Zinc deficiency in corn has been found in isolated instances in Kentucky during the past few years. Usually the deficiency is found in fields having a high pH or in high-phosphate soils with somewhat lower pH values. At present zinc deficiency in Kentucky soils does not appear widespread enough to justify recommending its application except where known deficiencies exist.
Miller, H. F.; Phillips, S. H.; and Wyatt, C. E., "Field Trials with Zinc on Corn" (1963). Agronomy Notes. 93.