Abstract:The emission pattern of greenhouse gas (GHG) has been intensively investigated in different agro-ecosystems, but the underlying microbial mechanism in soil is still poorly understood, especially under many possible measures for improving nitrogen utilization. Thus, a 28-day laboratory microcosm experiment was conducted with an upland soil to investigate the effect of urea and two nitrification inhibitors on nitrogen turnover process and global warming potentials (GWP) of N2O, CO2 and CH4, in which four treatments were established: CK (no fertilizer and inhibitor were applied), Urea (N 100 μg/g was applied to soil), Urea+15% Dicyandiamide (DCD, 15% of Urea-N in quantity), Urea+5% Allylthiourea (ATU, 5% of Urea-N in quantity). Meanwhile, the dynamics of different microbial abundances in treatments were also quantified by real-time quantitative PCR (qPCR). The results showed that ammonia-oxidizing bacteria (AOB) predominated intensive nitrification process and N2O emission in soil with urea application. Urea stimulated AOB growth and increased cumulative N2O by 235%, which rapidly occurred during the first 14 days. Bactria abundance raised in response to urea and improved CO2 emission by 18.5%. Urea+DCD severely inhibited AOB and decreased N2O emission by 59.4%, but stimulated bacteria and increased CO2 by 50.6%. Urea+ATU exhibited a strong toxicity on both bacteria and fungi and led to a decrease of CO2 by 28.4%, but unexpectedly didn't show any inhibition on nitrification intensity. A slight but significant inhibition and stimulation were observed on AOB and denitrifiers by ATU, respectively, but total emission of N2O fell by 35.2%. CH4 emission was inhibited in all treatments with urea and inhibitors. GWPs of N2O, CO2 and CH4 displayed significant differences among treatments: Urea+DCD>Urea>CK>Urea+ATU. The contributions of N2O and CO2 to GWP exceeded 98.4% in soil. This study implies various mechanisms of nitrification inhibitors on soil microbial guilds and GHG emission, and is essential for the implementation of agricultural management and the evaluation of global climate change.