Characterization of nitrous oxide emission from a rice-duck farming system in South China.

Agricultural activities are important contributors to the emissions of greenhouse gases. This study ascertained the dynamic emission of nitrous oxide (N(2)O) from a paddy field under a rice-duck farming system in South China. Two different cultivation and fertilizer treatments, namely, organic fertilizer + ducks (OF+D) and chemical fertilizer + ducks (CF+D) treatments, were employed in this study. Experimental data showed that diurnal variations of N(2)O emission were highly correlated with the activities of ducklings. The rates of N(2)O emission were normally increased in the early morning and late afternoon due to the frequent movement of ducklings at these time periods. Our study further revealed that the rates of N(2)O emission from the paddy field varied with the types of fertilizers used as well as with the stages of the rice growth. In general, the rates of N(2)O emission were higher for the CF+D treatment than for the OF+D treatment, whereas more N(2)O was emitted from the paddy field at the tillering stage than at the heading stage. The global warming potential with the use of the organic fertilizer was about 22% lower than with the use of the chemical fertilizer.