Impact of microplastics on soil microbiota and phosphorus dynamics - a review

Plastic products are widely used in many industries due to their low cost, plasticity, and resistance to corrosion. However, they can be degraded into microplastics (MPs) via physical, chemical, and biological processes. MPs pollution threatens agricultural soils and significantly reduces soil quality and ecosystem services. The application of plastic mulching, compost, and sewage sludge contribute to this pollution, increasing MPs quantity in the soil. MPs disrupt soil microbial community, particularly phosphate-solubilizing bacteria and fungi, worsening nutrient imbalances, and lowering soil fertility. These cascading effects undermine ecosystem productivity and agricultural resilience. Moreover, MPs interfere with phosphorus (P) processes by adsorbing phosphate ions onto their surfaces, reducing P availability, and inhibiting key P-cycling enzymes. However, the effects of MPs on soil P varied depending on the MPs type, size, concentration, and exposure duration. Furthermore, their interactions with harmful chemicals and aging processes increase the complexity of environmental studies. Research on the mode of action of MPs on soil microbial communities and P dynamics in the soil is still limited. This review synthesizes current knowledge on the effect of MPs on soil microbiota, P, and essential processes like P solubilisation. Moreover, the review evaluates the impact of different MPs polymers, concentrations, and experimental duration on soil microbial community and highlights the interaction between soil microbiota and P in MP-contaminated soils. Overall, this review fills the knowledge gap regarding the dynamics of P, a topic that remains relatively underexplored in microplastics research.