Manure generated from concentrated animal feeding operations (CAFOs) represents one of the major sources of steroid hormones found in surface water. This paper presents results of a study conducted near Concord, NE to determine the effects of manure handling (compost vs. stockpile), tillage (no-till, plow plus disk and disk), and rainfall timing (24 h and 30 d after manure application (DAT)) on the transport of steroids from row crop fields via surface runoff. Manure was collected following a feedlot study where one set of female cattle were administered growth promoting steroids and mycotoxins and one set received no treatments. Manure was either stockpiled for 9 months or composted prior to application. Twelve of 17 steroids or their metabolites were identified in the manure that was applied at agronomic rates to cropland in a no-till production system for more than 5 years. Chemical analysis of runoff samples detected steroids in less than 50% of the runoff samples and less than 10% of the samples contained more than one individual steroid or mycotoxin. The median concentration of androgens, and progestagens in surface runoff samples decreased by more than 50% between the 1 DAT to 30 DAT sampling dates. The percentage of detections increased between 24-h and 30-d after manure application largely due to increased levels of mycotoxins produced by the Fusarium genus of fungi common to corn fields. In addition, the physical and chemical properties of the steroids result appear to contribute to their long term degradation once applied to the soil. Based on this study, the combination of stockpiling manure prior to application and incorporation into the soil would likely result in the least potential for steroid transport to surface waters
