Effects of different land-use types on soil detachment capacity in loess areas

Abstract

Against the background of similar geomorphological characteristics and environmental temperatures, land-use types alter the soil detachment capacity (D_c) by changing soil properties and root traits. However, there is a lack of in-depth discussion regarding the response of D_c to land-use types in loess areas. The purpose of this study was to quantify the influences of different land-use types in loess areas on D_c, soil erodibility (k_r), and critical shear stress (τ_c) and explore the key factors affecting D_c under runoff erosion based on the links between root traits and soil properties, and combined with PLS-SEM algorithm, a meta-model of D_c influence mechanism was established. Two hundred and seventy undisturbed soil samples were collected from six different land-use types and scoured under nine specific combinations of flow rate and slope (flow rate: 0.167–0.5 L s⁻¹, slope: 10.5–20.8 %). The results showed that with the change in land-use type, D_c changed considerably. The average D_c of the shrubland was only 1/22 of that of the cropland. The change trend of k_r was consistent with that of D_c, while the change trend of τ_c had no obvious regularity. The relationships between the root density parameters and D_c were simulated using the exponential function and Hill curve, respectively, and the predictive effect of the Hill curve was better than that of the exponential function. Compared with the other comprehensive hydraulic parameters, shear stress (τ) was D_c’s most effective predictive factor. Correlation and path analyses revealed that soil organic matter (SOM) and root length density (RLD) were the best indicators of D_c. Furthermore, a dimensionless D_c prediction model suitable for different land-use types was established based on τ, SOM, and RLD, and the model exhibited a high accuracy (R² = 0.955, NSE = 0.911).