Differential ecological risks from the interaction between reductive soil disinfestation and biodegradable...

Biodegradable microplastics (MPs) are widely used in agriculture, but their ecological risks under intensive soil management like Reductive Soil Disinfestation (RSD) remain unclear. This study investigated the interactive effects of RSD and two MPs, polybutylene adipate terephthalate (PBAT) and polybutylene succinate (PBS), on the soil-plant system using Brassica chinensis L. A laboratory experiment integrated MP characterization, plant physiology, soil properties, and non-targeted metabolomics. Results showed that RSD significantly accelerated the structural degradation of PBAT and PBS, characterized by surface cracking and weakened O-C=O peaks. The impact of RSD on plant growth was material-dependent. In PBAT-contaminated soil, RSD promoted root length and fresh weight. Conversely, with PBS, RSD exacerbated growth inhibition and increased malondialdehyde content, despite partial recovery in photosynthetic efficiency. RSD profoundly regulated soil electrical conductivity (EC), organic matter (OM), and pH, while shifting microbial communities toward anaerobic-adapted taxa. Metabolomic profiling revealed that RSD-MP interactions disrupted core pathways, specifically galactose metabolism and the tricarboxylic acid (TCA) cycle, indicating systemic metabolic reprogramming triggered by degradation intermediates. While RSD improves soil health, it can transform into a stressor when coexisting with specific MPs. This work provides a theoretical basis for managing MP-contaminated agricultural soils.