Environmental fate and effects of mulch films on agricultural soil: A systematic review from application to residual impact

Plastic mulch films improve crop microclimate and yield but generate persistent residues and microplastics (MPs), posing ecological risks. Despite this, systematic reviews on the life-cycle fate of mulch films from application to residues remain limited. This review summarizes mulch film classification, physicochemical and microbial degradation mechanisms, migration fate factors, and impacts on soil carbon and nitrogen cycling, highlighting mulch film characteristics and soil properties as most important factors. Some key conclusions include: (1) film mulching alters soil hydrothermal conditions and gas exchange, thereby restructuring microbial activities; (2) residues and MPs modify soil structure, create new niches, and rewire functional gene networks, ultimately regulating soil carbon and nitrogen cycling; (3) the release of dissolved organic carbon (DOC) during mulch film degradation can enhance organic matter decomposition and nitrogen utilization. Critical research gaps remain, particularly in long-term field assessments and under multi-stressor scenarios. This review provides an integrative perspective on the environmental fate and functional impacts of mulch films, thereby advocating the development of sustainable mulching practices and risk control in agroecosystems.