granite grit

Linda Foulis
Tue, 08 Nov 2005 18:45:57 PST

< soil scientist enquired if my pot's top dressing was granite gravel.  It
is (grower and developer grades of chicken grit) and he mentioned the fact
that there was no wonder I didn't need to feed micronutrients because all 15
the plants need are made available in the right quantities from the top

At the risk of sounding like a complete moron, I really have to question the
above written by
John Lonsdale, last evening.  And my apologies before hand when someone
proves to me why this can be so.
How can micronutrients be derived from granite grit?  Especially in a
growing season, or even 10 growing seasons for that matter.  I can maybe see
it if using a sandstone grit, if there is such a thing.
All the granite I've ever come across has been an extremely hard rock and
not inclined to erosion or break down in which micronutrients would be
released, at least not in my life time.

Scientifically I am a moron as defined in any dictionary, however this
really stuck in my mind and I would like to learn how it is possible,
especially in the case of granite.  The bag of granite grit #2 that I just
picked up has been well washed and there is very little granite dust which
could be the source of micronutrients, but even then what would it take to
break down the granite dust to release those micronutrients?

I had to ask, I've been wrong before and can only stand to learn something
when proven wrong!

Okotoks, AB

BRRRR!  Snow is here to stay for a bit, the cold frame is almost packed up
for winter, lets hope a deer
doesn't walk through it!

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