Features Applications Beef
Plant buffers may limit spread of antibiotics

March 2, 2010 – Research
by scientists at the University of Missouri Center for Agroforestry suggests
that buffer strips of grasses and other plants can trap and break down
veterinary antibiotics in manure fertilizers.


March 2, 2010 – Research
by scientists at the University of Missouri Center for Agroforestry suggests
that buffer strips of grasses and other plants can trap and break down
veterinary antibiotics in manure fertilizers.

Buffer strips have already
demonstrated that they can be effective in protecting water quality,
controlling erosion and supporting wildlife around crop fields.

“That’s the beauty of it,”
said Keith Goyne, assistant professor of environmental soil chemistry in the MU
School of Natural Resources. “Vegetative buffers already are a recommended
practice for reducing sediment, nutrients and herbicides in surface runoff. Our
research is showing another benefit.”

The finding comes amid
emerging concerns about the use of veterinary antibiotics in livestock farming.
Thirty to 80 percent of any given dose of antibiotic may end up excreted as
waste rather than absorbed by the animal, Goyne said. When manure is used to
fertilize croplands, antibiotics in the manure-enriched soil may leave the farm
via surface runoff and eventually end up in streams, lakes or rivers.

While the concentrations
of the antibiotics appear to be too small to pose a direct threat to human
health, scientists worry that the presence of these compounds in soil and water
may foster the emergence of drug-resistant bacteria that could infect wildlife,
livestock and people. The compounds also may harm ecosystems by disrupting
communities of soil microbes, which play a crucial role in cycling nutrients
and decomposing organic matter.

Earlier studies by MU
scientists have shown that grass buffers in croplands can filter herbicides in
surface runoff by physically trapping sediment and nurturing microorganisms
that break down herbicides.

Goyne and colleagues –
including assistant professor of forestry Chung-Ho Lin, professor of soil
science Steven Anderson, graduate student Bei Chu, and two USDA soil scientists
based at MU, Robert Lerch and Robert Kremer – have been conducting laboratory
and field tests to see if buffers could play a similar role in filtering
antibiotics.

In one study, the
researchers collected soil samples from both croplands and grass and
agroforestry buffers at three MU research farms in Missouri – the Horticulture
and Agroforestry Research Center in New Franklin, Southwest Center in Mount
Vernon, and the Greenley Research Center in Novelty. They exposed the samples
to two common veterinary antibiotics, sulfadimethoxine and oxytetracycline.

Comparisons of soil from
croplands and buffers revealed that soils from several types of plant buffers
were effective at reducing concentrations of the antibiotics.

A report on the research
appeared recently in the journal Agroforestry Systems.

Related projects include a
study at MU’s Bradford Farm near Columbia that looks at the effectiveness of
three different buffer designs in reducing antibiotics in surface runoff.

The overall goal is to
determine which combinations of plant species and soil types are most effective
at filtering and degrading antibiotics, Goyne said.