ENZYMATIC MINERALIZATION OF ORGANIC PHOSPHORUS IN A VOLCANIC SOIL IN CHILE

A better understanding of organic- inorganic phosphorus transformation s is needed to improve management of phosphorus fertilization of culti vated soils. This study was conducted to determine if the mineralizati on of organic phosphorus compounds in a soil could be induced enzymati cally and observed using Phosphorus-31 Nuclear Magnetic Resonance Spec troscopy (P-31 NMR). Samples of an Osorno series (Typic Dystrandept) s oil were sterilized using gamma radiation, then incubated with alkalin e phosphatase, acid phosphatase, phosphodiesterase, and phytase. Soil extracts were prepared using 1.0 M KOH, then treated with a cation exc hange resin to remove interfering paramagnetics. P-31 NMR analysis of untreated and treated soil extracts showed a decrease in phytic acid a nd a corresponding increase in orthophosphate for the phytase-treated sample. Results indicate that soil organic P is mineralized enzymatica lly and that the NMR technique is useful for studying mineralization i n soils having sufficiently high levels of organic P.