Assessment of denitrification in organogenic forest soil by regulating factors

One of the dominating sources of the increase in atmospheric N2O are elevated emissions from terrestrial ecosystems. The N2O production in soil is probably dominated by two microbial processes, i.e. nitrification and denitrification, and their N2O production is regulated by an array of soil and environmental factors. This contributes to the large both spatial and temporal variability of emission rates measured in the field. To obtain reasonable estimates of large-scale emission rates this variability has to be dealt with, and one possible way could be to relate measured emission rates to relevant soil and/or environmental factors. In this study the relationship between soil factors (temperature, soil organic matter, soil moisture, pH, and NH4+, NO3- and NO2- contents) and the denitrification activity in organogenic forest soil was investigated. About 40% or less of the variation of the denitrification rates could be accounted for by soil factors, either by multiple regression or by partial least squares analysis of latent variables (PLS analysis). Interpretation of the relationships obtained was, however, difficult since many of them were unexpected, and some of the soil factors were internally related. In conclusion, the possibility to obtain significant and useful relationships between momentary denitrification rates and soil factors for spatial and temporal extrapolations was limited in this system.