The long-term uncertainty of biodegradable mulch film residues and associated microplastics pollution on plant-soil health

Summary

This field investigation assessed long-term degradation of commercially marketed biodegradable plastic mulch films and their generation of microplastics under realistic agricultural conditions. The authors found that whilst biodegradable microplastics are almost entirely biodegradable (80% to CO₂, 20% to microbial biomass), their rapid degradation generates greater quantities of microplastics in shorter timeframes than conventional plastics, potentially causing more pronounced alterations to soil microbial communities and nutrient cycling. The study highlights significant uncertainties regarding effects on plant health, crop productivity, greenhouse gas emissions, and the formation of nanoplastics, indicating that current assumptions about the environmental benignity of biodegradable mulch films require longer-term monitoring and field validation.

Regional applicability

The findings are directly applicable to United Kingdom horticulture, where biodegradable mulch films are increasingly adopted as sustainable alternatives to conventional plastics in field vegetable and soft fruit production. However, the study emphasises that field validation under UK soil and climate conditions, and longer-term monitoring of microplastics persistence and soil health impacts, are needed before robust policy recommendations can be made for UK agricultural practice.

Key measures

Soil carbon cycling (CO₂ production, microbial biomass), nitrogen and phosphorus cycling, microbial diversity and community composition, mesofauna abundance, plant health indicators, potential nanoplastics formation, N₂O and CH₄ emissions

Outcomes reported

The study evaluated effects of biodegradable microplastics (bio-MPs) on soil carbon and nutrient cycling, soil microbial and mesofauna communities, and plant health under agricultural conditions. The authors report that approximately 80% of carbon from bio-MPs is converted to CO₂, with 20% immobilised in microbial biomass, and that bio-MPs induce greater alterations in microbial diversity and community composition compared to conventional plastics.

Topic tags