A recent study by the Fertilizer and Fertilization Technology Innovation Team at the Institute of Agricultural Resources and Regional Planning (IARRP), Chinese Academy of Agricultural Sciences, has found that long-term green manure rotation significantly reduces methane emissions from rice paddies. The findings have been published in the prestigious journal Earth's Future.

While green manure is widely recognized for improving soil health, enhancing carbon sequestration, and reducing chemical fertilizer dependency, its impact on methane (CH₄) emissions in paddy fields has remained controversial. Previous studies have shown both increases and decreases in emissions, likely influenced by factors such as duration of green manure use, incorporation amount, carbon-to-nitrogen (C/N) ratio, and soil microbial community structure.

Southern China, the country's major rice-growing region, accounts for approximately 85 percent of China's paddy methane emissions and has extensive fallow fields during winter—offering vast potential for green manure application. Understanding how long-term rotations affect methane dynamics is therefore crucial for developing sustainable agricultural practices.

In this study, the IARRP team employed a multi-scale approach combining field measurements, molecular biology techniques, and process-based modeling to assess the impact of green manure–rice rotations on methane emissions. Results have shown that green manure management practices—particularly the number of years of cultivation and the amount of biomass incorporated—were the key drivers, explaining 78.4 percent of the observed methane emission variability.

The study found that green manure affects methane emissions primarily by altering the ratio between methanogenesis and methanotrophy gene abundances in the soil. Importantly, this ratio declines with increasing years of green manure use, indicating enhanced microbial methane oxidation over time.

By incorporating this microbial mechanism into a process-based model, researchers estimated that approximately 76 percent of paddy fields in southern China could achieve methane emission reductions after nearly 15 years of sustained green manure rotation. This provides solid scientific support for adopting green manure as a long-term mitigation strategy in rice production systems.

The study, titled "Sustained green manure‐rice rotations can mitigate methane emissions by enhancing microbial methane oxidation in southern China," was co-authored by Prof. Liang Hao and Associate Prof. Fu Jin of Hohai University, Prof. Zhou Guopeng of Anhui Agricultural University, and Prof. Zhou Feng of Peking University. Dr. Cao Weidong of IARRP and Prof. Zhou Feng served as corresponding authors.

The research was supported by the National Key Laboratory of Efficient Utilization of Northern Arid and Semi-Arid Cultivated Land, the 14th Five-Year National Key R&D Program of China (Project No. 2021YFD1700200), the National Natural Science Foundation of China (Grant Nos. 32072678, 32202609), and the National Green Manure Industry Technology System (CARS-22).

Citation:

Liang, H., Fu, J., Zhou, G.P., et al. (2025). Sustained green manure‐rice rotations can mitigate methane emissions by enhancing microbial methane oxidation in southern China. Earth’s Future, 13, e2024EF005698. https://doi.org/10.1029/2024EF005698

Original article link: 

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024EF005698