural land, and grasslands beyond their capacity. As a result of these spatio-temporal changes in land use, various soil properties undergo changes. This study aims to determine the changes in some physical (texture, bulk weight, particle density, total porosity), hydro-physical (water holding capacity, permeability, field capacity, wilting point), physico-chemical (organic matter, pH, electrical conductivity), and erodibility (dispersion ratio, colloid–moisture equivalent ratio, erosion ratio, clay ratio, aggregate stability and K-factor of Universal Soil Loss Equation-USLE) properties of soil depending on land use in the Deviskel Watershed in the city of Artvin in Türkiye. For this purpose, disturbed (composite) and undisturbed (cylinder) soil samples were taken from a 0 to 20 cm depth at 108 different points in the determined areas (36 from forests, 36 from agricultural areas, and 36 from grassland areas). It was determined that 15 of the 19 soil properties examined showed statistical differences depending on the change in land use. All the examined soil properties, except for clay content, particle density, dispersion ratio, and aggregate stability, were found to be statistically significantly affected by the change in land use, and the reasons behind these changes were discussed. The particle density had the lowest coefficient of variation value (15.26%) while electrical conductivity had the highest coefficient of variation value (91.25%). According to erosion tendencies, all watershed soils were found to be susceptible to erosion. The average aggregate stability was 88.52% in forest soils, 84.84% in agricultural soils, and 85.48% in grassland soils. The average USLE-K factor was determined to be 0.22 for forests, while it was determined to be 0.17 and 0.18 for agriculture and grassland areas, respectively. According to the USLE-K factor, 68.37% of the watershed was dominated by moderately erodible soils, while 31.63% consisted of highly erodible soils. Based on the colloid–moisture equivalent ratio, erosion ratio, and clay ratio, which are statistically different erodibility features, the grassland soils of the research area were found to be more susceptible to erosion than forest and agricultural soils. In terms of aggregate stability, which indicates resistance to water erosion, forest areas had higher values, while agricultural lands were more prone to erosion.