Effects of Micro/Nanoplastics on Crop Physiological Responses and Soil Environment: A Meta-Analysis

The increasing accumulation of plastics in agricultural soils poses a threat to soil ecosystems, plants and human life. Under environmental conditions, the accumulation leads to the formation of more reactive forms of plastics such as micro (<5 mm) and nano (<1 µm) plastics. The additives of these plastics are able to leach into the soil and disrupt soil biological, physical and chemical properties as well as affecting plant physiological activities. Given the varying findings across existing studies, this comprehensive meta-analysis helps to synchronize the different results and identify key drivers such as polymer type, shape, particle size, dose, exposure duration, and soil pH. A total of 50 studies with 478 observations were used for this meta-analysis. Overall, exposure of MPs/NPs significantly reduced biomass and NUE by 10.9%, while having only a minor effect on root-to-shoot ratio. Fibers, granular particles, and polyvinyl chloride (PVC), due to their additives, showed the strongest negative impacts on plant performance. PVC produced the greatest reduction in biomass (-24.03%, 95% CI: -67.9-20.7, *). Smaller particles (-9.63%, 95% CI: -80-86.6, ***), higher concentrations (-19.77%, 95% CI: -73.9-73.2, ***), longer exposure periods (-12.15%, 95% CI: -73.9-66.7, ***), and acidic growth media conditions (-12.63%, 95% CI: -80-40.8, ***) further intensified these effects on the biomass and NUE. The findings indicate that MPs and NPs can impair crop productivity by disrupting soil conditions, nutrient availability, and plant physiological processes, highlighting a growing challenge for sustainable agricultural production and soil health. Although advanced analytical techniques are developed, the analytical methods need improvements in the future and more on-field and long-term research studies investigating MP/NP effects on soil and plant ecosystems are required.