By adding NaOH or HCl,one neutral soil and one weakly alkaline soil was respect ively adjusted to a series of samples with different pH.After addition of NO₃^- the soil samples were anaerobically incubated with or without glucose for 24 h. After that N₂O production rate was measured.The results show that without glucose the optimum pH for the greatest N₂O production rate is about 5.25 for the neutral soil series,and 5.90 for the weakly alkaline soil series.With glucose,however,the optimum pH for N₂O production is different,at about 6.50 and 6.90 for the neutral soil series and the weakly alkaline soil series, respectively,demonstrating that the addition of easily available carbon source has raised the optimum pH for N₂O production. The experiment results also show that acidic condition could increase the ratio of N₂O to total reduced gas,as for the absolute value of N₂O production,however,the neutral condition is still more favorable.