Performance of a real-time and wireless electrochemical gas sensor for monitoring ammonia concentration in a naturally ventilated dairy barn

Abstract

One of the most widely used techniques for monitoring ammonia (NH₃) concentrations on livestock farms has been the photoacoustic gas analyser (PGA), which requires cabling, multiple repeated measurements at the same sampling point and lacks real-time remote capabilities. Electrochemical gas sensors (EGS) offer a promising alternative, allowing higher sampling frequencies, wireless operation and real-time data transmission. While EGS performance has been validated in laboratory settings, field testing remains limited. The objectives of this study were to determine the number of repeated PGA measurements required to achieve steady-state NH₃ concentrations and to compare them to EGS measurements in a naturally ventilated dairy barn. Ammonia concentrations were monitored at five sampling points on a commercial dairy farm using both technologies over 18 days. The results showed non-normal NH₃ concentration data distributions and similar patterns between them, ranging from 0.5 to 9.6 ppm for PGA and 0.6 to 13 ppm for EGS. A stabilisation of NH₃ measurements was observed between the 4th, 5th and 6th repeated measurements of PGA (p > 0.75). A strong agreement between PGA and EGS values was also observed (PC > 0.7 and RMSE < 0.9). This study demonstrates the feasibility of using EGS for real-time, wireless NH₃ monitoring in dairy barns, eliminating PGA operational requirements. In addition, EGS allows data to be collected at 1-min intervals, a significant improvement on the 1-h intervals typical of PGA systems. This resolution allows the detection of rapid NH₃ fluctuations, providing a practical solution for real-time NH₃ measurement in precision livestock farming applications.