Wednesday, November 15, 2006 - 10:30 AM

The Fate of Manure-borne, Land-Applied Hormones.

Francis Casey1, Gerald L. Larsen2, Heldur Hakk2, and Zhaosheng Fan1. (1) North Dakota State Univ, Dept of Soil Science, Fargo, ND 58105, (2) North Dakota State Univ, Animal Metabolism Unit, Bioscience Research Lab, PO Box 5638, Fargo, ND 58105

Natural hormones present in animal manures and applied to land surfaces have the potential to disrupt sensitive organisms. Laboratory incubation, batch, and column experiments were done on a series of soils. Results from the laboratory were used to interpret 3 years of field observations and experiments from a hog (Sus scrofa domesticus) farm. Field observations included subsurface water quality measurements from lysimeters and shallow wells, above which lagoon waste, raw manure, or compost was applied. In general, hormones were strongly bound to soil (Log Koc values were  >2.5 and >1.1 for 17b-estradiol (E2) and testosterone (T), respectively). Sorption was also correlated with organic matter and particle size, where low organic and sandier soils had less sorption. Lab incubation experiments indicated that degradation was primarily microbial. For E2, mineralization occurred under aerobic conditions (degradation rate (k)=0.0006 h‑1), and E2 persisted under anaerobic conditions. For T, transformation occurred under aerobic (k=0.012 h-1) and anaerobic (k=0.004 h-1) conditions. Transport of E2 and T was minimal in both disturbed and undisturbed soil columns. It was expected under field conditions that little or no hormones would be present in the subsurface water; however, peak concentrations detected in the lysimeter leachate (depth=0.6 m) ranged from 5–1000 ng L-1 and 2–10 ng L-1 for E2 and T, respectively. Peak well concentrations of E2 and T ranged from 1–70 ng L-1 and 1–76 ng L-1, respectively. This field soil, a Hamar typic Endoaquoll, is sandy with high water table fluctuations and periodic anaerobic conditions. The peak detections of hormone corresponded to high water table and high flux conditions. During low water table periods there were no detections of hormones in the lyimeters or wells. It was hypothesized that lagoon waste injected into the sandy soil had the potential to persist under anaerobic conditions and be mobile.