Multifaceted effects of microplastics on soil-plant systems: Exploring the role of particle type and plant species
Zhangling Chen, Laura Carter, Steven A. Banwart, Devlina Das Pramanik, Paul Kay
Abstract
Microplastics have emerged as a global environmental concern, yet their impact on terrestrial environments, particularly agricultural soils, remains underexplored. Agricultural soils, due to intensive farming, may serve as significant sinks for microplastics. This study investigated the effects of different types of microplastics—polyester microfibers, polyethylene terephthalate microfragments, and polystyrene microspheres—on soil properties and radish growth, while a complementary experiment examined the impact of polyester microfibers on the growth of lettuce and Chinese cabbage. Through both horizontal and vertical comparisons, this research comprehensively evaluated the interactions between microplastic particles and plant species in soil-plant systems. The results showed that polyester microfibers significantly affected soil bulk density, with effects varying based on planting conditions ( p < 0.01). Polyethylene terephthalate microfragments and polystyrene microspheres reduced the proportion of small soil macroaggregates under radish cultivation ( p < 0.01). Additionally, polystyrene microspheres significantly altered the total organic carbon stock in radish-growing soil, potentially affecting the microclimate ( p < 0.01). Interestingly, polyester microfibers promoted lettuce seed germination and significantly enhanced the root biomass of Chinese cabbage ( p < 0.05). Overall, the environmental effects of microplastic exposure varied depending on the type of particle and plant species, suggesting that microplastics are not always harmful to soil-plant systems and may even offer benefits in certain scenarios. Given the crucial role of soil-plant systems in terrestrial ecosystems, and their direct connection to food safety, human health, and global change, further research should explore both the positive and negative impacts of microplastics on agricultural practices. • PS microspheres reduced soil organic carbon by 29.5 %, possibly affecting microclimate. • PES microfibers lowered soil bulk density by 10.6 %, altering soil structure. • PS microspheres increased radish germination to 100.0 % by the fourth day. • PES microfibers boosted cabbage root biomass by 57.4 %, supporting plant growth. • PET microfragments reduced chlorophyll b in radish leaves by 40.9 %, impairing photosynthesis.