On 8 Oct, 21:39, "Christina Websell"
wrote:
"Bob Hobden" wrote in message

... Organic growers and those of a nervous disposition read no further. :-)
On of our allotment holders who has a number of allotments sterilises his
soil every few years with some powder which he incorporates into the top
layer of soil, waters well, covers with plastic sheeting and leaves for a
couple of weeks. He says the gas kills everything and has rid one of his
plots of Club Root and White Rot as well as killing any weed seeds so they
never build up. Sounds both a miracle and the work of the Devil to me.
Anyone know what he is using?

No, but wouldn't it worry you a bit to eat crops from that ground
afterwards? *It would me. *If I want chemically contaminated veg I can get
it from the supermarket.
Tina

You shouldn't need to worry on that count Tina, part of the procedure
is to clear the gas that does the sterilising. When that's gone there
is no residue to contaminate anything.
The covers are removed and the ground rotavated - it's then left for a
period after which several samples of the treated soil together with a
'control' sample of untreated similar soil.
Ordinary salad cress (it's extremely sensitive to this stuff) is sown
in each sample and the germination is observed. If no difference is
seen OK, otherwise the rotavation, waiting and testing are repeated as
required.
Having said all this, along with many other growers and gardeners, as
we learn more about the biology of soil at the micro level, flora,
fauna, fungi etc we begin to understand just how complex it is and
that in general - at least for outdoor crops the less we interfere
with it the better. Greenhouse cropping is a different game, it's
wholly artificial anyway so sometimes the systems are simplified by
using sterile media like rockwool etc or by sterilising an existing
medium using steam or chemicals. In the glasshouse environment it is
all too easy for pests and diseases to get out of hand if things
aren't kept clean and mother nature isn't always on our side in that
artificial set up.

Rod