RESUMEN
Residual plastic film in soil destroys the soil structure and changes the normal transportation and distribution of water and nutrient. In this work, we compared experiments on soil containing residual plastic film with a control experiment to investigate how residual film affects the transportation and distribution of water and nitrate (NO3-) in wetted soil. The experiment used Mariotte bottle, water tube, and soil tank to test six levels of residual-film concentration varying from 0 to 720â¯kg/hm2 in the soil. The wetting front, soil water content, and nitrate concentrations were all measured, and the results showed that when the concentration of residual-film was less than 360â¯kg/hm2, more water and nitrate remained in the upper part of the wetted volume due to block of residual film. Excessive residues (>360â¯kg/hm2) resulted in obvious phenomenon of preferential flow, which increased the wetting distance, wetted volume, and water content in the lower part of the wetted volume and the concentration of nitrate at the boundary of the wetted volume. These results not only help us to understand the consequences of plastic-film-residues pollution in terms of water and nitrate movement, but also provide scientific support to the development and establishment of reasonable irrigation, fertilization and management systems for polluted farmland with differential mulch residual concentrations.