Direct N2O emissions from rice paddy fields: Summary of available data

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Abstract
Rice cultivation is an important anthropogenic source of atmospheric nitrous oxide (N2O) and methane. We compiled and analyzed data on N2O emissions from rice fields (113 measurements from 17 sites) reported in peer‐reviewed journals. Mean N2O emission ± standard deviation and mean fertilizer‐induced emission factor during the rice‐cropping season were, respectively, 341 ± 474 g N ha−1 season−1 and 0.22 ± 0.24% for fertilized fields continuously flooded, 993 ± 1075 g N ha−1 season−1 and 0.37 ± 0.35% for fertilized fields with midseason drainage, and 667 ± 885 g N ha−1 season−1 and 0.31 ± 0.31% for all water regimes. The estimated whole‐year background emission was 1820 g N ha−1 yr−1. A large uncertainty remains, especially for background emission because of limited data availability. Although midseason drainage generally reduces CH4 and increases N2O emissions, it may be an effective option for mitigating the net global warming potential of rice fields.