This page was last updated Tuesday, June 07 2005
There are two types of elemental nutrients, mobile and immobile. The former are zinc, molybdenum, magnesium, nitrogen, phosphorus, and potassium. Deficiencies of these elements will cause older leaves to die or experience the effects first as the scarce element is transferred to the newer leaves.
The immobile elements are boron, calcium, copper, iron, manganese, and sulfur. Deficiencies of these elements will cause young leaves to suffer as the element cannot be moved and becomes unavailable for uptake and hence growth.
The aquarium literature is short of information along these lines. Water Plants in the Aquarium by Ines Scheurmann talks about the symptoms of CO2, nitrate, and phosphate excess, as well as CO2, iron, manganese and potassium deficiencies.
Hydroponic Food Production by Howard Resh contains a few pages devoted to the visible signs of deficiencies and toxic levels in both macro and micronutrients. He includes a procedure for narrowing the search for the element out of balance. I think some of it would apply to aquatic plants and when a problem arises in a tank, I look for the symptoms he mentions in his book, not always with success. What little I know, I gleaned from his book and it comes recommended.
A surplus of one element, say manganese, could cause a deficit of iron. Chlorosis caused by a shortage of sulfur turns the leaf pale green; a shortage of iron, yellow. He points out that it is extremely difficult to determine a problem without lab testing, and that deficiencies of two or more elements can result in visible signs quite different from those produced by a lack of either element singly. Also each species of plant reacts in a slightly different fashion. I don't know how much of this applies to us. I may be conjectural at best to attribute specific visual symptoms of land plants to similar problems in aquatics?
Previously I mentioned the division between mobile and immobile elements. Apparently it is not an either/or proposition, as there is some gradation. However, it is a good starting point.
Reference
Resh, Howard M. Hydroponic Food Production (1989), pps. 44-53, Woodbridge Press Publishing Company, P.O. Box 6189, Santa Barbara, CA 93160. (ISBN 0-88007-171-0)
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This page was last updated Tuesday, June 07 2005
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