Precipitation of plant available P by Ca from alkaline-stabilized biosolids and manure can reduce P phytoavailability. Phytoavailability of P in soils amended with alkaline-stabilized East Lansing biosolids cake and swine manure were investigated in a three-year field study. East Lansing N-viro soil (ELNVS) and swine NureSoil (SNS) were surface applied once to a sandy loam soil in October, 2001 at three rates each; 18, 130 and 269 Mg ha^-1 for ELNVS, and 29, 58 and 224 Mg ha^-1 for SNS plus an untreated control. The seven treatments were replicated four times and amendments were disked and then chisel plowed to incorporate the treatments into the top 15 cm of soil on each plot (9.2 m x 15.2 m). Each plot was split into two equal areas and the subplots (4.6 m x 15.2 m) each cropped with field corn (Zea mays L.) and soybeans (Glycine max L.) in 2002, 2003 and 2004 growing seasons. The ELNVS treatments increased soil Ca and Mg concentrations and pH, but SNS did not. Soil CaCl₂-extractable P and Bray P1 were reduced with increasing rate of ELNVS, but SNS did not reduce phytoavailable P. Plant P concentrations and uptake were reduced by ELNVS and increased by SNS as application rates increased. Therefore, the SNS was shown to be a P-source, while the ELNVS was a P-sink and reduced P phytoavailability.