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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
((http://www.soils.wisc.edu/~barak/soilscience326/ambig.htm).
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
Toronto