An improved UK-DNDC model for evaluations of soil temperature and nitrous oxide emissions from Canadian agriculture

Aims UK-DNDC model was modified to (1) enhance the estimates of soil temperature and N 2 O emissions in Denitrification Decomposition (DNDC) model by considering snow melt and frozen and unfrozen conditions along with the impacts of water flux density, thermal diffusivity, crop-canopy, snowmelt routine and snow-depth on N 2 O emission and (2) validate the modified DNDC model against measured data from five experimental cropping sites located in the west Canada. Methods Heat transfer processes and snowmelt routine of the DNDC have been modified to account for soil heat and water fluxes driven by snowmelt routine and their effects on denitrification and N 2 O emissions. The modified DNDC model was tested against the data from five sites, Canada. Then, the model was used to predict the spatial and temporal change of snowpack depth, soil temperature and N 2 O emissions. Results The validation results show that the modified model predicted daily soil mean temperature and daily N 2 O fluxes accurately in all seasons with very high average Pearson’s correlation coefficients at the three sites ( R avg = 0.91 and 0.85 for soil temperature and N 2 O emissions, respectively). Conclusions The modelled N 2 O emissions were sensitive to snowmelt and freeze-thaw cycle in the cold climate region while the modelled soil temperature was sensitive to water flux. This provides a tool for N 2 O estimate in Canada and should also be appropriate for utilize in the similar cold climate regions.