节水灌溉模式下稻田甲烷排放的季节变化

Effect of water-saving irrigation on the seasonal emission of CH_4 from paddy field

基于稻田节水灌溉技术和密闭静态箱技术田间原位采集甲烷气样,研究了控制灌溉模式对稻田甲烷季节排放规律的影响.结果表明,控灌稻田水稻全生育期的甲烷排放主要集中在分蘖前期和中期,甲烷排放总量为24.43 g?m-2,平均排放率为7.95 mg?m-2?h-1,比淹水稻田减少了39%.但分阶段的均值显著性检验显示,在泡田———分蘖中期"控灌稻田的甲烷平均排放率与淹水稻田无显著性差异(0.05<P=0.87),在分蘖后期———黄熟期"才明显低于淹水稻田(0.00=P<0.05).控灌稻田甲烷排放量在水稻全生育期月份上的分配与淹水稻田具有一致性,7月份是华东稻作区甲烷排放最多的月份,但控灌稻田甲烷排放量在各月的变幅较大.另外,控灌稻田低于饱和含水率的无水层状态能显著减少稻田甲烷的排放,且不因降雨或施入氮肥而被削弱,还可能成为吸收甲烷的汇.

Based on water-saving irrigation technique and observation in situ with closed static chamber technique, the effect of rice water-saving controlled irrigation on the seasonal emission law of CH4 from paddy field was investigated. The results show that the seasonal variation of CH4 emission from paddy field under controlled irrigation （PFCI） takes on distinct one-peak pattern, occurring at the initial tillering stage of rice. The total CH4 emission from PFCI was 24.43 g.m^-2, the seasonal average of CH4 emission rate was 7.95 mg.m^-2 . h^-1, reduced by 39% compared with that from paddy field under flooding irrigation （PFFI）. There is no statistically significant difference on the mean emission rates of CH4 between two kinds of irrigation patterns during the ponding to the peak tillering stage of rice （0.05〈P=0.87） ; while CH4 emission rate from PFCI is significantly lower than that from PFFI during the later tillering to ripening stage of rice （0.00=P〈0.05）. July is the most month of CH4 emission in the whole rice growth season in rice production areas of East China, while the amount of CH4 emission from PFCI changes greatly among various months. In addition, under controlled irrigation, no-water- layer status lower than saturated soil moisture can remarkably reduce CH4 emission from paddy field from the later tillering stage of rice onwards, and the reduction cannot be weakened due to the precipitation and the amendment of nitrogenous fertilizers. Furthermore, the PFCI possibly becomes one of the sinks absorbing the atmosphere CH4.