An empirical model and scenario analysis of nitrous oxide emissions from a fertilised and grazed grassland site in Ireland

This paper describes an empirical model of soil-evolved nitrous oxide emissions inferred from data gathered in a 2-year rotational grazing experiment investigating emissions from a fertilised and grazed grassland site. The model was used to simulate daily and annual emissions for the 9-year period between 1994 and 2002 under different possible fertiliser application scenarios. As the model only requires a small number of commonly available site-specific data inputs, this facilitates its use at different geographical locations. This is the first empirical modelling of daily fluxes to give estimates of annual emissions. Results reveal a high interannual variability of emissions that increases with the amount of nitrogen fertiliser applied. Simulation using the model for the period 1994–2002 indicated that higher soil moisture status on the day of fertiliser N application increased the average annual nitrous oxide emissions.