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This article in JEQ

  1. Vol. 36 No. 4, p. 1086-1095
    Received: Dec 19, 2006

    * Corresponding author(s): Zhongqi.He@ars.usda.gov
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Comparison of Phosphorus Forms in Wet and Dried Animal Manures by Solution Phosphorus-31 Nuclear Magnetic Resonance Spectroscopy and Enzymatic Hydrolysis

  1. Zhongqi He *a,
  2. Barbara J. Cade-Menunb,
  3. Gurpal S. Toorc,
  4. Ann-Marie Fortunaa,
  5. C. Wayne Honeycutta and
  6. J. Thomas Simsd
  1. a USDA-ARS, New England Plant, Soil, and Water Lab., Orono, ME 04469
    b Geological and Environmental Sciences, Stanford Univ., Stanford, CA 94305
    c Biological and Agricultural Engineering, Univ. of Arkansas, Fayetteville, AR 72701
    d Dep. of Plant and Soil Sciences, Univ. of Delaware, Newark, DE 19716


Both enzymatic hydrolysis and solution 31P nuclear magnetic resonance (NMR) spectroscopy have been used to characterize P compounds in animal manures. In this study, we comparatively investigated P forms in 0.25 M NaOH/0.05 M EDTA extracts of dairy and poultry manures by the two methods. For the dairy manure, enzymatic hydrolysis revealed that the majority of extracted P was inorganic P (56%), with 10% phytate-like P, 9% simple monoester P, 6% polynucleotide-like P, and 18% non-hydrolyzable P. Similar results were obtained by NMR spectroscopy, which showed that inorganic P was the major P fraction (64–73%), followed by 6% phytic acid, 14 to 22% other monoesters, and 7% phosphodiesters. In the poultry manure, enzymatic hydrolysis showed that inorganic P was the largest fraction (71%), followed by 15% phytate-like P and 1% other monoesters, and 3% polynucleotide-like P. NMR spectroscopy revealed that orthophosphate was 51 to 63% of extracted P, phytic acid 24 to 33%, other phosphomonoesters 6 to 12%, and phospholipids and DNA 2% each. Drying process increased orthophosphate (8.4% of total P) in dairy manure, but decreased orthophosphate (13.3% of total P) in poultry manure, suggesting that drying treatment caused the hydrolysis of some organic P to orthophosphate in dairy manure, but less recovery of orthophosphate in poultry manure. Comparison of these data indicates that the distribution patterns of major P forms in animal manure determined by the two methods were similar. Researchers can utilize the method that best fits their specific research goals or use both methods to obtain a full spectrum of manure P characterization.

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