Mineralization of 17-β Estradiol and Testosterone in Broiler Litter-Amended Soils.

The presence of reproductive hormones in the environment is of concern because these hormones may adversely affect living organisms. Hormones from animals enter the environment when animals either defecate or urinate on the land, or their wastes are landspread as part of good agricultural practice.  Landspreading broiler litter is especially important in Georgia because the State leads the United States in broiler litter production.  Broilers excrete between 0.3 and 61.8 µg testosterone, and 1.3 and 51.9 µg estradiol per kg of litter.  Few studies have examined the fate of the excreted hormones in litter following landspreading. We determined the effect of water potential and temperature on the mineralization of testosterone and estradiol.  Fresh broiler litter was amended with ¹⁴C-labeled testosterone and estradiol and applied to three different soil series. The soils were brought to water potentials of -0.03, -0.075, and -1.5 MPa, and were incubated at 10, 20, and 30°C.  Radiolabeled CO₂ (from mineralization) was measured by liquid scintillation, and hormone metabolites by liquid chromatography.  In all cases, mineralization of testosterone (ranging from 20 to 45%) was greater than mineralization of estradiol (ranging from 8 to 14%) over a 6-month period.  Generally, mineralization of testosterone and estradiol was soil series dependent.  Additionally, mineralization of testosterone and estradiol generally increased with increasing temperature and water potential.  Analysis of soil for metabolites, and humic and fulvic acids is ongoing.  Assuming that the hormones have not become part of the soil organic matter through humification, then the modest mineralization of estradiol and testosterone suggests that these hormones may continue to be a potential source of contamination to the environment.