Dynamics of ryegrass P in red soils

An investigation on the dynamics of transformation of P from ^32P-labelled ryegrass in red soils was conducted in laboratory.The results showed thast the rapid increase in flush ^32P related with biomass P was accompanied with the decrease in extractable ^32P on the first 3d of incubation in both sandy and clayey soils,and afterwards,itdisplayed great fluctuation in sandy soil,but hadlittle fluctuaston in clayey soil during 3-20d of incubation.At the later stage of incubation,the increase in extractable ^32P was accompanied with decrease in flush ^32P.The opposite changes in content of extractable ^32P and flush ^32P suggested transformation of ryegrass P was clkosely related to its utilization and its release from microorganisms in red soils.It can be concluded that addition of organic matter accelerated the release of soil native P according to the changes in the extractable soil P during incubation.