Atmospheric ammonia from undisturbed land

Emissions of ammonia from the land areas of the world are calculated by using a simplified model. Soil ammonium concentrations are obtained from relative decomposition and nitrification rates; Henry's law gives the equilibrium concentration of ammonia gas in the soil, and a simplified diffusion equation yields the flux to the atmosphere. The model predicts negligible ammonia production in the polar regions, a maximum in mid-latitudes, and relatively low emissions in the tropics. Northern hemisphere production is calculated to be about 32.5×106 tons yr−1, and that from the southern hemisphere 14×106 tons yr−1, giving a global total of about 47×106 tons yr−1. Comparison with the limited rain data is fairly good.