USDA scientists based in Peoria, Ill., are exploring the use of tannins from the quebracho tree in mitigating livestock odors, lead researcher Terry Whitehead told USDA's Rod Bain in a radio feature this week.
The research, Whitehead said, could eventually ease tensions between rural residents whose houses or farms sidle up to hog operations. It also presents a method that's animal-friendly.
ARS says hydrogen sulfide and other sulfur compounds make up about half of the offensive odorants from swine manure. Scientists have determined that a group of microbes called sulfate-reducing bacteria generate these compounds as part of the process of breaking down manure. Bacterial activity in manure pits also generates methane and nitrous oxide, which are both greenhouse gases.
Drawing on previous research that found tannins can block bacterial activity in the guts of ruminant livestock, Whitehead and Mike Cotta tested the method on incubated swine manure.
Seven days after the researchers added quebracho tannins to the manure, they found hydrogen sulfide and methane production had been reduced more than 90% and that production continued to dwindle for another three weeks.
Populations of sulfate-reducing bacteria also significantly declined, by 70% to 90%, in the tannin-enriched mix.
Currently, the quebracho is used as a powdered form, but it may eventually be a water solution to add to pits. Whitehead said the next step is to work with producers to test the product.
Hear the story below.