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通过模拟降雨试验研究不同坡度和降雨强度条件下,施用聚丙烯酰胺(PAM)对紫色土磷素流失的影响。结果表明:在控制径流上,施用PAM对较大坡度效果比缓坡明显(p<0.05),随坡度增加壤中流产流时间提前、流量增大。同时,坡耕地表面径流量和流速变化可能存在临界坡度范围(15°～20°),当坡度超过临界范围时,流速和流量反而减小。在磷素流失控制上,施用PAM对大坡度控制效果比小坡度显著(p<0.01)。施用PAM后,紫色土坡地表面径流量和径流速率均随降雨强度增大而增大,而径流中TP浓度逐渐减少,在中等雨强(34mm/h)时,PAM对紫色土磷素流失控制效果最好,其总磷(TP)流失量分别为低雨强(17mm/h)和大雨强(84mm/h)的77.37%和40.22%。由降雨径流量和磷输出的关系发现,雨强对TP浓度随径流量的变化趋势有一定影响,但影响较小;坡度对TP浓度的变化趋势基本没有影响。
Effects of polyacrylamide (PAM) on phosphorus loss in purple soil were studied by simulating rainfall experiments under different slope and rainfall intensities. The results showed that the effect of applying PAM on runoff was greater than that on gentle slope (p <0.05). With the increase of slope, the flow rate of soil middle flow was earlier and the flow rate increased. At the same time, there may be a critical slope range (15 ° ~ 20 °) on the surface runoff and flow rate of slope farmland. When the slope exceeds the critical range, the flow rate and flow rate decrease. In the control of phosphorus loss, the effect of applying PAM on large slope was significantly (p <0.01) less than that on small slope. After applying PAM, the surface runoff and runoff rate of purple soil slope increased with the increase of rainfall intensity, while the concentration of TP in runoff decreased gradually. Under moderate rainfall intensity (34mm / h), PAM controlled phosphorus loss in purple soil The total phosphorus (TP) loss was 77.37% and 40.22% of low rainfall intensity (17mm / h) and heavy rainfall intensity (84mm / h), respectively. From the relationship between rainfall runoff and phosphorus output, it was found that the rainfall intensity had a certain influence on the trend of TP concentration with the runoff, but had little effect. The slope had no effect on the trend of TP concentration.