Twenty‐nine soil samples representing 12 soil series and varying levels of P fertility were obtained from cooperating agricultural experiment stations in the southern U.S. Fertilizer P requirements were estimated from P sorption curves and correlated with P requirements established by field experiments. Estimated and measured P requirements were highly correlated (r =0.93**) with the quantitative relationship being nearly 1:1. With one exception, P sorption also accurately estimated needs of fertilized soils; in that one case, fertilizer needs were estimated at 45 kg P/ha although there was no response to P in the field.