Characterisation of soil phosphorus forms in the soil-plant system using radioisotopic tracer method

Soil incubation and pot experiments were conducted to follow the sorption processes of added phosphorus (P) fertiliser using radioisotope tracer technique. Increasing doses P (40, 80, 160, 320 mg P/kg soil) Chernozem Arenosol incubated for 1, 3, 13 weeks. After incubation, perennial ryegrass (Lolium perenne L.) was sown in one group pots, experiment had been continuing another 9 The yield, grass uptake, isotopically exchangeable (PIE), water-soluble (PW), ammonium lactate soluble (PAL) fractions soils measured. On Chernozem, plant PIE, PW PAL significantly less case longest period compared shorter incubations. This suggests a transformation into tightly sorbed form. Arenosol, there only small changes parameters as increased, suggesting intense PW/PIE ratio enhanced with increasing P-doses, ratios higher on Arenosol. caused greater increase than Chernozem. PIE + showed good correlation uptake proving this value can be indicator plant-available phosphorus.