Field and growth chamber studies comparing polyphosphate and orthophosphate fertilizers were conducted with soils of pH 7.2 ‐8.0. Applied P frequently increased grain yields in the field and plant dry matter production in the growth chamber along with P concentrations in the plants. Yield differences between poly‐ and orthophosphate P carriers were not significant. In one growth chamber study, ammonium polyphosphate (APP) produced significantly higher zinc concentrations in corn (Zea maysL.) than did ammonium orthophosphate (AOP) applications. In one field study, APP also produced significantly higher P concentration in grain sorghum (Sorghum bicolor) leaves than did AOP and potassium polyphosphate (KPP). Soil Zn applications usually increased plant Zn concentrations in the field and growth chamber.