Abstract
The comparative availability to Lolivm perenne of 32P myo‐inositol hexaphosphate (IH32P) and KH2 32PO. added to soil could be determined unequivocally from the 32P count of leaf material even when dry matter yields and total P content were not significantly different from the control. IH32P was equivalent to KH2 32PO4. in a soil with a low P retention at 200 p.p.m. P but not at 20 p.p.m. P. IH 32P was totally unavailable in two soils with high P retention at 200 p.p.m. and 20 p.p.m. P, whereas uptake of KH2 32PO4. was observed in each instance.