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Title: Hormone and pathogen content in soil after litter applications

item Jenkins, Michael

Submitted to: Poultry Waste Management Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/30/2010
Publication Date: 10/26/2010
Citation: Jenkins, M. 2010. Hormone and pathogen content in soil after litter applications. 2010 National Poultry Waste Management Symposium, October 26-28, 2010, Greensboro, North Carolina.

Interpretive Summary: Millions of tons of poultry litter are applied as fertilizer to cropped and pasture lands. The potent gender regulating hormones estradiol and testosterone, and fecal bacteria are components of this litter. When applied as fertilizer the hormones and fecal bacteria become soil constituents that can be transported via surface and subsurface water during rain events with runoff. Knowing the changes in soil concentration of the hormones and fecal bacteria after litter applications is important for determining when these potential contaminants might impact environmental and human health. A summary of published results from research performed by ARS scientists at Watkinsville and Tifton Georgia and the University of Georgia on the fate and transport of these hormones and fecal bacteria are presented. When poultry litter was applied at agronomic rates commensurate with the phosphorus and nitrogen requirement of a crop or pasture then increases in soil hormone concentrations greater than background concentrations decreased to background levels after a few days or no increase was observed at all. Concentrations of fecal bacteria greater than background concentrations appeared to impact surface water only if a runoff event occurred shortly after a litter application.

Technical Abstract: Poultry litter applications at agronomic rates established for a crop’s P or N requirements may contain as much as 385 mg estradiol ha-1, 605 mg testosterone ha-1, 4.4(10)12 Escherichia coli cells ha-1, and 4.4(10)13 fecal enterococci cells ha-1. Field experiments from small plot- to small watershed-scale have indicated that litter applications appeared not to increase background soil concentrations of either hormone. Litter applications can increase soil concentrations of fecal bacteria, but this increase appears to increase loads of fecal bacteria in runoff greater than background only if rain events occur shortly after an application.