A Mechanistic Model of Fugitive Emissions of Particulate Matter from Cattle Feedyards, Part I: Introductory Evaluation

ABSTRACT We present preliminary results of a bench-scale simulation of the mechanics of dust emissions from a cattle feedyard surface. The experimental apparatus simulated hoof action by dropping steel weights of standardized geometry onto an uncompacted layer of dried, sieved feedyard manure, varying the kinetic energy of the falling weight by adjusting the height from which it was dropped. The dust emitted by the impact of the falling weight on the uncompacted manure was captured on glass fiber filters, and its mass was determined by routine gravimetry. As expected, the mass of dust emitted by the hoof-action simulation was approximately proportional to the kinetic energy of the falling weight. In addition, for a given kinetic energy of a falling weight, the mass of dust emitted was influenced by the depth of the uncompacted manure layer onto which it fell, although the nature and physical meaning of that relationship are unclear. Additional experiments planned for the near future will illuminate the influence of bulk density and moisture content on the intrinsic dust susceptibility of the loose manure layer, as well as the relative contributions of anterior and posterior hoof action to the total dust emissions. The bench-top simulator provides a practical means of screening mulches and other surface treatments for their potential to suppress fugitive dust emissions from cattle feedyards and openlot dairies.