Intensive agriculture typically uses nitrogen-based fertilizers to increase yields for sustaining a growing human population.  Agriculture is the main source of atmospheric emissions of ammonia (NH₃), a precursor to particulate matter in the atmosphere. The impact of NH₃ emissions on air quality is of concern in the U.S. due to adverse effects on human health, and terrestrial and aquatic ecosystems. With reductions in nitrogen oxide emissions due to legislation implementation, the importance to NH₃ for particulate matter formation and atmospheric deposition of reactive nitrogen has increased.  Emissions of NH₃ from fertilized cropland occur as soon as fertilizer is applied on the farmed surface and emission can last from a few days to several weeks, depending on the properties of the specific fertilizer, plant properties, pedoclimatic conditions, environmental conditions, and agricultural practices. The complex interactions between agronomic and environmental conditions make necessary the use of modeling to study the NH₃ volatilization.

In this study, we implemented in the SURFATM-NH₃ model, which simulates the bi-directional exchanges of NH₃ between the biogenic surface and the atmosphere, a new parameterization of the stomatal and ground layer emission potentials (Γ_s and Γ_g). This operational parameterization enables a dynamic modelling of Γ_s and Γ_g by taking into account the N status of the plant which includes the N input and the atmospheric N deposition.

This new parameterization was evaluated with a dataset comprising NH₃ fluxes measured using the flux-gradient (FG) and relaxed eddy accumulation (REA) methods in a corn canopy fertilized with UAN and urease inhibitor NBPT over a period of approximately 3 months at the Energy Farm at the University of Illinois at Urbana‐Champaign, IL, USA. The results showed that the SURFATM- NH₃ model satisfactorily simulates the NH₃ fluxes by implementing the parameterization of Γ_s and Γ_g and by taking into account the effect of the urease inhibitor. The latter need to be more closely examined because it had a considerable effect on the rate and extent of NH₃ volatilization.