Good Timing!
Here's a snippet of a conversation with Prof. Elaine Ingham, a
microbiologist (who specializes in soil nutrition)
http://www.soilfoodweb.com/04_news/documents/08_06SFIE-zine.pdf
out of the States. Darryl just found this bit yesterday, (it's a few
years old), when he was looking up info for a client on organic
methodology. It pertains to the difficulty in breaking down DDT
accumulation in the soil.
Natalia
> I really enjoyed the the course you talked at recently in Fremantle. Can
> you remember me? I am an organic vegie grower,involved with the Organic
> Growers Association of WA.
> We have recently had an enquiry from someone wanting to grow commercially
> organically but they have a problem with DDT levels in their soil.
> I recall you talking about certain micro-organisms that are capable of
> reducing contamination levels in soil. Is this correct? and if so
could you
> give me some references/information to pass onto these people.
There are a number of publications on this topic, but I'd direct you to
a review
article by J.D. Doyle and C. Hendricks from the mid-1990's. Basically, there
are a number of Bacillus, Pseudomonas, and bacterial species that
degrade DDT
and a number of generic "white rot" fungi that also attack DDT. Most people
don't have the money to try to buy the whole range of microbial species that
attack DDT, nor do we know which species will be functional in different
conditions. Therefore, it is best to inoculate ALL the species you can,
and let
them sort out the conditions.
(Note: SFI works with a company that is developing, and may have
already, the specific species of microbes that degrade certain
environmental contaminants. We work on methods to deploy and maintain
those organisms in the real world, unlike some companies that grow the
inoculum in the lab and then send them to you without getting them
"ready" to face the real world.)
The fungi are the ones that degrade DDT best, with no toxic by-products.
Sometimes bacterial degradation ends up with a metabolite that is more toxic
than the DDT. So, getting the full range of organisms into hte soil is
critical.
> The only method I know of is one I read about, years ago, in a US
journal.
> It claimed that carrots could be used to decontaminate soil. Have you
heard
> of that one? any thoughts on it?
The important point there is that carrots release a significant number of
exudates into the soil. These exudates feed a bunch of organisms, some
of which
may, under certain conditions, be those that degrade DDT. But if you
don't have
the diversity needed to do the degradation, the carrots won't help at
all. Must
have the organisms, and the foods to feed them, in order to degrade toxins.
Hope this helps -
Elaine
pete wrote:
I don't remember how this topic started, so I don't know if this is
coincidentally, but it is Rachel Carson's 100th birthday, and NPR's
Lif on Earth ran a piece on her yesterday. Of note is an audio
clip of a lecture she gave, in which she says (approximately)
"I never advocated elimination off chemical spraying. I have
only said that we must learn to do it in a far more sophisticated
and intelligent manner".
-Pete
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