Abstract:In this study, field experiments with water scouring were conducted to analyze the characteristics of runoff and sediment yield, and nitrogen and phosphorus loss under the conditions of different slope lengths. Results showed that with a fixed inflow rate, the amount of infiltration along slope land increased, but the runoff decreased with the increase of slope length. Notably, there was a critical slope length, where the amount of infiltration equaled to runoff, but there was the negative linear relationships between the slope length and accumulated runoff. Similarly, the sediment yield also increased with the increasing slope length, but the total loss of sediment of per unit length was not significant (P>0.05). The cumulative sediment yield increased with the extension of slope length. For nutrient transport, power function was superior than exponential function in describing the changing process of nitrate nitrogen and soluble phosphorus. And the concentrations of nitrate nitrogen and effective phosphorus in sediment decreased over time. The nutrient enrichment ratio became greater as slope length increased. Also, there was a critical slope length inducing the total loss of nutrient to be maximum with the increase of slope length. Besides, the concentration of nitrate nitrogen in soil profile showed a peak feature with the increase of soil depth, and the peak occurred at different depths of soil. Furthermore, soil available phosphorus mainly distributed in 0—5 cm soil layer, and it was extremely low below 5 cm of soil depth. These results mentioned above provide a reference value for further analysis on the effect of slope length on water and soil nutrient loss.