Biodegradable mulch films affecting surface runoff, soil erosion, and film fragment loss from farmland

The use of conventional plastic mulch films is a common agricultural practice that can lead to persistent plastic film fragments entering soil systems. To prevent the accumulation of these fragments, soil-biodegradable mulch films are marketed as alternatives. Unlike conventional plastic mulch, soil-biodegradable mulch films are ploughed into the soil after use, where they biodegrade over time. This study aims to elucidate the effects of soil-biodegradable mulch film fragments—following six months of application on the soil surface—ploughed into soil on surface runoff, soil erosion, and lateral mulch film fragment loss during simulated rainfall events. Our results showed a significant increase in runoff coefficient for the pre-wetted (wet run) simulations in soils with soil-biodegradable mulch film fragments compared to soils without them, while differences in sediment delivery were insignificant. In the delivered sediments, large mulch film fragments (> 2 mm) were depleted, whereas small fragments (< 2 mm) were transported approximately proportionally to the topsoil of the plots. Overall, our results indicate that film fragments can affect surface runoff on arable land, and generally, soil erosion is a pathway of soil-biodegradable mulch film fragments transport into adjacent ecosystems, which is especially effective in the case of small film fragments (< 2 mm) available from topsoil.