Suzi,

Diatomaceous earth is the fossilized remains of diatoms which are silica based. 

Calcined Clay is the result of taking a secondary weather mineral  that has been heated to 600 - 700 Celsius.
Should note that the source of the clay is Bentonite a source for Muscovite and Illite which are both sedimentary rock forming clays. For turf ace and similar products, illite is used for the TOT structure. Originally discovered in the maquoketa Shale of Illinois. Hence the root of the name. 

OK, now please understand, I am not a scientist or an engineer, and you did a good job of explaining the differences. 

This girl has been in sales her entire life, and I want to know, compared side by side, Benefits and Features!!  What will either one do or not do for me? 

Can you give a simple answer?  It's a lot to ask, I know....  :-))

Suzi

Yes, I would agree that Diatomaceous Earth is very different.  The stuff I get is a fine powder to throw on plants/bugs and suffocate them.  Useful stuff, but doesn't sound like it has the properties of what is described in this thread. 

I was just wondering what you pay locally where you get it.   I'm near Phoenix.

Suzi,

DE will do nothing more than pure silica (beach sand). Act just like the general purpose sand one gets at loses or home depot. Except the Phi value (particle size) is very powdery. 

Calcined Clay is a whole different mineral. 

Looking at the structure of the illite clay you will see the purple spheres. This is the area that allows one to absorb the water without expanding the clay. This is from the TOT crystal formations mentioned earlier. 

OK, Teaching sales 101 here.
Turface:  Benefits, Features
Diatomaceous Earth:  Benefits, Features

I think we are in agreement that Turface is King, and I use it, but all we really want to know is what are the results when we do or do not use it in our mix, and why do others use the substitute of Diatomaceous Earth.

So many newbies here, and I know this thread is on Turface, which I use.  No clue why, but I use it!!  :-))

Here is my mix, formulated for me by Al on Garden Web, for my desert heat:
4 parts Turface

3 parts bark
2 parts crushed Gran I Grit (Grower Size) or #2 cherrystone  
1 part vermiculite

Plant a little high, and after the planting is established, mulch heavily with crushed granite.

I used the 1-1-1 mix - which is made of gran-i-grit, Turface and pine bark fines (you want all the particles roughly the same size) to fill  8" diameter PVC tubes planted vertically into the ground.

Strawberries were planted into holes drilled at regular intervals in the tube.

The mix worked well with daily, fertilized watering.   I had roughly 100 plants growing in 1 square foot quite happily and putting out lots of fruit.

Unfortunately, my water timer broke while I was away during a particularly hot run of days - all the plants were killed.

So, my moral for this story is two-fold:

1.   You must fertilize regularly; the mix has no nutrients
2.   You must water religiously; while it retains some water, it will dry out much more quickly than soil - especially if used (as expected) in pots, raised beds or in my case tubes.

I expect to order new plants come Spring and try again - the strawberries really were doing marvelously (until I killed them).

From everything I've read, a 5' tall 8" diameter planting of anything else would have had several major issues - consistent moisture throughout, compression and a limited life much shorter than the strawberries.

Andrew

The mix does not have nutrients, and this is why I put 1/4 C granulated slow acting fertilizer in with the mix.

I've been in that battery dead boat on the drip system.  Not fun.  Most recover, actually they all do, but it is a stressful thing.

Suzi

NAPA Auto sells a substitute for Turface-MVP...part # 8822.  I pay about $12.00 for a bag.  (Floor-Dry).

Turface-MVP sells in Yonkers, NY for about $14.00/50 LB bag.

Heavy to lift...wear a truss.



Frank

Ok I see on their website, there is a link to find a distributor in the area:
tp://www.turface.com/turface-products/infield-conditioners/turface-mvp

Yet another thing to buy for them figs!

I've also heard people using a product called "Dry Stall."   You can get a free sample on this link:
http://www.drystall.com/free-samples.html

Suzi - I am not sure if Turface is king, but it can be a very good soilless media component. I only have a couple of small citrus trees in a mix that contains a calcined clay material. Time will tell if it provides an advantage over my standard mix. I notice you have vermiculite in your mix. You might want to be cautious there. While vermiculite does have some good horticultural uses, it is typically not recommended for longer term use as it can compact and cause problems. Here is a good discussion of soilless mix characteristics with a section on vermiculite that you will not find too technical, I hope.
http://www.ces.ncsu.edu/depts/hort/nursery/cultural/cultural_docs/substrates/container-soiless-media.pdf

Good luck with your trees!