水稻田土壤N_2O和CO_2排放日变化规律及最佳观测时间的确定

The Diurnal Variation of the Emission of N_2O and CO_2,and the Best Observation Time in Paddy Field

采用静态箱（暗箱）-气相色谱法,对水稻田土壤中温室气体的排放进行了连续观测,以探索水稻田土壤N2O和CO2排放日变化规律,确定最佳观测时间。结果表明：氮肥的施用对N2O和CO2的排放具有显著的促进作用,各处理水稻田土壤N2O排放日变化规律有明显差异,而CO2排放的日变化规律差异不显著。在整个观测时期内（120 h）,对照处理水稻田土壤N2O的排放变化不大,且排放通量较低。施氮处理在施肥前24 h和施肥后24 h N2O的排放通量变化不明显,而在施氮肥后48~96 h内排放通量增大较显著,在96~120 h内,N2O的排放逐渐减少。各处理水稻田土壤CO2排放的日变化规律较相似,在施氮肥前,各处理水稻田土壤CO2排放无显著差异。在施氮肥后24~48 h、48~72 h、72~96 h和96~120 h观测时间段内,自当日15：00至次日9：00,各处理CO2的排放通量均呈现先减小后增大的趋势,且施氮处理CO2的排放通量显著高于对照处理。通过对120 h内水稻土壤N2O和CO2排放通量进行矫正分析,在9：00—11：00进行观测时,CO2和N2O的排放通量与一天的平均值最接近,能够代表一天温室气体排放通量。

In order to study the diurnal variation of N2 O and CO2 from paddy field, and determine the best time for observation, a field experiment was conducted with static-chamber and gas chromatograph. The results showed that, nitrogen fertilizer had a significant role in promoting the emissions of N2 O and CO2. The diurnal variation of the emission of N2 O had obvious difference in each treatment, but the flux of CO2 had little difference in each treatment. During the whole observation period（120 h）, the emission of N2 O from the check treatment, not only changes little, but also very lower. The emission of N2 O changes little before and after fertilization in 24 h, but increase significantly in 48-96 h, and decreased in 96-120 h. The diurnal variation of the emission of CO2 in paddy soil were similar in each treatments, there weren’t significant difference in the paddy soil before fertilization. The emission of CO2 of different observation period of 24-48 h, 48-72 h and 72-96 h had a trends of decreased first and then decreased in each treatment, and the flux of CO2of nitrogen treatment were significantly higher than that in check treatment. Based on the correct analysis, the average flux of CO2and N2O were more close to the emission of observation of 9：00-11：00, and could represent the emission of the day and finally determine the gas samples collection time was 9：00-11：00.