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

Abstract

Rice cultivation is an important anthropogenic source of atmospheric nitrous oxide (N 2 O) and methane. We compiled and analyzed data on N 2 O emissions from rice fields (113 measurements from 17 sites) reported in peer‐reviewed journals. Mean N 2 O 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 CH 4 and increases N 2 O emissions, it may be an effective option for mitigating the net global warming potential of rice fields.