Monitoring Gas Emissions in Open-circuit Chambers with a Measuring Device that can be used for Measuring of Emissions from Manure

To study animal emissions and possible shifts from rumen to manure, we built six open-circuit respiration chambers that are flexible and modular. In addition to methane, we also monitor carbon dioxide, nitrous oxide and ammonia in the chambers. For certain trials, measuring these gases in the manure could also be interesting; therefore, we constructed manure trays in the chambers. By fitting the manure trays with wheels, we facilitated quick and easy removal of manure, without opening the doors of the chambers. The collected manure could then be transferred to a barrel for simulating manure pits to study possible shifts in emissions. The equipment is configured to use the same devices for measurements in both the chambers and in manure barrels. The gas analyser is an infrared laser optical-feedback cavity-enhanced absorption spectrometer (OFCEAS). It is interference free and self-calibrating with no instrumental drift. The whole measuring system functions at continuous under-pressure of 110 mbar, created by a 50 µm sonic nozzle at each sampling point. The detection ranges for CH4, CO2, N2O and NH3 are set between 0-700 ppm, 0-5000 ppm, 0-5 ppm, and 0-70 ppm, respectively. The chambers are continuously monitored for temperature, air flow, water, system pressure and gas concentrations. When values are above or below the set thresholds, the operator is alerted by phone. This system for measuring gas emissions has no interference between the gases and has low maintenance costs.