Denitrification is a well recognized nitrogen (N) loss pathway in agricultural soils that contributes to poor utilization of N. We used the acetylene blockage method on undistrurbed soil cores to examine the relationships between denitrification rates, land management practices and soil processes in typical dairy crop rotations using liquid dairy manure (LDM) as the principal N source over a six year period. In a separate one-season experiment we also modified the method to include an aerobic pre-incubation for 2.5 h as a means of estimating nitrous oxide (N₂O) emisssions as a component of total denitrification. Mean daily denitrification rates (DDR’s) of a corn-soybean-wheat (CSW) rotation with (T) or without (NT) tillage and a perennial hayfield (PH) rotation ranged between 0.9 and 27.0 g N ha^-1 d^-1. Mean DDR’s of CSW were significantly higher in three out of six seasons when compared with PH. Across the entire study period, mean DDR's of CSW-T and NT (7.6 and 8.1 g N ha^-1 d^-1, respectively) were also significantly higher than PH (4.4 g N ha^-1 d^-1). CSW-T was significantly higher than CSW-NT in one of six years (10.1 and 4.5 g N ha^-1 d^-1, respectively). A positive relationship between water-filled pore space (WFPS) and DDR indicated a threshold of approximately 40 % WFPS for onset of significant denitrification. The relationship between soil nitrate levels and denitrification rates in the population data set demonstrated a limiting effect on DDR at levels below 2-5 mg N kg^-1. Environmental variables were more consistent drivers of denitrification in these rotations than were land management practices. In the one year experiment, there did not appear to be a consistent relationship between nitrous oxide emissions and total denitrification across sampling events during the growing season.