Temporal Nitrous Oxide Emissions from Beef Cattle Feedlot Manure after a Simulated Rainfall Event
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Nitrous oxide (NO) is a greenhouse gas (GHG) emitted from agricultural operations. The objective of this research was to quantify NO-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-m 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 NO 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 NO-N were monitored for 45 d, where two distinct episodes of NO-N production were observed over time. The first NO-N episode had a duration of 10 h and peaked 2 h after rainfall at a flux of 1.0 to 200 mg m h. 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 h. The second episode accounted for 69 to 91% of the cumulative NO-N emitted over the 45-d period. Each millimeter of rainfall increased cumulative NO-N emitted by 167.9 mg m ( = 0.99, < 0.001). This rainfall vs. cumulative emissions relationship will be useful for modeling annual NO-N emissions from open-lot beef cattle feedlots, and for assessing the effectiveness of best management practices for reducing feedlot GHG emissions.
author list (cited authors)
Parker, D. B., Waldrip, H. M., Casey, K. D., Todd, R. W., Willis, W. M., & Webb, K.