Greenhouse gases exchange of integrated paddy field and their comprehensive global warming potentials

Research on comprehensive global warming potentials(GWPs)of CO2,CH4,N2O helps evaluating reasonably contribution of integrated paddy ecosystem to mitigating greenhouse gases emission and provides some evidence to develop integrated rice-duck and rice-fish production. By adopting the closed chamber technique,emissions of CH4 and N2O were measured from paddy field of integrated rice-duck eco-system(RD),integrated rice-fish eco-system(RF) and conventional flooded paddy eco-system(CK). During the whole rice growing stages,emission of CH4 N2O came up to 19.11 g/m2 0.237 g/m2for rice-duck field; 26.71 g/m2 0.229 g/m2 for conventional paddy field and 25.01g/m2 0.237g/m2 for rice-fish field,respectively. By using dry matter accumulation analysis,net fixation of CO2 by rice plant above ground was 2766.4 g/m2 of rice-duck field,2533.9 g/m2 of conventional paddy field and 2759.59 g/m2 of rice-fish field. By analyzing the change of soil carbon pool,during the whole rice growing stage,paddy soil of every three treatments sequestrated equivalently CO2-C of 675.55 g/m2 by rice-duck field,575.43g/m2 by conventional paddy field and 562.62 g/m2 by rice-fish field. The result of greenhouse exchange of the three types of the paddy fields were net fixation of CO2 and emission of CH4,N2O. Comprehensive global warming potentials of rice-duck treatment were the lowest among the three. Feeding ducks in paddy field was proved to reduce CH4 emission significantly,thus may decrease global warming potential by 1.6 times contrasted to that of conventional paddy field.