Microplastics Can Change Soil Properties and Affect Plant Performance

TLDR

Microplastics can alter soil biophysical properties, yet the cascade of effects from abiotic changes to soil–plant interactions, including microbes and plant traits, remains poorly understood. The study aimed to evaluate how six distinct microplastic types influence soil health indicators and spring onion (Allium fistulosum) performance. Researchers assessed these effects using a broad suite of soil health proxies and plant performance metrics across the six microplastic treatments. Significant changes in plant biomass, tissue elemental composition, root traits, and soil microbial activities were observed, with impacts depending on particle type—microplastics resembling natural soil particles produced smaller differences, whereas polyester fibers and polyamide beads caused the most pronounced effects, implying that widespread microplastic contamination could affect plant performance and agroecosystems.

Abstract

Microplastics can affect biophysical properties of the soil. However, little is known about the cascade of events in fundamental levels of terrestrial ecosystems, i.e., starting with the changes in soil abiotic properties and propagating across the various components of soil–plant interactions, including soil microbial communities and plant traits. We investigated here the effects of six different microplastics (polyester fibers, polyamide beads, and four fragment types: polyethylene, polyester terephthalate, polypropylene, and polystyrene) on a broad suite of proxies for soil health and performance of spring onion (Allium fistulosum). Significant changes were observed in plant biomass, tissue elemental composition, root traits, and soil microbial activities. These plant and soil responses to microplastic exposure were used to propose a causal model for the mechanism of the effects. Impacts were dependent on particle type, i.e., microplastics with a shape similar to other natural soil particles elicited smaller differences from control. Changes in soil structure and water dynamics may explain the observed results in which polyester fibers and polyamide beads triggered the most pronounced impacts on plant traits and function. The findings reported here imply that the pervasive microplastic contamination in soil may have consequences for plant performance and thus for agroecosystems and terrestrial biodiversity.