Effects Of Precipitation And Fertilization On N And P Runoff Loss In Nursery And Water Qualityin In Drainage Ditches

At present,nitrogen and phosphorus non-point source pollution in China’s crop farming has become increasingly severe,and it has become one of the important factors affecting the environmental quality of surface water.In order to reduce the effects of precipitation and fertilization on N and P runoff-loss in nursery and water quality in drainage ditches,an experiment was carried out to explore the effects of the initial rainfall,continuous rainfall and fertilization on the surface runoff and the loss of nitrogen and phosphorus in the nursery and the drainage ditches with the field monitoring method and a portable ecological ditch removal device.The results showed that:(1)Rainfall intensity and rainfall affected the concentrations of nitrogen and phosphorus in the ecological ditches.The rainfall intensity directly affected the initial scour effect of rainfall.The key prevention and control time after heavy rain was within 85 minutes.The key prevention and control time after moderate rain was within 70 minutes.The higher the rainfall intensity,the greater event mean concentration(EMC)and event pollutant loads per unit area(EPL)in the surface runoff.The relationships between rainfall and runoff losses of nitrogen and phosphorus were positively related.The correlation formula of total nitrogen,total phosphorus and rainfall was:y=64.65x+12.433,R~2=0.7362,y=583.6x+8.6057,R~2=0.8579,of which X represents the loss of total nitrogen and phosphorus in different forms,Y represents the rainfall.(2)The fertilizer type and time of fertilization were important key factors affecting the quality of the ditch.Total nitrogen loss was the lowest in the Osmocote Exact(15-9-12)plot,it was 1.81kg/ha,and total phosphorus loss was the lowest in the Nursery Mix(19-3-10)plot.it was 0.36kg/ha,Reasonable application of fertilizer can reduce the loss of nitrogen and phosphorus in the ditches,so it should be avoided fertilization before intense fall.(3)Aquatic plants could reduce the concentrations of nitrogen and phosphorus in drainage ditches.In comparison with without aquatic plants,the aquatic plants reduced effectively the concentration of nitrogen and phosphorus in the drainage ditches.The concentration of total nitrogen in the ecological ditch with the aquatic plants could be reduced by 0.446 mg/L,and the concentration of total phosphorus in the ecological ditch could be reduced by 0.063 mg/L.The ecological ditch with the aquatic plants decreased 2.313 and1.158 t/a of TN and TP discharges to rivers,respectively.