稻鸭、稻鱼共作生态系统CH_4和N_2O温室效应及经济效益评估

Methane and Nitrous Oxide Emissions from Rice-Fish and Rice-Duck Complex Ecosystems and the Evaluation of Their Economic Significance

【目的】稻鸭、稻鱼共作生态系统是中国南方稻作区两种主要复合种养模式。研究稻鸭、稻鱼共作生态系统中CH4和N2O排放产生的温室效应并对其经济价值进行评价,旨在为进一步开发利用稻田综合利用模式提供理论基础和实践依据。【方法】采用静态箱技术,研究稻鸭、稻鱼共作生态系统CH4和N2O排放规律,并运用增温潜势对稻鸭、稻鱼共作生态系统CH4和N2O排放的温室效应及经济效益进行估算。【结果】在水稻生长期间,稻鸭、稻鱼共作系统中CH4排放峰值均出现在分蘖盛期和抽穗期,其平均排放通量均显著(P<0.05)低于常规淹水稻田;N2O的排放通量在稻田淹水期间保持较低值,而在稻田落干后迅速升高。养鸭显著(P<0.05)提高了稻田N2O的排放,养鱼降低了稻田N2O的排放。2006和2007年稻鸭、稻鱼处理CH4和N2O排放产生总温室效应分别为4728.3、4611.0kgCO2·hm-2和4545.0、4754.3kgCO2·hm-2,其温室效应成本分别为970.89、946.81 yuan/hm2和933.25和976.23 yuan/hm2,明显低于CK的5997.6和5391.5 yuan/hm2。除去CH4和N2O排放产生温室效应的环境成本,采用稻鸭、稻鱼生态种养技术的经济效益分别比常规稻田增加2210.64、4881.92yuan/hm2和3798.37、5310.64 yuan/hm2。【结论】稻鸭、稻鱼共作能有效的抑制稻田温室气体排放并显著降低其温室效应。因此,稻鸭、稻鱼共作是减少温室气体排放的有效措施之一,具有较好的推广价值。

[Objective] The rice-duck and rice-fish ecological systems are the major complex planting and breeding models of rice paddy fields in Southern China. Studying on methane and nitrous oxide emissions and their economic value from these ecosystems can provide a theoretical and practical basis for further development and utilization of these classical agricultural techniques. [Method] Methane and nitrous oxide emissions from rice-duck （RD） and rice-fish （RF） ecological systems were measured in situ by using static chambers technique. Using global warming potentials （GWPs）, the greenhouse effects of methane and nitrous oxide and the economic value were assessed. [Result] Results shown that the peak of methane emission fluxes appeared at full tillering stage and complete heading stage, and the average emission fluxes from RD and RF were significant lower than that from CK. Nitrous oxide fluxes remained low in flooding irrigation and high in draining of water. Compared with CK, the total amount of nitrous oxide emissions from RD significantly higher and RF lower. In 2006 and 2007, the total greenhouse effects of methane and nitrous oxide were 4 728.3 kg CO2.hm^2 and 4 611.0 kg CO2.hm^-2, 4 545.0 kg CO2-hm^2 and 4754.3 kg CO2-hm^2, respectively. So the cost of greenhouse effect was 970,89 yuan/hm^2 and 946.81 yuan/hm^2, 933.25 yuan/hm^2 and 976.23 yuan/hm^2, respectively, which were significant lower than that from CK （5 997.6 yuan/hm^2 and 5 391.5 yuan/hm^2）. Except for the environment cost of methane and nitrous oxide, the achieved economic benefits from RD and RF were higher than that from CK （2 210.64 yuan/hm^2 and 4 881.92 yuan/hm^2; 3 798.37 yuan/hm^2 and 5 310.64 yuan/hm^2, respectively）. [Conclusion] Rice-duck and rice-fish complex ecological planting and breeding models can effectively decrease and control methane and nitrous oxide emissions, and they are effective strategies to reduce greenhouse gas from rice paddy fields. Thus, they are worthy to be populated by farmer in view of their economic benefit.