滴灌施肥对设施菜地N2O排放的影响及减排贡献

以京郊典型设施菜地为研究对象,设置了农民习惯(FP)、水肥一体化(FPD)、优化水肥一体化(OPTD)和对照(CK)4个处理,采用静态箱-气相色谱法,分析了设施菜地N_2O排放特征及其影响因素,评估了滴灌施肥对水氮利用效率的影响和N_2O排放量的减排贡献。结果表明:N_2O排放在施肥和灌溉事件后呈现出一段短而急促的排放峰,基肥期排放峰持续10 d左右,追肥持续时间为3~5 d,水肥一体化技术能降低N_2O排放峰值和持续时间,N_2O排放通量变化范围为-2.67~22.56 mg N·m~(-2)·h~(-1);在保持作物产量的条件下,FPD、OPTD处理分别比FP处理减少N_2O排放29.41%、32.63%,FPD处理的氮肥偏生产力和灌溉水利用效率比漫灌FP处理分别增加14.62%和43.54%。可见,在相同施氮量的条件下,改常规漫灌方式为滴灌,能降低设施菜地N_2O排放29.4%,同时氮肥和灌溉水利用效率分别提高14.62%和43.54%,是未来设施菜地值得推荐的一种生产技术。

Effects of fertigation on N2O emissions and their mitigation in greenhouse vegetable fields

In this paper, four treatments, i.e. control(CK), farmers'' practice(FP), farmers'' practice with drip irrigation(FPD), and optimal fertilization with drip irrigation(OPTD), were conducted in the suburbs of Beijing. FPD consisted of drip irrigation with fertilizers dissolved in the irrigation water. OPTD had the same fertigation but N fertilizer was reduced by 40%. Soil N₂O fluxes were measured year round by static chambers. Soil temperature, moisture, and nitrate levels were monitored in parallel with N₂O measurements for all plots. Finally, the effects of fertigation on water and fertilizer use efficiency and soil N₂O emissions in this system were analyzed. Results indicated that the N₂O emission fluxes in the treatments ranged from -2.67 mg N·m^-2·h^-1 to 22.56 mg N·m^-2·h^-1. Fertilization and irrigation were the major factors inducing N₂O emission peaks for a certain time. The N₂O emission peaks lasted for 10 days after basic fertilization, and for 3 to 5 days after additional fertilization. The fertigation management reduced N₂O emission peaks and lasting time. Soil temperature was a significant factor affecting the N₂O emissions in cucumber season. Compared with the FP treatment, FPD and OPTD reduced the annual N₂O emissions by 29.41% and 32.63%, whereas FPD treatment increased the nitrogen partial productivity and irrigation water use efficiency by 14.62% and 43.54%, respectively. It is concluded that the fertigation management practice could not only increase water and fertilizer use efficiency, but also reduce N₂O emissions while maintaining or increasing crop yields from the greenhouse vegetable system.