Location: Livestock Nutrient Management ResearchTitle: Temporal and spatial variability of methane emissions from Texas open-lot beef cattle feedyard pens
|CASEY, KENNETH - Texas A&M Agrilife|
|Min, Byeng Ryel|
|Willis, William - Will|
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/11/2021
Publication Date: 2/14/2022
Citation: Parker, D.B., Casey, K.D., Waldrip, H., Min, B., Woodbury, B.L., Spiehs, M.J., Campbell, T.N., Meyer, B.E., Willis, W.M. 2022. Temporal and spatial variability of methane emissions from Texas open-lot beef cattle feedyard pens. Transactions of the ASABE. 64(6):1781-1794. https://doi.org/10.13031/trans.14672.
Interpretive Summary: Methane is a greenhouse gas that has been linked to climate change. High carbon concentrations make livestock manure at beef cattle feedyards a potential source of methane emissions. There have been few studies to quantify methane emissions from feedyard pens in semiarid environments. Scientists from USDA-ARS (Bushland, Texas and Clay Center, Nebraska) and Texas A&M AgriLife Research (Amarillo, Texas) quantified methane emissions from pens at a commercial beef cattle feedyard in the Texas Panhandle. Emissions varied greatly over space and time. The quantity of methane emitted from the pen surface was less than one percent of the methane emitted from the entire feedyard, as the majority of methane emissions were emitted directly from the mouth of the animals. Thus, future research to mitigate feedyard methane emissions should focus on methane emissions from the animal. This pen surface emissions data will be used to refine models and update greenhouse gas emission inventories for beef cattle feedyards.
Technical Abstract: Texas is one of the top livestock-producing states, where more than 5 million beef cattle are finished in large feedyards on earthen-surfaced pens. Manure deposited on open-lot pen surfaces can contribute to emissions of greenhouse gases (GHG) such as methane (CH4). Two week-long sampling campaigns were conducted in April (cool season) and August (warm season) to quantify CH4 emissions from the feedyard pen surface. Emissions were monitored before and after 12.7 mm simulated rainfall events. Temporal and spatial variability in emissions were quantified using automated and portable recirculating flux chambers, a multiplexer system, and a real-time CH4 analyzer. During the cool season, CH4 flux was 1.09 and 0.12 g animal-1 d-1 before and after rainfall, respectively. During the warm season, CH4 flux was 0.65 and 0.26 g animal-1 d-1 before and after rainfall, respectively. This suggested that CH4 was produced in the lower, anaerobic layer of the manure pack and CH4 emissions were inhibited following rainfall, most likely due to the microbial oxidation of CH4 in the upper layers through methanotrophy or from slowing of diffusion from the blocking of pore space. The overall mean pen surface CH4 flux was 0.53 g animal-1 d-1. This flux accounted for a very small percentage (<1 percent) of overall estimated feedyard GHG emissions expressed as CO2eq. Thus, efforts to mitigate GHG from open-lot beef cattle feedyards in the Texas panhandle should focus on those sources with higher percentage of overall GHG such as enteric methane, pen surface nitrous oxide, and nitrous oxide from fertilized cropland.