Wood Chips Ameliorate the Negative Effects of LDPE Microplastic on Wheat Growth and Soil Microbial Community

As an emerging pollutant, microplastics (MPs) pose a potential risk to ecosystem health due to recycling technology’s limitations and long-term durability. Wood chip amendments can enhance the holding capacity of water and nutrients and improve the soil structure and quality of terrestrial ecosystems. However, the effects of wood chip amendments on MPs-contaminated soil-plant systems are still unclear. In this experiment, we employed a combination of field experiments, soil and plant measurements, molecular techniques (DNA extraction and sequencing), and advanced statistical analyses. A comprehensive assessment was conducted on the effects of Low-density polyethylene (LDPE) MPs on soil properties, wheat growth, and soil microbial communities, and the potential of wood chips as a mitigating agent was also evaluated. The results indicated that wood chips improved soil nutrient content, enhanced the activity of enzymes related to carbon, nitrogen, and phosphorus cycling, and promoted crop growth, all of which were negatively affected by LDPE. The effect of MPs on fungi was greater than that on bacterial communities, and adding wood chips could improve the α-diversity of fungal communities rather than bacteria. LDPE may increase the abundance of pathotrophic fungal groups, such as Stachybotrys and Alternaria. However, certain pathotrophic groups have been found to potentially facilitate the degradation of LDPE-MPs. LDPE reduced the symbiotroph groups and increased the competitiveness and complexity of the community in the microbial co-occurrence network. LDPE treatment inhibited the N-cycling bacteria group, while adding wood chips could promote most of the N-cycling bacteria groups. Wood chips increased saprotroph groups such as Trichoderma, which are able to degrade plastics. Wood chips emerge as a cost-effective and environmentally friendly solution to improve soil quality and mitigate the negative impacts of microplastics on crop growth.