Dust-emission potential of cattle feedlots as affected by feedlot surface characteristics

A laboratory chamber was developed for measuring the dust-emission potential of cattle feedlot surfaces as affected by surface characteristics. The chamber has cross section of a 0.61 m × 0.61 m and a length of 3.7 m. A feedlot surface is simulated by utilizing a layer of dry, uncompacted, sieved feedyard manure, either with or without a compacted soil layer underneath. The chamber simulated the vertical action of the cattle hoof by dropping a 4.5-kg weight onto the manure surface. The particulates emitted were collected with high-volume PM ₁₀ samplers. The effects of kinetic energy of the falling weight (9, 32, and 54 J), manure depth (2.5, 5.1, and 10 cm), degree of compaction of the manure surface (loose, slightly compacted), and manure moisture content (from 6 to 20% wet basis) were investigated. For each manure depth, PM ₁₀ emission potential was directly related to the kinetic energy of the falling weight. For each weight drop, little variation of PM ₁₀ emission potential was noted with change of manure depth. Additionally, PM ₁₀ emission potential was inversely proportional to the manure moisture content. Surface application of water decreased PM ₁₀ emission associated with the falling weight, but penetration of the wetted crust by the falling weight increased the emission potential for subsequent tests. Also, upon drying of the wetted surface layer, PM ₁₀ emission increased considerably, depending on the condition of the manure surface, as well as the amount of water applied.