Re: Aquatic Plants Digest V2 #422

>Subject: Cobalt in fertilizer?
>I've noticed some people suggesting there be some cobalt available for
>aquatic plants.
>Is this really the case and if so what levels are optimal and what levels
>are toxic? What are cobalt deficiency symptoms if any? I was always under
>the impression that cobalt is more toxic than copper, but then again I'm
>not a chemistry student.

Cobalt is known to be needed in trace amounts by nitrogen fixing organisms,
so it would be useful for legumes, like beans, alfalfa, and clover, and a
few non-legume plants that have a symbiotic relationship with nitrigen
fixing bacteria.  Other than that, plants are not known to have a
requirement for cobalt.  Since no aquarium plants that I know of have
symbiotic N-fixing bacteria except Azolla, I wouldn't worry about adding
cobalt, unless you are having a nitrogen deficiency problem with your

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174
In warm, sunny Jackson, Mississippi, where we may break a high temperature
record tomorrow.