Micronutrients
The majority of the micronutrients are not mobile in the plant. Deficiency symptoms are usually found on new growth. Their availability in the soil is highly dependent upon the pH and the presence of other ions. The proper balance between the ions present is important as many micronutrients are antagonistic to each other. This is especially true of the heavy metals where an excess of one element may show up as a deficiency of another. If the pH is maintained at the proper level and a fertilizer which contains micronutrients is used once a year deficiency symptoms (with the exception of iron deficiency symptoms) are rarely found on indoor plants. Many of the micronutrients are enzyme activators.
Iron (Fe) Absorbed as Fe++, Fe+++, Not mobile in the plant, Leachable
Boron (B) Absorbed as BO3– , Not mobile in the plant, Leachable
Zinc (Zn) Absorbed as Zn++, Not mobile in the plant, Leachable
Copper (Cu) Absorbed as Cu++, Cu+, Limited mobility in the plant, Very immobile in the soil
Manganese (Mn) Absorbed as Mn++, Not mobile in the plant, Leachable
Molybdenum (Mo) Absorbed as MoO4–, Immobile in the plant, Not leachable
Chlorine (Cl) Absorbed as Cl–, Highly mobile in the plant, Leachable
Nickel (Ni) Absorbed as Ni++. Mobile in the phloem, Not leachable
Cobalt (Co) Absorbed as Co++. Needed by plants recently established, Essential for nitrogen fixation
Little is known about its deficiency or toxicity symptoms.