Re: Cobalt in fertilizer

> From: krombhol at felix_teclink.net (Paul Krombholz)
> >Subject: Cobalt in fertilizer?

> 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
> Azolla.

Hmmm.  My impression is that all life is dependent on vitamin B-12, which 
contains cobalt, and that it is only synthesized by procaryotes.  If 
anyone has information indicating that plants can either roll their own 
B-12 or are not dependent on it, I would be most interested to see it. 

I don't know if N-fixing organisms have additional requirements for
cobalt.  I am aware that nitrogenases require either Mo or V, and other
things like iron that are required by all life.