北方典型设施菜地土壤N2O排放特征

为明确北方典型设施菜地N2O的排放特征,在“中国蔬菜之乡”——山东省寿光市的秋冬茬设施番茄土壤上利用静态暗箱-气相色谱法,对不施氮肥(CK)、单施有机肥(OM)、农民习惯施(FP)和减氮优化施肥(OPT)4个处理下的N2O排放通量进行了观测,并分析了其对N2O排放量和蔬菜产量的影响.结果表明,施肥并灌溉后的一段时间内,会观测到N2O的“脉冲式”排放,最高排放峰值出现在基肥+灌溉后,且排放高峰持续近20 d,而由追肥引起的排放峰值小且持续时间仅3～5 d.统计分析表明,温度和水分都是影响设施菜地N2O排放的环境因素.各处理土壤N2O排放总量差异显著,顺序依次为:FP (14.77 kg/hm2)＞OPT(9.73kg/hm2＞OM(6.84 kg/hm2)＞CK(2.37 kg/hm2),N2O排放系数介于0.83％～1.10％之间,接近或超过IPCC 1.0％的推荐值.与FP处理相比,减少近60％化肥N的OPT处理下番茄产量增加2.2％.在目前管理措施下,合理减少有机肥和化肥施氮量是设施蔬菜地N2O减排的有效途径.

Emission Characteristics of Soil Nitrous Oxide from Typical Greenhouse Vegetable Fields in North China

To make clear the emission characteristics of soil N2O from typical greenhouse vegetable fields in North China,an experiment was conducted in greenhouse tomato field in Shouguang city,Shandong province,China's "Home of Vegetables".The N2O fluxes were observed in four experimental treatments,as follows:none N fertilizer (CK),single organic fertilizer (OM),conventional fertilization (FP) and optimized and reduced nitrogen fertilization (OPT),by a close chamber-gas chromatograph method.The effects of different fertilization treatments on N2O emission and tomato yield were analyzed.The results showed that following the fertilization and irrigation,the pulsed emissions of N2O were measured.The N2O emission peak appeared after basal fertilizer application and irrigation and could be maintained for about 20 days.While the N2O emission peak caused by topdressing was smaller and last only 3-5 days.The statistical analysis showed that the N2O fluxes were affected by air temperature,soil temperature and WFPS at soil depth of 3 cm.The total contents of soil N2O fluxes had significant differences among experimental groups.The total content orderly was FP of 14.77 kg/hm2,OPT of 9.73 kg/hm2,OM of 6.84 kg/hm2 and CK of 2.37 kg/hm2.The N2O emission coefficient ranged from 0.83％-1.10％,which was close to or more than the recommended value (1.0％)by IPCC.Compared with the FP treatment,the tomato yield in OPT treatment,whose application rate of chemical N fertilizer decreased by about 60％,increased by 2.2％.Under the current management measures,the reasonable reduction on application rate of organic manure and chemical nitrogen fertilizer could effectively reduce the N2O emissions in greenhouse vegetable fields.