iMulch: Identification and quantification of plastic films used in agriculture

As plastics production continues to grow globally, topics such as “microplastics“ and “plastics in the environment“ are the focus of discussions and are becoming more and more relevant. While the occurrence, distribution, and effects of plastics in limnic and marine waters have already been investigated, the data on plastic emissions in soils is still relatively thin. To date, neither the exact pathways, quantities, and concentrations of polymers in soil nor the effects of plastics on organisms and the soil ecosystem are known.

Within the iMulch project, methods are being developed and validated that enable plastics (micro- and macroplastics) to be detected in soils and drainage waters. The main focus should lie on detecting possible effects on the soil ecosystem, as well as on analyzing the effect of drainage water on municipal wastewater treatment processes. Plastic emissions from what is known as mulch film from agriculture are set to be analyzed as an example. The iMulch project thus contributes to assessing the effects of plastic emissions not only in water but also on the soil ecosystem. The research into a terrestrial system complements the examination of aquatic systems and thus makes it possible to take a holistic view of plastic emissions.

Polyethylene mulch films are being used more frequently and extensively on agricultural land to regulate soil temperature and moisture. In order to investigate the effects of mulch films, Fraunhofer UMSICHT is working on a joint research project with its partners to develop a test stand in which films on the soil surface are artificially aged at a constant temperature and under UV light. During the artificial aging process, samples are taken at different soil depths to determine the proportion of plastic particles that originate from the film. Both conventional and biodegradable mulch films are tested. In addition, drainage water is sampled and analyzed in the field and the behavior of plastic films is investigated in an experimental wastewater treatment plant. The collected samples are analyzed with regard to weathering, distribution, ecotoxicity, and displacement, and an eco-assessment is also created. Finally, prevention and substitution strategies are derived from the results in order to reduce plastic film fragments in the environment.

Development of test stands  

The test stand to be developed within the project to artificially age agricultural film on soils under the influence of UV radiation, regular humidification, and controlled temperature is an innovation. This test stand can be used to test and evaluate all kinds of films for applications in an open environment with soil contact, thus enabling the aging of agricultural films to be analyzed in an innovative manner. In addition, Fraunhofer UMSICHT is constructing a laboratory wastewater treatment plant to systematically investigate the degradation mechanisms of mulch film residues at the individual process stages. Soil test stand and laboratory wastewater treatment plant will be used for similar studies following the project.

• Institut für Energie und Umwelttechnik – IUTA – e.V.
• Fischer GmbH
• RWTH Aachen, Institut für Angewandte Mikrobiologie
• Fraunhofer-Institut für Molekularbiologie und angewandte Ökologie IME