Research Bulletin (Iowa Agriculture and Home Economics Experiment Station)


Yield responses of soybeans [Glycine Max (L.) Merrill] to phosphorus and potassium fertilizers have the reputation of being small and inconsistent unless the soil tests low to very low with respect to these elements. Consequently, soybean fertilization is commonly left to the residual effect of fertilization of other crops in the rotation such as corn. Field experiments were conducted with the general objective to investigate means whereby the magnitude and consistency of soybean responses to fertilization may be improved.

Differential responses exist in corn. Jones (18) concluded that some inbred lines have a lower K requirement than others and also are more sensitive to high K levels. Differential responses among soybean varieties may be studied in a side-by-side comparison in fertilizer trials, and measurement of differential responses among four varieties was the primary objective of this work.



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