Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 9/5/1999
Publication Date: N/A
Interpretive Summary: Considerable quantities of gases such as ammonia, hydrogen sulfide, and other odorous compounds can be emitted from the surface of beef cattle feedyards. These emissions are produced by bacteria that ferment nutrients present in the manure. These gas emissions can potentially have adverse effects on air quality, therefore this experiment was designed to use a laboratory-scale system to study methods that decrease gaseous emissions from feedlot surfaces. Ammonia emissions were measured from a mixture of soil, urine, and feces. Different chemicals were tested to see if they decreased ammonia emissions. Aluminum sulfate (Alum) decreased ammonia emissions by 90%. Other compounds such as calcium chloride and a urease inhibitor decreased ammonia production by 40 to 70%. The estimated costs to use these chemicals ranged from approximately $0.72 to $33 per animal. In order for feedyards to use these chemicals, it will be necessary for farmers to pay higher prices for the feedyard manure based on its higher nitrogen content. Additional studies are needed to determine how often these chemicals need to be applied to the feedlot surface and to determine their safety.
Technical Abstract: A laboratory study was conducted to evaluate soil amendments for reducing ammonia emissions from open-lot beef cattle feedyards. A mixture of 1550 g of soil, 133 g of feces, and 267 g of urine was placed into sealed plastic containers of dimensions 20 cm x 20 cm x 12 cm depth. Using a vacuum system, clean air at a rate of 3.2 L/min was passed over the soil-manure surface and ammonia was trapped by bubbling the air through dilute hydrochloric acid. Treatments consisted of a blank (soil with no manure), control (soil-manure mixture with no amendment), 4500 kg/ha Al2(SO4)3 (alum), 9000 kg/ha alum, 375 kg/ha commercial product for reducing ammonia emissions (CP), 750 kg/ha CP, 4500 kg/ha CaCl2, 9000 kg/ha CaCl2, 9000 kg/ha brown humate, 9000 kg/ha black humate, 1 kg/ha of the urease inhibitor N-(n-butyl)- thiophosphoric triamide (NBPT), and 2 kg/ha NBPT. There were four replications of each treatment. Ammonia emissions were monitored for 21 days following application of the amendments. Cumulative ammonia emissions after 21 days, expressed as a percentage of the control, were 0.4% for the blank, 8.5% for 4500 kg/ha alum, 1.7% for 9000 kg/ha alum, 73.6% for 375 kg/ha CP, 68.2% for 750 kg/ha CP, 28.8% for 4500 kg/ha CaCl2, 22.5% for 9000 kg/ha CaCl2, 32.4% for 9000 kg/ha brown humates, 39.8% for 9000 kg/ha black humates, 35.9% for 1 kg/ha NBPT, and 34.4% for 2 kg/ha NBPT. Results of these experiments suggest that ammonia emissions from open feedlots can be significantly reduced using chemical additives, but the costs may be prohibitive. Environmental impacts from the amendments should be evaluated before use in a commercial setting.