Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2001
Publication Date: 11/16/2001
Interpretive Summary: Beef cattle producers face many challenges as the result of increased public concerns regarding effects of confined animal feeding operations on the environment. Appreciable quantities of ammonia can be omitted from feedlot surfaces and waste water retention ponds: the result of microbial break down of nitrogen containing compounds in excreted in feces and urine. .Decreasing the quantities of ammonia emitted from beef cattle feedyards would decrease the potential for adverse effects on air quality, reduce odors and increase the value of cattle manure as a fertilizer by increasing its nitrogen:phosphorus ratio. In this experiment, we used a laboratory scale system to evaluate the effects of several compounds on ammonia emissions from a mixture of soil, feces, and urine. The compounds tested decreased ammonia production by 30 to 98%. The most effective compounds were alum, calcium chloride, and a urease inhibitor. However, only the urease inhibitor seemed to be economically feasible. Because chemicals decrease ammonia production via different methods, more research is needed to determine if combinations of these chemicals can work synergistically to economically decrease emissions of ammonia from feedyards.
Technical Abstract: A laboratory study was conducted to evaluate soil amendments for reducing ammonia emissions from open-lot beef cattle feedlots. A mixture of 1550 g of soil, 133 g of feces, and 267 g of urine was placed into plastic containers of dimensions 20 cm x 20 cm x 12 cm depth. Using a vacuum system, clean air (3.2 L/min) was passed over the soil-manure surface and ammonia was trapped by bubbling the air through dilute sulfuric acid. Treatments consisted of a blank (soil with no manure), control (soil-manure mixture with no amendment), 4500 kg/ha A12(SO4)3 (alum), 9000 kg/ha alum, 375 kg/ha commercial product for reducing ammonia emissions (CP), 750 kg/ha CP, 4500 kg/ha calcium chloride (CaC12), 9000 kg/ha brown humate, 9000 kg/ha black humate, 1 kg/ha of the urease inhibitor N-(n-butyl)thiosphosphoric triamide (NBPT), and 2 kg/ha NBPT. There were four replications of each treatment. Ammonia emissions were measured 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 CaC12, 22.5% for 9000 kg/ha CaC12, 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. Calculated costs of the amendments ranged from $0.12 to $5.53 per application per head. Results suggest that ammonia emissions from open feedlots can be reduced using amendments, but the costs may be prohibitive. Site-specific environmental impacts should be evaluated before using these amendments in a commercial setting.