秸秆还田条件下不同水分管理对双季稻田综合温室效应的影响

以南方红壤区双季稻-紫云英为研究对象,利用静态箱-气相色谱法分别分析包括绿肥和稻草等秸秆还田条件下不同水分管理对稻田CH4和N2O排放、水稻产量以及综合温室效应(GWP)的影响。试验设持续淹水(F)、中期烤田(F-D-F)和间歇灌溉(F-D-F-M)处理。结果表明,秸秆还田条件下双季稻田周年CH4排放量介于208.3kg/hm2(F-D-F-M处理)和678.2kg/hm2(F处理)之间,其中,晚稻生长季占周年CH4排放量的60.6%~71.7%。F处理周年CH4排放量显著高于F-D-F和F-D-F-M处理(P0.05)。秸秆还田条件下双季稻田周年N2O排放量为4.75~8.19kg/hm2。与F处理相比,F-D-F-M处理周年N2O排放通量显著增加(60.9%);而F和F-D-F处理之间没有显著差异。早稻和晚稻各处理产量分别为7.76~8.02t/hm2和7.22~8.69t/hm2。秸秆还田条件下,双季稻单位面积GWP和单位产量GWP分别为7648.8~18471.8kg/hm2和0.48~1.12 kg/kg,其中F-D-F和F-D-F-M处理分别显著低于F处理(P0.05)。因此,在秸秆还田条件下采用中期烤田和间歇灌溉替代持续淹水,可以同步实现双季稻高产和减轻农业生产对气候的潜在影响。

Effects of Water Regime on Yield scaled Global Warming Potential Under Double Rice Cropping System With Straw Returning

This study provided an insight into a complete green house gases(GHG) accounting of   global warming potential(GWP) as affected by water regime  in typical double rice cropping system with crop residue returning.  The three water treatments included continuous flooding (F), flooding midseason drainage reflooding (F D F) and flooding midseason drainage reflooding moist intermittent irrigation (F D F M) in rice growing seasons.  Methane and N2O fluxes were measured using static chamber method.  The results showed that annual CH4 emissions ranged from 208.3 kg/hm2 for the F D F M plots to 678.2 kg/hm2 for the F plots, being  60.6%-71.7%   from late rice season.  The CH4 emission was significantly reduced by midseason drainage and intermittent irrigation in comparison with continuous flooding.  Annual N2O emission was 4.75-8.19 kg/hm2  in the double rice cropping system.  Compared with the F plots, the N2O emission slightly reduced in the F D F plots, while it was remarkably increased in the F D F M plots.  Among treatments, the grain yields of early rice and late rice were 7.76 8.02 t/hm2 and 7.22-8.69 t/hm2, respectively.  The  GWP ranged from 7648.8 kg/hm2 for the F D F M plots to 18471.8 kg/hm2 for the F plots   in double rice cropping system with crop residue returning.  The  GWP ranged from 0.48 kg/kg  to 1.12 kg/kg,   significantly reduced for the F D F and F D F M plots as compared to F plots.  Therefore, agricultural economic viability and GHGs mitigation can be simultaneously achieved by midseason drainage and intermittent irrigation instead of continuous waterlogging    in the double rice cropping system with crop residue returing.