Advances in Empirical Models of Denitrification and Nitrous Oxide Production.

Denitrification is a major nitrogen loss pathway from agricultural soils with significant environmental and economic impacts. Nitrous oxide (N₂O) contributes to global warming and under certain soil conditions dinitrogen (N₂) emissions can be large enough to penalise productivity and profitability. Soil moisture, nitrate, temperature, pH and labile carbon all play significant roles in the estimation of N₂O and N₂ emissions. Models for N₂ emissions generally relied on partitioning coefficients based on total denitrification (N₂+N₂O). The accuracy of N₂ models is questionable due to the lack of reliable data and the methodological constraints in measuring N₂ directly from soil. In contrast, soil based emissions of N₂O are directly measurable and models for N₂O are relatively successful in estimating the total N₂O emissions for a specific season but generally fail when replicating temporal dynamics over the season. Improvements in simulations are now apparent with advances in laboratory and field methodologies for N₂ determination and the inclusion of gaseous diffusion from depth to accommodate lag phases in emissions.