Characterization of runoff phosphorus loss from a combination of long-term fertilizer application and cultivation on sloping croplands

Abstract

Study region: Purple soil sloping cropland, a representative landscape in the upper reaches of the Yangtze River, and is the main distributed agricultural basis of the Sichuan Basin, Southwest China. Study focus: This study investigated the responses of runoff P loss to several rainfall categories, the combined application of manure and chemical fertilizers, and contour cultivation by analyzing 120 rainfall events that transpired between 2008 and 2022 on a representative purple soil sloping cropland. There were five treatment combinations utilized in this study: no fertilizer application with downslope cultivation (CK), chemical fertilizer application with downslope cultivation (T1), manure and chemical fertilizer application with downslope cultivation (T2), 1.5-fold chemical fertilizer application with downslope cultivation (T3), and chemical fertilizer application with contour cultivation (T4). New hydrological insight of the region: The runoff depth during large rainstorms was significantly higher (21.5–252.4 %) than that of other rainfall categories (p < 0.05). Dissolved phosphorus (DP) loss was highest during rainstorms, whereas the highest particulate phosphorus (PP) loss was observed during large rainstorms. The runoff depth and sediment yield were significantly higher in CK than those in other treatments (p < 0.05). There were significant linear relationships between runoff depth and PP loss, DP concentration (p < 0.05). The results of this study have great significance in improving our understanding of the characteristics associated with runoff P loss in sloping croplands in Southwest China.

Keywords

• Phosphorus loss
• Long-term fertilization
• Rainfall
• Non-point source
• Sediment
• Yangtze River Basin