The warming winter accelerated methane emissions during subsequent rice growing season from paddy fields

Xian Wu (1) , Lei Wu (2) , Yue Luo (1) , Zheng Sun (3, 4) , Ronglin Su (1) , Jinli Hu (1) , Huabin Li (1) , Jingsong Zhao (1) , Jinshui Wu (5) , Ronggui Hu (1)

1 HZAU - Huazhong Agricultural University [Wuhan]
2 CAAS - Chinese Academy of Agricultural Sciences
3 METIS - Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols
4 IFPEN - IFP Energies nouvelles
5 Chinese Academy of Sciences [Hunan]

Global temperature is projected to increase, which impacts the ecological process in northern mid- and high-latitude ecosystems, but the winter temperature change in ecosystems is among the least understood. Rice paddy represents a significant contributor to global anthropogenic CH 4 emissions and has a strong climate forcing feedback; however, the legacy effects of warming winter on CH 4 emissions in the subsequent growing season remain uncertain. Here, we conducted field and incubation experiments to determine the effects of winter soil temperature changes on CH 4 emissions in the subsequent growing season. First, in the 3 year field experiment, we continuously measured CH 4 emissions from the rice cropping system. The winter soil temperature and its variation showed significant differences over the 3 years. In the warming-winter year, the rice paddy accumulated less NH 4 + –N and more dissolved organic carbon (DOC) in the soil during winter, resulting in high CH 4 emissions. Second, we incubated the paddy soils without flooding at three temperatures (5 °C, 15 °C, and 25 °C) for 4 weeks to simulate warming winter, and subsequently incubated at same temperature (25 °C) under submerged conditions for 4 weeks to simulate growing season. The result was consistent with field experiment, increased soil temperature significantly increased soil DOC content and decreased NH 4 + –N content in ‘winter season’. The CH 4 emissions in the subsequent ‘growing season’ increased by 190% and 468% when previous incubation temperature increased 10 °C and 20 °C. We showed strong and clear links between warming winter and CH 4 emissions in the subsequent growing season for the first time, suggesting that CH 4 related processes respond not only to warming during the growing season but also in the previous winter. Our findings indicate that nonuniform global warming causes a disproportionate increase in climate forcing feedback to emit more CH 4 .

Mots clés: warming winter; temperature; methane; rice paddy; growing season

Domaines: Milieux et Changements globaux

Xian Wu, Lei Wu, Yue Luo, Zheng Sun, Ronglin Su, et al.. The warming winter accelerated methane emissions during subsequent rice growing season from paddy fields. Environmental Research Letters, 2023, 18 (2), pp.024012. ⟨10.1088/1748-9326/acad8f⟩. ⟨hal-03992966⟩