While geological phosphate reserves are continually depleting and effective phosphorus (P) recycling methods are still being developed, more efficient fertilisation of P can help to avoid unnecessary losses of this nutrient. In this way, environmental damage resulting from excessive P inputs to agricultural soils could also be reduced. The aim of this study is to identify a P concentration which is optimal for high seed quality of one cultivar of spring wheat and spring barley in addition to possessing a high nutritional value. While a critical threshold at 1.65 mg P/g grain for the studied barley cultivar has been identified, above which germination capacity and power were close to 100%, no such concentration was applicable to wheat. This concentration is well below the widely accepted doctrine, which calls for a P concentration of 2 mg/kg and could thus lead to a lower and thus more efficient use of the nutrient. Furthermore, in this study, an estimation of food quality by the molar ratio of phytate of the two micronutrients iron and zinc illustrates that such a concentration could only be found for zinc but not for iron.