Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 2003
Publication Date: February 15, 2004
Citation: He, Z., Griffin, T.S., Honeycutt, C.W. 2004. Enzymatic and systematic release of hydrolysable organic phosphorus in swine manure and soils. Journal of Environmental Quality. 33:367-372 Interpretive Summary: Organic phosphorus (P) exists in many chemical forms that differ in their susceptibility to hydrolysis and, therefore, bioavailability. Quantifying hydrolysable organic P from various sources may allow improved P management. Several enzymes able to release (hydrolyze) organic P have been used to characterize hydrolysable organic P in soils, animal manure, and other sources. However, experimental conditions and incompleteness in these enzyme systems complicate data interpretation. In this study, we proposed a step by step addition of three enzymes to quantify the various forms of hydrolysable organic P. This procedure allowed us to quantify organic P forms in three soils with different properties and management histories. Further refinement of this approach may provide a universal means to quantify hydrolysable organic P from a wide range of sources, thereby allowing improved P management.
Technical Abstract: Organic phosphorus (Po) exists in many chemical forms that differ in their susceptibility to hydrolysis and, therefore, bioavailability. In this study, we improved the enzymatic hydrolysis approach we previously proposed for characterization of Po in animal manure, and tested its applicability for investigating Po in soils, recognizing that soil and manure differ in numerous physico-chemical properties. We applied 1) acid phosphatase from potato, 2) acid phosphatases from both potato and wheat germ, and 3) both enzymes plus nuclease P1 to identify and quantify simple monoester P, phytate-like P, and polynucleotide-like P, respectively, in 100 mM sodium acetate (pH 5.0). This systematic hydrolysis procedure released Po in sequentially extracted H2O, NaHCO3, and NaOH fractions of swine manure, soils with different cultivation histories, and soils amended with animal manure. The stepwise addition of enzymes minimizes potential errors arising from enzymatic hydrolysis of overlapping substrates. The single pH/buffer conditions reduced background error associated with different pH and buffer systems used in previous research. Additional fine-tuning of the systematic approach may provide a universal tool for evaluating hydrolysable Po from a wide range of sources.