A critical review of biodegradable plastic mulch films in agriculture: Definitions, scientific background and potential impacts

Biodegradable plastic mulches (BDMs) can offer an eco-sustainable alternative to conventional polyethene (PE) mulch films in agriculture. While PE films must be removed after use, BDMs are tilled into the soil, where they are expected to biodegrade. However, their long-term impacts on the soil ecosystem (functions, processes, and microbial communities) remain unclear. This review critically analyses evidence about the potential of BDMs as a possible eco-friendly alternative to traditional PE mulches. It updates the available literature on the possible fate and impacts of BDMs on agriculture ecosystems, pinpointing crucial aspects that deserve further investigation. The combined findings indicated that BDM incorporation into the soil could stimulate microbial activity that may ultimately affect soil organic matter dynamics. However, using BDMs should be linked to the risks of incomplete biodegradation by releasing residual bio-microplastics, bio-nanoparticles and additives. We here highlighted gaps in knowledge (i.e. impact on soil ecology and the risk of toxicity) and the need for long-term studies in natural environmental conditions as well as field experiments to evaluate the actual impact of BDMs on soil health and agroecosystem sustainability. Moreover, there still needs to be more clarity of standards covering the conditions under which the biodegradable plastic mulch films biodegrade to ensure safe end-of-life.