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Balancing non-CO2 GHG emissions and soil carbon sequestration in U.S. rice paddies: implications for natural climate solutions
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  • Jingting Zhang,
  • Hanqin Tian,
  • Yongfa You,
  • Xin-Zhong Liang,
  • Zutao Ouyang,
  • Naiqing Pan,
  • Shufen Pan
Jingting Zhang
Research Center for Eco-Environmental Sciences, State Key Laboratory of Urban and Regional Ecology, Chinese Academy of Sciences
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Hanqin Tian
Schiller Institute for Integrated Science and Society, Boston College

Corresponding Author:[email protected]

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Yongfa You
Auburn University
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Xin-Zhong Liang
University of Maryland, College Park
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Zutao Ouyang
Department of Earth System Science, Stanford University
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Naiqing Pan
Auburn University
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Shufen Pan
Auburn University
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The U.S. rice paddy systems play an increasingly vital role in ensuring food security, which also contribute massive anthropogenic non-CO2 (CH4 and N2O) greenhouse gas (GHG) emissions with expanding cultivation area. Yet, the full assessment of GHG balance, considering trade-offs between soil organic carbon (SOC) sequestration and non-CO2 GHG emissions, is lacking. Integrating an improved agricultural ecosystem model with a meta-analysis of multiple field studies, we found that U.S. rice paddy was a rapidly growing net GHG emission source, increased 138% to 8.88 ± 2.65 Tg CO2eq yr-1 in the 2010s. CH4 emission made the most significant contribution (10.12 ± 2.28 Tg CO2eq yr-1) to this increase in net GHG emissions in the 2010s, but increasing N2O emissions, accounting for ~2.4% (0.21 ± 0.03 Tg CO2eq yr-1), cannot be ignored. SOC sequestration could offset about 14.0% (1.45 ± 0.46 Tg CO2eq yr1) of the climate-warming effects of soil non-CO2 GHG emissions in the 2010s. The aggravation of net GHG emissions stemmed from intensified land use/cover changes, rising atmospheric CO2, and heightened synthetic N fertilizer and manure application. Climate change exacerbated around ~21% of soil N2O emissions and ~10% of soil CO2 release in the 2010s. Nonetheless, adopting no/reduced tillage resulted in a substantial decrease of ~10 % in net soil GHG emissions, and non-continuous irrigation exhibited the potential to mitigate around 39% of soil non-CO2 GHG emissions. Great potential for emissions reduction in the mid-South U.S. by optimizing synthetic N fertilizer and manure ratios, reducing tillage, and implementing non-continuous irrigation.
25 Sep 2023Submitted to ESS Open Archive
25 Sep 2023Published in ESS Open Archive