Nitrous Oxide Production And Consumption Potential In An Agricultural And A Forest Soil

Both a laboratory incubation experiment using soils from an agricultural field and a forest and field measurements at the same locations were conducted to determine nitrous oxide (N2O) production and consumption (reduction) potentials using the acetylene (C2H2) inhibition technique. Results from the laboratory experiment show that the agricultural soil had a stronger N2O reduction potential than the forest soil, as indicated by the N2O/N-2 ratio in denitrification products. Without C2H2 inhibition, N2O could reach a maximum concentration of 51 and 296ppmv in headspace of the agricultural and forest soil slurries, respectively. Addition of glucose decreased the maximum N2O concentration to 22ppmv in headspace of the agricultural soil slurries, but increased to 520ppmv in the forest soil slurries. Addition of exogenous N2O did not change such N2O accumulation maxima during the incubations. The field measurements show that average N2O emission rates were 0.56 and 0.59 kg N ha(-1) in the agricultural field and forest, respectively. When C2H2 was provided in the field measurements, N2O emission rates from the agricultural field and forest increased by 38 and 51%, respectively. Nitrous oxide consumption under elevated N2O condition (about 300ppmv) was found in all five agricultural field measurements, but only in three of the six forest measurements under the same conditions. Field measurements agreed with the laboratory experiment that N2O reduction activity, which plays a critical role in abating N2O emissions from soils, largely depended on soil characteristics associated with land use.