Measurement of Denitrification Products in Soil by the Acetylene Inhibition Method

Abstract

The acetylene (C2H2) inhibition method was applied in combination with the nitrous oxide (N2O) measuring system reported previously to measure the amount of denitrified nitrogen (N2). Acetylene of a rate of 30 ml/day must be supplied from the bottom of pot just before gas sampling to complete the acetylene inhibition in wet soil (90% of water holding capacity) packed in 1.5 liter pots. Acetylene gas contained in the sample gas was removed with a Hg(ClO4)2 scrubber before N2O determination because C2H2 masked the NO peak recorded on the gas chromatogram. Pot experiment was carried out by using this method. Tanasi soil (volcanic ash) treated with NH4 + or NO3 − (305 μg N/g soil) was incubated at 90% of the water holding capacity in the presence and absence of C2H2. Glucose was added to the soil at the rate of 0.1% of oven dry soil. Water treatments consisted of Dry (gradual drying)- and Wet (no changes in water content)-treatments, and the periods of sampling were 61 and 22 days, respectively. In the NH4 + ...