June 18, 2008,
Minneapolis-St.Paul, Mn. – Composting and land-management practices may
be the key to reducing the appearance of manure-applied antibiotics in
surface and ground waters, a new study from the University of Minnesota
June 18, 2008, Minneapolis-St.Paul, Mn. – Composting and land-management practices may be the key to reducing the appearance of manure-applied antibiotics in surface and ground waters, a new study from the University of Minnesota shows.
Antibiotics fed to farm animals find their way into soil and water when manure is spread onto farm fields. As much as 70 percent to 90 percent of antibiotics fed to animals eventually end up in the manure used as fertilizer. In a series of studies, scientists evaluated what happens to veterinary antibiotics in liquid hog and solid beef manure. University researchers found that antibiotics in manure may later appear in surface and ground waters, most often during spring snowmelt. Another study compared no-till farming with chisel plowing and found that plowing mixes the manure with soil and helps reduce the amount of antibiotics leached.
The study was conducted in the karst region of southeastern Minnesota, Iowa, Illinois and Wisconsin.
Further research of composting and longer-term manure storage showed promise as techniques for minimizing the amount of antibiotics in manure before land application. Because manure was applied in the fall and most losses occurred during spring snowmelt, applying manure in the spring may be a way to curtail leaching of the antibiotics. Surface mixing of manure is another important land management practice that can minimize leaching and runoff losses of manure-applied antibiotics.
Holly Dolliver, lead scientist on the project, notes that while small quantities of dissolved antibiotics do have the potential to reach surface and ground water, "the concentrations are significantly below the toxicity levels for human or aquatic organisms."
The study also raises questions about whether other drugs used in livestock production also are being inadvertently applied to soil, said research leader Satish Gupta, a professor in the university's department of soil, water and climate.
The studies, published in the current issue of the Journal of Environmental Quality, were funded by the U.S. Department of Agriculture and the state Rapid Agricultural Response Fund administered by the University of Minnesota.
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