Soil organic carbon as a function of land use and topography on the Loess Plateau of China

•The effects of land use intensified from summits to slope areas to gullies.•The effects of land use extended from 20cm on the summit to 80cm in the gullies.•Significant interactions between land use and topography on the SOC were observed.•Land use and topography were key predictors of the SOC spatial distribution. Land use and topography are two primary factors that affect the spatial distribution of soil organic carbon (SOC) at the watershed scale, particularly in areas of multiple land uses and complex topography on the Loess Plateau. The General Linear Model (GLM) combined with Duncan’s Multiple Range Test (DMRT) were used to conduct variance tests and evaluate the effects of topography (summit, sloping areas and gullies), land use (farmland, orchard, grassland, shrubland and woodland), and their interactions on the vertical and horizontal distributions of SOC at soil depths of 0–10, 10–20, 20–40, 40–60, 60–80 and 80–100cm. The effects of land use intensified from the summits to the slope areas to the gullies. The SOC concentrations throughout the 100cm-thick soil profiles in farmland in slope areas and gullies were, respectively, 45.4% (P