Greenhouse Gas Emissions from Ground Level Area Sources in Dairy and Cattle Feedyard Operations

A protocol that consisted of an isolation flux chamber and a portable gas chromatograph was used to directly quantify greenhouse gas (GHG) emissions at a dairy and a feedyard operation in the Texas Panhandle. Field sampling campaigns were performed 5 consecutive days only during daylight hours from 9:00 am to 7:00 pm each day. The objective of this research was to quantify and compare GHG emission rates (ERs) from ground level area sources (GLAS) at dairy and cattle feedyard operations during the summer. A total of 74 air samples using flux chamber were collected from the barn (manure lane and bedding area), loafing pen, open lot, settling basin, lagoons, and compost pile within the dairy operation. For the cattle feedyard, a total of 87 air samples were collected from four corner pens of a large feedlot, runoff holding pond, and compost pile. Three primary GHGs (methane, carbon dioxide, and nitrous oxide) were measured and quantified from both operations. The aggregate estimated ERs for CH₄, CO₂, and N₂O were 836, 5573, 3.4 g hd⁻¹ d⁻¹ (collectively 27.5 kg carbon dioxide equivalent (CO₂e) hd⁻¹ d⁻¹), respectively, at the dairy operation. The aggregate ERs for CH₄, CO₂, and N₂O were 3.8, 1399, 0.68 g hd⁻¹ d⁻¹ (1.7 kg CO₂e hd⁻¹ d⁻¹), respectively, from the feedyard. The estimated USEPA GHG ERs were about 13.2 and 1.16 kg CO₂e hd⁻¹ d⁻¹, respectively, for dairy and feedyard operations. Aggregate CH₄, CO₂ and N₂O ERs at the dairy facility were about 219, 4 and 5 times higher, respectively, than those at the feedyard. At the dairy, average CH₄ ERs estimated from the settling basin, primary and secondary lagoons were significantly higher than those from the other GLAS, contributing about 98% of the aggregate CH₄ emission. The runoff holding pond and pen surface of the feedyard contributed about 99% of the aggregate CH₄ emission. Average CO₂ and N₂O ERs estimated from the pen surface area were significantly higher than those estimated from the compost pile and runoff pond. The pen surface alone contributed about 93% and 84% of the aggregate CO₂ and N₂O emission, respectively. Abatement and management practices that address GHG emissions from these sources will likely be most effective for reducing facility emissions.