Title: Comparison of Phosphorus Forms in Wet and Dried Animal Manures by Solution Phosphorus-31 Nuclear Magnetic Resonance Spectroscopy and Enzymatic Hydrolysis Authors
|Cade-Menun, Barbara - STANFORD UNIVERSITY|
|Toor, Gurpal - UNIV OF ARKANSAS|
|Fortuna, Ann Marie|
|Sims, J Thomas - UNIV OF DELAWARE|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 21, 2007
Publication Date: May 25, 2007
Citation: He, Z., Cade-Menun, B.J., Toor, G.S., Fortuna, A., Honeycutt, C.W., Sims, J. 2007. Comparison of Phosphorus Forms in Wet and Dried Animal Manures by Solution Phosphorus-31 Nuclear Magnetic Resonance Spectroscopy and Enzymatic Hydrolysis. Journal of Environmental Quality. 36:1086-1095 Interpretive Summary: Increased understanding of manure phosphorus (P) composition is needed for developing best management practices to optimize recycling of manure P while minimizing the adverse environmental effects of animal manure application. Both enzymatic hydrolysis and solution 31P nuclear magnetic resonance (NMR) spectroscopy have been used to characterize P compounds in animal manures. However, no comparison of the two methods has been reported in the literature. Thus, it is not clear to what degree the P forms identified by the two methods are similar. In this work, we analyzed the P forms in dairy and poultry manure, quantitatively comparing the similarities and differences between the two methods. Comparison of the two sets of data indicated that the patterns of P distribution in animal manure determined by the two methods were similar with a correlation coefficient of 0.93. Therefore, it is acceptable to compare P data obtained by the two methods although some discretion should be applied. As each method had its advantages and disadvantages and the P forms detected by the two methods are not always the same, we recommend researchers either choose the most appropriate method for their specific research goals, or use both methods to more fully characterize P in the manure.
Technical Abstract: Both enzymatic hydrolysis and solution 31P nuclear magnetic resonance (NMR) spectroscopy have been used to characterize P compounds in animal manures. However, no comparison of the two methods has been reported in the literature. In this study, we compared P compounds in dairy and poultry manures identified by enzymatic hydrolysis and NMR spectroscopy. For the dairy manure, enzymatic hydrolysis revealed that the majority of extracted P was inorganic P (56%), with the remainder organic P (10% phytate-like P, 9% simple monoester P, 6% polynucleotide-like P) and non-hydrolyzable P (18%). Similar results were obtained by NMR spectroscopy, which showed that inorganic P was the major P fraction (64-73 %), followed by orthophosphate monoesters (phytic acid: 6%; other monoesters: 14-22%) and orthophosphate diesters (phospholipids: 6%; DNA: 1%). Phosphonates, pyrophosphate and polyphosphates were 1% each. In the poultry manure, enzymatic hydrolysis showed that inorganic P was the largest fraction (71%), followed by monoesters (phytate-like P: 15%, monoester P: 1%) and diesters (polynucleotide-like P: 3%), with the remainder as non-hydrolyzable P (9%). Using 31P NMR, orthophosphate was 51-63% of extracted P, phytate was 24-33%, other orthophosphate monoesters were 6-12%, and phospholipids and DNA were about 2% each. Comparison of these data indicates that the patterns of P distribution 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.