PAM对不同坡度坡地产流产沙及氮磷流失的影响

聚丙烯酰胺(PAM)是一种高效土壤改良剂,能影响土壤入渗、产流及溶质迁移、淋失.通过人工模拟降雨试验,研究了5°、15°和25°3个坡度水平下PAM对黄土高原沟壑区黑垆土坡地土壤侵蚀及氮磷流失情况的影响.结果显示:施加PAM后增加了5°和15°坡面的总产流量却减少了25°坡面的总产流量;PAM组初始产沙量较大,8 min以后,施加PAM组与对照组产沙速率出现差异并开始降低,表明施用PAM的起作用时间约为8~10 min,5°、15°和25°3个坡度的减沙率分别为38.2%、3.7%和53.9%.PAM对3个坡度径流中磷浓度有减小作用且不受坡度变化的影响,对5°和15°坡面铵态氮浓度影响不明显,但对25°坡面铵态氮浓度有明显减小作用,此外,PAM的施用能降低铵态氮初始流失浓度.施加PAM能影响土壤水分的再分配过程并减少3个坡度坡面硝态氮和磷的向下淋失.施加PAM后,5°、15°和25°坡面磷流失总量显著减少,减小幅度分别为77.6%、64.5%和85.1%;径流硝态氮流失总量随着坡度的增加先增加后减少,在15°~20°之间存在改变PAM对硝态氮影响作用的转折坡度值,PAM处理后的硝态氮流失量与径流量在0.05水平上显著相关,相关系数为0.998;PAM能够显著减少陡坡25°坡面溶解态铵态氮的流失量,减少幅度为60.1%.该项研究结果可为当地PAM的合理有效施用和提高水分及养分利用率提供科学指导.

Impacts of PAM on runoff,sediment,nitrogen,and phosphorus loss under the different slope lands

PAM is an effective soil conditioner that can affect soil infiltration,runoff,solute transport,and nitrogen leaching. In this paper,impacts of PAM on soil erosion and nitrogen and phosphorus loss under 5°,15° and 25° slopes on dark loessial soils in gully region of the Loess Plateau were studied under the artificial rain experiments. The results showed:1After applying PAM,the total runoff of 5° and 15° were increased but on 25° slope was reduced; initial sediment yield was higher in the PAM group,and 8 min later sediment yield started to reduce and there were significant differences between PAM and the control group. This indicated that work time of PAM was started about 8 to 10 minutes later or so,and the sediment reduction of three slope (5°,15°,25°)were 38.2%,3.7% and 53.9%,respectively. 2In PAM group,phosphorus concentrations of all three slope reduced and it was not affected by the change of slope; for the 5ånd 15° slope,the effect of PAM on ammonium nitrogen concentration was not obvious,but the ammonium nitrogen concentration of 25°slope reduced significantly; In addition,the application of PAM could reduce the initial concentration of ammonium nitrogen. 3PAM could affect the moisture redistribution process and reduced the downward leaching of nitrate nitrogen and phosphorus of all three slope (5°,15° and 25°). 4After applying PAM,the total phosphorus loss of 5°,15° and 25° slope decreased by 77.6%,64.5% and 85.1% respectively; Total nitrate nitrogen loss was increased with the increase of slope first and then decreased,and there was a slope between 15°~20° slope that could change the effect of PAM on nitrate nitrogen; In PAM group,nitrate nitrogen loss was significant correlated with runoff at the 0.05 level,the correlation coefficient was 0.998; PAM could significantly reduce dissolved ammonia nitrogen loss by 60.1% in 25° slope. The study results could provide effective guidance for the application of PAM to improve utilization of water and nutrients.