The crux of microplastics in soil - a review

The prevalence of microplastics in soil has recently attracted substantial interest as they pose a major threat to the agricultural ecosystem. Microplastics (MPs), though widely found in marine habitats and explored in detail, their presence in agricultural soil remains relatively unexplored. Microplastics are entering the environment either directly through manufactured particles or those originating from the breakdown of larger macroplastics. In soil, microplastics can be transported both horizontally and vertically through the soil fauna. Hence, in order to understand the possible threats posed by microplastics in soil to the environment, this review aims in conducting a meta – analysis to integrate the recent studies in sources, fate and migration of microplastics into agriculture, impacts on soil health, trophic transfers to food chains and the associated adverse impact on soil biota. Results reveals that major sources of microplastics in soil includes sludge followed by wastewater and mulch film. Its effect on soil properties depends on the soil type, size, concentration and type of polymer. Though the occurrence of microplastics in soil has been reported in various countries, its presence in various other countries is still unexplored. Furthermore, several studies validates the effect of microplastics on soil biota at various trophic stages and even endanger human health by food chains. MPs exert both ecotoxicity and genotoxicity in plants. It delays germination by affecting both the vegetative and reproductive growth of plants. It also affects the ecosystem through the sorption of organic and inorganic pollutants. Nevertheless, detailed insights on the effect of microplastics on soil beneficial organisms and the trophic transfer onto humans requires further studies.