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Phosphorus Speciation in Broiler Litter and Turkey Manure Produced from Modified Diets
Author(s) -
Toor Gurpal S.,
Peak J. Derek,
Sims J. Thomas
Publication year - 2005
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2005.0687
Subject(s) - phytase , hydroxylapatite , broiler , chemistry , fractionation , phytic acid , phosphate , phosphorus , manure , zoology , nuclear chemistry , environmental chemistry , agronomy , food science , biochemistry , chromatography , biology , organic chemistry , enzyme
ABSTRACT Modifying poultry diets by reducing mineral P supplementation and/or adding phytase may change the chemical composition of P in manures and affect the mobility of P in manure‐amended soils. We studied the speciation of P in manures produced by broiler chickens and turkeys from either normal diets, or diets with reduced amounts of non‐phytate phosphorus (NPP) and/or phytase, using a combination of chemical fractionation and synchrotron X‐ray absorption near edge structure (XANES) spectroscopy. All broiler litters were rich in dicalcium phosphate (65–76%), followed by aqueous phosphate (13–18%), and phytic acid (7–20%); however, no hydroxylapatite was observed. Similarly, normal turkey manure had 77% of P as dicalcium phosphate and had no hydroxylapatite, while turkey manure from diets that had reduced NPP and phytase contained equal proportions of dicalcium phosphate (33–45%) and hydroxylapatite (35–39%). This is attributed to the higher total Ca to P ratio (>2) in modified turkey manures that resulted in transformation of more soluble (dicalcium phosphate) to less soluble P compounds (hydroxylapatite). Chemical fractionation showed that H 2 O‐extractable P was the predominant form in broiler litter (56–77%), whereas aqueous phosphate determined with XANES was <18% indicating that H 2 O probably dissolved mineral forms of P (e.g., dicalcium phosphate). Results show that HCl extraction primarily removed phytic acid from broiler litters and normal turkey manure, while it removed a mixture of hydroxylapatite and phytic acid from modified turkey manures. The combination of chemical fractionation and XANES provided information about the nature of P in these manures, which may help to devise best management practices for manure use.