Nitrous oxide emission as affected by alternate anaerobic and aerobic conditions from soil suspensions enriched with ammonium sulfate

Abstract

The effect of several anaerobic and aerobic cycles of varying duration on N 2O emission and labelled N loss was investigated in ( 15NH 4) 2SO 4 amended soil suspensions. No N 2O was evolved from the continuously-anaerobic treatment. The continuously-aerobic treatment produced approximately 0.8 μg N 2O-N g −1 dry soil in 56 days. Alternate anaerobic-aerobic cycles increased the net N 2O evolution with 7.2 μg N 2O-N g −1 dry soil produced in 56 days from the 7-day anaerobic, 7-day aerobic treatment. The net N 2O evolution increased further when the duration of the anaerobic and aerobic periods was increased from 7-7 days to 14-14 days (15.7μg N 2O-N g −1 dry soil in 56 days), although the total 15N loss from the system was approximately the same for the two treatments. The results of this study show that N 2O evolution from soils is likely to be greater under fluctuating moisture conditions than under either continuously well-aerated conditions, or continuously excess-moisture conditions.