Gypsum bedding in bedded pack barns may be dangerous

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Last week we reminded farmers and manure handlers that all stored manure can produce hazardous gases at levels of concern in some conditions.  Some of these gases (like hydrogen sulfide [H2S]) are toxic and heavier than air and therefore are prone to sink to low areas like storage pits, sumps, or other depressions and accumulate to potentially LETHAL levels.

We also reported specifically on concerns we have with possible increased risk for exposure to high levels of H2S from long-term liquid manure storages used to store manure from barns where gypsum is used for cow bedding.   These concerns are based on recent measurements taken by staff from the Benton fire department and the Yates County Soil and Water Conservation District (SWCD) where greater than 100 ppm H2S was measured at the edge of a long-term liquid manure storage structure.  This level is identified as immediately dangerous according to the US Occupational Safety and Health Administration (OSHA). 

The Yates County measurements are consistent with reports of high levels measured on at least one Pennsylvania farm where gypsum also was used for bedding and manure was stored.   Gas concentrations are rapidly diluted with distance from the storage structure, so there should be little or no concern during agitation or clean out beyond the immediate farmstead.

What’s New?

Since last week it has come to our attention that gypsum is also being used by some New York State farmers as a bedding material in deep bedded pack barns.  Deep bedded pack systems have the same anaerobic (little or no oxygen) conditions as long-term liquid manure storages – the conditions needed for the formation of H2S by microbes. 

Therefore, the potential for human exposure to high levels of H2S is possible with bedded pack situations as well as long-term liquid manure storages.  In fact, the opportunity for a farmer to be exposed to high levels of H2S may possibly be even higher with bedded packs, especially during clean-out.  The packs are normally under roof, and enclosed barns may not provide enough air movement to maintain safe working conditions.

Late last week, staff from the Benton fire department and Yates County Soil and Water Conservation District (SWCD) measured more than 100 ppm H2S in a barn where a deep bedded back was being removed.  Once again, gypsum had been used as part of the overall bedding material.

As a reminder, human exposure to hydrogen sulfide levels above 20 ppm can cause headaches, dizziness, and fatigue.  According to OSHA, a concentration of 100 ppm H2S is immediately dangerous to life and health because the symptoms can make it difficult or impossible to escape from a dangerous situation.  Levels over 100 ppm paralyze the olfactory nerve (sense of smell) causing the victim to not know they are breathing in the gas, and exposure at this level for 48 hours may cause death.  At levels above 500 ppm, staggering and collapse can occur in 5 minutes, death after 30-60 minutes.  Since we are finding random air samples over 100 ppm H2S, it is possible to have pockets of H2S near or in storage/bedded pack structures during agitation or clean-out that are at much higher levels.

Farmers, family members, workers, and visitors are urged to avoid any and all manure gases, especially from long- term storages or bedded packs where gypsum is mixed in with manure in any significant quantities.  Note:  for operations that daily haul manure and use gypsum for bedding, we expect little or no production of H2S, but care should be taken to minimize risks here too.

When cleaning out a barn’s bedded pack manure:

  • Make sure no unnecessary people are near the pack, especially at the location where the pack is being removed.
  • If hand clean-out is required using pitchforks, consider wearing a belt-mounted personal gas exposure alarm system to alert you if exposure is exceeding safe limits.
  • Open all barn doors, windows, curtains and any other air inlets/outlets if the barn is naturally ventilated or turn on the mechanical ventilation system to full capacity before beginning the clean out process.
  • Set up large fans and/or blowers around where operators will be working to mix air and dilute any gases.

In conditions where sufficient ventilation cannot be achieved, equipment operators properly trained on use of a respirator and who are wearing them should be the only ones working in the barn when clean out is occurring.  In addition to the above, farmers should:

  • Consider using other materials for bedding until this issue is better understood.
  • Have an emergency plan in place.

Train all family members and employees in the dangers of manure gases.

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Terry Weaver, USA Gypsum    
November, 04, 2013 at 02:17 PM

The dangers of handling manure along with gypsum bedding have been the subject of current media attention. USA Gypsum applauds the recent press which highlights best practices to ensure manure handling safety for all manure. Since 1998 (over 15 years), USA Gypsum has been supplying gypsum bedding additives to dairy farmers. Today, thousands of farmers add gypsum to their bedding on a daily basis and report that it helps to provide a dry, soft, comfortable surface for clean healthy cows, which improves income by reducing somatic cell counts and mastitis incidents. Many farmers also report improved foot health in their cows. Gypsum added to bedding and mixed with manure amends the soil by supplying calcium and sulfates which most dairy farmers already purchase. Gypsum also reduces ammonia emissions and dissolved phosphorus runoff. Gypsum works well with no till production because, unlike lime, gypsum is soluble and penetrates soil without incorporation Dangerous gases are always present when handling manure and have been well documented for decades. A Penn State press release reported that from 1975 through 2004, 77 fatalities and 21 severe injuries were documented from manure handling. In addition, in 1992, the American Society of Agricultural and Biological Engineers (ASAE) issued a manure storage safety standard. The report pointed out that hydrogen sulfide is normally released from all stored manure. “Concentrations reaching 200-300 ppm have been reported within a few minutes after the start of manure agitation and have been reported as high as 1000 ppm during vigorous agitation”. Moreover, it was identified as the most dangerous gas produced because it is heavier than air and hangs near the ground. (cont.)

Terry Weaver, USA Gypsum    
November, 04, 2013 at 02:21 PM

In 2003, the National Research Center reported that all dairy manure contains sulfur. Sources of sulfur are animal diets including amino acids, water soluble vitamins, and sulfate in the water. The study concluded that the emission of hydrogen sulfide from manure storage is complicated and poorly understood. This explains why manure handlers cannot assume that conditions are safe just because they have been doing something the same way for years without incident. While there have been discussions about gypsum bedding and links to hydrogen sulfide, the most complete research on adding gypsum to dairy bedding was recently completed in Canada and no hydrogen sulfide was detected during agitation. However, there are many other farm specific variables such as nutrition, amount of gypsum added, primary bedding type, waste wash water, foot baths, silage leachate and other additives to the manure storage. In order to better understand dairy manure emissions, USA gypsum is sponsoring on-farm demonstrations conducted by Penn State University to document dairy manure handling gas emissions. Observations at farms in three dairy manure categories will be compared during spring & fall agitation: (1) typical bedding; (2) gypsum used in bedding, and (3) amendment added to manure from gypsum-bedded herd. From nine to fifteen farm demonstration sites will offer a range of typical conditions. A detailed farm characterization will document manure composition, animal characteristics, bedding management, feed management, and details of manure storage management. (Cont.)

Terry Weaver, USA Gypsum    
November, 04, 2013 at 02:21 PM

Farm characteristics will be associated with environmental measurements prior to and during manure storage agitation. Instrumentation will monitor gas concentrations and weather conditions while laboratory analyses will be conducted on manure samples to determine physical and chemical characteristics related to air emissions. Finally, all farmers and others in the industry should remember that while manure handling accidents are rare, they can be deadly but are preventable. The most important recommendation is to be very cautious when agitating liquid manure and to stay away from the site during agitation. This step and other safety recommendations protect producers, their families and manure handlers no matter the feed, water, temperature, and humidity or bedding type. I look forward to continued discussions with the industry on this issue.


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