SOYBEAN RESPONSE TO AVAILABLE POTASSIUM IN THREE SILT LOAM SOILS.

The range in soil environments has likely contributed to variation in the determination of that level of K availability at which no further yield increase to K is expected. Potassium response of soybean left bracket Glycine max (L. ) Merr. right bracket from three different soil environments was studied in the field to determine if a single index of K availability could be found. Relationships between grain yield, R1-R2 leaf K concentration, ammonium acetate exchangeable K, Ca, Mg, and water soluble K, Ca, and Mg were determined. Determinations of soil solution phase composition may improve our understanding of the role(s) of soil properties on divergent patterns of response to K nutrition.