Effects of elevated ozone concentration on CH4 and N2O emission from paddy soil under fully open‐air field conditions

• Published in: Global Change Biology Vol. 21; no. 4; pp. 1727 - 1736
• Main Authors: Tang, Haoye, Liu, Gang, Zhu, Jianguo, Kobayashi, Kazuhiko
• Format: Journal Article
• Language: English
• Published: England Blackwell Science 01.04.2015; Blackwell Publishing Ltd; Wiley
• Subjects: Agriculture; Air Pollutants; Air Pollutants - chemistry; biomass; carbon; CH4 emission; China; Climate change; Cultivars; Ecosystem; elevated ozone; Emissions; FACE; flowering; Global warming; hybrids; Methane; Methane - metabolism; N2O emission; Nitrous Oxide; Nitrous Oxide - metabolism; Oryza; Oryza - genetics; Oryza - metabolism; Ozone; Ozone - chemistry; paddies; paddy soil; paddy soils; Plant biomass; Rice; rice cultivar; Rice fields; Soil; Soil - chemistry; Soils; Terrestrial ecosystems; tillering; China; paddy soil; elevated ozone; biomass; N2O emission; rice cultivar; CH4 emission; FACE
• ISSN: 1354-1013; 1365-2486; 1365-2486
• DOI: 10.1111/gcb.12810

We investigated the effects of elevated ozone concentration (E‐O₃) on CH₄and N₂O emission from paddies with two rice cultivars: an inbred Indica cultivar Yangdao 6 (YD6) and a hybrid one II‐you 084 (IIY084), under fully open‐air field conditions in China. A mean 26.7% enhancement of ozone concentration above the ambient level (A‐O₃) significantly reduced CH₄emission at tillering and flowering stages leading to a reduction of seasonal integral CH₄emission by 29.6% on average across the two cultivars. The reduced CH₄emission is associated with O₃‐induced reduction in the whole‐plant biomass (−13.2%), root biomass (−34.7%), and maximum tiller number (−10.3%), all of which curbed the carbon supply for belowground CH₄production and its release from submerged soil to atmosphere. Although no significant difference was detected between the cultivars in the CH₄emission response to E‐O₃, a larger decrease in CH₄emission with IIY084 (−33.2%) than that with YD6 (−7.0%) was observed at tillering stage, which may be due to the larger reduction in tiller number in IIY084 by E‐O₃. Additionally, E‐O₃reduced seasonal mean NOₓflux by 5.7% and 11.8% with IIY084 and YD6, respectively, but the effects were not significant statistically. We found that the relative response of CH₄emission to E‐O₃was not significantly different from those reported in open‐top chamber experiments. This study has thus confirmed that increasing ozone concentration would mitigate the global warming potential of CH₄and suggested consideration of the feedback mechanism between ozone and its precursor emission into the projection of future ozone effects on terrestrial ecosystem.