Microplastics (MP) are increasingly recognized as emerging contaminants in agricultural soils, where they can affect soil physical and chemical properties, soil organisms, and plants, thereby influencing agroecosystem functioning. This doctoral research investigated the effects of three types of MPs derived from ground commercial mulch films made of low-density polyethylene (LDPE), poly(butylene adipate-co-terephthalate) (PBAT), and starch on selected soil physical properties, soil invertebrates, and plants. Laboratory and pot experiments revealed that the presence of MP influenced soil water repellency, with stronger effects observed in sandy loam soils. At higher concentrations of PBAT and starch-based MPs, an approximately 5% increase in plant-available water was detected, indicating texture-specific soil responses. The presence of MP indirectly affected the terrestrial isopod Porcellionides pruinosus through changes in the soil microenvironment; starch-based MPs induced statistically significant alterations in cellular stress biomarkers, whereas LDPE and PBAT MPs caused no major physiological effects. Direct ingestion of MP did not affect survival but altered feeding activity and hemolymph parameters. In the model plant Sinapis alba L., LDPE MP did not affect germination rate, but a marginally significant increase in seedling length was observed at the highest concentration. The findings demonstrate that MP effects are complex and depend on polymer type, soil texture, concentration, and exposure duration. This study contributes to a better understanding of MP impacts in agricultural soils and provides a scientific basis for developing sustainable soil management practices and reducing microplastic pollution.
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