Effect of surface mulching materials on infiltration of muddy water on loamy soils

The test was carried out in Ansai and Chunhua experimental stations on the Loess Plateau in China. The tested soils were loess soil with a texture of light loam in Ansai and loam in Chunhua. The mulching materials include plastic film, water permeable plastic film, hay and sponge plastic sheet with 50% coverage on soil surface. The application of mulching materials generally decreased the infiltrability of muddy water into soil, and enlonged the time required to reach the steady infiltration stage. The magnitude of reduction in infiltrability differed with mulching materials. Plastic film decreased infiltration most, followed by water permeable plastic film and hay, and sponged plastic sheet least. It appeared that the mulching materials changed the hydrodynamics characteristics of the infiltration surface, and acted as a ‘bottle neck’ to water infiltration. Moreover, soil texture had a significant effect on infiltration under mulching. The steady infiltration rate was 39% lower and the duration required to reach the steady infiltration stage was 60%～80% higher for mulching with plastic film than that for non-mulching control in the loam soil. In contrast, the impact of mulching on cumulative infiltration was greater in the light loam than in the loam soil. Characteristic impedance parameters relate to mulching materials and soil texture were put forward. These parameters provide a probability for calculating muddy water infiltration under partial mulching conditions from the data obtained under uncovered conditions.