Nitrogen fertilizer used in rice fields can increase methane emissions during the fallow period. A study in China found that fields treated with nitrogen emitted significantly more methane compared to untreated fields. This increase was due to higher levels of soil organic carbon and dissolved inorganic nitrogen, which provided more food for methane-producing microbes. The study also showed that soil temperature had a big impact on methane emissions throughout the rice-growing season and fallow period. Overall, applying nitrogen fertilizer during the rice-growing season can lead to higher methane emissions during the following fallow period in flooded rice paddy fields.