ABSTRACT
The word combination “trace element” was once used to identify those elements that today are called “micronutrients”—B, Cl, Cu, Fe, Mn, Mo, and Zn-elements essential for plants in order to complete their life cycle (see Chapter 12, “Micronutrients Considered Essential to Plants”). Because these elements are found in relatively low concentrations (i.e., less than 0.01% of dry weight in plant tissue), the designation “trace” was considered appropriate at the time of their discovery.
