A number of studies have used NMR to characterize soluble organic phosphorus in animal waste. However, most of the work up to date has focused on characterization of organic P that is extracted using concentrated NaOH or EDTA/NaOH. Little information is available on water dissovled organic phosphorus (DOP) species in animal wastes. Our previous research on poultry wastes has shown that the concentration of DOP can increase between 70% and 30 times depending on the type of waste when extracted at pH 6 compared to extraction at the unmodified pH of the waste. In this research we used NMR to characterize DOP extracted from broiler litter and layer manure at two pH levels: original pH measured in deionized water, and pH 6. Extracts were freeze dried and subsequently redissolved in deuterium oxide. The 31P-NMR spectra were acquired on a Varian Inova 500 MHz spectrometer (11.75T; 202.5 MHz for 31P) without proton decoupling. An acquisition time of 0.8s, delay time of 5s, 450 pulse and 4000 scans were used in this experiment. Our 31P NMR study demonstrated that monoester is the main DOP species in layer manure at original pH. Speciation of DOP under pH 6 in our samples will be further discussed.