Monday, November 5, 2007
99-7

Phosphatase Hydrolysis of Soil Organic Phosphorus Fractions.

Irenus A. Tazisong1, Zachary N. Senwo1, Robert W. Taylor1, and Zhongqi He2. (1) Natural Resources & Environmental Sciences, Alabama A&M University, 4900 Meridian St, Normal, AL 35762-1208, (2) USDA-ARS, USDA-ARS-New England Plt Soil Wtr, University of Maine, Orono, ME 04469

Plant available inorganic phosphorus (Pi) is usually limited in highly weathered Ultisols. The high Fe, Al, and Mn contents in these soils enhance Pi retention and fixation. The metals are also known to form complexes with organic phosphorus (Po) compounds. Hydrolyzation of Po compounds is needed for Pi release. The ease with which the Po compounds are hydrolyzed depends on metal-Po complex strengths. Soils amended with poultry litter and inorganic nitrogen fertilizers in cropping systems may lead to the redistribution of Po and Pi concentrations and fractions amongst the metals and organic matter content. Our study was carried out to partition Po and Pi into various fractions, and to study the ease with which each Po fraction is hydrolyzed by various enzymes from different sources. Results from our study showed that the Al associated Po > Fe bound Po > Organic matter bound Po. The Pi was in the order of Fe bound > Al associated > organic matter. The ease with which the various enzymes hydrolyzed the Po will be presented.