Great Basin Naturalist


Acetylene gas is very useful in laboratory and in situ assay procedures for nitrogen fixation and denitrification. There is concern, however, that measurements of denitrification may be underestimated because nitrification, a major source of nitrate, is inhibited by C2H2. The objective of this study was to examine the effects of C2H2 partial pressure and length of exposure time on nitrification in soils. Acetylene partial pressures of 0.1, 1.0, and 10.0 kPa were found to effectively inhibit nitrification in soil samples incubated in the laboratory. Both the partial pressure of C2H2 and the length of exposure time were found to affect the recovery time of nitrification in soil samples. Nitrification recovered within seven days in samples exposed to 0.1 and 1.0 kPa C2H2 for only 24 hours. The recovery of nitrification in samples exposed to 10.0 kPa C2H2 for 24 hours or to 0.1 and 1.0 kPa C2H2 for 216 hours was delayed for an additional seven days, however.