"chris French" wrote in message
...
In message , Janet Baraclough
writes
The message
from "Mike Lyle" contains these
words:


I'm assuming that the experiments were carried out with the usual
controls, in order to avoid what I think of as "the reading-scheme
phenomenon" (impressive results achieved with a new teaching method,
but turning out to be just because of the extra attention received by
both pupils and teachers).

snip

At the time I was there, there were no "control beds ", using just stone
dust as a dressing, and I have never seen reference to such a comparison
being attempted.

ISTR that in the article by Colin Shaw I mentioned he talked about
comparing beds with and without the rock dust
--
Chris French


Chris,I took Janet's post to mean she had not seen trials or comparisons
being made at SEER.
There are a plethora of trials along similar lines to the one you mentioned.
I would maintain that any differences are due to drainage/soil structure and
not nutrient enhancement from assorted rock dusts.
Here is a good trial (by an Undergraduate) which broadly confirms Colin's
results
http://www.geocities.com/HotSprings/...alisation1.htm