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Abstract
Greenhouse and field experiments were conducted to study the effect of potassium (K) salts on chlorosis in soybeans, and the influence of these salts on selected soil properties.
Chlorosis ratings, chlorophyll measurements of soybean leaves and HCO$\sbsp{3}{-}$ of soil saturation extracts were influenced by the companion anions of soil applied potassium (K) salts. (1) The Cl$\sp-$, NO$\sbsp{3}{-}$, and SO$\sb4\sp{2-}$ anions of K reduced visual chlorosis ratings and reduced HCO$\sbsp{3}{-}$ in soil solution. On the other hand, the HPO$\sb4\sp{2-}$ and HCO$\sbsp{3}{-}$ anions increased visual chlorosis ratings, decreased chlorophyll content and enhanced HCO$\sbsp{3}{-}$ levels in soil solution. (2) Soybean seed yields were directly related to chlorophyll concentration of leaves. (3) Chlorophyll concentration of soybean leaves increased with an increase in leaf sulfur concentration. (4) Application of Fe-EDDHA did not affect any of the measured soil variables nor plant nutrient content, but was associated with a 2 to 4-fold increase in leaf chlorophyll concentration. The Fe-EDDHA may therefore affect the mechanism of chlorophyll biosynthesis. (5) Cation/anion ratios in plants ranged from 4.5 to 8.5. Increases in the cation/anion ratios were related to decreases in leaf chlorophyll.
