A review of gaseous ammonia emissions from slurry pits in pig production systems Review Article

Twenty-six experimental studies of ammonia emissions from pig buildings that utilise some form of pit/slurry system have been analysed and compared. Using standard values for pig weight and total Kjeldahl nitrogen (TKN) content in the waste when these quantities were unspecified, experimental ammonia emissions were compared on a per cent loss (of excreted TKN) basis. Correction factors were determined for measurements made during specific parts of the year, with corresponding differences in temperature, or time of day, and adjustments were made to put emission data on an annual average basis, when applicable. When corrected in this way, measurements made in the United States and in Europe were 22% and 21%, respectively. The standard deviation and standard error of the mean were 9% and 1.8%, respectively. The 95% confidence interval of the mean was 17.6–24.9%. The proposed emission factor data are reasonably consistent and emission factors higher or lower must be critically compared to the existing experimental base.