2008 Joint Annual Meeting (5-9 Oct. 2008): Phosphorus Solubility and Functional Groups in Dairy Feces from Two Farms.
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693-19 Phosphorus Solubility and Functional Groups in Dairy Feces from Two Farms.



Tuesday, 7 October 2008
George R. Brown Convention Center, Exhibit Hall E
Zhengxia Dou1, John Toth1, Jim Ferguson1 and Zhongqi He2, (1)University of Pennsylvania, 382 West Street Rd., Kennett Square, PA 19348-1692
(2)USDA-ARS, University of Maine, New England Plant Soil Water Lab, Orono, ME 04469
The forms of P were examined in fecal samples from two dairy farms. Farm A samples averaged 11,302 mg/kg as total P and 3,979 mg/kg as water extract P, compared to 4,173 mg/kg and 1,456 mg/kg for Farm B samples.  P speciation was determined in extracts of water, 0.025 M NaOH with 50 mM EDTA (NaOH), or 100 mM Na acetate, pH 5.0 plus 20 mg Na dithionite/ml (NaAc) using 31P-NMR.  Water extracted 35% of total P whereas NaOH and NaAc extracted >80% of total P.  The 31P-NMR results suggest that in general water is not an effective extractant as several important P forms (phosphonate, IHP, pyrophosphate, and polyphosphate) were not detected in the extracts but their existence were confirmed in NaOH and NaAc extracts.  However, water extracts had greater amounts of DNA and other diester P than the other two solutions.  This suggests that degradation might have occurred in the alkaline- or acid- based solutions. Regardless of type of extractant, the vast majority of total P in dairy feces existed as orthophosphate. Furthermore, orthophosphate accounted for a higher proportion of total P in the sample from Farm A (82 and 85%) than Farm B (64 and 72%).  
See more of: Nutrient Availability and Environmental Risk from Land Application (Posters)
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