Hog manure pits foaming up

Problems with manure foam in deep-pit barns of pork production facilities are increasingly being identified in Nebraska.

“It definitely falls into the category of a growing problem,” says Rick Stowell, a University of Nebraska-Lincoln Extension agricultural engineer and associate professor of biological systems engineering.

Producers should be especially aware that foaming pits and flash fires in livestock barns appear to be linked, cautions Stowell. “One year does not confirm a trend, but there were more barn explosions reported in the fall of 2009 than usual in areas that were seeing foam problems.”

The biogas in the bubbles of the foam is largely methane, so there clearly is a fire risk associated with breaking up foam, he explains. “This risk is greatest when barns are empty, and ventilation is shut down.”

Stowell explains that in 2009, even though the foam problem was being reported in Illinois, Iowa and Minnesota, there was no indication it was in Nebraska. It was a different story in 2010, he says.

Key Points

An unsolved problem with foaming in hog pits is said to be growing.

The foaming problem may show up in one hog facility,but not in another.

University of Nebraska is working with researchers in other nearby states.


“There are three cases of foam-filled pits I am aware of now,” he says. “That’s not a big number, but what I have found is there are probably another five not reported for every call I receive, so we’re probably looking at a dozen or two dozen.”

Stowell describes the manure foam as “often dark gray with a greasy consistency, although it can be tan and quite frothy.”

The foam may develop quickly, with several inches forming on the manure surface within a matter of days. Stowell says 2 feet of foam was observed recently in a building in northeast Nebraska, and 4 to 6 feet of foam has been documented in some barns in other states.

Foam on slats and foam spray exiting from pit fans may be evidence of a foaming pit, according to Stowell. “A growing layer of foam may make it difficult to keep pigs clean and ventilate buildings properly.”

Ventilate buildings

Stowell recommends that you ensure your buildings are well-ventilated — especially when foam is being disrupted. “Once you stir up or agitate the foam, it will release methane quickly into the barn. You should be ventilating and have all ignition sources off when you agitate your pits.”

He likens foam to a new disease outbreak because of its biological nature. “It may show up in one barn, but not in an identical barn next door,” he says. “One barn may take longer to foam than another; moving foaming manure to non-foaming pits may spread the foam; and if a barn foamed last year, it appears likely that the pit will foam again.”

While dietary and management changes have been investigated as possible causes of increased foam, no definitive answers are available yet, says Stowell.

“There doesn’t seem to be one single thing that we can tie it to. It seems like with diet changes and maybe some of the pit additives and ways that producers are managing the pits, we have just created a new environment. The hypothesis at this point is that there is a bacterial population that is more active than it used to be. This is an area that needs further research.”

Research efforts

Stowell and other UNL researchers are currently involved in cooperative efforts with the University of Minnesota, University of Illinois and Iowa State University. Research is being directed at discovering how to prevent the foam, if possible. Effective measures for getting rid of foam when it does appear also need to be developed and proven in the field.

Larry Jacobson, University of Minnesota Extension agricultural engineer, agrees that recent research has shown that the foaming is apparently due to a variety of complex interactions that are not yet understood.

Information gathered from producer surveys suggests that in some production systems, 25% of the barns are experiencing some foaming problems, with 10% seeing 6 inches of foam or more, says Jacobson. Survey results also indicate there is no clear link between diet, barn construction or barn management. Incidence of foaming seems to be less in Nebraska and Illinois than in Minnesota and Iowa.

Jacobson says that ongoing research work, primarily through extensive manure tests, will investigate the difference in foaming rates between the states. Comparing manure test results may illustrate factors linked to foam formation.

Stowell says Nebraska producers can help in this regard. With foaming becoming widespread in other states, there is a need to compare deep-pit manure from geographic areas and production systems where foaming has definitely not appeared against manure from foaming pits. He asks producers whose facilities fit either description to contact him at 402-472-3912 to arrange for agitated manure samples to be collected when the pit is pumped.

Additional information may be found online at www.manure.
umn.edu/applied/health_safety.html#pitpumpingsafety.

Carlton writes from Lincoln.

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OOZING FOAM: In this photo, the fan was removed to show the foam escaping from the swine barn. It is gray and has a greasy consistency. University of Nebraska-Lincoln photo

This article published in the February, 2011 edition of WALLACES FARMER.

All rights reserved. Copyright Farm Progress Cos. 2011.