Degradation of mulch films in different soils and its effects on soil properties and ecotoxicology

With the extensive use of mulch films, problem of pollution by mulch film residues has become increasingly serious. Mulch film residues can affect soil physicochemical properties and enzyme activities, reduce soil quality, and may pose ecological risks. In this study, we used three different agricultural soils with different properties collected from three important agricultural production bases in China to reveal the differences in the degradation effects of low-density polyethylene (LDPE) mulch film and biodegradable mulch film (BDM) in soils under laboratory conditions. The effects of mulch film residues on soil properties and the ecotoxicology they pose to environmental were also assessed. BDM started to degrade significantly within one month and degraded fastest in the Black Soil, in which it degraded almost completely after 180 days. LDPE mulch film residues had less interference with the physicochemical properties of the soil than the BDM residues. The cation exchange capacity, total carbon and total organic carbon of the soil were less disturbed by the mulch film residues. Extracts from soils treated with both types of mulch film residues did not adversely affect Triticum aestivum L. seed germination and normal growth of Raphidocelis subcapitata and L929 cells. This study provides important data on the degradation of BDM in different soils, its impact on soil properties, and its ecotoxicological effects, and compares these findings with LDPE mulch film. The findings help advance the understanding of BDM's environmental impact and support its sustainable agricultural application.