Field and Growth‐Chamber Evaluations of Potassium Polyphosphate

Abstract

Abstract Results of field and growth chamber investigations indicate that potassium polyphosphate (KPP) is as effective as ammonium orthophosphate (AOP), ammonium polyphosphate (APP), and triple superphosphate (TSP) as a P source for corn ( Zea mays L.) and grain sorghum ( Sorghum bicolor L.). At one field site, on a soil high in total Fe, low P availability early in the growing season from both KPP and APP limited crop response. Field investigations of banded applications of KPP and AOP in direct contact with wheat ( Triticum aestivum L.) and grain sorphum seed had little effect on seedling emergence. In a growth chamber, however, a high P rate as banded AOP retarded dry‐matter yield of grain sorghum. Application of large amounts of P as KPP, AOP, APP and TSP to corn in the presence of low available Zn significantly reduced Zn concentrations in the plants but there was no significant difference in the effects of the various P carriers.