不同水肥条件对绿洲农田土壤N2O排放的影响

Effects of Different Irrigation and Fertilization Conditions on Soil N2O Emission from Oasis Farmland

研究土壤干湿变化对绿洲农田土壤氧化亚氮（N2O）排放的影响,可优化绿洲农田灌溉施肥措施、减少绿洲农田土壤N2O排放。基于室内培养试验,将100 g风干土置于730 m L马氏瓶中,放入25℃培养箱内培养,采用称重法严格控制施氮量和土壤含水量,通过注射器连接三通阀抽取瓶内气体,测定不同施氮量和干湿变化下绿洲农田土壤N2O排放量,结果表明：（1）土壤干湿变化显著影响农田土壤N2O排放,未施氮情况下,干燥处理下土壤N2O累积排放量是湿润处理下土壤N2O累积排放量的1.28倍;（2）与未施氮处理相比,施氮显著促进了土壤N2O排放,施肥土壤N2O排放速率在施氮后0-4 d内出现排放高峰,随后显著降低;（3）施氮后湿润土壤N2O排放速率显著高于干燥条件下的土壤N2O排放速率（P〈0.05）,湿润土壤N2O累积排放量为2.07 mg·kg^-1,是干燥条件下土壤N2O累积排放量的1.16倍。因此,在绿洲农田滴灌施肥期间,适当增加滴灌施肥的时间间隔调控土壤干湿状况,可有效减少绿洲农田土壤N2O的排放。

The effects of soil drying-wetting alternation on nitrous oxide（N2O）emission from oasis farmland were analyzed,which could provide the basis for optimizing irrigation and fertilization and reducing N2O emission of oasis farmland.A laboratory incubation experiment was performed to determine the effect of soil drying-wetting alternation on its N2O emission from oasis farmland in arid area.The 100 g dried soil was placed in a 730 m L mason jar,then the mason jar was placed in a 25℃incubator,and the nitrogen content and soil moisture content were strictly controlled through connecting a syringe with a three-way valve to extract gas from the mason jar.The result are as follows：（1）Soil drying-wetting alternation influenced significantly the cumulative N2O emission of oasis farmland soil.Without fertilization,the cumulative N2O emission of dryly-treated soil was 1.28 times of that of wetly-treated soil;（2）Compared with non-nitrogen treatment,fertilization promoted significantly the soil N2O emission,the highest N2O emission occurred after nitrogen was applied for 0-4 days,and then the soil N2O emission was reduced obviously;（3）The N2O emission rate of the wetted soil was significantly higher than that of the dried soil after nitrogen was applied.The cumulative N2O emission of wetted soil was 2.07 mg·kg^-1,and it was 1.16 times of that of dried soil.Therefore,the soil N2O emission from oasis farmland could be reduced by properly prolonging the time interval of drip irrigation and fertilization.