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Global warming

Delayed Flooding after Green Manure Incorporation Decreases Methane Emissions in Rice Paddy Fields

Strategic Insights

— 2 min read

Scientists at Fujian Normal University in Fuzhou, China, have discovered that combining green manure incorporation with optimized water management can effectively mitigate methane emissions while sustaining rice productivity. Through a two-year field experiment, the researchers found that withholding flooding for 10 days significantly reduced methane emissions and greenhouse gas intensity, with a reduction of 51.6% in 2022 and 36.1% in 2023. This approach offers a promising strategy for climate-resilient and sustainable rice farming.

Key Takeaways:

  • The study found that green manure incorporation significantly increased methane emissions, but delayed flooding substantially reduced methane emissions without affecting nitrous oxide emissions.
  • Withholding flooding for 10 days (10DbF) produced the lowest methane emissions and global warming potential, reducing greenhouse gas intensity by 51.6% in 2022 and 36.1% in 2023.
  • Methane emissions were positively correlated with soil total nitrogen and water-dissolved organic carbon, indicating their key regulatory roles.
  • Microcosm experiments showed that 10DbF postponed the methane emission peak and reduced cumulative emissions by 405.1% compared to immediate flooding (0DbF).
  • Quantitative PCR analysis revealed a significant decline in mcrA gene abundance and in the mcrA/pmoA ratio under 10DbF, while pmoA gene abundance remained largely unaffected.
  • Microbial community profiling indicated clear shifts in methanogenic and methanotrophic assemblages, with delayed flooding decreasing the relative abundances of amplicon sequence variants (ASVs) within key methanogenic taxa.

Statistics:

  • Methane emissions were reduced by 51.6% in 2022 and 36.1% in 2023 when delayed flooding was used after green manure incorporation.
  • Withholding flooding for 10 days reduced cumulative emissions by 405.1% compared to immediate flooding (0DbF).
  • The study found that methane emissions were positively correlated with soil total nitrogen (STN) and water-dissolved organic carbon (WDOC), indicating their key regulatory roles.
  • The research was supported by the Ministry of Agriculture and Rural Affairs of the People's Republic of China, the Agriculture Research System of China, the National Natural Science Foundation of China, and the National Key Research and Development Program of China.

Sources:

  • Delayed flooding after green manure incorporation decreases methane emissions and greenhouse gas intensity in rice paddy fields. Geoderma, 2025,462():117528. The publisher for Geoderma is Elsevier. A free version of this journal article is available at https://doi-org.sdpl.idm.oclc.org/10.1016/j.geoderma.2025.117528.
  • NewsRx. Fujian Normal University Researchers Describe Recent Advances in Alkanes (Delayed flooding after green manure incorporation decreases methane emissions and greenhouse gas intensity in rice paddy fields). Global Warming Focus. October 20, 2025; p 1254.

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