Emissions of Hydrogen Sulfide from the Pen Area of a Beef Cattle Feedyard in the Texas High Plains

Hydrogen sulfide (H2S) is an odorous gas that at elevated concentrations can be toxic. At confined livestock facilities including beef cattle feedyards, it is produced through the anaerobic decomposition of manure. Research was conducted from 2007 to 2010 at a regionally representative, 18000 hd capacity, commercial feedyard located in Deaf Smith County, Texas. Cattle were housed in open corrals that covered 36.5 ha. During the study, the feedyard received cattle at an average weight of 300 kg and shipped cattle from the feedyard to slaughter at an average finished weight of 495 kg, so that cattle gained about 200 kg during residency in the feedyard. Cattle were assigned to pens based on weight, and weight groups were randomly located in corral pens within the feedyard source area. Ambient air was continuously sampled from 3.3 m above the pen surface near the center of the feedyard pen area. Hydrogen sulfide was measured continuously using pulsed florescence analyzers located inside a temperature‐controlled instrument shelter. An onsite meteorological station recording at least wind speed, wind direction, air temperature, solar radiation, barometric pressure and rainfall was located within the feedyard facility. Flux density was modeled using WindTrax, a backward Lagrangian stochastic (bLs) model. Measured H2S concentrations were generally low, averaging 4.2 ppb (Mar 2007 – Jun 2008) with occasional short periods of elevated concentrations often associated with rainfall events. An upper emission rate (3.86 g hd d-1) was derived by averaging emission fluxes during months where the rainfall received exceeded 50 mm, while a lower emission rate (2.13 g hd d-1) was derived by averaging emission fluxes during months in which less than 50 mm of rainfall was received.