【摘要】 采用静态暗箱/气相色谱法连续2 a田间原位测定,研究川中丘陵区冬灌田CH4和N2O的排放特征和不同耕作制度对冬灌田CH4和N2O排放的影响.结果表明,1a只种1季中稻冬季灌水休闲的冬灌田(PF),在水稻生长期,CH4平均排放通量为(21.44±1.77)mg.(m2.h)-1,非水稻生长期为(3.77±0.99)mg.(m2.h)-1,分别大大低于以前文献报道的在西南其它地方观测值;全年CH4排放量以水稻生长期CH4排放量为主,非水稻生长期CH4排放量仅占全年总排放量的23.2%.冬灌田N2O排放通量年均值为(0.051±0.008)mg.(m2.h)-1,且主要集中在水稻生长季,非水稻生长期N2O排放量仅占全年总排放量的8.1%.在采用水旱轮作制后,冬灌田CH4排放量大大降低,稻-麦轮作(RW)和稻-油菜轮作(RR)全年CH4排放量分别为PF的43.8%和40.6%.但冬灌田改为水旱轮作制后,N2O排放量显著增大,RW和RR的N2O年排放量分别是PF的3.7倍和4.5倍.综合考虑冬灌田在采用不同耕作制度后排放CH4和N2O的全球增温潜势(GWP),无论是短时间尺度还是长时间尺度,采用3种耕作制度全年所排放的CH4和N2O所产生的综合GWP都为:PF RW≈RR.在20a、100a和500a时间尺度上,PF分别约是RW和RR的2.6、2.1和1.7倍.冬灌田改为水旱轮作制度后能大大减少CH4和N2O所产生的综合GWP.更多还原

【Abstract】 Using the static opaque chamber method,a field experiment was conducted in situ for two years to study the effects of three cultivation systems on CH₄ and N₂O emissions from permanently flooded rice fields in a hilly area in Southwest China.The results show that the average CH₄ fluxes from a permanently flooded rice field with a single middle rice crop and flooded with no winter crop（PF） were（21.44±1.77） mg·（m²·h）^-1 and（3.77±0.99） mg·（m²·h）^-1 during rice-growing and non-rice growing periods,respectively,where both values were much lower than many previous reports from similar regions in Southwest China.The annual CH₄ emission was mainly occurred in the rice growing period,being only 23.2% of the total annual CH₄ flux emitted from the non-rice growing period,though the latter occupied two thirds of a year.The annual average flux of nitrous oxide was（0.051±0.008） mg·（m²·h）^-1 and the N₂O emission also intensive in the rice growing period.However,being only 8.1% of total annual N₂O flux emitted from the non-rice growing period.After implementing the rice-wheat rotation（RW） and rice oil-seed rape rotation（RR）,the CH₄ emissions were reduced substantially,only 43.8% and 40.6% of those of PF,respectively.However,the N₂O emissions were increased after conducting RW and RR systems,which were 3.7 and 4.5 times larger than those of PF.The global warming potentials（GWPs） of the CH₄ and N₂O emissions under the three tillage-cropping systems were assessed in an integrated way.The results show that the integrated GWPs of the CH₄ and N₂O emissions are in the following sequence: PFRR≈RR.Within 20,100 and 500 years spans,the GWPs of the CH₄ and N₂O emissions of PF were 2.6,2.1 and 1.7 times larger than those of RW（or RR）,respectively.After introducing rice-wheat or rice oil-seed rape rotation systems into the permanently flooded rice fields,the integrated GWPs of the CH₄ and N₂O emissions were decreased largely.更多还原