Nitrous oxide emissions from drained peat soil beneath pasture

Nitrous oxide (N2O) emissions (E-N2O) from drained peat soils used for pastoral agriculture have not been measured throughout the year in New Zealand. In response to this research gap, E-N2O was measured fortnightly for 1 year in the Waikato region in a plot that was not grazed or nitrogen (N) fertilised. The time series was variable, the frequency distribution skewed and the fortnightly means correlated. To account for these factors, the data were log(e) transformed and an order 2 autoregressive model used to estimate a mean E-N2O of 4.3gNha(-1)d(-1) and 95% confidence limits of 0.6-29.1gNha(-1)d(-1). There was a statistically significant, inverse relationship between E-N2O and the depth to groundwater. In winter, when rainfall totalled 393mm, E-N2O and soil N content were significantly greater under a rain shelter designed to minimise N loss by leaching, than in an uncovered plot.