WEST LAYFAYETTE, Ind., July 21 (UPI) -- Amounts of carbon discharged from manure spread on tiled fields is about the same as other sources of fertilizer, Purdue University scientists in Indiana said.
Tiles set beneath farm fields direct excess water from the soil into streams. It was traditionally believed tiles flush manure into water systems more quickly, increasing the growth of bacteria, such as E.coli, which consume the dissolved carbon found in effluent, Purdue agronomists Ron Turco and Sylvie Brouder said.
Six years of drainage studies, however, showed amounts of carbon discharged into streams was the same in tiled fields fertilized with manure as in tiled fields using other sources of fertilizer, Brouder and Turco wrote in the Journal of Environmental Quality.
"It was surprising in a way that carbon loads were relatively low at the discharge points," Brouder said. "The assumption was that manure was adding significantly."
Future studies are to evaluate how antibiotics and hormones from manure are transferred to streams through tiled fields, the researchers said.