Temporal Nitrous Oxide Emissions from Beef Cattle Feedlot Manure after a Simulated Rainfall Event

Nitrous oxide (N2O) is a greenhouse gas (GHG) emitted from agricultural operations. The objective of this research was to quantify N2O‐N emissions from simulated open‐lot beef cattle feedlot pens after rainfall. A recirculating‐flow‐through, non‐steady state chamber system consisting of five 1‐m2 st...

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Bibliographic Details
Published in:Journal of environmental quality 2017-07, Vol.46 (4), p.733-740
Main Authors: Parker, David B., Waldrip, Heidi M., Casey, Kenneth D., Todd, Richard W., Willis, William M., Webb, Kathleen
Format: Article
Language:English
Subjects:
Air Pollutants
Animals
Cattle
Manure
Methane
Nitrous Oxide - analysis
Red Meat
Texas
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Summary:Nitrous oxide (N2O) is a greenhouse gas (GHG) emitted from agricultural operations. The objective of this research was to quantify N2O‐N emissions from simulated open‐lot beef cattle feedlot pens after rainfall. A recirculating‐flow‐through, non‐steady state chamber system consisting of five 1‐m2 steel pans was designed for quantifying emissions. A lid was placed sequentially on each pan, and headspace air was recirculated between the pan and a real‐time N2O analyzer, measuring concentrations every 1 s. Air‐dried manure (89.2% dry matter) from a commercial feedlot in the Texas Panhandle was placed in the pans and then 0, 6.3, 12.7, 25.4, or 50.8 mm of water was applied to simulate a one‐time rainfall event. Emissions of N2O‐N were monitored for 45 d, where two distinct episodes of N2O‐N production were observed over time. The first N2O‐N episode had a duration of 10 h and peaked 2 h after rainfall at a flux of 1.0 to 200 mg m−2 h−1. The second episode had a duration of 40 d and peaked 15 d after rainfall at a flux of 0.06 to 35 mg m−2 h−1. The second episode accounted for 69 to 91% of the cumulative N2O‐N emitted over the 45‐d period. Each millimeter of rainfall increased cumulative N2O‐N emitted by 167.9 mg m−2 (r2 = 0.99, P < 0.001). This rainfall vs. cumulative emissions relationship will be useful for modeling annual N2O‐N emissions from open‐lot beef cattle feedlots, and for assessing the effectiveness of best management practices for reducing feedlot GHG emissions. Core Ideas A rapid (60 s) method was developed to quantify fluxes of N2O‐N from manure. In a 45‐d period, there were two distinct N2O‐N episodes after simulated rainfall. The first N2O‐N episode peaked 2 h after rainfall, the second 15 d later. The second accounted for ∼80% of total N2O‐N emitted during the 45‐d period. Each millimeter of rainfall increased N2O‐N emissions by 168 mg m−2 over 45 d.
ISSN:0047-2425
1537-2537
DOI:10.2134/jeq2017.02.0042