Thank you for requesting me to answer your question.
I've re-posted the original material posted in clarifications and
comments - and below that you'll find more information that might be
helpful to you.
Bermuda is dead
See second Q. and A.
Herbicide Injury to Yard and Garden Plants
Inactivation Activated Charcoal
"Most soil-active herbicides can be inactivated or absorbed by
applying activated charcoal at a rate of 1 to 2 lbs. per 100 sq. ft.
and incorporating it to a depth of 6 inches. Early treatment is
essential to prevent the movement of herbicide deeper into the
"In some cases, it may be necessary to completely remove the
contaminated soil and replace it with clean soil. Be absolutely sure
that the injury is the result of herbicide contaminated soil before
resorting to this costly procedure."
Glyphosate Factsheet (2 pages)
see Figure 6 Persistence or Glyphosate in U.S. Agricultural Soil Map of US.
"Note: Numbers, as well as the length of the columns, give the
half-life, in days, of glyphosate in soil. Half-life is the length of
time required for half the applied glyphosate to break down or move
out of the test site.
Source: U.S. EPA. Environmental Fate and Effects Division. 1993.
Pesticide environmental fate one line summary; Glyphosate. Washington,
D.C., May 6.
Glyphosate's persistence in soil varies widely, but its half-life in
agricultural soil can be over 4 months."
Persistence and Movement in Soil
"Glyphosate's persistence in soil varies widely, so giving a simple
answer to the question "How long does glyphosate persist in soil?" is
not possible. Half-lives (the time required for half of the amount of
glyphosate applied to break down or move away) as low as 3 days (in
Texas) and as long as 141 days (in Iowa) have been measured by
glyphosate's manufacturer. (See Figure 6.) Initial degradation
(breakdown) is faster than the subsequent degradation of what remains.
Long persistence has been measured in the following studies: 55 days
on an Oregon Coast Range forestry site: 249 days on Finnish
agricultural soils; between 259 and 296 days on eight Finnish forestry
sites; 335 days on an Ontario (Canada) forestry site; 360 days on 3
British Columbia forestry sites; and, from 1 to 3 years on eleven
Swedish forestry sites. EPA's Ecological Effect's Branch wrote, "In
summary, this herbicide is extremely persistent under typical
Glyphosate is thought to be "tightly complexed [bound] by most soils"
and therefore "in most soils, glyphosate is essentially immobile."
This means that the glyphosate will be unlikely to contaminate water
or soil away from the application site. However, this binding to soil
is "reversible." For example, one study found that glyphosate bound
readily to four different soils. However, desorption, when glyphosate
unbinds from soil particles, also occurred readily. In one soil, 80
percent of the added glyphosate desorbed in a two hour period. The
study concluded that "this herbicide can be extensively mobile in the
Roundup - An Article that Every Gardener Needs to Read
Sustainable Soil Management
I answered another question that might be of interest to you:
Lastly, in order to find definitive information regarding your
specific area, why not make a call to your Local County Extension
Office and see what they suggest.
"These offices are staffed by one or more experts who provide useful,
practical, and research-based information to agricultural
- Click on your state (California is divided into Northern and Southern areas)
- Click on the map to select your county
- You'll be directed to a page with all contact information
Roundup glyphosate soil restoration
herbicide removal restore soil
Monsanto Roundup half-life
Best regards and Good Luck to you,