Monday, November 2, 2009
Convention Center, Exhibit Hall BC, Second Floor
Up to 80% of the phosphorus (P) in poultry manure (PM) can be present in organic forms that require mineralization via phosphatase enzymes prior to plant utilization. To determine the correlation between soil P distribution and phosphatase activity we sequentially extracted two Maine soils amended with poultry manure with H2O, 0.5 M NaHCO3, 0.1 M NaOH, and 1.0 M HCl at 0 (control), 100 (PM100), or 200 (PM200) mg manure P per kg soil during 108 days of aerobic incubation. We determined activities of acid (AcPase, pH 6.5) and alkaline (AkPase, pH 11.0) phosphomonoesterase, and phosphodiesterase (PDase), and quantitated inorganic (Pi) and organic (Po) P in each fraction. Correlation between PDase and P fractions was not consistent between soils or treatments and was largely insignificant. Significant positive correlations were found between both types of phosphomonoesterase and Po in NaHCO3- and NaOH-extracts in the low-indigenous P Newport soil with Control and PM100; however, there was no correlation with the high-indigenous P Caribou soil or when
Newport soil was amended with PM200. These observations suggest that Po stimulates phosphomonoesterase activity when soil P levels are low but high Pi concentrations may inhibit activity or decouple this relationship.