Water-soluble phosphorus (WSP) in animal wastes has received recent attention because phosphorus extraction by water may closely simulate extraction by rainfall and runoff water in the field. However, no comprehensive study has been conducted on WSP extraction from animal waste. In preliminary work with broiler litter the amount of extracted WSP increased 53% and 18% after changing broiler litter: water ratio from 1:10 to 1:100 and extending shaking time from 2 to 24 h, respectively, whereas acidifying broiler litters and layer manures suspensions to pH 6.0 increased 74 to 134% the amount of extracted WSP. We studied the effects of three shaking times (1, 4, and 24 h), three waste: water extraction ratios (1:10, 1:100 and 1:200), and two pH's (unmodified animal waste pH, and pH 6.0) on WSP and bioavailable phosphorus (BP) in animal waste. Five samples each of broiler litter, layer manure and dairy manure were selected to represent the variability in waste composition. 2-(N-morpholino) ethanesulphonic acid (MES) was used as buffer for pH 6. Total dissolved phosphorus (TDP) was measured by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), Molybdate Reactive Phosphorus (MRP) was determined by the ascorbic acid colorimetric method, and Dissolved Unreactive Phosphorus (DUP) was calculated as the difference between TDP and MRP; BP was estimated from the amounts fixed by iron oxide-impregnated paper strips. It was found that decreasing pH of samples from original pH to pH 6, and increasing the sample to liquid extracting ratio from 1:200 to 1:10 increased the TDP in extracts significantly. However, shaking time did not significantly affect TDP. Detailed information on effects of extraction ratios, shaking times and pH on WSP and BP from animal wastes will be further discussed.