AMMONIA AND HYDROGEN SULFIDE FLUX FROM BEEF CATTLE PENS: IMPLICATIONS FOR AIR QUALITY MEASUREMENT METHODOLOGIES AND EVALUATION OF EMISSION CONTROLS

Abstract

Ammonia (NH3) and hydrogen sulfide (H2S) are emitted from beef cattle feedlots with NH3being greater by nearly three orders of magnitude. Nearly 30% of the U.S. beef cattle are fed inthe High Plains of Texas. Earlier research indicates that abatement technologies may be neededto significantly reduce NH3 emissions. To date, little is known about the appropriatemeasurement methods to evaluate the effectiveness of NH3 emission controls. In this research,we determined the (a) variability of NH3 and H2S fluxes within a single pen and (b) therelationships between NH3 and H2S fluxes and manure characteristics as a part of a larger fieldstudy to determine the effectiveness of the urease inhibitor NBPT. A dynamic, flow-throughchamber system was used to estimate NH3 flux from experimental beef cattle pen with a 15.6m2/head stocking density. The total of 27 measurements were completed within one day using aflux chamber interfaced with an on-site, mobile-instrument shelter. Manure samples from eachlocation were analyzed for moisture content, total kjeldahl nitrogen (TKN), NH4-N, NO3-N, andC:N to characterize their relations with NH3-N and H2S-S flux. The NH3-N flux varied by nearly30 fold between 512 to 14,993 g/m2-min. The H2S-S flux varied from 0.52 to 8.07 g/m2-min.In addition, flux from fresh urine and feces were also measured for nearly one day. Thecumulative NH3-N emissions from fresh feces were 2.5 to 13.7% of NH3-N from urine. Theapparent variation of flux within a typical pen has important implications on the selection ofappropriate measurement methods for statistically significant evaluation of emission controls.