The use of various residual organic products as fertilizer results in ammonia volatilization. This loss of available nitrogen lessens the fertilizing value of the organic product, and leads to environmental impacts. Various models can help predict the potential magnitude of emissions of a given product and thus can help in any measures taken to lessen NH3 emissions. But currently there is a lack of process based models accounting for a large range of products, regardless of origin and treatment. Volt’Air, a process-based model, has recently been improved for slurry application. A more realistic representation of the slurry was obtained by adding a specifically parameterized slurry layer above the soil profile. The present study aims at evaluating the capability of this representation to adapt to organic products characterized by high dry matter contents, and thus susceptible to form a fiber matrix at the soil surface, with properties differing from those of the soil. We first evaluated the model regarding the ammonia volatilization fluxes. We used existing wind tunnel data sets experimentally collated as part of the Qualiagro project at INRA from 1998 to 2006. The products are dairy farm yard manure and three contrasting types of compost obtained from municipal and domestic wastes. Then, this same dataset was used for a sensitivity analysis of both the evaporation and the ammonia volatilization fluxes. It was performed on the parameters of the organic products that have to be specifically characterized: (i) analytical properties (ammoniacal N content, pH and adsorption) and (ii) physical properties (optical, thermal and hydraulic properties). Sensitivity analysis was also performed on parameters pertaining to the technical choices made for the application: application rate with a potential subsequent uneven application and incorporation characterized by its depth, its efficiency and the delay after application.