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Re: Lead, an Important Nutrient

Ooops! I just noticed that in the list of essential and beneficial elements
I posted last night, Cobalt was listed twice. This was a mistake.

I also notice that Sodium is included in the list - it is not listed as
"essential" by Diana Walstad (or, apparently by many others). According to
the article at http://portland.maine.edu/~thomascb/nutri.html, sodium is
involved in osmotic and ionic balance in plants. Phillip Barak (University
of Wisconsin) describes Sodium as one of the "beneficial" elements, rather
than an "essential" one

 Regarding the inclusion of Nickel, Barak says "leguminous plants that
internally transport fixed nitrogen as ureides (natural urea-like compounds)
require Ni (nickel) for the enzyme urease, which is otherwise not required
by nonlegumes.

Barak has an excellent overview of plant nutrition at
http://www.soils.wisc.edu/~barak/soilscience326/. (This was originally
brought ot my attention by Steve Pushak.)

On the subject of "lead", I did find one reference that claimed that lead
can replace calcium in certain reactions but the reaction is unable to
complete itself if lead has been absorbed rather than a calcium ion.
Unfortunately, I can't find the reference again......

James Purchase