An ammonia budget for Australia

The paper reviews research into sources and sinks of ammonia (NH3) in the Australian landscape and presents an NH3 budget for the continent. Emissions from uncultivated land areas were reckoned to be the most important source, followed by excreta from domestic animals, emissions from fertilized fields, and biomass burning. Coal burning and excreta from wild animals (kangaroos) were of minor importance. The total emission of NH3 was estimated to be 1.9 Tg N y-1, 1.6% of the global total. In a comparable budget for the globe, biomass burning was listed as the biggest source, but this and emissions from uncultivated land areas are the biggest unknowns in both budgets. Ammonia concentrations and deposition rates in Australia are presently too small to constitute serious pollution problems as they do in parts of Europe, but the depositions may be large enough to play an important role in the nitrogen (N) economy of native plant and microbial ecosystems.