The deposition of reactive nitrogen to terrestrial ecosystems is a major threat to ecosystem integrity and biodiversity in Europe and other regions in the world. Yet, considerable uncertainties in the deposition estimates and underlying processes exist. These uncertainties also affect nature protection policies as well as emission regulation and mitigation strategies. This session welcomes studies investigating atmospheric deposition of reactive nitrogen species such as ammonia and oxidized nitrogen to terrestrial ecosystems. The session will greatly benefit from discussing different experimental approaches, using e.g. micrometeorological methods or deposition samplers, as well as process based and large-scale deposition modelling and the combinations thereof. Next to fundamental research on deposition processes and methods, studies creating the link to impacts and policy implications are especially encouraged, strengthening the connection between science output and societal application.