Manure Manager

Features Gas safety Safety
Rise above the hazards

Recognizing risks associated with gypsum bedding.

October 24, 2023  by Rosalie Tenison

Davis Hill of Penn State Extension (retired) demonstrates the use of a self-contained breathing apparatus, which should be worn when entering confined spaces. Images courtesy of Robert Meinen

In a roughly 12-month period a decade ago in Pennsylvania and Maryland, four people died and two children required treatment in three separate incidents involving manure storage. The tragedies alerted agriculture extension staff and researchers of an impending threat related to manure. Within months of examining multiple storage facilities, the experts determined the culprit to be manure mixed with gypsum bedding. A cooperative effort between Pennsylvania State University and the State’s agricultural extension department was launched to educate on the dangers of manure storage and how to prevent catastrophe.

“The research demonstrated clearly that farmers using gypsum bedding faced dangerous levels of hydrogen sulfide (H2S) as the manure was agitated,” explains Robert Meinen, one of the scientists involved with the research. When released, he says, H2S can be toxic within minutes. According to Meinen, comparison farms using sawdust or other bedding without gypsum materials were not likely to experience the dangerously high levels of toxic gas. The research team determined the culprit was gypsum bedding, a material derived from recycled construction materials, such as drywall, that is ground into a useful material, particularly in dairy operations. Considered environmentally friendly for its re-purposing of material formerly destined for landfill, the bedding is high in calcium sulfate and gentle for animals. However, once the bedding is transferred with manure to storage, particularly anaerobic or oxygen-free storage, a chemical change occurs creating hydrogen sulfide, one of the most toxic gases farmers can encounter. In the incident where the two children survived the gas, they were merely playing beside the manure pit during agitation. Since H2S is heavy and lays close to the ground, the two- and four-year-old entered an invisible cloud of toxicity. Had their father not acted quickly to pull them to safety, this story would have had a more tragic outcome.

“We needed to create awareness that these materials cause danger,” says Meinen. “When the manure is agitated, the gas is released immediately and can remain at dangerous levels for up to one hour and beyond.” As a result of the research, the team came up with a list of recommendations for construction and management of manure storage and strategies for working with it safely.

Meinen describes H2S as a gas that acts like dry ice while remaining invisible and far more toxic. When released, dry ice creates a cloud as it connects with warm air and the cloud often hangs close to the ground before drifting skyward and gradually dissipating. It’s a good visual for farmers to keep in mind when they approach their manure storage even though they can’t see the cloud that is gathering around them.


Since identifying the cause, the extension staff at Penn State and the agriculture department began a campaign to educate anyone associated with manure management on safety. According to the United States Department of Labor, at only 200 ppm, H2S can cause uncomfortable respiratory tract irritation and pulmonary edema. At 500 ppm, a person exposed to the gas will collapse within five minutes, experience eye damage, and could die within 30 to 60 minutes.

Meinen recommends wearing an H2S monitor when working around manure, especially during agitation. He says it is worrisome that less than five percent of people working with manure use the monitors. Since the gas is invisible and highly toxic, tragedy could strike before someone is aware of a problem. He adds that vowing to stay five more minutes to get the job done, even though symptoms of gas exposure may be manifesting themselves, is self-destructive.

“I recommend monitors be worn any time a dangerous job, such as cleaning tanks or pumping, is undertaken. Always try to have two people involved in the work,” says Meinen. “If entry into a storage for repair is necessary, use safety harnesses and consider wearing a self-contained breathing apparatus.” Open-air storage is better than enclosed storage but, if enclosed storage is used, ensure there are multiple exits. Meinen also recommends that, when a new storage is designed or an existing storage is upgraded, locate pumping equipment outside or away from storage rather than confining it in a small building or enclosed space.

Once research was complete and the problem identified, the education effort was cooperative. Meinen says the gypsum bedding suppliers got on board to provide education. Meanwhile, he and his colleagues have been talking about the issue at stakeholder meetings around the state. “We don’t know if we have saved lives, but we have reached out to many farmers and believe awareness is out there,” he says. “We have heard of no serious incidents since his campaign.”

Meinen also developed a self-assessing list that he gives to farmers. “I’ve been talking for 12 years about my list I call ‘body alarms’ and I’ve been told by some they remembered the list and avoided danger.”

Knowing any hazards that could result from your choice of bedding will increase awareness when you deal with the resulting waste. As you begin disposal or agitation processes, wear PPE and don’t ignore physical signs your health is at risk. Meinen says: “Don’t work yourself to death.” Instead, be aware of the hazards and take breaks rather than pushing on to complete a task. Move slowly, and keep children away from watching you work with manure. Move away if your body alarm goes off because, in the presence of H2S, your life truly depends on it. •


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