LAUSR

ABSTRACT Tillage erosion coupled with water erosion complicates soil erosion process on hilly croplands. This study aims to investigate the role of water discharge and slope gradient in the impact of tillage erosion on runoff and sediment yield by simulated tillage and scouring experiments. Results show that simulated tillage duration (10-, 20-, 30-, 35-, 40-year tillage) had positive effect on runoff yield, while soil infilling in rill by tillage (12, 21 kg m−1) retarded runoff yield. Sediment yield by overland flow is closely related to soil redistribution by tillage. Water discharge rate positively promoted the impact of tillage durations on runoff and sediment yield. In the premise of rill infilling, sediment yield increased significantly with increasing slope gradient, while runoff yield decreased by 29.3%, 1.7% and 1.3% for 0, 12, 21 kg m−1 soil flux at the slope gradient of 15° compared with those for the slope gradient of 10°, respectively, implying a coupling relationship between rill infilling and slope gradient. Our results indicate that tillage erosion can alter hydrologic processes of the hillslope and exacerbate sediment yield, and water discharge and slope gradient can reinforce the impact of tillage erosion on runoff and sediment yield.