模拟降雨条件下不同PAM用量及其与强化剂联用对紫色土磷素流失的影响

采用人工模拟降雨试验研究不同PAM用量及其与不同强化剂联用对紫色土坡面磷素流失的影响。结果表明:分别施加4,8,16g/m2分子量600万、水解度20%的阴离子型PAM均能显著降低坡面径流量、总磷(TP)及颗粒态磷(PP)浓度,并显著增加壤中流体积。2次降雨中,PAM应用效果均与PAM用量有关。第1次降雨以8g/m2 PAM效果最佳,相比对照,径流量减少62.28%,TP减少80.71%,PP减少95.78%;第2次降雨以16g/m2效果最佳,相比对照,径流量减少53.28%,TP减少77.52%,PP减少98.40%。相比PAM单施,分别联用石膏和石灰石后,坡面径流量增加,TP和DP浓度均显著降低。第1次降雨以石膏联用效果更佳,其中TP减少83.91%,DP减少85.34%;第2次降雨2种强化剂效果相近,TP分别减少76.10%和75.28%,DP也分别减少78.17%和79.46%。可见,施用PAM和强化剂能够显著降低磷素流失量,对农业面源污染的控制有一定作用。

Effect of Different PAM Application Rates and Combined with Chemical Enhancers on Phosphorus Losses from Purple Soil During Simulated Rainfall

Through simulated rainfall experiment,effect of different polyacrylamide(PAM) application rates and combination application with various chemical enhancers on phosphorus losses from slope purple soil,were investigated.The results showed that respectively application of 4,8,16 g/m2 PAM(molecular weight 6 millions,anion type,20% hydrolysis rate) significantly decreased runoff volumes,total phosphorus(TP) and particle phosphorus(PP),meanwhile obviously increasing interflow volumes were observed,which all suggested that PAM application effect was related with application rates.For two rainfall events,in first event application rate as 8 g/m2 was optimal in first event,which respectively decreased runoff volumes,TP and PP by 62.28%,80.71% and 95.78% as compared with control group.Meanwhile,in second event,application rate as 8 g/m2 was better rather than other rates.In comparison with control,runoff volumes,TP and PP decreased by 53.28%,77.52%,and 98.40% respectively.Additionally,as compared with treatment with PAM mono-application,respective combination application with gypsum and limestone both significantly increased runoff volumes but decreased concentrations of TP and PP.Especially,in first rainfall event,treatment with gypsum combination was optimal,which respectively decreased TP and PP by 83.91% and 85.34%,but in second rainfall event,no obviously differences between two combination application were observed,which respectively decreased TP by 76.10% and 75.28%,and respectively PP by 78.17% and 79.46%.Thus,application of PAM with chemical enhancers can significantly decrease P losses,which may play an important role for controlling agricultural non-point pollution.