黄土高原地区两种土地利用方式CO2和N2O排放特征

Characteristics of CO2 and N2O Emissions Under Two Land Use Types in the Loess Plateau of China

为探究黄土高原地区两种不同土地利用方式下二氧化碳(CO2)和氧化亚氮(N2O)的排放特征,在长武黄土高原农业生态试验站,分别以15 a树龄的果园和麦田为研究对象,采用静态暗箱-气相色谱法对土壤CO2和N2O的排放进行了周年(2017年7月~2018年7月)田间原位观测.试验共设置果园施肥(AF)、果园对照(ACK)、小麦施肥(WF)和小麦对照(WCK)这4个处理.结果表明,土壤CO2和N2O排放随季节变化明显,降雨和施肥后均出现明显排放峰.AF处理的CO2和N2O累积排放量比WF处理高7.14%和461.4%.但ACK的CO2累积排放量比WCK低10.41%,而N2O的累计排放量比WCK高109.5%.果园N2O的排放通量与表层土壤温度、水分显著正相关(P<0.01),果园和麦田的CO2排放通量均与表层土壤温度显著正相关(P<0.05),而与表层土壤水分相关性不显著.因此,田间管理和环境因素综合影响土壤CO2和N2O排放,施肥量和土壤水热是造成两种土地利用方式CO2和N2O的排放特征和温室效应差异的主要因素.

To evaluate the emission characteristics of carbon dioxide(CO2)and nitrous oxide(N2 O)in the Loess Plateau,a field in situ study was conducted from July 2017 to July 2018 under two land-use types(15 year old apple orchard and wheat field)using static chamber-gas chromatographic techniques.Four treatments were conducted in this experiment as follows:apple orchard with fertilization(AF),apple orchard without fertilization(ACK),wheat field with fertilization(WF),and wheat field without fertilization(WCK).The results showed that CO2 and N2 O emissions varied significantly with the season,and the emission peaks appeared after rainfall and fertilization.The cumulative amount of CO2 and N2O emissions from the AF treatment were 7.14%and 461.4%higher than that of the WF treatment,respectively.However,the cumulative amount of CO2 emissions under the ACK treatment was 10.41%lower than that of the WCK treatment,whereas the cumulative amount of N2O emissions was 109.5%higher than that of the WCK treatment.The N2O emission flux from the orchard was significantly positively correlated with soil temperature and moisture(P<0.01).The CO2 emission fluxes from the orchard and wheat field were significantly positively correlated with topsoil temperature(P<0.05)but were not correlated with topsoil moisture.Thus,the combination of field management and environmental factors affected soil CO2 and N2 O emissions.The fertilizer regime and soil hydrothermal conditions were the main factors influencing the characteristics of CO2 and N2O emissions under different land-use types.