Abstract: With continuous increases in the amount and duration of plastic film used, the residual film in farmland soil is accumulated and tended to be fragmented, which affects soil water infiltration. We carried out an experiment of one-dimensional vertical infiltration of soil moisture. We examined the effects of different residual film density and area on soil water cumulative infiltration under 21 experimental treatments with 5 residual film area levels (0.25, 0.5, 1, 2, 8 cm²) and 5 residual film density levels (0, 60, 180, 300, 420 kg·hm^-2). The results showed that soil water infiltration rate was accelerated and the total infiltration amount was increased by adding a certain amount of residual film into the clay loam soil with bulk density of 1.53 g·cm^-3. The total infiltration amount of different residual film area always appeared mutation or turning point when the single residual film area was 1 cm². When the residual film area and density were larger or smaller than that, the cumulative infiltration amount would be significantly affected, with the treatment of 0.5 cm² residual film area and 200 kg·hm^-2 residual film density being obvious demarcation. When the residual film area was 0.25 cm², the cumulative infiltration reached the maximum. When the residual film with a single area ≤0.25 cm² was uniformly mixed into the soil, the slope of soil water cumulative infiltration curve was significantly different from that of other residual film treatments, forming a “new structure” soil with unique water infiltration characteristics.

Key words: one dimensional vertical infiltration, residual film density, residual film area, cumulative infiltration amount