Gas concentration monitoring techniques by using an infrared photo-acoustic multi-gas analyser and low-cost devices in an open dairy barn.

Intensive livestock housing systems can play a relevant role in the reduction of ammonia (NH3) and greenhouse gases (GHG) emissions. Gas concentrations monitoring represents the first step to increase knowledge on the release of gases in the atmosphere and their reduction. In the literature few research studies have investigated the measurement techniques and sampling strategies in Mediterranean context where dairy barns are characterized by wide opening. The objectives of the investigation involve the study of the parameters’ setting, number of repetitions for each measurement, position of the sampling points as well as assessing the use of low-cost instrument for gas concentration monitoring. Concentrations of NH3, methane (CH4) and carbon dioxide (CO2) were acquired in an open barn during warm periods by the use of an infrared photoacoustic spectroscope and low-cost portable instruments based on electrochemical and infrared sensors. Statistical analyses were applied to assess data variability. Specific information was provided on how to collect data and obtain reliable measurements by focusing on the acquisition and monitoring of gas concentrations in the barn environment by the use of the two different kinds of devices. The monitoring optimization was found to be affected by the measurement techniques, the sampling strategy (i.e., sampling frequency, number and position of sampling locations, and set-up of the instrument) and monitoring purposes (i.e., measurement of gas, emission estimation, assessment of mitigation strategies).