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Aims <p>This study aims to elucidate how elevated CO<sub>2</sub> (eCO<sub>2</sub>) modulates N<sub>2</sub>O-related microbial processes in paddy soils by quantifying the responses of ammonia-oxidizing microorganisms (AOA/AOB) and denitrifying communities carrying <i>nirS</i>/<i>nirK</i> through field trials.</p> Methods <p>We conducted a 2-year field experiment with ambient CO<sub>2</sub> (CK) and eCO<sub>2</sub> (CK + 200&#xa0;ppm), approximating an atmospheric concentration of approximately 600&#xa0;ppm projected for 2100. We quantified <i>amoA</i> (archaeal and bacterial) and denitrification genes (<i>nirS</i>, <i>nirK</i>, <i>nosZ</i>) by qPCR and profiled <i>nirS</i>/<i>nirK</i> communities by Illumina sequencing; targets were chosen because <i>amoA</i> tracks nitrification, <i>nirK</i>/<i>nirS</i> capture the rate-limiting NO<sub>2</sub><sup>−</sup> reduction, and <i>nosZ</i> represents the only microbial N<sub>2</sub>O sink.</p> Results <p>eCO<sub>2</sub> significantly increased <i>amoA</i> (AOA and AOB), <i>nirS</i>, and <i>nirK</i> gene abundances at multiple rice growth stages across both years (<i>p</i> &lt; 0.05), whereas <i>nosZ</i> showed no consistent increase. Cumulative N<sub>2</sub>O emissions rose by 17–29% with a mean of 24% under eCO<sub>2</sub>, despite a lower denitrification N<sub>2</sub>O-production potential at grain filling in one comparison. eCO<sub>2</sub> also elevated dissolved organic carbon and soil enzyme activities, consistent with stimulation of nitrification and denitrification and a net shift toward N<sub>2</sub>O production relative to consumption.</p> Conclusions <p>End-of-century eCO<sub>2</sub> is likely to increase the abundance and activity of ammonia-oxidizing and denitrifying microorganisms and to tilt N<sub>2</sub>O production over consumption, enhancing N<sub>2</sub>O emissions from paddy soils; these responses have implications for greenhouse-gas budgets and the management of flooded rice systems under rising CO<sub>2</sub>.</p> Graphical Abstract <p></p>

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Elevated atmospheric CO2 alters N2O-producing microbial communities and nitrogen cycling in paddy soils

  • 期刊论文

  • 发表日期：

    2025年12月4日

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  • Zhurong Wu,
  • Chao Liu,
  • Yuanyuan Wang,
  • Andlia Abdoussalami,
  • Hao He,
  • Zhenghua Hu,
  • Lidong Shen,
  • Qi Li,
  • Wenjing Chen,
  • Min Xu

摘要

Aims

This study aims to elucidate how elevated CO2 (eCO2) modulates N2O-related microbial processes in paddy soils by quantifying the responses of ammonia-oxidizing microorganisms (AOA/AOB) and denitrifying communities carrying nirS/nirK through field trials.

Methods

We conducted a 2-year field experiment with ambient CO2 (CK) and eCO2 (CK + 200 ppm), approximating an atmospheric concentration of approximately 600 ppm projected for 2100. We quantified amoA (archaeal and bacterial) and denitrification genes (nirS, nirK, nosZ) by qPCR and profiled nirS/nirK communities by Illumina sequencing; targets were chosen because amoA tracks nitrification, nirK/nirS capture the rate-limiting NO2− reduction, and nosZ represents the only microbial N2O sink.

Results

eCO2 significantly increased amoA (AOA and AOB), nirS, and nirK gene abundances at multiple rice growth stages across both years (p < 0.05), whereas nosZ showed no consistent increase. Cumulative N2O emissions rose by 17–29% with a mean of 24% under eCO2, despite a lower denitrification N2O-production potential at grain filling in one comparison. eCO2 also elevated dissolved organic carbon and soil enzyme activities, consistent with stimulation of nitrification and denitrification and a net shift toward N2O production relative to consumption.

Conclusions

End-of-century eCO2 is likely to increase the abundance and activity of ammonia-oxidizing and denitrifying microorganisms and to tilt N2O production over consumption, enhancing N2O emissions from paddy soils; these responses have implications for greenhouse-gas budgets and the management of flooded rice systems under rising CO2.

Graphical Abstract