High-Dose Biochar Hinders Micro/Nanoplastic-Induced Soil Positive Priming by Reducing Substrate Quality and Microbial Activity

Summary

Micro/nanoplastics are increasingly introduced into croplands via agricultural inputs such as mulching films and may accelerate soil organic carbon (SOC) turnover through priming effects. However, how long-term soil management practices influence these priming effects, and thus their implications for cropland carbon sequestration, remains unclear. Here, we conducted a 70-day incubation by adding polyethylene micro/nanoplastics at environmentally relevant concentrations (0.1, 0.5, and 1% w/w) to soils that had received biochar or straw amendments for 14 years. Using δ¹³C source partitioning, we found that micro/nanoplastics induced positive priming in control and low-dose biochar soils, driven by dilution from micro/nanoplastic-leached dissolved organic carbon (DOC), which increa