Table 9 outlines current DTPA soil test interpretations for these three micronutrients. Iron, copper and manganese soil test interpretations. Foliar sprays of 0.5 to 3.0 pounds of iron per acre are the most effective. Soil applications are not as consistent in correcting iron deficiencies. Applying farmyard manure best achieves long-term correction.
Copper is least likely to show up as a deficiency on our mineral soils in Missouri.
Foliar applications according to manufacturer suggestions should be adequate. Foliar or band applications of manganese at 1 to 2 pounds of manganese per acre should correct deficiencies that may occur. No soil tests for boron or molybdenum are currently offered by the University of Missouri. In Missouri, apply boron annually to alfalfa at a rate of about 1 pound of boron per acre to avoid deficiency. Liming soils to a salt pH of 5.5 or greater should avoid any potential deficiency of molybdenum on any crop grown in Missouri.