How do temperature and rainfall affect nitrous oxide emissions from open-lot beef cattle feedyard pens?

Authors: Parker, David; Waldrip, Heidi; CASEY, KENNETH - Texas A&M Agrilife; Woodbury, Bryan; Spiehs, Mindy; Webb, Kathleen; Willis, William - Will

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2018
Publication Date: 5/14/2018
Citation: Parker, D.B., Waldrip, H., Casey, K.D., Woodbury, B.L., Spiehs, M.J., Webb, K., Willis, W.M. 2018. How do temperature and rainfall affect nitrous oxide emissions from open-lot beef cattle feedyard pens? Transactions of the ASABE. 61(3): 1049-1061. doi:10.13031/trans.12788.
DOI: https://doi.org/10.13031/trans.12788

Interpretive Summary: Nitrous oxide emissions from beef cattle feedyards increase considerably above 88 degrees Fahrenheit. Nitrous oxide is a greenhouse gas that has been linked to climate change. High concentrations of nitrogen and carbon make livestock manure at beef feedyards a source of nitrous oxide emissions. While the effects of rainfall on nitrous oxide emissions have been studied intensively, little is known about the effects of other variables like temperature. Scientists from USDA-ARS (Bushland, Texas and Clay Center, Nebraska) and Texas A and M AgriLife Research (Amarillo, Texas) studied how temperature affects nitrous oxide emissions from beef cattle feedlot manure. Nitrous oxide emissions were monitored after rainfall at eight manure temperatures ranging from 41 to 115 degrees Fahrenheit, representative of winter and summer temperature extremes. Nitrous oxide emissions were negligible at the lowest temperature. Emissions increased with increasing temperature, with a sharp jump in emissions above 88 degrees Fahrenheit. Keeping feedlot pens dry, especially during the hot summer months, will help to reduce nitrous oxide emissions from livestock manure.

Technical Abstract: Temperature is a primary factor affecting greenhouse gas (GHG) emissions from agricultural soils, but little is known about how temperature affects nitrous oxide (N2O) emissions from manure. The majority of grain-fed cattle in the Texas Panhandle are finished in large, earthen-surfaced, open-lot feedyards. Manure accumulates in feedyard pens and creates an environment high in nitrogen (N) and carbon (C) that can lead to N2O losses. In previous studies, N2O-N emissions from feedyard manure have been highly variable, ranging from negligible amounts from dry manure to 200 mg per square meter per hour after a simulated rainfall event. The objective of this research was to determine how temperature affects N2O emissions from feedyard manure following rainfall. A recirculating-flow-through, non-steady-state chamber system with 1 square meter pans was used to monitor N2O emissions from beef cattle manure following a single 25.4 mm simulated rainfall event. Emissions were monitored at manure temperatures of 5.0, 11.2, 17.2, 21.5, 26.8, 31.0, 38.1, and 46.2 degrees Celsius. At all temperatures, a single N2O episode was observed following rainfall, peaking 2 to 11 hours after rainfall with duration of 2 to 3 days. A second N2O episode was observed at temperatures greater than 31.0 degrees Celsius, peaking 3 to 4 days after rainfall with duration of 18 days. When present, the second N2O episode accounted for 72 to 83 percent of the 20-day cumulative emissions. A step-increase in cumulative N2O emissions was observed between 26.8 and 31.0 degrees Celsius, believed to be due to a major shift from denitrification to nitrification as the primary process of N2O production. Empirical regression models were developed for predicting cumulative N2O emissions based on temperature, which showed 88 percent agreement between predicted and field-observed N2O-N flux rates. These regression models will be useful for further quantification of N2O emissions from open-lot beef cattle feedyards in the U.S. southern High Plains, and for assessment of practices for reducing GHG emissions.