Supernatant solution phosphorus concentrations required by five soybean (Glycine max) cultivars

Abstract Dry matter yields at flowering and seed yield responses of five soybean cultivars (Bragg, Semstar, Flegler, Davis and Wills) to six soil phosphorus levels in an Oxic Paleustalf were determined in a pot experiment. Ninety percent maximum dry matter yield at flowering was attained at the following supernatant solution P concentrations (determined from P sorption curves): Bragg, 0.012 μg ml‐1; Davis, 0.009 μg ml‐1; Semstar, 0.010 μg ml‐1; Flegler, 0.011 μg ml‐1; Wills, 0.012 μg ml‐1. Ninety percent maximum seed yield was attained at a supernatant solution P concentration of 0.007 μg ml‐1 by Bragg, Semstar, Flegler and Wills. Davis required 0.011 μg P ml‐1 for 90% maximum seed yield. It is concluded from these results that Bragg, Semstar, Flegler and Wills will have similar phosphorus fertilizer requirements, but Davis will require larger additions of phosphorus than the other cultivars for maximum seed yield.