On Thursday, December 13, 2012 4:07:00 PM UTC-8, Farm1 wrote:
David you may recall that soem time back we had a discussion here on

glyphosate residues - it arose from a post that was made by Sheldon and

where I responded about how it seemed to leave residues that had an impact

on roses. You asked if anyone had seen and 'real' info on any residues.



The Jan/Feb 2013 (and yes, that 2013 date is correct) copy of the ABC

'Organic Gardener' mag has a response from Jerry C-W in the Q and A section

about this very topic and he's given has lots of cites. It seems there is

lots of well researched findings on the residues and he mentions which foods

it can be found in which were grown a year after application.

More message actions
6:18 PM (2 minutes ago)
- show quoted text -
while I have been hanging out in rec.gardens i noticed this question. I haven't researched glyphosate fate in soils directly but I have read some of the literature. glyposate is essentially a phosphonated amino acid. There are many bacterial strains that can completely degrade glyphosate to CO2, phosphate and amino acid. With the right genes bacteria eat glyphosate very well, as a carbon and energy source, as a P source and as an N source. However, in a soil that has not been previously exposed to glyphosate, it will take weeks to months to develop a microbial population that degrades glyphosate. Subsequent applications were found to be degraded quite rapidly and completely, within a week, IIRC.

So whether significant glyphosate would remain in a particular soil would depend on whether the soil had been exposed to glyphosate previously. If it had (within a few years), the soil bacterial population probably would have sufficient copies of the glyphosate degradation pathway (only a couple genes) to degrade the chemical to undetectable.

Also I was under the impression that glyphosate is an effective plant killer only in foliar application, but I may be wrong.

Stuart

PS: Best luck to the Aussies on the list in the threatened zones.