Biodegradable plastic mulches: Distinct effects on microbial communities but no impact on soil multifunctionality...

Biodegradable plastic mulches (BDMs) are increasingly promoted as environmentally friendly alternatives to conventional mulches. However, the ecological impacts of different BDMs on soil remains incompletely understood. A field experiment was conducted to investigate the effects of five poly (butylene adipate-co-terephthalate)-poly (lactic acid) composite BDMs (BASF12, Hongrui12, Hongrui14, Britain15, and Jialemi15) on soil physicochemical properties and microbial communities throughout the cabbage growth season. The results showed that BDMs application did not result in significant negative effects on soil properties or crop yield during the experimental period. Although degradation rates and aging characteristics differed among mulch types, most soil properties and soil multifunctionality remained relatively stable. Compared with no mulching, cabbage yield increased by 2.59-7.57%. Microbial analyses revealed distinct responses between bacteria and fungi. Fungal β-diversity showed a significant negative relationship with microbial nutrient limitation under BASF12 and Britain15, whereas the opposite trend was observed under Hongrui12, Hongrui14, and Jialemi15. Redundancy analysis further showed that soil nutrient-related variables, particularly dissolved organic carbon, dissolved organic nitrogen, and microbial biomass nitrogen, were key drivers of microbial communities, with fungal community exhibiting stronger environmental relevance than bacterial community. These findings provide important insights into the ecological effects of BDMs.