Influence of oxygen on denitrification and aerobic respiration in soil

Abstract

The influence of the partial pressure of oxygen on denitrification and aerobic respiration was investigated at defined P02 values in a mull rendzina soil. The highest denitrification and respiration rates obtained in remoistened, glucose- and nitrate-amended soil were 43 μ1 N20 h−1g−1 soil and 130 μ1 O2 h−1g−1 soil, respectively. At -55 kPa matric water potential, corresponding to 40% water saturation, N20 was produced only below P02 40 hPa. The Km, for O2 was 3.0 x 10−6 M. Formation of N2O and consumption of O2 occurred simultaneously with half maximum rates at P02 6.7–13.3 hPa. Nitrite accumulated in soil below 40 hPa and increased with decreasing pO2. The upper threshold for N20 formation in amended soil was P02 33–40 hPa (39-47 μM O2).