Denitrification rate relationships with soil parameters in the field

Abstract

It has been recently shown that there is a large spatial variability in denltrification rates measured in the field. The objective of this study was to assign this variability to twelve measurable or determined soil parameters known or suspected to be Important to denitrification during the early part of the growing season. Relationships were sought with 16 cores at a grid spacing of 25 cm on three sites (dates) within a 0.07 ha area of a cultivated silt loam soil. The denitrification rate was estimated from the N₂O production rate with the acetylene blockage technique. Only few statistical significant relationships were found with simple and multiple regression analyses and there was a lack of consistency from site to site. Plotting the data revealed a tentative negative relationship between the N₂O production rate and percent air‐filled porosity. A few cores at each site showed a much greater N₂O production rate for no discernable reason, but these rates were also negatively related to percent air‐filled porosity. Tentative positive relationships between N₂O production rate and total organic carbon or water‐soluble carbon were similarly found.