"Mike Lyle" wrote in message
...

OK, I'll accept that -- unfortunately missed the prog. So how does it
work? And has it worked in other places? I can see that from time to
time a depleted soil might need trace-mineral replacement; but surely
that's a rare case?

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).

--
Mike.

There's some general stuff about some Australian trials (1997)
on here -

http://www.rosneath.com.au/ipc6/ch02/oldfield/

quote

A Summary Of Our Reporting To Date:

Granite dust promotes the fast and healthy growth of tree
seedlings in the nursery.

Granite dust particularly benefits nitrogen-fixing trees.

Granite dust can provide some potassium to plants on demand.

Although granite dust has a high pH it does not seem to raise
significantly the pH of acid soils.

Granite dust has been shown to reduce the yield of wheat
under field conditions.

Diorite dust may reduce weed competition to the benefit
of a wheat crop.

Quarry dust improves water infiltration rates to the benefit
of non-wetting soils.

Quarry dust improves water retention in free draining soils.

Quarry dust benefits dairy pastures by promoting legume growth
at the expense of less productive species when applied as an
additive to slurry from cattle sheds.

Granite dust has given a marginally higher yield from a lupin
crop than either chemical fertiliser or a commercial rockdust blend.

Composting earthworms prefer a feed ration to which rockdust has
been added.

Quarry dust may affect the way plants respond to electromagnetic
radiation, in particular excess solar radiation.

Granite dust does not seem to benefit well-nurtured gardens.

Nevertheless a granite and marble dust mixture appeared to benefit
garden crops grown on an alluvial loam.

Granite dust contains 27ppm lanthanum, a rare earth considered
by the Chinese to be a plant growth promoter.

Quarry dust may deter wingless grasshoppers.

Tree seedlings raised in a soil mix containing 5% granite dust
appear to resist insect predation.

Tree seedlings raised in a granite dust enriched potting mix appear
to continue fast healthy growth after planting out under adverse
climatic and soil conditions typical of the West Australian wheatbelt.

There could be a link between the use of rock dust and the noted
absence of fungal attack in the early stages of seedling growth.

© Copyright Permaculture Association of Western Australia Inc.
and authors, 1997.

/quote



michael adams


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