Intermittent measurements to determine ammonia emissions from livestock buildings

The European Union (EU) has set ammonia emission restrictions for the different member states. To comply with the new regulations, the EU wants new techniques such as adapted feeding strategies and low emission building techniques to reduce ammonia emissions from livestock buildings. However, such ammonia restriction measures are only useful when their efficiency can be measured in the field. Current reliable measuring techniques are mainly based on continuous measurements over a long period (up to 200 days), and this requires expensive equipment. This makes them unsuitable for permanent evaluation on a large number of buildings. The main objective of the study presented here was the development of a procedure to determine NH3 emissions from livestock buildings in the field, based on a limited number of measuring days. This method allows several buildings to be evaluated 'simultaneously' with the same measuring installation. In this study, high frequent ammonia measurements were taken from real livestock buildings for a year and were used to calculate NH3 emission factors for pig houses. A procedure was developed based on the knowledge that NH3 emission is strongly related to other variables that can be more easily measured over a yearly period, such as temperature, ventilation rate, number of animals and animal weight. Another assumption was that farm management could have significant influence on NH3 emission, and consequently, this must be incorporated into the predictions. The prediction error between the measured and the calculated total NH3 emission was less than 3% when only 8 days were selected over a whole year, on condition that 4 days were selected within the same growth period and 4 other days are selected in at least two other growth periods. (C) 2004 Silsoe Research Institute. All rights reserved Published by Elsevier Ltd.