| The study adopted plot and field experiment to observe the methane emission, soil physical and chemical characteristics, paddy nutrient content and ecological and economical benefits of wetland rice-duck complex ecosystem. It aimed at affording scientific basis for comprehensive assessment of the function of rice-duck complex ecosystem and laying theoretical foundation for coordinating the conflict between rice production and environmental protection and searching for ideal measure to mitigate methane emission and achieve agricultural sustainable development.Study contents of this experiment included: The influence of raising duck in paddy fields on methane emission. There is no report in this respect so far; The influence of raising duck in paddy fields on soil physical and chemical characteristics; The study on ecological and economical benefit of rice-duck ecosystem. Main results for this study are as follows:1 .The study on methane emission law of wetland rice-duck complex ecosystem. The results showed that methane emission had obvious daily and seasonal variation law in rice-duck complex ecosystem. The daily change law of methane was consistent with daily temperature change. The seasonal change pattern of early rice wasn't consistent with that of late rice. The methane emission peak of early rice appeared in young panicle differentiation stage of rice. The fluxes of methane emission of late rice was the greatest in full tillering stage of paddy. Rice-duck ecological planting and breeding pattern decreased greatly total methane emission of paddy fields, especially decreased methane emission rate and amount during emission peak period, the total methane emission of early rice decreased 3.185g/m from full tillering stage to boot stage. The decrease rate was 60.7%. From initial tillering stage to full tillering stage, the absolute methane emission of late rice decreased 6.11g/m2. It catched a special attention that the methane emission amount of unit rice yield and of unit income were 55.0-61.9% and 17.3-26.9% of contrast respectively by raising duck. Soil oxidation-reduction characteristics affected the fluxes of methane emission. The correlation coefficients between the total reducing matter, active reducing matter, active organic reducing matter and fluxes of methane emission were 0.805*, 0.791* and 0.769* respectively. The improvement of soil oxidation-reduction status of wetland rice-duck complex ecosystem was one of the reasons which resulted in decrease of methane emission.2.The study on soil physical and chemical characteristics of wetland rice-duck complex ecosystem. The results showed that, compared with CK, with rice-duck complex ecological planting and breeding, organic matter, total N, available N, available P, available K increased 11.3-29.3%, 3.0-15.1%, 5.9-9.6%, 3.8-9.7%, 23.4-27.3% respectively; The soil physical characteristics improved greatly, soil bulkdensity decreased 0.01g/cmJ. The >0.25mm soil aggregate increased 2.65-3.12%, the difference reached extremer significant level in early rice and late rice, and structure coefficient increased 2.56-6.63%. Meanwhile, soil environment improved obviously. Because of the increase of soil fertility and improvement of soil aeration, which is beneficial to absorption of N, P, K nutrient for paddy, nutrient of rice and plant body both improved in varying degree.3.The study on ecological and economical benefit of rice-duck complex ecosystem. The results showed, compared with the pattern of applying pesticide but not raising duck in paddy fields, the pattern of raising duck but not applying pesticide in paddy fields raised rice yield 10.9%, gained adult duck 324kg/hm2 and the integrated control for pest, disease and weed reached 76.5%, of which disease resistance is 91%, pest prevention was 74.5%, weed control coefficient was 0.64. The results showed that raising duck without applying pesticide in paddy field was a type of high efficient eco-agriculture pattern with beneficial circle.From above results, we can see that rice-duck com...
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