黄淮海平原典型农田土壤N_2O的排放特征

Characterization of Emissions of Nitrous Oxide from Soils of Typical Crop Fields in Huang-Huai-Hai Plain

【目的】明确黄淮海平原地区典型作物种植类型下,农田土壤N2O排放特征,并探明不同环境因子对其排放通量的影响。【方法】采用静态箱法测定了黄淮海平原典型农田(冬小麦/夏玉米、棉花、休闲地)土壤N2O的排放通量及其季节变化特征,并分析了土壤温度、土壤水分、不同氮肥量对土壤N2O通量的影响。【结果】3种种植方式N2O排放在秋季均呈现总体下降趋势,至12月中旬左右降到最低,随着春季气温的升高则呈总体上升趋势。冬小麦/夏玉米地土壤N2O排放高峰值为433.5μgN2O·m-2·h-1,出现在7月下旬;棉花地为146.5μgN2O·m-2·h-1,出现在6月中旬;休闲地为175.16μgN2O·m-2·h-1。在棉花地和休闲地,N2O排放通量随地温增加而呈指数增长,而在冬小麦/夏玉米地则没有观测到N2O排放通量与地温之间的相关关系,但与土壤含水量的变化趋势基本一致。施用氮肥对土壤N2O的排放具有明显的促进作用。【结论】N2O排放表现出多峰的日变化特征,呈明显的季节变化;土壤中N2O的产生与释放受多种环境因子的影响,而且不同环境条件不同作物影响因子所起的作用是不一样的。

[Objective] To identify the characterization of N2O emissions from different crop types fields, and to study the impact of different factors on N2O emissions. [ Methods ] Daily and seasonal variation of soil N2O fluxes were measured using close chamber method in typical crop fields （winter wheat/summer corn, cotton, and non-crop） in Huang-huai-hai Plain. The influence of soil temperature and moisture on soil N2O flux was also discussed. [Results] showed that the peak value of N2O emission flux appeared in July with 433.5μgN2O·m^-1·h^-1 in winter wheat-summer corn rotation fields, 146.5μgN2O·m^-1·h^-1 in cotton fields （the peak value appeared in June） and 175.16μgN2O·m^-1·h^-1 in fallow fields. The N2O emission was exponentially correlated with the soil moisture, but it did not happen in wheat-summer corn rotation field. The more N2O emissions also occurred in the fields with higher nitrogen fertilizer. [ Conclusion ] N2O emissions showed several peaks of daily fluxes and obvious seasonal variation patterns. The emission and production of N2O was influenced by many factors, and also different factors made different impact on the N2O emissions.