Aqueous suspensions of poultry manure are usually alkaline. Previous research has shown that the top 1.0-cm of soils and the thatch of pastures in NE Georgia have a pH around 6.0, and that broiler litter pH decreases to soil/thatch values within a month after its application. Phosphate solubility increases with acidification so determining soluble P at an alkaline pH may underestimate what would be released after application. The objective of this study was to find suitable buffers for P extraction from poultry manure at pH 6.0. Samples of four broiler litters and two layer manures with contrasting P contents were selected. Molybdate reactive phosphorus (MRP) and dissolved unreactive phosphorus (DUP) were determined in extracts obtained with deionized water, nine buffers [acetate, N-(2-Acetamido)-2-aminoethansulphonic acid (ACES), N-(carbamoyl-methyl) iminodiacetic acid (ADA), Bis(2-hydroxyethyl)imino-tris(hydroxymethyl) methane (Bis-tris), 1,4 piper azine-bis-(ethane sulphonic acid) (PIPES), 2-(N-morpholino) ethanesulphonic acid (MES), potassium hydrogen phthalate (KHP), imidazole and cacodylate] at pH 6.0 in 0.01 M concentrations, and from suspensions titrated with 0.5N HCl to end pH 3, 4, and 6. MRP and DUP extractions at pH 6.0 were markedly higher than without acidification, although responses differed among wastes. MRP concentrations almost doubled in high-P broiler litter and layer manure. DUP increases ranged from 70% in the high-P layer to almost 30 times in the low-P broiler. MES was the most promising buffer because its results were comparable to those obtained with HCl indicating effects on extractable P essentially through acidification. Results suggested also that several buffers acted both through pH reduction and preferential binding of cations originally bound to organic P forms. In addition, MES did not interfere with MRP colorimetric determination.