Production of dinitrogen and nitrous oxide in soil suspensions as affected by redox potential

Abstract

The effect of soil redox potential on N2O and N2 emission from soil suspensions was studied under laboratory conditions. Crowley silt loam soil suspensions were equilibrated under controlled (−200, −100, 0, +100, +200, +300, and +400 mV) redox levels, and the amounts of N2 and N2O evolved quantified. At higher redox levels (+300, and +400 mV) nitrification was the dominant soil biological process controlling N chemistry. A small amount of N2O evolved during nitrification. A redox value between +300 and +200 mV was found critical for denitrification to occur. Both N2 and N2O were produced during denitrification. The maximum amount of N2O evolved at a redox value of 0 mV. Dinitrogen emission increased at lower redox levels. The highest N2/N2O evolution ratio was observed at −200 mV and the ratio decreased with increasing redox. A lack of N-balance during denitrification at redox levels of +100, and +200 mV is also reported.