Feedlot pen dust is the result of dry, un-compacted manure, including bedding and soil, being pulverized into a fine powder by livestock activity and then being kicked-up into the air by hoof action and wind. As warm, dry conditions reduce the manure’s moisture content, it becomes more susceptible to being broken down into fine particles.
The primary dust control method - reducing pen manure volume - is the most effective. Excess manure is removed from the pen, monitored and followed by the removal of any loose, un-compacted materials that accumulate over the summer.
‘Normally, we suggest that the best approach is to scrape the feedlots by the beginning of June,’ explains Trevor Wallace, nutrient management specialist with Alberta Agriculture and Forestry. ‘However, the rain this spring and summer has helped keep dust levels down. Regardless of the timing, the most effective first step at minimizing dust is removing manure from the pens.’
Secondary dust control methods include applying water to pen surfaces and increasing stock density. These methods increase the moisture content of the manure, so it will not breakdown into a powder.
Wallace says that applying water is a secondary method of controlling dust because water application will not be effective at controlling dust if the water does not moisten the entire depth of manure.
‘Generally, when more than 2.5 cm of un-compacted manure is present in the pens, the volume of water required to penetrate the manure profile is significant and cannot be practically applied without creating a wet surface that can lead to pen floor damage and odour.’
The most common methods of applying water include the use of water trucks, solid-set sprinkler systems and traveling gun watering systems.
‘Weather will impact the water application efficiency,’ he adds. ‘While it is more effective to apply water in the late afternoon, it may be too windy to do this properly. Alternatively, water applied in the morning or midday is wasted if evaporative demand is high.’
Increasing stock density helps increase pen moisture content by distributing manure and urine over a smaller area, which reduces the breakdown of manure into a fine powder.
He says that research suggests doubling the livestock density can reduce pen dust by up to 50%.
‘This practice also creates an exclusion area where any un-compacted manure, collected during pen cleaning, could be stockpiled to ensure livestock do not disturb the pile and generate dust. These 2 practices can be combined to reduce pen dust potential."
Wallace adds that although a dust management plan is not a requirement under the Agricultural Operation Practices Act (AOPA), the Natural Resources Conservation Board may require a feedlot to have and implement a dust management plan in response to repeated nuisance dust complaints.
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