Nitrous oxide (NO2) is a major atmospheric greenhouse gas. The soil physical properties and fertility will directly affect the production and release of NO2. Alfalfa has the advantages to improve soil physical properties and fertility,and the soil physical and chemical properties variation degree is associated with fixed the number of alfalfa planting years. A static chamber-HPLC method was used to detect NO2 emission fluxes in the fallow field,3,4,and 10 years-aged lucerne (Medicago sativa) field at the Loess Plateau. In addition,the DeNitrification-DeCoposition (DNDC) model was also applied to estimate the NO2 emission variations in our study,which fit pretty well with the measured NO2 emission fluxes. Compared to the fallow field,observed values of the N2O emission increased with the ages of lucerne field. Interestingly,the detected negative NO2 emission values in our analysis were disparate with the model calculations. The time of released NO2 from differently aged lucerne field fluctuated and accumulated highly between 170-240 days during the growing season,the most release was estimated at 210 day in the DNDC model. Although the DNDC model could estimate the NO2 emission fluxes in lucerne field at the Loess Plateau,further parameter modifications are required to include the negative flux emissions in the analysis.
〔1〕 Solomon S.The Physical Science Basis:Contribution of Working group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change〔M〕.Cambridge:Cambridge University Press,2007.
〔2〕 Ravishankara A R, Daniel J S, Portmann R W. Nitrous oxide (N2O):The dominant ozone-depleting substance emitted in the 21st century〔J〕.Science,2009,326(5 949):123-125.
〔3〕 卢琦.荒漠化对全球气候变化的响应〔J〕.中国人口资源与环境,2002,12(1):95-98.〔Lu Qi.Response of desertification to global climatic change〔J〕.China Population Resources and Environment,2002,12(1):95-98.〕
〔4〕 陈宝书.牧草饲料作物栽培学〔M〕.北京:中国农业出版社,2005.〔Chen Baoshu.Forage Cultivation〔M〕.Beijing:China Agriculture Press,2005.〕
〔5〕 任继周,李向林,侯扶江.草地农业生态学研究进展与趋势〔J〕.应用生态学报,2002,13(8):1 017-1 021.〔Ren Jizhou,Li Xianglin,Hou Fujiang.Research progress and trend on grassland agroecology〔J〕.Chinese Journal of Applied Ecology,2002,13(8):1 017-1 021.〕
〔6〕 赵凤岐,董宽虎,刘文忠.山西苜蓿产业化发展模式与内涵的探讨〔J〕.草业学报,2007,16(3):120-127.〔Zhao Fengqi,Dong Kuanhu,Liu Wenzhong.Discussion on the connotation and development mode for industrialization of Medicago sativa production in Shanxi Province〔J〕.Acta Prataculturae Sinica,2007,16(3):120-127.〕
〔7〕 Rochette P,Janzen H H.Towards a revised coefficient for estimating N2O emissions from legumes〔J〕.Nutrient Cycling in Agroeco systems,2005,73(2/3):171-179.
〔8〕 Duxbury J M,Bouldin D R,Terry R E,et al.Emissions of nitrous oxide from soils〔J〕.Nature,1982,298:462-464.
〔9〕 Chapuis Lardy L,Wrage N,Metay A,et al.Soils,a sink for N2O? A review〔J〕.Global Change Biology,2007,13(1):1-17.
〔10〕 焦燕,黄耀.影响农田氧化亚氮排放过程的土壤因素〔J〕.气候与环境研究,2003,8(4):457-466.〔Jiao Yan,Huang Yao.Influence of soil properties on N2O emissions from farmland〔J〕.Climatic and Environmental Research,2003,8(4):457-466.〕
〔11〕 Beheydt D,Boeckx P,Sleutel S,et al.Validation of DNDC for 22 long-term N2O field emission measurements〔J〕.Atmospheric Environment,2007,41(29):6 196-6 211.
〔12〕 邹亚丽,韩方虎,耿丽英,等.温度和湿度对紫花苜蓿土壤氮矿化的影响〔J〕.草业学报,2010,19(4):101-107.〔Zou Yali,Han Fanghu,Geng Liying,et al.Effects of temperature and moisture on soil nitrogen mineralization of Lucerne stands〔J〕.Acta Prataculturae Sinica,2010,19(4):101-107.〕
〔13〕 杨玉海,蒋平安.不同种植年限苜蓿地土壤理化特性研究〔J〕.水土保持学报,2005,19(2):110-113.〔Yang Yuhai,Jiang Pingan.Studies on soil properties of lucerne with different cultivating ages〔J〕.Journal of Soil and Water Conservation,2005,19(2):110-113.〕
〔14〕 Abdalla M,Jones M,Yeluripati J,et al.Testing DayCent and DNDC model simulations of N2O fluxes and assessing the impacts of climate change on the gas flux and biomass production from a humid pasture〔J〕.Atmospheric Environment,2010,44(25):2 961-2 970.
〔15〕 Li C,Frolking S,Butterbach-Bahl K.Carbon sequestration in arable soils is likely to increase nitrous oxide emissions,offsetting reductions in climate radiative forcing〔J〕.Climatic Change,2005,72(3):321-338.
〔16〕 Cai Z,Sawamoto T,Li C,et al.Field validation of the DNDC model for greenhouse gas emissions in East Asian cropping systems〔J〕.Global Biogeochemical Cycles,2003,17(4):1-10.
〔17〕 Wang M,Wang Y.Using a modified DNDC model to estimate N2O fluxes from semi-arid grassland in China〔J〕.Soil Biology and Biochemistry,2003,35(4):615-620.
〔18〕 Li D,Lanigan G,Humphreys J.Measured and simulated nitrous oxide emissions from ryegrass-and ryegrass/white clover-based grasslands in a moist temperate climate〔J〕.PLoS ONE,2011,6:26 176.
〔19〕 王涛,周莹,王先之,等.黄土高原旱塬区陇东苜蓿草地 N2O 释放动态及微生物驱动因子的研究〔J〕.西北植物学报,2013,33(10):2 113-2 119.〔Wang Tao,Zhou Ying,Wang Xianzhi,et al.N2O emission dynamics and its microbial mechanism of a 3-year-old alfalfa grassland in the arid Loess Plateau〔J〕.Acta Botanica Boreali-Occidentalia Sinica,2013,33(10):2 113-2 119.〕
〔20〕 Corre M D,Van Kessel C,Pennock D J.Landscape and seasonal patterns of nitrous oxide emissions in a semiarid region〔J〕.Soil Science Society of America Journal,1996,60(6):1 806-1 815.
〔21〕 史瑞和,鲍士旦,秦怀英.土壤农化分析〔M〕.北京:中国农业出版社,1996.〔Shi Ruihe,Bao Shidan,Qin Huaiying.Soil and Agricultural Chemistry Analysis〔M〕.Beijing:China Agriculture Press,1996.〕
〔22〕 陈海心,孙本华,冯浩,等.应用DNDC模型模拟关中地区农田长期施肥条件下土壤碳含量及作物产量〔J〕.农业环境科学学报,2014,33(9):1 782-1 790.〔Chen Haixin,Sun Benhua,Feng Hao,et al.Apply DNDC model to simulate soil carbon content and crop yield under cropland long-term fertilization in Guanzhong area〔J〕.Journal of Agro-Environment Science,2014,33(9):1 782-1 790.〕
〔23〕 Kim D G,Giltrap D,Hernandez-Ramirez G.Background nitrous oxide emissions in agricultural and natural lands:A meta-analysis〔J〕.Plant and Soil,2013,373(1/2):17-30.
