化肥减量对紫色土坡耕地磷素流失的影响

Effects of chemical fertilizer reduction on phosphorus loss in slope purple soil farmland

采用人工径流小区对紫色土坡耕地降雨产流、磷素流失浓度进行定点观测,研究不施肥(CK)、常规施肥(T1)、优化施肥(T2)、化肥减量配施秸秆(T3)4种不同处理对紫色土坡耕地磷素在地表径流、壤中流中流失的影响.结果表明,壤中流是紫色土坡耕地的主要产流方式,占比高达70%以上,其中磷素主要通过泥沙、地表径流2个途径流失.化肥减量配施秸秆处理的全磷流失通量为0.412kg/(hm^2·a),相比其他施肥处理下降了29.37%~62.62%;正磷酸盐流失通量表现为优化施肥>常规施肥>化肥减量配施秸秆>不施肥,其地表径流流失通量占比达到55.35%~84.65%;化肥减量配施秸秆处理下地表径流中颗粒态磷流失通量最低,为0.032kg/(hm^2·a),相比于常规施肥和优化施肥处理,显著下降了70.92%和60.28%;化肥减量配施秸秆处理不仅对地表径流中的磷素流失具有很好的消减效应,对壤中流中的磷素流失同样具有很好的消减效应,配施秸秆处理下壤中流全磷平均流失通量最小,为0.031kg/(hm^2·a).因此,化肥减量配施秸秆对于控制三峡库区紫色土坡耕地磷素流失,降低库区农田土壤污染和水体富营养化风险具有可行性.

In this study,the artificial runoff plot was used to observe the rainfall runoff and phosphorus loss concentration in purple soil slope farmland.There were four treatments:no fertilizer application(CK),conventional fertilizer application(T1),optimized fertilizer application(T2),and reduced fertilizer combined with straw(T3)were set to study the phosphorus loss of interflow and surface flow in purple soil slope farmland.The results showed that the interflow was the main mode of flow of purple soil slope farmland,accounting for more than 70%,but phosphorus was mainly lost through sediment and surface runoff.The loss flux of total phosphorus in the treatment of reduced fertilizer combined with straw treatment was 0.412kg/(hm^2·a),which was 29.37%~62.62% lower than other fertilization treatments.The orthophosphate loss flux showed the rule of optimized fertilization>conventional fertilization>reduced fertilizer combined with straw>non-fertilization,and the surface runoff loss flux was occupied 55.35%~84.65%.In the treatment of reduced fertilizer combined with straw application,the loss flux of particulate phosphorus in surface runoff was the lowest,which was significantly decreased by 70.92% and 60.28% compared with conventional fertilization and optimized fertilization,respectively.The treatment of reduced fertilizer combined with straw not only has an effective reduction effect on the loss of phosphorus in surface runoff,but also has a good reduction effect on the loss of phosphorus in interflow.Reduced fertilizer combined with straw is feasible to reduce the loss of phosphorus in purple soil slope farmland and reduce the risk of eutrophication in the Three Gorges Reservoir Area.