Determination of potential N2O-reductase activity in soil

There were significant differences between soils in potential N2O-reductase activity, but the optimal experimental conditions were similar. The acetylene inhibition technique underestimated N2O-reductase activity in soil relative to the direct-N2 method, especially in the treatment where fertilizer N was withheld for 15 yrs. We recommend that the optimal experimental conditions for the determination of the potential N2O-reductase activity are established also for other soils. More studies are needed to fully understand the interactive effects of long-term N fertilization on nosZ gene expression and N2O-reductase activity in soils.