Comparison of the effects of five long-term land use and management practices on runoff, soil erosion, and nutrient loss under natural rainfall in the Mollisol region of Northeast China

Clarifying the effects of various land-use and management practices on soil erosion and nutrient loss of sloping land can help optimize land use patterns and management strategies. This study assessed the effects of five long-term land-use and management practices on runoff, soil erosion, and nutrient losses. Field data from runoff plots established in 2006 in bare land (BL), natural vegetation restoration (NVR), no tillage (NT), reduced tillage (RT), and conventional tillage (CT) were used in two seasons of natural rainfall (from July to September in 2021 and 2022). The results indicated that the runoff depth (RD) was 84.1% and 43.2%-81.7% lower, the sediment yield (SY) was 99.9% and 96.9%-99.8% lower, the total nitrogen (TN) loss was 99.1% and 93.1%-98.6% lower, and the total phosphorous (TP) loss was 99.8% and 96.7%-99.7% lower in the NVR and three tillage practices, respectively than in the BL. The RD, SY, and nutrient losses were significantly lower in NT than in RT and CT. The TN loss in runoff contributed to 88.3% and 87.6% of the TN loss in the NVR and NT, respectively, whereas the TN loss in the sediment (TN-SL) for BL accounted for 94.7% of the TN loss in BL. Meanwhile, most of the TP loss (56.1%-99.7%) was attributed to soil erosion rather than runoff in the five treatments. Furthermore, the effect of runoff and SY on nutrient losses differed significantly for the five land-use and management practices. The effects of runoff and SY on the TP loss were negligible in the NVR and three tillage treatments. However, the effects on the TN loss were larger. Rainfall erosivity had the largest effect on runoff, SY, and nutrient loss in the five treatments. Our findings can help land managers to select sustainable measures to control soil and nutrient losses in sloped farmland in Northeast China. Land use change significantly alters soil and nutrients loss law. Compared with bare land, revegetation and tillage measures weaken the sensitivity of soil erosion to runoff, improve the potential of TN loss with runoff and sediment, but have weak effect on the potential of TP loss with runoff and sediment. image