Ammonia and Amine Emissions from a Large Cattle Feedlot

Abstract

Volatilization of ammonia (NH₃) and amines is widely recognized as an important mechanism for loss of feedlot waste nitrogen to air and water resources, but quantitative measurements of these emissions have not been made. We used a micrometeorological technique to determine vertical NH₃ and amine flux densities above a large cattle feedlot in northeastern Colorado. The NH₃ flux density averaged 1.4 ± 0.7 kg N/ha per hour in periodic measurements during the spring and summer of 1977, and was estimated to have a similar magnitude during the previous fall and winter. Somewhat lower fluxes were recorded when the feedlot surface was wet, but these were offset by higher‐than‐average fluxes as the surface dried. The amine‐N flux was < 1% as great as that of NH₃‐N and made an insignificant contribution to the feedlot's N balance. Trimethylamine flux was always the highest and exceeded the sum of all other amine fluxes. Total NH₃ and amine emissions represented about one‐half the rate of urinary N deposition, or about one‐fourth the rate of total N deposition, estimated for this feedlot. Our data support the hypothesis advanced by other authors that animal wastes are a major source of atmospheric NH₃, and in some areas are the principal source.