Ammonia (NH3) nitrogen (N) losses from surface-applied manure can be large, reducing the amount of N available to the crop and, therefore, the economic value as a fertilizer N credit. Ammonia emission into the atmosphere can also contribute to environmental problems. Ammonia emission can contribute to eutrophication of surface waters (especially marine and estuarine) via atmospheric deposition. The decreased amount of available N in manure reduces the N:P ratio and leads to a more rapid build-up of P in the soil for a given amount available N. And ammonia in the atmosphere can combine with fine particulates to lower air quality.
Soil Science Extension
University of Wisconsin Madison