Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 9/10/2004
Publication Date: 11/4/2004
Citation: He, Z., Dao, T.H., Honeycutt, C.W. 2004. Release of insoluble organic phosphate in animal manure by phytase under reducing conditions. American Society of Agronomy Meetings. Seattle, WA. November 2004. CD-ROM Interpretive Summary:
Technical Abstract: Increased understanding of manure P chemistry is needed because the physicochemical properties of manure P influence its bioavailability and transport in the environment. After removal of soluble phosphate, poultry litter and dairy manure solids were incubated with the reducing agent sodium dithionite and/or 3-phytase to identify the water-insoluble manure P fraction. Either dithionite or 3-phytase alone released significant amounts of insoluble P in poultry litter. Dithionite alone did not increase P release from dairy manure residues. Maximum P release was observed in both manure solids by combining dithionite and 3-phytase. Elemental analysis showed that the increased P release was related to the reduction of Fe(III) to Fe(II) by dithionite, increasing the solubility of Fe-inorganic and -organic P compounds. 3-Phytase further hydrolyzed soluble Fe(II)-organic P. The data suggested that poultry litter contained both insoluble Fe-organic and -inorganic P compounds. Insoluble Fe-P in dairy manure was mainly present in organic forms. These data indicate that changes in the chemical and biological environments of manure, such as anaerobic conditions and enzymatic activity, can influence manure P solubility and therefore bioavailability.