Runoff of Estrogen Hormone 17β‐Estradiol from Poultry Litter Applied to Pasture

Environmental loading of hormones contained in poultry litter may cause or contribute to disruptions in the health and reproduction of animals. A runoff study was conducted to evaluate the hypothesis that poultry litter applied to pasture contributes the estrogen hormone 17β‐estradiol to runoff. The objectives were to determine the effects of (i) rate of litter application, (ii) amending litter with alum [aluminum sulfate (Al2(SO4)3 · 14H2O)], and (iii) multiple storms on runoff concentrations and losses of 17β‐estradiol from poultry litter applied to fescue (Festuca arundinacea Schreber) plots. Normal litter and litter treated in production houses with 1.2 kg alum m−2 were applied to four replicated plots 1.52‐m wide by 3.05‐m long on Captina silt loam (fine‐silty, siliceous, mesic Typic Fragiudult) at 1.76, 3.52, 5.28, and 7.05 Mg ha−1. Simulated rain was applied immediately thereafter and 7 d later at 50 mm h−1. Runoff samples were collected at 5‐min intervals for 30 min beginning 2.5 min after runoff began, and a single flow‐weighted composite was obtained from the six discrete samples. The 17β‐estradiol content of the composites was determined by enzyme‐linked immunoassay. First‐storm runoff concentrations and mass losses increased with application rate and were 1.28 µg L−1 and 198.8 mg ha−1 from the highest application rate of normal litter. Amending the litter with alum reduced mean 17β‐estradiol concentrations by 42% and losses by 46% in first‐storm runoff. Overall, second‐storm runoff concentrations and losses were 66 and 69% less than from the first storm. This research indicates that field‐applied poultry litter can contribute 17β‐estradiol to runoff, that this hormone can persist for at least 7 d under field conditions, and amending poultry litter with alum can significantly reduce transport in runoff.