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Laterite, Flourite...now Arcillite?!

> Date: Mon, 30 Mar 1998 21:45:44 -0800 (PST)
> From: "A. Inniss" <andrewi at u_washington.edu>
> 	While poking around in a local garden supply shop in my home town
> in Canada, I came across a new product which sounds like yet another
> laterite-like clay.  Put out by Profile, it is:
> "A Natural Mineral Blend that has been kiln fired [...] will last year
> after year [...] contains thousands of internal and external pore spaces
> [...] holds on to precious plant nutrients and exchanges them directly
> with plant roots, increasing the eficiency and benefits of your plant
> fertilizer [...] is not a chemical or fertilizer, is not toxic, and has no
> effect on pH [...] provides a haven for valuable microorganisms that
> normally are filtered out and provides a suitable environment for fish to
> lay eggs."
> 	At $14.99CDN for a bag probably a bit larger than a bag of
> Flourite ($24.98US), it looks interesting.  What it is saying in its
> advertizing, I gather, is that it has a good CEC and so on.  Sounds like
> another "laterite substitute." Supposedly it merely needs to be submerged
> and saturated, and then will not float or break down.
> 	PROFILE Professional Aquatic Plant Soil is 100% Arcillite, a
> substance I wasn't able to find in any of what meager resources I had
> immediately at hand.  Any soil scientists care to comment on Arcillite?  I
> wasn't able to see it or get an idea of its grain size, unfortunately, as
> the nature of the bag its in precludes that.
> 	I don't have any place to experiment with it at the moment, but
> perhaps one of you might give it a whirl and report back.

Arcillite is a calcined montmorillonite clay.  According to a U of Florida
web page (http://hammock.ifas.ufl.edu/txt/fairs/2455):

	There are now a number of companies in the United States which quarry
	clay and heat it in specialized kilns which cause the clay to expand
	under high temperature into a highly porous fused structure which is
	physically and chemically stable. The next steps involve crushing large
	chunks of calcined clay into smaller particles which are subsequently
	graded into specific particle size ranges. Light weight concrete
	products and road surfacing additives are two popular applications.

(Stuff about use in high-traffic turf areas, potting soil mixtures snipped)

	Many calcined clays have properties which make them desirable as
	potting media components. Those clays which are receiving the most
	attention are more porous and therefore considerably lighter in weight
	than Turface. Calcined clays are essentially indestructible particles,
	which provide non-capillary pore space to a mix due to the large spaces
	created between particles, and hold water internally within their
	open-pore particle structure. Most calcined clays have good cation
	exchange capacity which helps in the retention of nutrients but have no
	nutrient value of their own.

The last time I looked into this, I was looking for info about Turface, 
which is a similar product with a nice terra cotta color and a texture
somewhat like kitty litter.  It retains its shape when wet, unlike kitty
litter, and is softer than crushed brick or crushed terra cotta flower
pots.  I ran into a web page for Profile which I can't find now.  I did
run into a reference to use as a soil amendment for turfgrass, so I assume
it is similar to Turface in its physical and chemical properties.  I seem
to remember that it was formed into small cylinders, rather than the random
crumbles of Turface.

Turface is much beloved of bonsai, cacti and alpine plant enthusiasts.
A powder form is available for drying out muddy athletic fields before 
a game.  It's heavier than most soil amendments like perlite and vermiculite,
which makes it more expensive due to shipping costs, but it's much lighter
than gravel.  It sinks easily and stays sunk.

At any rate, I've been wanting to use Turface as a substrate for some time,
but haven't been able to get a large bag of it.  I got a small sample bag,
and it is nice looking stuff, only slightly dusty.  Note that while these
calcined clays have good CEC, they have no nutrient value.  I wonder if the
pores are suitable for bacterial conversion of nitrate to nitrogen.

If anyone wants to try either of these products, it is probably cheaper
sold as a soil amendment than as a specialized aquatic plant soil.

Btw, the distributor for Turface in Canada is Plant Products, Ltd. in
Brampton, Ont.  I think this is the same company Sears and Conlin got
their lifetime supply of trace elements from.