Biodegradable Plastic and Paper Mulch Effects on Soil Moisture Dynamics.

Plastic mulch films are often used in agriculture to conserve soil moisture. Most of the plastic mulch currently used worldwide is made of low-density and linear low-density polyethylene, which has to be removed and disposed after harvest, incurring significant environmental costs. Biodegradable plastic and paper mulch could offer a valuable alternative to polyethylene. The objective of this study was to compare the effects of biodegradable mulches and standard polyethylene mulch on soil moisture dynamics during a growing season. A field experiment was carried out with pie pumpkin (Cucurbita pepo), which were irrigated and grown on raised beds covered with the following mulch treatments: biodegradable paper, biodegradable plastic, polyethylene, and no mulch. Soil moisture was measured at 10- and 20-cm depths. A numerical model (HYDRUS-2D) was used to simulate the moisture dynamics under the different mulch treatments. In the model, mulch treatments were represented by using different boundary conditions at the soil surface. Polyethylene mulch, which created an impermeable surface layer, effectively reduced evaporation and maintained highest water content among the treatments. Biodegradable paper mulch, which was partially permeable to evaporation and rainfall throughout the growing season, resulted in soil moisture that was intermediate to that obtained for no mulch and polyethylene mulch treatments. Biodegradable plastic mulch, which was initially similar to that of polyethylene mulch in terms of effects on soil moisture, disintegrated during the growing season and allowed rainfall and evaporation to penetrate the soil surface. Field data and model simulations indicate that, in terms of soil moisture dynamics, the biodegradable paper and plastic mulches are a viable alternative to polyethylene mulch.