Abstract

The comprehensive impacts of agricultural management on nitrous oxide (N 2O) emissions are not well documented. Field experiments with 2 3 factorial designs were conducted to investigate the influence of water regimes, nitrogen fertilizer, and straw incorporation on N 2O emissions from rice paddies in Nanjing, China. In addition to the main factorial design, three single factor designs were included: water regime, N rate, and mid-season drainage duration, each with three levels. The results demonstrate that there were significant differences in the responses of soil N 2O emissions to water regime, nitrogen fertilizer, and straw amendment as well as interaction between straw and nitrogen fertilizer. The cumulative seasonal N 2O emissions from the treatments with mid-season drainage averaged 0.41 kg N ha −1, ranging from 0.20 to 0.73 kg N ha −1. These emissions were higher than those from continuously flooded treatments, which averaged 0.28 kg N ha −1 and ranged from 0.13 to 0.55 kg N ha −1. The integrated application of straw and nitrogen fertilizer mitigated N 2O emissions by approximately 50% under both water regimes. N 2O emissions were mainly promoted by the transition period from the upland crop season to the flooded rice season, by nitrogen application, and by depression with straw amendment. Three groups were formed according to a polynomial relationship between seasonal N 2O emissions and rice production. The results of this study suggest that the integrated application of straw and nitrogen fertilizer can mitigate N 2O emissions from rice agriculture without a decrease in rice production.

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