• 关键词：土壤性质  厌氧培养  N₂O  红壤

• 基金项目：国家自然科学基金项目(No40471065);中科院知识创新工程项目(NoCXTD-Z2005-4);校青年基金(No20072001A)

• 续勇波
• 1. 中国科学院南京土壤研究所土壤与农业可持续发展国家重点实验室, 南京 210008; 2. 云南农业大学, 昆明 650201

• 蔡祖聪
• 中国科学院南京土壤研究所土壤与农业可持续发展国家重点实验室, 南京 210008

• 摘要：将采集于江西鹰潭的45个发育于不同成土母质和不同利用方式的土壤样本,在密闭、淹水、充N₂的严格厌氧条件下进行了28d的培养试验(30℃),在培育过程中,定期测定NO₃^--N(加入量为200mg·kg^-1)含量和培养瓶上部空间N₂O的含量变化.实验结果表明,N₂O含量(N)随培养时间t的变化可用方程N=A×(1-exp(-k₁t))-B×exp(k₂t)拟合(A表示培养过程中N₂O总排放量;B为常数;k₁和k₂分别为N₂O排放速率常数和还原速率常数,拟合值和实测值之间回归方程的决定系数R²=0.84±0.11).不同土壤之间培养期间N₂O总排放量(A)的变异可以用培养7d内被反硝化的NO₃^--N量和N₂O排放率(A值与28d内被反硝化的NO₃^--N总量的百分比)进行解释(R²=0.829,p<0.01).被反硝化的NO₃^--N量则主要受土壤有机碳含量或有机氮矿化量控制,N₂O排放率则随k₂的增大而呈指数下降(p<0.01).由此可见,在该实验条件下,还原N₂O能力强的土壤,在相同量的NO₃^--N被反硝化的情形下,排放的N₂O可能较少.但影响k₂值的主要因素还有待进一步研究.

• Abstract：The potential capacities of N₂O emission and reduction to N₂ during anaerobic incubation of forty-five subtropical soils in Jiangxi province were determined. Samples were collected from different land use and derived from different parent soil materials, then treated with 200 mg NO₃^--N kg^-1 soil at 30℃ for 28 days. The variations in headspace N₂Oconcentration and NO₃^--N, NH₄⁺-Ncontent in the soil slurry with incubation time were measured. The results indicated that the N₂Oconcentration(N)with incubation time (t) was the net result of N₂Oemission and N₂O reduction to N₂, which could be described with the equation: N =A×(1-exp (-k₁t))-B×exp(k₂t), where Ais the total N₂O emission during the incubation, Bis a constant, k₂ and k₂ are the N₂Oemission rate constant and reduction rate constant, respectively. The average of the determinant coefficients of 45 soil samples (R²) was 0.84 with a standard deviation of 0.11 (p<0.05 for all samples). The total N₂Oemission (A) during the 28-day incubation varied with the soils and its variation could be explained by the amount of NO₃^--N denitrified in the first 7 days of incubation and the N₂O emission ratio (defined as a percentage of A-value to the amount NO₃^--N denitrified during the 28-days incubation) (R²=0.829, p<0.01). Soil organic carbon content and/or organic nitrogen mineralization were the key factors determining the amount of reduced NO₃^--N. The N₂O emission ratio decreased with increasing k₂ value (p<0.01). Therefore, soils with higher N₂O reduction capacity under anaerobic conditions would emit less N₂O when the same amount of NO₃^--N was denitrified. However, the factors and their mechanisms for controlling k₂ are not clear and more work is needed.

• Key words：soil properties  anaerobic incubation  nitrous oxide  red soils

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