A pioneering two-year field study has revealed that biodegradable microplastics, often hailed as eco-friendly alternatives to conventional plastics, are quietly reshaping the chemistry of farmland soils in unexpected and complex ways. Published on August 22, 2025, in Carbon Research as an open-access original article, this research was co-led by Dr. Jie Zhou from the College of Agriculture at Nanjing Agricultural University, China, and Dr. Davey L. Jones from the School of Environmental and Natural Sciences at Bangor University, UK—a powerful Sino-British collaboration bridging soil science, microbiology, and climate resilience. The team investigated how polypropylene (PP)—a common conventional plastic—and polylactic acid (PLA)—a widely used biodegradable plastic—affect soil organic carbon (SOC) in real-world agricultural conditions. Both were added at realistic concentrations (0.2% w/w) to topsoil (0–20 cm), with an unamended plot serving as control. While neither plastic changed the total amount of carbon stored, the story beneath the surface was dramatically different.