Location: Livestock Nutrient Management ResearchTitle: Spatial variability in nitrous oxide and methane emissions from beef cattle feedyard pen surfaces Author
Submitted to: Waste to Worth Conference
Publication Type: Abstract Only
Publication Acceptance Date: 11/11/2016
Publication Date: 4/20/2017
Citation: Casey, K., Waldrip, H., Parker, D.B., Todd, R.W. 2017. Spatial variability in nitrous oxide and methane emissions from beef cattle feedyard pen surfaces. Waste to Worth Conference, April 18-21, 2017, Raleigh, NC.
Technical Abstract: Greenhouse gas emissions from beef cattle feedlots include enteric carbon dioxide and methane, and manure-derived methane, nitrous oxide and carbon dioxide. Enteric methane comprises the largest portion of the greenhouse gas footprint of beef cattle feedyards. For the manure component, methane is the predominant gas produced on a mass basis; however, nitrous oxide is more important if expressed in terms of carbon dioxide equivalents. Limited research has been conducted on methane and nitrous oxide emissions from feedyard manure, particularly on beef cattle operations in ths Texas Panhandle. The objectives of this study were to evaluate the magnitude and variability in methane and nitrous oxide emissions from Texas feedyards using non-flow through non-steady state (NFT-NSS) chambers. Our goal was to develop a functional understanding of the environmental variables that influence and control greenhouse gas emissions in order to contribute towards modeling efforts for predicting the environmental footprint of beef cattle production. NFT-NSS chamber bases were inserted into the manure pack of commercial feedyard pens (10 chambers per pen) and headspace gas samples were taken daily at 10 min intervals for 30 min for a period of 5 d. Headspace gas concentrations were determined with a gas chromatograph equipped with flame ionization, electron capture, and thermal conductivity detectors. Greenhouse gas flux rates were determined by quadratic regression. Results showed that emissions of both methane and nitrous oxide were highly variable within pens (spatial variablility) and temporally. Rainfall events had a profound impact on manure-derived greenhouse gas emissions. In addition, emissions were quickly influenced by changes in temperature. These interacting factors create challenges in analyzing nitrous oxide and methane data from feedyard, making it difficult to develop simple models for predicting emissions.