Several weeks back, we reported that the Benton, N.Y., fire department and Yates Soil and Water Conservation District measured more than 100 parts per million of hydrogen sulfide next to a long-term dairy manure storage pit during agitation – next to, not in the pit. It occurred on a farm where gypsum has been used for bedding.
More recently, that fire department also registered similarly high H2S levels over a bedded manure pack – again, where gypsum had been applied. The dangerously high gas levels prompted Cornell Pro-Dairy experts to issue a "heads up" warning to farmers and manure handlers. But the Cornell experts acknowledge that in operations that daily-haul manure and use gypsum, there's little or no H2S production.
So was gypsum the culprit?
Gypsum is a significant source of calcium and sulfur. And naturally occurring bacteria in long-term manure storage use that sulfur to make hydrogen sulfide.
But gypsum isn't the only sulfur contributor to livestock rations. Distillers' grains also increasingly used in dairy farms. While there was no proven DG link at the Yates County dairies, and there's research evidence that DGs do contribute to manure-generated H2S.
An Iowa State University study, for instance, found that H2S output spiked eight-fold after finishing hogs were fed 30% DG in their diets. A South Dakota State University study reported increasing amounts of H2S from beef cattle fed increasing percentages of DGs.
U.S. Gypsum response
"We've been supplying gypsum bedding since 1998 without problems or concerns until recently," says Terry Weaver, president of USA Gypsum, Reinhold, Pa. "Since reports began to surface, we began looking for peer-reviewed academic research to determine normal gas levels and manure analysis."
Finding none, USA Gypsum has begun collecting gas logging data in conjunction with Penn State University researchers, looking for patterns. Thus far, results haven't been consistent. Adding a gypsum, he contends, doesn't automatically trigger elevated H2S.
"The safety of our customers and manure handlers is extremely important to us," adds Weaver. "Safety around manure storage can be reduced to two simple points: Stay away during agitation, and never enter a manure pit without training and safety equipment – as recommended by many sources for many years."