Annual livestock numbers, the distribution of livestock housing systems and NH3 emission factors were used to calculate ammonia emissions (NH3) from cattle farming for the years 1990 to 2020. Emission factors for loose housing with outdoor exercise areas were computed using a model-based calculation based on emission measurements from six dairy housing systems, milk urea levels, temperatures and typical wind speeds. The NH3 emission factors modelled varied from 22 to 25 gper livestock unit (LU) per day (d). An NH3 emission factor of 16.4 g LU-1 d-1 for the tied housing system was derived from literature data. From 1990 to 2000 NH3 emissions were initially slightly down, whereas they had increased again by 2005. If livestock numbers stagnate at the 2008 level, NH3 emissions of 4 to 12 % higher than in 1990 are anticipated for 2020. This is because of the more widespread distribution of loose housing with larger soiled surfaces.
Ammonia from cattle housing systems: development of emissions in Switzerland