Daily, Monthly, Seasonal, and Annual Ammonia Emissions from Southern High Plains Cattle Feedyards
- Richard W. Todd *a,
- N. Andy Colea,
- Marty B. Rhoadesb,
- David B. Parkerc and
- Kenneth D. Caseyd
- a USDA–ARS, Conservation and Production Research Lab., P.O. Drawer 10, Bushland, TX 79012
b Dep. of Agricultural Sciences, West Texas A&M Univ., Box 60998, Canyon, TX 79016
c USDA–ARS, Meat Animal Research Center, P.O. Box 166, Clay Center, NE 68933
d Texas AgriLife Research, 6500 Amarillo Blvd. W., Amarillo, TX 79106. Assigned to Associate Editor Martin H. Chantigny. Mention of trade names or commercial products is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture
Ammonia emitted from beef cattle feedyards adds excess reactive N to the environment, contributes to degraded air quality as a precursor to secondary particulate matter, and represents a significant loss of N from beef cattle feedyards. We used open path laser spectroscopy and an inverse dispersion model to quantify daily, monthly, seasonal, and annual NH3 emissions during 2 yr from two commercial cattle feedyards in the Panhandle High Plains of Texas. Annual patterns of NH3 fluxes correlated with air temperature, with the greatest fluxes (>100 kg ha−1 d−1) during the summer and the lowest fluxes (<15 kg ha−1 d−1) during the winter. Mean monthly per capita emission rate (PCER) of NH3–N at one feedyard ranged from 31 g NH3–N head−1 d−1 (January) to 207 g NH3–N head−1 d−1 (October), when increased dietary crude protein from wet distillers grains elevated emissions. Ammonia N emissions at the other feedyard ranged from 36 g NH3–N head−1 d−1 (January) to 121 g NH3–N head−1 d−1 (September). Monthly fractional NH3–N loss ranged from a low of 19 to 24% to a high of 80 to 85% of fed N at the two feedyards. Seasonal PCER at the two feedyards averaged 60 to 71 g NH3–N head−1 d−1 during winter and 103 to 158 g NH3–N head−1 d−1 during summer. Annually, PCER was 115 and 80 g NH3–N head−1 d−1 at the two feedyards, which represented 59 and 52% of N fed to the cattle. Detailed studies are needed to determine the effect of management and environmental variables such as diet, temperature, precipitation, and manure water content on NH3 emissions.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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