Dan Anderson and Jay Harmon from Iowa State University's Department of Agricultural and Biosystems Engineering discuss the dangers of gases that can be released when agitating and pumping liquid manure. They offer strategies for safe agitation and ventilation. Anderson is an assistant professor and agricultural engineering extension specialist. Harmon is a professor and extension livestock housing specialist in agricultural engineering.
AMES, Iowa – Hydrogen sulfide gas is a serious issue both in and around barns with liquid manure storage. The decomposition of organic matter in manure results in the release of several gases: ammonia, carbon dioxide, methane and hydrogen sulfide among them. Most of the time these gases are emitted at low levels, but any time manure is being agitated or pumped, or the surface is disturbed, hydrogen sulfide can be rapidly released.
Although all are potentially dangerous, hydrogen sulfide tends to be the most concerning in these cases. Hydrogen sulfide has an intense rotten egg smell, so it is relatively easy to detect its presence, even in very low concentrations, but people quickly suffer olfactory fatigue and lose the ability to smell it. This makes it necessary to use analytical instruments to detect dangerous levels.
Hydrogen sulfide monitors can be purchased to help keep those working around manure safe. A monitor, which is small enough to wear, ranges in cost from $99 to $800 and will alert you if the situation is dangerous. There are numerous options available for monitoring hydrogen sulfide levels when working with manure. Below are links to five meters to consider. These meters typically have audible alarms that will sound an alert as dangerous concentrations develop.
Neither endorsement of companies, individuals or their services mentioned is intended, nor is criticism implied of similar companies, individuals or their services not mentioned.
Hydrogen sulfide can spike quickly and without warning during pit pumping. This can result in hazardous concentrations for both the animals and the farm employees around the facility. Aggressive agitation can contribute to the risk of gas spikes when agitation first begins and when the pit becomes nearly empty. The manure agitation technique used can make a big difference in how much, and how quickly, hydrogen sulfide is off-gassed from the manure.
People should NEVER enter a building being pumped. Use yellow caution tape to mark barn entrances to block door or consider lockout tags during pumping. If possible, remove animals before pumping. For barns with multiple pits, move cattle out of the room with the pit being agitated.
Following are a few best practices regarding manure application.
Consider adding pump out curtains (tarps) around the manure agitator to limit air exchange of hydrogen sulfide gas near the applicator. This curtain blocks some of the pit air from swirling back towards the pump operator.
For more information on this topic or other manure related issues, please contact the Iowa Manure Management Action Group.