Investigating Methane Emissions From Cattle Facilities in Northeastern Colorado

Agriculture is the second‐largest anthropogenic source of methane (CH 4 ) in the United States, after oil and natural gas production. Regions like northeastern Colorado are home to animal feeding facilities and oil and natural gas production. The proximity of interfering CH 4 sources makes it challenging to quantify CH 4 emissions from cattle. Using aircraft measurements of CH 4 , ammonia (NH 3 ), and ethane (C 2 H 6 ) from the Transport and Transformation of Ammonia (TRANS 2 Am) campaign, we calculated CH 4 emissions from concentrated animal feeding operations (CAFOs) with a mass‐balance equation and a multivariate regression (MVR) approach. We calculated an average CH 4 emission rate from beef cattle facilities as 7.2 ± 2.7 g head −1 hr −1 . A unique aspect of the TRANS 2 Am campaign was the repeated sampling of individual CAFOs, which helped constrain uncertainties in the mass balance and MVR approaches and enabled the evaluation of CAFO emission variability. Additionally, this study examines CH 4 emission variability as a function of the number of cattle, cattle type, and time of day. Although both the number of cattle and cattle type are factors in CH 4 emissions, they do not fully account for the range of CH 4 emissions observed in this study. The results of this study suggest that facility management practices drive some of the observed variability, highlighting the need to measure emissions from individual facilities and link them to specific management practices to understand the variability in cattle emissions.