Effects of Elevated Atmospheric CO2 Concentrations on CH4 and N2O Emission from Rice Soil: An Experiment in Controlled-environment Chambers |
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Authors: | Weiguo Cheng Kazuyuki Yagi Hidemitsu Sakai Kazuhiko Kobayashi |
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Affiliation: | (1) Greenhouse Gas Emission Team, Department of Global Resources, National Institute for Agro-Environmental Sciences, Tsukuba Ibaraki, 305–8604, Japan;(2) Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku Tokyo, 113–8657, Japan |
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Abstract: | The effects of elevated concentrations of atmospheric CO2 on CH4 and N2O emissions from rice soil were investigated in controlled-environment chambers using rice plants growing in pots. Elevated CO2 significantly increased CH4 emission by 58% compared with ambient CO2. The CH4 emitted by plant-mediated transport and ebullition–diffusion accounted for 86.7 and 13.3% of total emissions during the flooding period under ambient level, respectively; and for 88.1 and 11.9% of total emissions during the flooding period under elevated CO2 level, respectively. No CH4 was emitted from plant-free pots, suggesting that the main source of emitted CH4 was root exudates or autolysis products. Most N2O was emitted during the first 3 weeks after flooding and rice transplanting, probably through denitrification of NO3− contained in the experimental soil, and was not affected by the CO2 concentration. Pre-harvest drainage suppressed CH4 emission but did not cause much N2O emission (< 10 μg N m−2 h−1) from the rice-plant pots at both CO2 concentrations. |
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Keywords: | Drainage Elevated CO2 Methane Nitrous oxide Rice soil |
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