Location: Livestock Nutrient Management ResearchTitle: Nitrous oxide emissions from an open-lot beef cattle feedyard in Texas
|CASEY, KENNETH - TEXAS A&M AGRILIFE|
|Willis, William - Will|
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2019
Publication Date: 10/22/2019
Citation: Parker, D.B., Casey, K.D., Waldrip, H.M., Min, B.R., Woodbury, B.L., Spiehs, M.J., Willis, W. 2019. Nitrous oxide emissions from an open-lot beef cattle feedyard in Texas. Transactions of the ASABE. 62(5):1173-1183. https://doi.org/10.13031/trans.13396.
Interpretive Summary: Nitrous oxide is a greenhouse gas that has been linked to climate change. High concentrations of nitrogen and carbon make livestock manure at beef cattle feedyards a source of nitrous oxide emissions. There have been few studies to quantify feedyard nitrous oxide emissions in the semiarid West Texas environment. Scientists from USDA-ARS (Bushland, Texas and Clay Center, Nebraska) and Texas A & M AgriLife Research (Amarillo, Texas) studied how the weather affects nitrous oxide emissions from a commercial beef cattle feedyard. Nitrous oxide emissions were six times higher during the warm season than the cool season. Following rainfall, nitrous oxide emissions increased by 2 to 5 times. Methods to decrease nitrous oxide emissions from West Texas feedyards should focus on post-rainfall events in the summer. These data will be used to update greenhouse gas emissions inventories for beef cattle feedyards.
Technical Abstract: Nitrous oxide (N2O) is a greenhouse gas (GHG) with a global warming potential much greater than carbon dioxide (CO2). Nitrous oxide is emitted from the manure-covered pen surface of open-lot beef cattle feedyards, and there are more than six million beef cattle fed in the Southern Great Plains region. A field research project was conducted to determine the temporal and spatial variability in N2O emissions from the pen surfaces of a commercial feedyard after simulated rainfall. Two week-long monitoring cycles were conducted in April and August, 2018 in the Texas Panhandle. Temporal variability was assessed using six continuous automated flux chambers per pen, and spatial variability was assessed using a portable chamber at up to 61 locations in a single pen. Diurnal fluxes varied 5- to 10-fold over a 24 h period. Flux varied seasonally, with an arithmetic mean of 0.56 mg N2O (as N) per square meter per hour in April and 3.21 mg N2O (as N) per square meter per hour in August. Fluxes measured spatially across the pen surface over a 2 h period in midday were lognormally distributed, with geometric means of -0.81 mg N2O (as N) per square meter per hour in April and 0.095 mg N2O (as N) per square meter per hour in August. Fluxes peaked shortly after simulated rainfall. Arithmetic mean N2O flux for the 2 d after rainfall increased over background by 4.6-fold in April and 1.7-fold in August. Manure properties measured at the time of flux measurement were poorly correlated with N2O emissions and were of little value for predicting N2O emissions, which confirmed that further work on the biochemistry of feedyard manure is warranted. The results of this field research will help refine models for predicting N2O emissions from open-lot beef cattle feedyards and help to develop effective mitigation methods to conserve feedyard N.