This article compares three ammonia (NH₃) deposition models in a dune ecosystem and investigates the uncertainty of these models. The Zhang model aligned best with the measurements, whereas the DEPAC (DEPosition of Acidifying Compounds) and Massad models overestimated and underestimated the NH₃ deposition respectively. The study found that NH₃ exchange with wet plant leaves was an important but uncertain process. It offers recommendations to improve future models and suggests measurements to lower the existing uncertainty.