Zinc deficiencies is a concern in southern Illinois. Studies have been conducted periodically over the years in Illinois on the need of zinc (Zn) by agronomic crops. However, an in-depth evaluation of the need for and response to zinc by corn and soybean has not been conducted in southern Illinois for over 24 years. A survey of farm fields for soil test zinc in seven southern Illinois counties found most fields had levels that were at or above sufficiency for most crops. Considerable variability in zinc soil test values was found within any one field. No particular soil characteristic or morphological feature could be attributed to the variability. In a study to determine the responsiveness of corn to zinc, four field sites were chosen that had areas that tested low or marginally sufficient for soil test zinc levels. Zinc was applied as two sources (ZnSO4 or MicroPel) at rates of 0, 2.5, and 5.0 lb Zn/ac. Even though low testing sites were chosen, corn response to applied zinc was mostly non-significant. A significant yield response to zinc was observed at only one location. Soil tests for zinc after harvest revealed that test values increased as a result of the applied zinc. The magnitude of the zn-soil increase was not affected by source type applied.
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