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依据位于重庆北碚始于1991年的国家紫色土肥力与肥效监测基地上长期不同施肥定位试验,选取其中不施肥+秸秆不还田、不施肥+秸秆还田、施PK肥+秸秆不还田、施N肥+秸秆不还田、NPK正常施肥量+秸秆不还田、NPK正常施肥量+秸秆还田和1.5倍NPK施肥量+秸秆还田等7个处理,采用静态箱法对土壤N_2O排放开展了连续2a小麦生长期的田间原位观测.结果表明:两麦季4个施氮处理N_2O排放波动幅度均较大,且基肥和追肥后出现较强排放,3个未施氮处理N_2O排放波动较平缓,并均明显低于施氮处理.N_2O排放第二季较第一季要弱,年际差异较大,其原因主要是土壤WFPS第二季要明显低于第一季,而同一麦季不同处理下N_2O排放差异主要是由土壤NO_3~--N质量分数不同造成的.秸秆还田增加了N_2O排放,单施氮肥对N_2O增排效果相比之下则更明显,而秸秆还田与化学氮肥协同作用同样促进了N_2O生成与排放.平衡施肥较偏施氮肥N_2O排放量低,实际生产中考虑N_2O减排应尽量选择平衡施肥.两麦季化肥或秸秆N来源下农田N_2O排放系数均值分别为0.85%,0.61%,综合考虑外源输入N时均值为0.69%,均低于IPCC推荐值(1%),可见估算N_2O排放量时针对不同N素源农田应选用相对应N素N_2O排放系数.
According to the long-term fertilization experiment on purple soil fertility and fertilizer efficiency monitoring base in Beibei of Chongqing, which was started in 1991, no fertilization + straw returning, no fertilization + straw returning, no PK fertilizer + straw returning, N fertilizer + straw not returning to field, NPK normal fertilization + straw returning, NPK normal fertilization + straw returning and NPK fertilization 1.5 times + straw returning 7 treatments. The results showed that the fluctuation of N 2 O emission was relatively high in the four wheat-nitrogen treatments in two wheat seasons, with strong emission after basal fertilizer and top dressing, and three N 2 O treatments without nitrogen application The fluctuation of N 2 O in the second season was weaker than that in the first season, and the difference was greater in the interannual period. The main reason was that the second quarter of soil WFPS was obviously lower than the first season, while the same The differences of N 2 O emission under different treatments were mainly caused by the difference of NO_3 ~ N content in soil, while straw addition increased N_2O emission, while the effect of nitrogen application on N_2O emission enhancement was more obvious than that of straw addition The synergistic effect of Tian and chemical nitrogen fertilization also promoted N 2 O generation And emissions.The balance of fertilization is lower than that of nitrogenous fertilizer N 2 O. The average emission coefficient of N 2 O under two wheat seasons of chemical fertilizer or straw N source is 0.85% and 0.61%, respectively, Considering the input of N, the average value is 0.69%, which is lower than the recommended value of IPCC (1%). It can be seen that the corresponding N-N emission factor should be used for estimating N2O emission for different N-prime farmland.