In article , wrote:

I know this is austin.gardening but:

1. I thought this would be interesting to know for members of this ng to
know for future reference of someone trapsin' through.

2. Has anyone ever heard of this? (Nitro-phos website is not up)

I had not heard of this but a search reveals that expanded shale is like
perlite. Perlite is made from a silicacious rock. Expanded shale is made
from shale (a rock formed from clay). In both cases the rock is heated to
a point where it is somewhat fluid and the water within it expands to
"pop" it (something akin to popcorn). So the volume increases
tremendously and internal air channels are formed. So both materials
essentially provide, a light, airy nutrient holding medium.


3. Does anyone know about Shale in general and how it might help the
soil?

Shale is a sedemetary rock that is formed from clay. In its expanded form
it is totally inert and acts passively - to provide air channels and
moisture/nutrient holding channels (this is based on the material I found
at designerdirt.com which may be a commercial arm of the Dallas TAMU
people - they seem to cite work from there). If you would add perlite to
your soil, you could add this for a similar reason. I do not know if
there is any unique advantage. Both of these materials are used by
hydroponic and or orchid growers etc. So if you search those sorts of
sources you could find out if there is any unique advantage of one over
the other.

Its main use appears to be make specialized kinds of concrete
(light/insulating etc) so that is probably where you could buy it in bulk
- from guys selling concrete aggregates.

See: http://www.norliteagg.com/maps/intro.htm

I thought that the picture of volume of various materials was exactly the
same as the picture at a TAMU page, but I cannot find the TAMU page.

Roland