Investigating the Degradation of Biodegradable Mulch Films in Agricultural Soil: A Molecular Approach

The fate of biodegradable mulch films (BMFs) in agricultural soils is a serious concern for environmental sustainability. This study investigates the degradation under real field conditions of BMFs composed of starch and poly(butylene-adipate-co-terephthalate). Pristine (BIO-0) and artificially UV-aged (BIO-A192) films were buried for 16 months in agricultural soil under Mediterranean climate conditions. Progressive degradation of the films was observed, and after 478 days, approximately 23% of BIO-0 and 17% of BIO-A192 remained in the soil, accompanied by the release in soil of macro- and microplastic residues. Advanced Mass Spectrometry analytical techniques revealed the degradation pathways of the films, showing that residues were enriched in aromatic components due to selective polymer degradation. Thermal studies identified key degradation products and additives, which decreased as degradation advanced. Additionally, the presence of fillers and minor additives, added to improve crystallization, mechanical properties, and biodegradation, was also confirmed. These findings emphasize the complexity of BMFs degradation in real-world conditions, pointing out the need of field studies alongside laboratory tests. By combining advanced analytical techniques, this study provides insights into the environmental impact of BMFs and supports the development of more sustainable agricultural materials.