Most of a crop's phosphorus (P) uptake (>80%) is redistributed to its grain (or tubers) by harvest. So analysis of grain (or tubers) assesses a crop's final P status. Recent research on grain crops in NW Europe has confirmed results of old research which showed that grain P concentrations <0.32% indicate that yield could have been greater with an enhanced soil P supply, achieved by building soil P content. Comparison of soil P analysis with grain P analysis (Fig.2) shows that soil analysis does not reliably predict final crop P status. Many crops grown on soils deemed to have adequate soil P (>16 mg/l) had grain P levels which showed yields could have been increased by building soil P supplies. Hence grain analysis is an essential tool to support management of crop P nutrition, additional to soil P analysis. We estimate that the average loss in profit on crops with grain P <0.32% was ~£2,360/field! Efficiency of P capture from soil is expected to relate to low soil pH, availability of topsoil moisture, and intensity of topsoil rooting, and mycorrhizal associations with topsoil roots.