Viewing post #322417 by dave

Last month when I was down at the Arbor Gate nursery in Tomball, TX, the owner was promoting to me the benefits of expanded shale as a soil conditioner.

According to Doug Welsh of Texas AgriLife:

'Blue Shale' from the Midway Shale formation is present in a pattern across Texas through Corsicana to Texarkana and stopping near Laredo. It is usually found 10-15 feet underground. It was formed during Cretaceous times when Texas was a large lakebed and the lakebed sediments solidified under pressure into the present-day shale formation.

Jack Sinclair of TXI Industries has explained that the shale is mined and ground to 1" to l/2" range particles and then kiln fired. As it progresses through the kiln for 40 minutes at 2,000 degrees C, certain chemical processes take place in the silica content (60-70%) causing the material to expand. The expansion of Kitty Litter (calcined clay), for example, occurs at only 800-900 degrees.

As the material cools, cavities are left after gases escape, leaving a porous lightweight chunk capable of absorbing water and releasing it slowly at a later time.

I brought home a bag and have been messing around with it a bit but haven't used it long enough to really get a feel for its benefits. I will say, however, that the soil does have a better feel to it shortly after adding the shale. I plan to conduct much more trials during 2013. When planting new bulbs and perennials I've been mixing the material in with the native soil. I'm also wanting to add some to my potting soil, and I think it will be an excellent media for hydroponics/aquaponics projects.

If it does what I think it will, then I will likely get a dump truck load from TXI.

Has anyone else ever used this?