Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 2005
Publication Date: April 1, 2006
Citation: Jenkins, M., Endale, D.M., Schomberg, H.H., Sharpe, R.R. 2006. Fecal bacteria and sex hormones in soil and runoff from cropped watersheds amended with poultry litter. Science of the Total Environment. 358:164-177. Interpretive Summary: The poultry industry generates millions of tons of poultry litter annually, much of which is applied to pastures and cropped fields as fertilizer. Fecal bacteria, some of which are pathogenic to humans, and the potent sex hormones, estradiol and testosterone, are natural components of litter. Scientists, policy-makers, and the poultry industry require information to determine if these components pose an environmental risk when litter is appropriately applied. Scientists at the USDA-ARS J. Phil Campbell Sr. Natural Resource Conservation Center in Watkinsville, GA, determined the fate and transport of fecal bacteria and sex hormones in the environment from litter applied as nitrogen fertilizer to four cropped watersheds under conservation tillage in the Piedmont area of northeast Georgia. They found that rain events occurring shortly after litter application increased levels of fecal bacteria in runoff, which may impact surface water quality. However, litter applications did not increase the level of sex hormones in the environment. The scientists cautioned that other researchers have reported higher levels of sex hormones in litter than found in the litter used in this study, therefore, they cannot conclusively say that applying litter at appropriate agronomic rates will not increase estradiol and testosterone in the environment. They recommend that further research is needed to determine the range of hormone concentrations found in litter from various operational practices, and to identify management practices that minimize hormones that may be released to the environment. This information can be used by the poultry industry and environmental agencies to ensure safe application of the 14 million tons of poultry litter generated annually in the USA.
Technical Abstract: The application of poultry litter to agricultural fields can provide plant nutrients for crops and forage production, but fecal bacteria and the sex hormones estradiol and testosterone are components of litter that can be detrimental to the environment. We investigated the fate and transport of fecal bacteria, estradiol and testosterone from surface applied poultry litter to four small watersheds. Poultry litter was applied to meet the nitrogen requirements of pearl millet (Pennisetum glaucum L.) in 2000 and grain sorghum [Sorgham bicolor (L.) Moench] in 2001. Neither Salmonella nor Campylobacter were detected in the litter but the fecal indicator bacteria were. The load of total coliforms, Escherichia coli, and fecal enterococci applied with the litter averaged 1.6E12, 90.4E11, and 5.3E12 cells ha-1, respectively; and the load of estradiol and testosterone averaged 3.1 and 0.09 mg ha-1, respectively. Runoff events first occurred seven months after the first litter application in 2000, and three weeks after the second application in 2001. The concentrations of soil communities of total coliforms and fecal enterococci, but not E. coli, were greater than background levels three weeks after the first litter application. Average background levels of total coliforms, fecal enterococci, and E. coli were 1.7E8, 7.9E7, and 2.9E3 cells kg-1 soil. With the exception of the runoff event three weeks after the second litter application, the levels of fecal indicator bacteria in runoff reflected background concentrations. At the rate of litter application the concentrations of estradiol and testosterone in the litter did not appear to impact the background levels in the soil and runoff. Because concentrations of sex hormones in litter from other broiler operations are known to be greater than the litter we applied, further study on the connection between concentrations of sex hormones in poultry litter and operational practices is recommended.