不同施肥量对设施菜地N2O排放通量的影响

为明确北京地区设施菜地的N2O排放特征，寻求既能减少N2O排放又使蔬菜增产或保持原有产量的切实有效措施，该研究采用静态箱/气相色谱法对北京地区设施菜地的黄瓜进行了全生长季N2O排放通量的观测，并分析了不同施肥量对N2O排放量、蔬菜产量和经济效益的影响。结果如下：土壤N2O排放通量的季节变化有明显的时间变异性，试验初期受基肥的影响，N2O排放量较大，随着时间的推移，土壤N2O排放量有所减少并保持稳定；试验后期由于追肥，出现一次排放高峰，且持续时间较长。各处理土壤N2O排放总量的次序是：T4（常规施肥量+鸡粪）＞T3（3/4常规施肥量+鸡粪）＞T1（1/4常规施肥量+鸡粪）＞T2（1/2常规施肥量+鸡粪）＞Tn（鸡粪）＞T0（无肥处理），各处理之间N2O排放量差异达到极显著水平。综合考虑施肥量、N2O排放量和黄瓜产量，研究认为T3（3/4常规施肥量+鸡粪）的施肥量比较合理，可以为合理施肥、降低农民生产成本以及估算中国农田温室气体排放量和编制温室气体排放清单提供 依据。

Effects of different fertilizer levels on N2O flux from protected vegetable land

To identify the characteristics of N2O emission from protected vegetable land in Beijing, and to seek a way that decreases N2O emission and increase or keep cucumber yield, with the method of static chamber-gas chromatograph technique, N2O emission was monitored in cucumber field from protected vegetable land in Beijing. The effects of different amounts of fertilization on N2O emission, vegetable yields and economic benefit were analyzed. The results showed that significant temporal variability of N2O flux from all treatments was observed in different growing stages of cucumber. Larger emission happened at the initial stage of the experiment. N2O emission decreased and remained stable with time. At the late stage, a peak emission happened and continued for a long time because of larger amount of top dressing. The order of total N2O emission was: T4 (conventional fertilization + chicken dug，in short “CF+CD”) >T3 (3/4CF+CD) > T1 (1/4CF+CD) > T2 (1/2CF+CD) > Tn (CD) > T0 (Control treatment), and there existed significant difference between treatments. By considering fertilizer rates, N2O emission and cucumber yield, it was concluded that the fertilization rate of T3 (3/4CF+CD) was very reasonable, which could provide basis for applying fertilizer rationally, reducing farm production costs, estimating greenhouse gas emissions from cropland and compiling national greenhouse gases emission inventory