Methane and nitrous oxide emissions from rice seedling nurseries under flooding and moist irrigation regimes in Southeast China

Measurements of methane (CH(4)) and nitrous oxide (N(2)O) fluxes have been extensively taken following rice seedlings transplanted into paddy fields, while little is known about CH(4) and N(2)O fluxes from rice seedling nurseries. Fluxes of CH(4) and N(2)O were simultaneously measured in rice seedling nurseries under the water regimes of continuous flooding and moist irrigation without waterlogging in Southeast China in 2010. Fluxes of CH(4) and N(2)O from continuously flooded nurseries averaged 10.33-14.84 mg m(-2) h(-1) and 28.64-34.35 μg N(2)O-Nm(-2) h(-1) for the different fertilizer applied plots, respectively. Relative to continuous flooding, moist irrigation decreased total CH(4) by 14-50% but increased N(2)O by 72-186%, dependent on the fertilizer types. Compared with inorganic N fertilizer, organic manure application increased CH(4) by 44% and 148% in the continuously flooded and moist irrigation nurseries, respectively. Rice seedling growth parameters were the greatest in moist irrigation nurseries with inorganic N fertilizer application. Moist irrigation instead of continuous waterlogging and shifts from organic manure to combined organic/inorganic N fertilizer inputs have been increasingly experienced in Chinese rice seedling nurseries, which would benefit for mitigating the combined global warming potentials of CH(4) and N(2)O from rice seedling nurseries in China.