Micronutrients or minor elements are required by plants in very small quantities, usually less than a pound per acre per year. This does not diminish their importance. Although micronutrient deficiencies or toxicities are not widespread in Wisconsin, they can occur and reduced growth or crop failure can result. Toxicities can also occur since several of these elements have rather narrow ranges between deficiency and toxicity levels.

In the past several years, increased interest has been shown toward the micronutrients due to: (1) accumulation of more information regarding needs and plant responses; (2) induced deficiencies from higher crop yields; (3) greater removal from long-time cropping; (4) greater concern over crop quality and nutritional value; and (5) a better understanding of disease and other nutrient interactions.