聚丙烯酰胺施用量、初始含水率和容重对土壤水分入渗特性的影响

  目的  聚丙烯酰胺（PAM）被认为是最有潜力的人工合成土壤改良剂。研究PAM对土壤水分入渗的影响，为黄土高原水土流失防治和土壤改良提供依据。  方法  通过室内模拟土柱试验，分析了PAM施用量、初始含水率和容重对一维垂直积水入渗的累积入渗量与湿润锋运移距离的影响，并通过多元回归分析得到各因子影响程度。  结果  （1）不同PAM施用量处理120 min累积入渗量和120 min湿润锋运移距离总体上呈减小趋势，减小程度与PAM施用量有关。（2）无论是否施用PAM，120 min累积入渗量随初始含水率和容重的增加均呈现不同幅度的减少，而120 min湿润锋运移距离随初始含水率和容重的增加分别表现为增大和减小的趋势。（3）各因子对120 min累积入渗量和120 min湿润锋运移距离的影响程度排序均为:容重 > PAM施用量 > 初始含水率。（4）建立了基于非线性回归方法的多元土壤水分入渗经验模型。  结论  PAM对于改良黄土高原地区旱作土壤的水分状况具有良好效果。

Effects of Polyacrylamide Application Amounts,Initial Water Contents and Bulk Densities on Soil Infiltration Characteristics

  Objective  Polyacrylamide (PAM) has been considered as a suitable soil amendment. The study on the effect of PAM on soil infiltration would provide basis for soil improvement Loess Plateau.  Method  The effects of PAM application amounts, initial water contents and bulk densities on the cumulative infiltration and wetting front migration distance of one-dimensional vertical ponding infiltration were analyzed through laboratory simulated soil column test.  Result  The results showed that PAM decreased the infiltration amount and the wetting front migration distance of 120 minutes, and the reduction degrees were related to the PAM application amounts. Whether PAM was applied or not, the cumulative infiltration amounts decreased in different extent with the increase of initial water contents and bulk densities, but the wetting front migration distances increased and decreased with the increase of initial water contents and bulk densities, respectively. The contribution of bulk density to 120 min cumulative infiltration was the largest (61%), followed by PAM application amount (26%), and the initial water content was the smallest (13%). Likewise, the contribution rate to the 120 min wetting front migration distance was as follows: bulk density (48%), PAM application amount (28%) and initial water content (24%). The Kostiakov model could simulate the infiltration process of soil water after application of PAM, but the infiltration parameters were different. In order to further clarify the relationship between each factor and soil cumulative infiltration, a multivariate soil water infiltration empirical model based on nonlinear regression method was established.   Conclusion  PAM has a potential effectiveness on amending soils in the Loess Plateau.