The concentrations of available phosphorus and H2PO4−activities were determined with depth in a silty clay soil receiving 40 kg P ha−1yr−1(surface broadcast with no incorporation on brome sod) for 20 or 40 yr. The soil was sampled in increments to a depth of 3.0 m. Available P, by the Bray and Kurtz P-1 method, and H2PO4−activities, from total solubilities in 0.01MCaCl2extracts, were determined. Available P was found to be greater in fertilized soils than in the unfertilized control soil to a depth of 45 cm. Similarly, Bray-P concentrations were greater to a depth of 30 cm in soils receiving continuous fertilization than soils in which fertilization was stopped after the first 20 yr. The activity of H2PO4−was strongly dependent on soil depth, P fertilization, and soil pH. Measured H2PO4−activities showed only weak correspondence to solid phase solubilities, but a short equilibration time and a lack of Al3+activity data made the comparison incomplete. Available P and H2PO4−activities were correlated when both were high, but there was no correlation when Bray-P concentrations were less than 13 mg P kg−1. The high activities in the soil extracts indicate that leaching of inorganic P may have a major role in the translocation of P, but the role of highly mobile organic P compounds could not be discerned from the present data.