Estrogen concentrations in manure runoff: Pelletized manure reduces toxic runoff

The study was conducted on the experimental plots on the Coastal Plain agricultural soils in Middletown, DE. It measured and compared the amounts of both toxic, free forms of estrogen hormones and less toxic species found in runoff. Corn was planted as a cover crop and chicken manure was applied in either a pelletized form or a raw litter form. Reduced tillage and no tillage treatments were also employed. Samples of surface runoff were collected after 10 rain storms during the 2008 summer growing season from April through July.

Sudarshan Dutta, the author of the study, found that the amounts of estrogen were lower in plots fertilized with pelletized manure and plots that received no-tillage treatments.

Additionally, Dutta discovered the entire range of estrogen concentrations in the samples was significantly lower than those observed in other previous agricultural studies. Nevertheless, concentrations of the less toxic conjugate forms of estrogen were higher than the toxic, free forms.

According to Dutta, prior studies did not usually measure the conjugate forms of estrogen, saying it is necessary to measure these forms.

"The higher concentration of conjugate forms of estrogens underscores the need for reporting all forms of the hormones. This is especially critical considering that conjugate species can be converted to the toxic free forms under certain environmental conditions," he says.

The study was partly funded through a grant by the United States Department of Agriculture and the results are published in the September-October 2010 issue of the Journal of Environmental Quality.