Nitrous oxide and methane emissions from beef cattle feedyard pens following large rainfall events

Authors: Parker, David; CASEY, KENNETH - Texas A&M Agrilife; Willis, William - Will; Meyer, Beverly

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2021
Publication Date: 8/23/2021
Citation: Parker, D.B., Casey, K.D., Willis, W.M., Meyer, B.E. 2021. Nitrous oxide and methane emissions from beef cattle feedyard pens following large rainfall events. Transactions of the ASABE. 64(4):1211-1225. https://doi.org/10.13031/trans.14480.
DOI: https://doi.org/10.13031/trans.14480

Interpretive Summary: Nitrous oxide and methane are greenhouse gases that have been linked to climate change. High concentrations of nitrogen and carbon make livestock manure at beef cattle feedyards a source of greenhouse gas emissions. There have been few studies to quantify greenhouse gas emissions in the semiarid West Texas environment. Scientists from USDA-ARS (Bushland, Texas) and Texas A and M AgriLife Research (Amarillo, Texas) studied how large rainfall events affect nitrous oxide and methane emissions from commercial beef cattle feedyard pens. Nitrous oxide emissions dropped below detection levels for 10 days following a large 3-inch rainfall event that saturated the pen surface. Methane emissions dropped below detection levels for 5 days following the large rainfall event, then increased to pre-rainfall levels by day 8. These results differ from our earlier research, which showed that nitrous oxide emissions increased following smaller (0.5- to 1-inch) rainfall events. These data will be used to refine models and update greenhouse gas emission inventories for beef cattle feedyards.

Technical Abstract: More than six million beef cattle are fed annually in feedyards on the semiarid Southern Great Plains (SGP). Manure deposited on the open-lot pen surfaces contributes to greenhouse gas (GHG) emissions. Nitrous oxide (N2O) and methane (CH4) are GHG linked to climate change, and both have global warming potentials greater than carbon dioxide (CO2). Two sampling campaigns were conducted in 2019 to quantify N2O and CH4 emissions from open-lot pen surfaces. The occurrence of large, unforecast rainfall events during both campaigns provided an opportunity to compare GHG emissions from the dry manure before rainfall, and from the wetted pen surface for one to two weeks following precipitation. Temporal variability was quantified by continuous sampling using six to eight automated flux chambers, a multiplexer system, and real-time analyzers. Spatial variability was quantified using a recirculating portable chamber on a 5 x 8 grid. Nitrous oxide emissions dropped below detection levels for 10 days after the precipitation event. Nitrous oxide emissions were related to nitrification or other aerobic processes. Methane emissions dropped below detection levels for five days after the precipitation event, then increased to pre-rainfall levels by day 8. When present, N2O and CH4 emissions followed a diel pattern, with the highest emissions occurring during the afternoon when manure pack temperatures at the 25 mm depth were 36 to 38 degrees C and ambient temperatures were 31 to 32 degrees C. Average CH4 emissions from the feedyard pen surface were 96-fold lower than estimated enteric CH4 emissions. The results of this field research will be used to refine empirical models for predicting annual N2O and CH4 emissions from open-lot beef cattle feedyards on the semiarid SGP.