ThetransformationoforganicP(Po)fromorganicmanuresintwotypesofsoils(ultisolandentisol)andtheinfluencesofexternaladditionoforganicsubstanceorinorganicP(Pi)onPoundertheconditionofthe60%maximumwatercapacitywereinvestigated.TheresultsobtainedfromPofractionationexperimentsindicatedthatallthePofractionsexceptforthehighlyresistantPofractiondecreasedduringincubation.ApplicationofpigfecesandcowfecescouldlargelyincreaseeachfractionofPointhesoils.ImmediatelyafterapplicationoforganicmanureintothesoilsalargepartoflabileandmoderatelylabilePofromorganicmanurewastransferredintomoderatelyresistantPo,whichmightbeduetothefactthatCa-orMg-inositolPwasprecipitatedintoFe-inositolP.However,theavailabilityofPofromorganicmanureinthesoilswouldincreaseagainafterincubationbecauseofthetransformationofmoderatelylabileandresistantPofractionsintolabilePofractions.AdditionofcelluloseorPiintothesoilsshowedagoodeffectonincreasingallthePofractionsexceptforthehighlyresistantPo,andthiseffectwasmuchmorepronouncedwhencellulosewasappliedincombinationwithPi.Therefore,inviewoftheeffectoforganicmanureonimprovingPnutritiontoplant,attentionshouldbepaidtoboththePoandtheorganicsubstancesfromorganicmanure,ItissuggestedthatapplicationofPifertilizercombinedwithorganicmanuremaybereferredtoasaneffectivemeansofprotectingPifromchemicalfixationinsoil.
