It's a mystery

The mystery of the foaming manure pits remains unsolved.

Finding clues is proving more difficult than was expected, said Larry Jacobson, professor in the University of Minnesota Bioproducts and Biosystems Engineering Department and Extension engineer.

"It's really a head scratcher," Jacobson said.

It was in fall 2009 that David Schmidt first started receiving several calls about foam in swine manure pits. The foam could come up a couple feet overnight, sometimes oozing through the slats. It was a nuisance because it filled up the available manure storage area and got pigs dirty. It also was hazardous, said Schmidt, a University of Minnesota research engineer in the Bioproducts and Biosystems Engineering Department. When the foam breaks, either through agitation or sprinkling with water, it releases the methane that's trapped in bubbles and can cause explosions. A couple barns blew up in fall 2009, Schmidt said. Most were empty and were being power-washed.

He's aware of 10 barns in three states that have had explosions because of manure foam. One was a calf and heifer raising facility with a deep pit. The others were swine barns.

Schmidt conducted a survey last year to see how prevalent manure foam is and found that 10 percent to 25 percent of barns have six inches of foam in the manure pits. The survey contained questions about pit age, production practices, feed and water.

Dried distiller's grain were suspected as a culprit behind the foam, but while everybody is feeding DDGs, not everybody has foam, Schmidt said.

Typically one in four barns has it, Schmidt said.

They have found cases where there are two rooms in the same barn and foam is found on one side of the barn and not on the other, Jacobson said.

They have collected studies and found that foaming seems to be more of an issue in the Midwest than in Nebraska or Ohio, for example, he said.

It's also disappeared from a couple regions that had it before, Schmidt said. Iowa still has a lot of barns with manure foam.

"The problem hasn't went away, it's still there," Jacobson said.

Sleuthing to find clues will continue.

Other people in the Bioproducts and Biosystems Engineering Department will do microbial work on manure and foam.

Schmidt is trying to get manure samples for testing. Foam will also be tested.

He encourages farmers to try pit additives that are billed to decrease foam. Sometimes theyl work, he said. The additives will likely work better if there is only a little manure in the pit.

The whole issue of foaming can be pretty complicated when other industries are looked at, Jacobson said. He suspects there are some very sensitive factors that cause foaming to occur.

"Because we don't know why it's happening, it's harder to come up with solutions," Schmidt said.

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