Insufficiencies among the micronutrients hydroponically are of raw occurrence. In many situations, micronutrients are being added to nutrient solution formulations at concentrations not needed, the only exception possibly being for zinc (Zn). In many instances, the rooting medium itself may be a primary source of some micronutrients, iron (Fe) in particular. Also, depending on the reagents used to make a nutrient solution formulation, a number of micronutrients may exist as contaminates. Dust can be a major micronutrient source, particularly Fe, therefore that element may not be needed as an addition to the nutrient solution formulation. Chelates of the micronutrients are of no advantage in a solution culture system. Growers should assay a prepared nutrient solution formulation for its elemental content, including the micronutrients, before use, and then make adjustments so that insufficiencies are not likely to occur. An assay after use of a nutrient solution can be used to determine if and what micronutrients are being added to the nutrient solution with use. Based on these assay results, micronutrient additions to a nutrient solution formulation can result in reagent cost savings as well as reduce the potential for an insufficiency, deficiency or excess, from occurring. The major element that has the greatest impact on micronutrient root absorption is phosphorus (P), reducing Zn and enhansing manganese (Mn). Therefore, avoiding P excess is essential in order to minimize the “P effect.”
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