ENZYMATIC MINERALIZATION OF ORGANIC PHOSPHORUS IN A VOLCANIC SOIL IN CHILE

A better understanding of organic- inorganic phosphorus transformations is needed to improve management of phosphorus fertilization of cultivated soils. This study was conducted to determine if the mineralization of organic phosphorus compounds in a soil could be induced enzymatically and observed using Phosphorus-31 Nuclear Magnetic Resonance Spectroscopy (P-31 NMR). Samples of an Osorno series (Typic Dystrandept) soil were sterilized using gamma radiation, then incubated with alkaline phosphatase, acid phosphatase, phosphodiesterase, and phytase. Soil extracts were prepared using 1.0 M KOH, then treated with a cation exchange resin to remove interfering paramagnetics. P-31 NMR analysis of untreated and treated soil extracts showed a decrease in phytic acid and a corresponding increase in orthophosphate for the phytase-treated sample. Results indicate that soil organic P is mineralized enzymatically and that the NMR technique is useful for studying mineralization in soils having sufficiently high levels of organic P.