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Old 08-10-2003, 03:02 PM
Neil Jones
 
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Default Glyphosate & its side effects

Martin Brown wrote:

In message , Neil Jones
writes

You are being hoisted on your own petard. You continually repeat a
statement which is OBVIOUSLY not truthfull. Glyphosate is not
necessarily inactivated on contact with soil. There are several
studies which show this and I have posted references before. You don't
need studies to show this because it is an OBVIOUS conclusion from the
nature of the chemistry involved.


Whilst there are some "soils" where glyphosate is not immediately bound
up. They are in general so utterly infertile that you aren't likely to
be using weedkiller on them in the first place.

Glyphosate and for that matter several other common weedkillers are very
tightly bound to clays and/or organic material in soils on first contact
and so physically deactivated. The destruction of the molecule takes
longer but the stuff is very effectively tied up on hitting the ground.


I am afraid you are quite wrong on your science. You appear not to have
a proper
understanding of the processes involved. If it were to be as tightly
bound
as you claim then id would not be degrated. Basically it appears that it
is
bound rather as phosphate is by adsorption onto the surface of certain
materials.
In fact it pops on and off and the soil doesn't have to be that poor for
a diminution
of growth to be observed.

This is what just one study says.

" Although glyphosate is commonly thought to exhibit no residual
activity, recent field work with tomatoes has shown that phytoactive
residues can persist, at least in sandy soils. Adsorption may also be
low, and phytoactivity high, in soils with a low unoccupied P-sorption
capacity. This paper reports experiments designed to re-assess the
threat of glyphosate residues to crop plants.

http://www.regional.org.au/au/asa/19...636cornish.htm

So it may depend on the amount of phosphate present. Very fertile soils
may have a lot and therefore it is not adsorbed.


It *has* to hit green plant material to work.


You keep going on about green plants as if this is something
significant.

You said previously,

"It is extremely specific to green plants that
are conducting photosynthesis."

I think this demonstrates that you don't understand the issue.
Glyphosate or
N-phosphonomethylglycine, to give its chemical name, does not have a
direct effect on
photosynthesis and also affects other non-photosynthetic organisms.

N-phosphonomethylglycine works by blocking the action of an enzyme
called 5-enolpyruvylshikimate-3-phosphate synthase which catalyses an
imporant step in the production of amino acids.

This metabolic pathway is NOT exclusive to photosythetic organisms and
occurs in a wide range of other creatures. For example it does occur
in the bug that causes malaria.

I certainly cannot judge the validity of whether Glyphosate is safe or
not on what you are saying.





Whilst I don't necessarily concur with the original posters
conclusion, It is not a good idea for you to poke fun and call people
clueless when you post things which, to me at any rate, look as if it
is YOU who does not understand the processes at work.


Likewise.

Regards,
--
Martin Brown


--
Neil Jones- http://www.butterflyguy.com/
"At some point I had to stand up and be counted. Who speaks for the
butterflies?" Andrew Lees - The quotation on his memorial at Crymlyn Bog
National Nature Reserve