title: Daily, monthly, seasonal, and annual ammonia emissions from Southern High Plains cattle feedyards.
abstract: 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 NH emissions during 2 yr from two commercial cattle feedyards in the Panhandle High Plains of Texas. Annual patterns of NH fluxes correlated with air temperature, with the greatest fluxes (>100 kg ha d) during the summer and the lowest fluxes (<15 kg ha d) during the winter. Mean monthly per capita emission rate (PCER) of NH-N at one feedyard ranged from 31 g NH-N head d (January) to 207 g NH-N head d (October), when increased dietary crude protein from wet distillers grains elevated emissions. Ammonia N emissions at the other feedyard ranged from 36 g NH-N head d (January) to 121 g NH-N head d (September). Monthly fractional NH-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 NH-N head d during winter and 103 to 158 g NH-N head d during summer. Annually, PCER was 115 and 80 g NH-N head d 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 NH emissions.
authors.affiliation: USDA-ARS, Conservation and Production Research Lab, Bushland, TX, USA. richard.todd@ars.usda.gov
authors.forename: Richard W
authors.initials: RW
authors.lastname: Todd
authors.forename: N Andy
authors.initials: NA
authors.lastname: Cole
authors.forename: Marty B
authors.initials: MB
authors.lastname: Rhoades
authors.forename: David B
authors.initials: DB
authors.lastname: Parker
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Casey
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000641:Ammonia / Q000032:analysis*; D000821:Animal Feed; D000822:Animal Husbandry; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D003612:Dairying; D004032:Diet / Q000662:veterinary; D008372:Manure / Q000032:analysis; D008954:Models, Biological; D009584:Nitrogen / Q000032:analysis; D012621:Seasons; D013057:Spectrum Analysis; D013781:Texas; D014887:Weather
chemical_list: D000393:Air Pollutants; D008372:Manure; D000641:Ammonia; D009584:Nitrogen