N₂ production via aerobic pathways may play a significant role in nitrogen cycling in upland soils

Abstract

The importance of di-nitrogen (N₂) production via aerobic pathways has been verified in a significant number of pure microbial strains. However, to date there are no reports confirming this in situ. In this study, we extracted micro-biota from three typical upland soils with variable properties and incubated them under aerobic and anaerobic conditions, with nitrate, to investigate whether N₂ production occurred via aerobic pathways and the relative importance of it when compared with the N₂ production via anaerobic pathways. Our results showed that N₂ can be produced in soil extracts under aerobic conditions, and that the N₂ produced via aerobic pathways equated to 29–51% of that produced via anaerobic pathways. Thus N₂ production via aerobic pathways may play a significant role in soil nitrogen (N) cycling. Our results demonstrate that an O₂ deficit may not to be a requirement for converting reactive N back into inert N₂, and consequently this process may be more widespread in upland soils than currently thought.