不同土地利用方式下土壤温度与土壤水分对黑土N2O排放的影响

采用静态箱一气象色谱法，对黑土区3种不同土地利用方式（草地、裸地和农田）下土壤氧化亚氮（N：O）的排放特征及其与土壤温度和土壤水分的关系进行研究。结果显示：试验监测期间（2011年5月27日-9月30日），不同土地利用方式下，土壤N：0累积排放量分别为草地52．08mgN·m^-2裸地64．43mgN·m^-2农田70．16mgN·m^-2，农田土壤N：O累积排放量比草地和裸地分别高出35％和9％，草地、裸地和农田的N2O平均排放通量分别为16．56、20．36、21．44μgN·m^-2·h^-1。草地和裸地中，土壤N2O排放通量与土壤温度和土壤水分（充水孔隙度，WFPS）相关性均不显著，但在农田中，土壤N20排放通量与土壤温度（5cm和10cm）和土壤水分（5cm）均呈显著正相关（P〈0．05）。另外，土壤N2O累积排放量与土壤硝态氮和矿质氮含量均呈正相关关系。研究表明，黑土草地开垦可促进土壤N2O的排放，且不同土地利用方式下土壤N2O排放的主要影响因子不同。

Impact of Soil Temperature and Moisture on Soil N2O Emission from Mollisols Under Different Land-use Types

Using static closed chamber and gas chromatography techniques, we examined the patterns of soil nitrous oxide（N2O） emission from Mollisols in Northeast China as affected by changes of land use（grassland, bare land, and cropland）, and related soil N2O fluxes to soil temperature and moisture. The results showed that, during the monitoring period（from May 27 to September 30, 2011 ）, the cumulative N2O emission was higher in cropland（ 70.16 mg N· m^-2） than those in grassland（52.08 mg N· m-2） and bare land（ 64.43 mg N· m-2） by 35% and 9%, respectively. The mean N20 emission fluxes in grassland, bare land, and cropland were 16.56 μgN·m^-2·h^-1, 20.36 μgN·m^-2·h^-1v, and 21.44μgN·m^-2·h^-1, respectively. In grassland and bare land, there were no significant correlations between soil N2O flux and soil tempera- ture and soil moisture （water-filled pore space ）, whereas in cropland, soil N2O flux was significantly correlated with soil temperature （5 cm, 10 cm） and soil moisture（5 cm）（all P〈0.05 ）. In addition, soil cumulative N2O emissions were positively correlated with soil nitrate nitrogen and inorganic nitrogen content. Our results suggest that conversion of grassland to cropland in Mollisols can promote soil N2O emission, and the main driving factors for soil N2O emission vary under different land uses.