Increase in nitrous oxide production in soil induced by ammonium and organic carbon

Abstract

We observed that soil cores collected in the field containing relatively high NH inf4 sup+ and C substrate levels produced relatively large quantities of N2O. A series of laboratory experiments confirmed that the addition of NH inf4 sup+ and glucose to soil increase N2O production under aerobic conditions. Denitrifying enzyme activity was also increased by the addition of NH inf4 sup+ and glucose. Furthermore, NH inf4 sup+ and glocose additions increased the production of N2O in the presence of C2H2. Therefore, we concluded that denitrification was the most likely source of N2O production. Denitrification was not, however, directly affected by NH inf4 sup+ in anaerobic soil slurries, although the use of C substrate increased. In the presence of a high substrate C concentration, N2O production by denitrifiers may be affected by NO inf3 sup- supplied from NH inf4 sup+ through nitrification. Alternatively, N2O may be produced during mixotrophic and heterotrophic growth of nitrifiers. The results indicated that the NH inf4 sup+ concentration, in addition to NO inf3 sup- , C substrate, and O2 concentrations, is important for predicting N2O production and denitrification under field conditions.