The use of biodegradable plastics in agriculture is becoming more and more frequent –for example for the production of mulch films – leading the scientific community to explore the sustainability of such materials.
These agricultural films offer similar benefits to those made in conventional plastics in terms of crop performance and reliance; in this case, however, after use, they are left to degrade in the soil, thus avoiding the issue of their removal and disposal as waste.
PAPILLONS researchers’ position regarding bioplastics for agricultural use, coinciding with that of a larger part of the international research community, affirms that these products’ use should be governed by a science-informed risk analysis and management approach, and not only on a simple risk reduction approach. A recommendation document provided to the European Commission, available on the official PAPILLONS website outlines this position in detail.
Research conducted by PAPILLONS and other international research groups shows that during the degradation of bioplastic films in soil, microplastics are formed. These microplastics, similar to those derived from conventional plastics, can influence the chemical and physical properties of the soil and affect plant growth and health at environmentally plausible concentrations.
However, unlike microplastics from non-biodegradable plastics, which can persist indefinitely, micro-bio-plastics tend to degrade thanks to the activity of the soil’s microbiological community. The duration of this process can vary from a few to many years, depending on environmental conditions, with cold temperatures or arid conditions expected to significantly delay the process. The continuous application of bioplastic films could therefore lead to a transitory accumulation of micro-bio-plastics in soil that could theoretically reach levels several-fold higher than the amount of material applied in a single application, possibly exceeding some thresholds for adverse effects.
While the option of removing bioplastic mulch films after use and transporting them to composting facilities to prevent release of plastic debris might be a solution, PAPILLONS researchers highlighted that the implementation of this option faces several challenges. It would entail various economic and environmental costs, such as those associated with waste transportation and processing. It would also require thicker films to enable collection without breaking and fragmentations, which would still result in the release of plastic debris. Thicker films would demand greater consumption of raw materials, impacting both the economic performance and the environmental footprint of these materials, and potentially lead to longer degradation times in composting facilities.
Other solutions proposed by PAPILLONS researchers include focusing on site- and material-specific risk assessments that consider both the physical and chemical interactions of micro-bio-plastics with soil and its biota. Such analyses should particularly assess the reversibility of these effects and the time required for the soil to recover its natural structure, function, and biodiversity. Under such a risk assessment framework focused fundamentally on the maintenance of soil resilience, management options could consider the possibility of temporarily and regularly suspending the use of these materials (e.g. through the rotation of agricultural practices and crops) on a given soil to allow for recovery. This would also require a quality control and labeling system for ensuring the use of safe materials and the proper implementation of risk management measures. Similar regulatory framework exists in Europe, such as part of the food safety law, which should serve as inspiration also for the bioplastic sector.
A third way suggested by PAPILLONS researchers highlights the vast potential for innovation in the bioplastics sector, which could provide new materials, ideally sourced from renewable resources, with better environmental compatibility. Leveraging a broader portfolio of innovative materials, new designs for mulching applications could enable degradation times better suited to the various environmental conditions in which they are used, reducing the progressive accumulation of micro-bioplastics over the medium and long term.
PAPILLONS consortium essentially asserts that the use of bioplastics in agriculture should be guided by a risk analysis and management approach based on scientific evidence, supported by a new European regulatory framework that includes effective quality control and continuous updates to risk definition and analysis. We are still missing such a regulatory framework globally, despite the growing use of bioplastics worldwide. PAPILLONS continues to work on providing new data and knowledge in this field, inspiring innovation in regulations, the agricultural sector, and industry toward eco-sustainable agriculture.
Bibliographic reference: PAPILLONS, 2022. Early policy recommendations from Papillons and Minagris. https://www.papillons-h2020.eu/knowledge-hub/papillons-minagris-contribution-to-early-policy-recommendations/