Effects of Long-term Fertilization and Tillage on the Production of Runoff and Sediment on Purple Soil Slope Cropland

[Objective] This study is aimed at investigating the effects of long-term fertilization and cultivation on the production of runoff and sediment on purple soil sloping cropland. [Methods] The experiment stipulated that each community should adopt the typical planting mode of winter wheat summer corn rotation on purple soil sloping cropland. Five treatments were set up on 15° purple soil slopes, which were no fertilizer application in downslope cultivation (CK), combined application of manure and fertilizer with downslope tillage (T1), single application of chemical fertilizer with downslope tillage (T2), single application of chemical fertilizer increment with downslope tillage (T3), and single application of chemical fertilizer with cross-slope monopoly cultivation (T4). There were three replications for each treatment. A total of 107 erosive rainfall events were monitored during 2008—2020, and the variation characteristics of runoff depth, sediment yield, and sediment concentration under each event rainfall and different fertilizer tillage treatments were analyzed. [Results] Among the fertilization and cultivation treatments, the maximum annual runoff depth per unit area was 100.37 mm, and the minimum was 4.56 mm. Except for the insignificant difference in runoff depth between T2 and T3 treatments (p>0.05), there was a significant difference in runoff depth between the other treatments (p<0.05), and the runoff depth of all treatments was significantly smaller than that of the CK treatment, and the mean values were in the order of CK>T3>T2>T1>T4. Except for the insignificant difference in sediment content between T1 and T2 treatments (p>0.05), there was a significant difference in sediment content between the other treatments (p<0.05), which were significantly smaller than the CK treatment, and the mean values were in the order of CK > T3 > T2 > T1 > T4. The sediment concentration showed no significant difference among T1, T2 and T3 (p>0.05), but they were significantly smaller than that of the CK treatment (p<0.05) and significantly higher than that of the T4 treatment (p>0.05), and the mean values were in the order of CK > T3 > T1 > T2 > T4. The sediment content under each treatment was negatively correlated with rainfall amount with a power function (p<0.05). [Conclusion] The combined application of organic fertilizer and chemical fertilizer along the slope cultivation and cross-slope monopoly cultivation contributed greatly to the reduction of surface runoff and sediment production on purple soil sloping cropland.