Synergy effect of silicate fertilizer and iron slag: A sustainable approach for mitigating methane emission in rice farming

Although silicate fertilizer has been recently recognized for its ability to suppress methane (CH4) emissions in paddy fields, the effects of its consecutive application during the rice farming period are still a subject of debate. Moreover, while it was known that silicate fertilizer can mitigate CH4 emissions through several electron acceptors, the effect of additional application of electron acceptors have not been extensively studied. This study evaluated the effect of silicate fertilizer with varying concentrations of iron slag on CH4 emissions and rice yield over the 3 years rice farming period. Seasonal CH4 fluxes exhibited a significant decrease with the application of silicate fertilizer, with the treatment containing 2.5 % iron slag showing the maximum reduction of 35 % in 2020. Additionally, in 2021 and 2022, the application of silicate fertilizer with 2.5 % iron slag resulted in a decrease of total seasonal CH4 emission by 22 % and 23 %, respectively. Rice grain yield exhibited a significant increase with the inclusion of iron slag in the silicate fertilizer, which resulted in a 37 % and 16 % higher yield compared to no-silicate fertilization and no‑iron slag silicate fertilization, respectively. Therefore, iron slag-based silicate fertilizer could be a beneficial soil amendment to mitigate CH4 emissions in rice paddy fields and improve rice productivity without negative effects on the atmospheric and soil ecosystem.