Effect of wheat straw incorporation on soil detachment capacity on sloping farmland in the agricultural region of the Loess Plateau, China

Purpose Wheat straw is typically incorporated into topsoil by local farmers on sloping farmland. The changes in soil properties after straw incorporation might significantly influence soil detachment capacity driven by concentrated flow (D-c). This study was conducted to investigate the effect of wheat straw incorporation on D-c on sloping farmland in the agricultural region of the Loess Plateau. Materials and methods Soil samples (diameter 9.8 cm, height 5 cm) were collected from five plots (four with wheat straw incorporation and one with bare soil), and were scoured under 15 different flow shear stresses (five flow discharges x three slope gradients) in a hydraulic flume (4.0 m in length, 0.2 m in width) to determine D-c. The soil properties, including soil moisture content (SMC), soil bulk density (BD), total porosity (TP), organic matter content (OM), mean weight diameter (MWD), soil cohesion (Coh), and penetration resistance (PR) were measured to explain the variations in D-c with wheat straw incorporation. Results and discussion Wheat straw incorporation significantly increased TP, OM, MWD, Coh, and PR, however, the SMC and BD fluctuated over straw incorporation with no distinctive trend. The measured D-c was significantly affected by wheat straw incorporation. Compared with bare soil, the D-c with wheat straw incorporation decreased by 25.03-42.68%. The OM, MWD, Coh, and PR were the main factors affecting D-c, particularly MWD and Coh. The D-c decreased with Coh as a power function and with MWD as an exponential function. A model was developed to estimate the variation in D-c with wheat straw incorporation based on stream power, Coh, and MWD (R-2 = 0.95; NSE = 0.95; p < 0.01). Conclusions The present results revealed that wheat straw incorporation significantly decreased D-c by increasing OM, MWD, Coh, and PR and provided a reference for reducing soil erosion in typical agricultural areas of the Loess Plateau.