PAM与SAP交并施用对旱区坡耕地氮素淋溶的影响

Effects of combined application of polyacrylamide and super absorbent polymers on nitrogen leaching from sloping lands in arid area

通过在旱区坡耕地上模拟降雨试验,研究在降雨强度40 mm·h ^-1 和历时为3 h的条件下,7种线性水溶性高分子聚合物(PAM)和新型节水保水材料(SAP)交并施用方式对径流和氮素淋溶的影响。结果表明:与对照处理(不施用PAM和SAP)相比较,施加PAM和SAP有效减少了径流量和氮素淋溶量,减少的地表径流量达93.29%,相应地降低水中总氮淋溶量达25.58%,保水作用SAP强于PAM;同时,减少的土壤侵蚀量达91.85%,相应地降低泥沙中总氮淋溶量达37.96%;由降雨后土壤剖面养分分布可知,0~15 cm深度土壤的含氮量比对照组高50.24%。说明施加PAM和SAP增加了根系层的持水和保肥能力,降低了土壤养分随水的深层渗漏,且保土作用PAM强于SAP。在坡耕地施加PAM和SAP不但可以减少水土流失,而且能降低土壤氮素的流失,防止肥料对地下水的污染。

The combined application of polyacrylamid (PAM) and super absorbent polymers (SAP) are important for reducing soil nitrogen (N) runoff loss. To further understand the process, we studied the effects of seven combined application methods of PAM and SAP on runoff and N leaching under a simulated rainfall intensity of 40 mm·h ^-1 for a duration of 3 hours on sloping lands in arid area. The results showed that, compared with the control treatment, the combined application of PAM and SAP effectively reduced N runoff and N leaching. The runoff was decreased by 93.29% and the amount of total N leaching in runoff was reduced by 25.58%. The water holding effect of SAP was better than PAM. At the same time, the amount of soil erosion was reduced by 91.85%, and the amount of total N leaching in sediment was decreased by 37.96%. From the nutrient distribution of soil profile after rainfall, the N content in 0~15 cm soil was 50.24% higher than that of the control group, which indicated that the combined application of PAM and SAP increased the ability of water and N holding of the root layer, and reduced the deep layer leakage of soil nutrients with water. Soil conservation effect of PAM was better than SAP. The combined application of PAM and SAP in sloping lands can not only reduce soil erosion, but also can reduce soil N loss and prevent the pollution of fertilizers to groundwater, which provides a theoretical basis for the combined application of PAM and SAP in arid area.