Submitted to: International Journal of Food, Agriculture, and the Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/11/2005
Publication Date: 1/15/2006
Citation: He, Z., Senwo, Z.N., Mankolo, R.N., Honeycutt, C.W. 2006. Distribution of phosphorus species in poultry litter characterized by sequential fractionation coupled with phosphatase hydrolysis. International Journal of Food, Agriculture, and the Environment. v. 4:304-312. Interpretive Summary: The chemical composition of phosphorus in manure significantly impacts its transport and potential bioavailability. Increased knowledge of manure P chemistry is therefore required to optimize recycling of manure P and minimize the adverse environmental effects of animal manure application to cropland. We investigated the distribution of P forms in 23 poultry litters. Findings in this study indicate that, unlike dairy manure which contains more soluble inorganic (bioavailable) P, poultry litters contained about equal amounts of easily bioavailable P and stable P. The stable P species can only be taken up by plants after they have been converted to soluble inorganic P through a series of chemical/biochemical reactions. Thus, poultry litter P applied to cropland may have a slower but longer lasting environmental impact compared to dairy manure. This characteristic must be taken into consideration when developing sustainable P management practices for poultry litter.
Technical Abstract: Increased knowledge of phosphorus (P) chemistry of poultry litter is required to optimize recycling of poultry litter P and minimize the adverse environmental effects of animal manure application to cropland. In this study, the distribution of P forms in 23 poultry litters was investigated with sequential fractionation coupled with orthophosphate-releasing enzymatic hydrolysis. Poultry litters were first sequentially fractionated into water-soluble, bicarbonate-soluble, hydroxide-soluble, and hydrochloric acid-soluble P. Fractions were then enzymatically incubated at pH 5.0 to identify and quantify simple labile monoester P, polynucleotide P, and phytate (myo-inositol hexakisphosphate)-like P, respectively. Inorganic P accounted for an average of 78% of P in water fractions, and 66% of P in bicarbonate fractions. Enzymatically hydrolysable organic P was 5 and 16% of P in the water and bicarbonate fractions, respectively. In hydroxide and acid fractions, 50 to 90% of P was present in organic forms. Among them, 40-70% was phytate-like P and 10-30% was simple monoester P. Findings in this study indicate that poultry litter contained similar amounts of easily bioavailable P (water- and bicarbonate-extracted inorganic P and hydrolyzable organic P) and stable P (hydroxide- and acid-extracted P). Information from such studies may contribute to environmentally sound poultry litter management practices.