Microplastic Pollution in Agricultural Soils and Abatement Measures – a Model-Based Assessment for Germany

Microplastic pollution in soils is a recent environmental problem and the lack of knowledge about the impacts and the extent of the problem are raising questions and concerns among researchers and politicians. Using a normative simulation model, we assess the extent of microplastic pollution in German agricultural soils originating from the land application of sewage sludge and compost. We estimate the microplastic concentration in German agricultural soils, the area of polluted land, and we compare the efficiency and effectiveness of some selected abatement measures. For 2020, we estimate that microplastic concentration in agricultural soil reaches a maximum concentration of between 30 and 50 mg/kg dry weight on 2% of utilised agricultural area and a marginal concentration on 22% of utilised agricultural area. Without the implementation of abatement measures, we expect the microplastic concentration to increase two to three times by 2060. Assessing the abatement measures, we find that for sewage sludge, thermal recycling is a more efficient and effective than equipping washing machines with microplastic-filters in private households. The use of plastic detection systems in the biowaste collection process reduces the plastic content of the compost and thus the release of microplastic into the soil. Detection systems are a more efficient measure for compost than thermal recycling. Concerning sludge, the findings indicate that the German strategy of thermally recycling sewage sludge is an efficient and effective measure to reduce microplastic pollution in soils. Reducing the plastic content of collected biowaste complies with the principles of a circular economy.