紫色土坡耕地磷素流失特征及施肥方式的影响

Phosphorus losses and effects of fertilization on sloping cropland of purple soil

通过雨季典型降雨-径流事件中不同施肥方式下土壤磷素流失的野外定位观测,研究紫色土坡地磷素随地表径流和壤中流流失的通量、过程特征及其施肥方式的影响。结果表明,紫色土坡耕地地表径流过程呈多峰的时间变化特点,壤中流呈单峰且其产流时间滞后于地表径流;雨季次降雨平均径流量为23.6～29.1mm,壤中流是雨季的主要径流输出方式。地表径流总磷(TP)平均浓度远高于壤中流,泥沙吸附态磷(PP)是地表磷素流失的主要形态;溶解态有机磷(DOP)是壤中流流失的主要磷素形态。施肥方式显著影响地表径流TP浓度,常规施肥(NPK)、有机肥-化肥配施(OMNPK)、有机肥(OM)、秸秆-化肥配施(RSDNPK)各施肥处理的地表径流TP平均浓度呈依次减小的顺序。次降雨平均磷素流失负荷呈RSDNPK<OMNPK<OM<NPK的规律;壤中流是紫色土坡耕地磷素流失不可忽视的重要通道。施肥方式仅能控制地表径流磷素流失,而控制壤中流磷流失的效果不佳,有待更深入的研究。

The phosphorus losses and effects of fertilization on sloping cropland of purple soil were studied by in situ field monitoring. Results showed that the average discharges of runoff were 23.6-29.1mm in wet season, and the interflow was the main pathway of runoff for sloping cropland of purple soil in. The average contents of total phosphorus （TP） of overland flow were 0.65-1.81mg/L, particulate phosphorus （PP） was the main form of P lost by overland flow. The average contents of total dissolved phosphorus （TDP） of interflow were 0.024-0.037mg/L The dissolved organic phosphorus（DOP）was the main form of P lost by interflow. The TP lost by overland flow were influenced by fertilization distinctly. The TP contents in runoff were in the following sequence related to fertilizations： RSDNPK〈OM〈OMNPK〈NPK. The TP loss fluxes re- lated to fertilizations was in the sequence： RSDNPK〈OMNPK〈OM〈NPK. The interflow was also an important pathway of phosphorus losing from purple soil. Phosphorus losses through overland flow could be controlled by fertilization practices. However, phosphorus loss fluxes through interflow can not be effectively reduced by fertilization modes, which needs more researches in the future.