Atmospheric CO₂ concentrations and water management practices both affect greenhouse gas (GHG) emissions from rice paddies, but interactive effects between these two factors are still unknown. Here, we show the first study to compare the impact of elevated atmospheric CO₂ (eCO₂) on GHG emissions under continuously flooded irrigation (CF) and under intermittently flooded (IF) conditions. Elevated CO₂ stimulated CH₄ emissions under CF by 50% in a field experiment and by 46% in a pot experiment, but it had no effect under IF in both experiments. Elevated CO₂ had no effect on N₂O emissions in either the field or pot experiment. Rice root biomass, aboveground biomass and grain yield increased with eCO₂, but were not affected by water management. Elevated CO₂ only stimulated the abundance of methanogens under CF, suggesting that increased soil O₂ availability with IF limited methanogenic activity under eCO₂. Our findings suggest that estimates of CH₄ emissions from global rice agriculture with eCO₂ need to account for recent changes in water management.

大气中的 CO ₂浓度和水资源管理措施都会影响稻田的温室气体 (GHG) 排放，但这两个因素之间的交互影响仍然未知。在这里，我们展示了第一项研究，比较了在连续漫灌 (CF) 和间歇漫灌 (IF) 条件下大气 CO ₂ (eCO _{2 ) 升高对温室气体排放的影响。}在现场实验中，升高的 CO ₂刺激 CH ₄排放量在 CF 下增加了 50%，在盆栽实验中增加了 46%，但在两个实验中在 IF 下都没有影响。升高的 CO ₂对 N _{2没有影响}田间或盆栽实验中的 O 排放。水稻根系生物量、地上生物量和粮食产量随着eCO ₂的增加而增加，但不受水分管理的影响。升高的 CO ₂仅在 CF 下刺激了产甲烷菌的丰度，这表明在 eCO ₂下，IF 限制了产甲烷活性增加了土壤 O ₂可用性。我们的研究结果表明，使用 eCO _{2对全球水稻农业产生的 CH 4}排放进行估算需要考虑近期水资源管理的变化。