Soil organic matter is crucial for maintaining soil fertility and carbon sequestration, but traditional agricultural practices often lead to its loss. Organic farming attempts to mitigate this issue through methods such as composting and green manures. In recent years, biodegradable plastic mulch films (PFM) have garnered attention for their ability to significantly enhance crop yields while being environmentally friendly. However, there are concerns about whether these films might accelerate the decomposition of soil organic matter and disrupt the soil’s ecological balance. So, how do these novel films affect soil health over the long term?
A study conducted by Martin SAMPHIRE and colleagues at Bangor University in the UK addresses this question through a three-year field trial. The article was recently published in Frontiers of Agricultural Science and Engineering (DOI: 10.15302/J-FASE-2025608).
This research compared the differences between biodegradable PFM and a no-cover control group, while also incorporating common organic farming practices such as green manure composting, poultry manure fertilization, and winter cover management. The findings revealed that the use of PFM increased the yield of all crops by 43%–46%, and winter green manure yield also increased by 18%. This gain is attributed to the “mini-greenhouse effect” created by the mulch film: increased soil temperatures accelerated nutrient mineralization, reduced moisture evaporation by over 30%, and physically isolated weeds, creating an ideal microenvironment for crop growth.
More importantly, this increase in yield did not come at the expense of soil health. Continuous monitoring showed that while PFM promoted microbial activity and accelerated the decomposition of some organic matter, the root exudates from crops and the additional return of residues provided effective compensation. Ultimately, the soil organic matter content stabilized between 12.6% and 13.4%, with no statistically significant difference compared to the no-cover plots. Further analysis using high-throughput gene sequencing technology revealed that the proportions of key microbial taxa, such as Acidobacteria and Proteobacteria, remained stable, and the bacterial diversity index was not significantly disturbed.
The soil restoration effects of green manure compost exceeded expectations. The results indicated that in plots where municipal green manure compost was applied, the soil organic matter content increased by 15%, significantly higher than in the poultry manure treatment group. This confirms that the input of organic materials with a high carbon-to-nitrogen ratio is a key pathway for maintaining soil carbon reserves. The synergistic application of PFM and compost not only supplemented soil carbon sources through compost but also enhanced nutrient use efficiency via the mulch film, creating a positive cycle of “increased yield and soil health”.
This study validates the long-term ecological safety of biodegradable PFM in temperate maritime climates, breaking the traditional belief that “mulch films increase yield at the cost of soil fertility”. The research team emphasizes the need to monitor the dynamic changes of persistent soil organic carbon over scales longer than ten years and recommends that organic farms prioritize the combination strategy of “PFM + green manure compost”.
DOI: 10.15302/J-FASE-2025608