SOIL MICROSITES AS A SOURCE OF DENITRIFICATION VARIABILITY

The spatial variability exhibited by soil denitrification rates is high. As is typical for natural denitrification rate measurements, the individual rates of most samples of a given data set are low; however, a few samples often exhibit extremely high rates. Such data are characterized by highly skewed sample frequency distributions. This study was initiated to investigate the underlying mechanisms responsible for these observations. It was found that 'hot-spots' of high specific denitrification activity were associated with particulate organic C material in the soil. This observation served as the basis of a computer model that evaluates the influence of density and dispersion pattern of these high activity sites on the measured rates of denitrification.