The effect of potassium on iron chlorosis in calcareous soils

Abstract
Potassium fertilization at rates of 135 to 405 mg K / kg soil ameliorated iron chlorosis in peanuts grown in an extremely calcareous soil (63% CaCO3); such treatments doubled and tripled chlorophyll contents. Potassium availability in soils was important in achieving this effect. K2SO4 was found to be more effective than KCl. These results are attributed to the cation‐anion balance of ion uptake and consequent rhizosphere acidity.