不同耕作方式下冬小麦田N2O排放特征的差异性研究
Characteristic variations of N2O flux in winter wheat field under different tillage methods

采用静态箱—气相色谱法对空白对照（CK）、常规施肥（CG）、免耕（CB）、秸秆还田（CJ）4种处理小麦田的N2O排放通量进行原位监测，同时测量土壤温度、水分及NH+4等相关影响因子的变化情况。研究结果表明：(1) 4种处理方式下麦田N2O排放通量具有明显的季节性变化规律，N2O排放通量变化趋势基本一致，其中空白对照各处理N2O的排放通量受季节性影响变化较小。(2) 在小麦生长季，4种处理方式下的农田均表现为N2O的排放源。与空白对照相比，常规耕作、免耕和秸秆还田处理下N2O的排放总量分别增加了0.89 kg·hm-2、0.41 kg·hm-2和1.02 kg·hm-2。(3) 气温和土壤5 cm、10 cm温度与N2O排放通量不存在显著的相关性，因而温度不是影响麦田N2O排放的限制性因素。各处理N2O排放通量与土壤水分均呈现正相关（P<0.05）。通过对比几次降水与施肥前后N2O排放通量的关系，发现降水后施肥能显著减少N2O排放。降水引起的土壤水分增加是影响N2O排放通量剧烈变化的因素。(4) 免耕和秸秆还田分别在N2O减排与小麦增产方面效果最好。N2O减排与小麦增产作为农业可持续发展的基本要求，秸秆还田处理效果最优。
The N2O emission fluxes and seasonal variations by four treatments including blank control (CK), conventional tillage (CG), no tillage (CB), and straw application tillage (CJ) were sampled and measured by static chamber-gas chromatographic. The soil temperature, water content, NH+4, Eh and other related factors were monitored at the same time. The results indicated that N2O emission flux by four treatments showed significantly seasonal variations and each treatment displayed a consistent trend. However, emission flux of the blank control were less subjective to seasonal changes in volatility than others. In addition, during wheat growing season, all farmland treatments were N2O emission sources. Compared with the blank control, the N2O total emission fluxes by conventional tillage, no tillage and straw application tillage were increased by 0.89 kg·hm-2, 0.41 kg·hm-2 and 1.02 kg·hm-2, respectively. Moreover, air temperature and soil temperature at 5 cm and 10 cm layers were not related to N2O emission flux, indicating that these were not the significant limiting factors as the wheat field N2O emissions flux. N2O emission fluxes by all treatments and soil moisture showed a positive correlation (P<0.05). By comparing the relationship between precipitation and pre and post fertilization, it was found that N2O emissions flux could be significantly reduced by fertilization after rains. The increase of water content caused by precipitation was the factor that affected the dramatic change of N2O emissions flux. Furthermore, no tillage and straw application tillage had the best effects on N2O emissions and wheat production among the four treatments. For N2O abatement and wheat yield, straw application tillage is the most appropriate approach.