种植蔬菜地与裸地氧化亚氮排放差异比较研究

采用大型原状土柱试验研究了种植蔬菜地与未种植蔬菜裸地土壤氧化亚氮（N2O）排放的差异。试验结果表明,施肥但未种植蔬菜的裸地土壤N2O排放量远大于种植蔬菜地的土壤N2O排放量,裸地土壤N2O平均排放通量为193μg.m-2.h-1,而种植蔬菜后土壤N2O平均排放通量减少至60μg.m-2.h-1;相应地,裸地的N2O排放总量也要远高于种植蔬菜地的N2O排放总量。同时,低施氮量（N1,500 kg.hm-2）下裸地的N2O排放量要比高施氮量（N2,750 kg.hm-2）且种植蔬菜时裸地的N2O排放量大,如2007年10月至2008年9月试验期间,N1处理下裸地总N2O-N排放量为9.54 kg.hm-2,而N2处理（种植蔬菜）下总N2O-N排放量仅为4.21 kg.hm-2。此外,未种植蔬菜时裸地土壤N2O排放系数远大于种植蔬菜时,如N1种植蔬菜时为0.39%,但未种植蔬菜的裸地土壤排放系数为1.76%。研究说明种植作物与否对土壤N2O排放有重要影响,因此在估算农田土壤N2O排放温室气体量时,需考虑裸地的贡献能力。

Comparison of nitrous oxide emission from bare soil and planted vegetable soil

Undisturbed soil monolith lysimeter was used to investigate the difference of nitrous oxide（N2O） emission from the bare soil with N fertilizer application and the soil with vegetable planted.Results showed that N2O emission（emission flux and total emission） from the bare soil exceeded that from the soil with vegetable planted.The average N2O emission flux from the bare soil was 193 μg·m-2·h-1,while it decreased to 60 μg·m-2·h-1 with the vegetable planted.Meanwhile,total N2O emission from the bare soil with lower nitrogen fertilizer applied（N1,500 kg·hm-2）（9.54 kg·hm-2） was greater than that from the soil with higher nitrogen fertilizer applied（N2,750 kg·hm-2）（4.21 kg·hm-2） during the experimental period（October 2007-September 2008）.In addition,N2O emission factor from the bare soil（1.76%） was more than that from the soil with vegetable planted（0.39%）.The results demonstrated that soils which were covered by crops or not（bare） had a great effect on soil N2O emission,so,it is important to take bare soil into account when estimating the N2O emission from agricultural soils.