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.