Why use Calcined Clay in soil mixes???

[Boo Hollow]

To all users whom use Turface MVP, Oil-Sorb, Hydroton or other calcined clay product in their soil mixes, I am asking why. I cannot find any information that supports its use - pros/cons, etc., and would appreciate feedback from those that may have references, personal experiences, or reasons for using.

I do understand that there may be CEC benefits, but less than adding organic matter and it all depends on the clay being fired.

My personal experience is that it is slow to dry, hold too much water and can foul with algae on the surface. The cost is prohibitive if growing anything more than a few plants and I currently do not see any benefits to using this product over scoria (lava rock), pumice or perlite. I see that there have been lots of discussions regarding additives and the dislike for perlite because it floats to the top, but limited commentary on this product.

Boo -

[Allen Repashy]

I use Turface and really like it..... things just seem to grow very well in it... no scientific studies, just observations. I actually use it as an incubation substrate for reptiles, and the stuff we plant with is a byproduct from the gecko farm. I think it would be a bit expensive to use in anything larger than a four inch pot. It runs $10.00 for a #50 pound bag. It holds a LOT of water without feeling "wet". We have grown a lot of small aloe and agave in a mix of coir and turface and it performs very well.

[thistlesifter]

Turface

Hydroponic-style growing can be accommodated with Turface-mix (T-Mix). It forms a matrix for finer roots to 'hang' on as they are drenched regularly.

We tried it 3 years ago substituting it for our regular mix during re-potting. During growing season it was more effective than some other mixes that were being used similarly. We substituted it for pumice and or perlite to mix with our own organic. Used the same proportions, treated it the same way with our liquid treatment.

Approximately 75 flats of 2.5" to 5.25" potted succulents were eventually moved into the T-mix during the season.

As we reduced quantity and frequency of watering during the cooler months, we began to notice that the T-Mix plants were not responding to 'opportunistic' growing temperature periods in the late Fall and Winter.

As it began to warm up in the Spring the T-Mix plants did not respond as well to warming trend. The roots were underdeveloped compared to plants grown in our 4 other mixes used for different applications.

We don't heat our GH's , but we do have a small closed 200sq.seed room section in one GH with bottom heat for seed and rooting during cooler months . T-Mix plants in that room did not respond as well and all had underdeveloped roots.

We didn't have Agaves or Aloes in Turface mix at all. Primary focus was Haworthias, Echeverias, Mesembs , Euphorbias and a few flats of Cacti. The Euphorbias worked quite a bit better in the T-Mix than the other Genera.

By Mid-Spring we had moved all but the most robust Echeveria specimen, back into their previous mixes.

We had done some searching and found sources for Turface. The cost was favorable to that of Pumice/Perlite in bulk quantities. We still have a little here. I now use it for what it was being used by the county. (To make a muddy trail into a usable pathway in county parks and athletic fields.)

It is much more pleasant to work with Turface than pumice or perlite. We had recommended it during the summer to quite a few customers and I didn't hesitate to advise them or our experiences as they developed.

Turface use is definitely a trade-off in many areas and I know quite a few folks in the east that still use it. I suspect their watering/supplementation regimen is quite different and that too would get a different result. The same could be true with us. The vast majority of our plants remained in our standard mixes, There was no difference in the way we watered the T-Mix plants.

Bob

Cacti suffered most with T-mix.

[Boo Hollow]

I have found that wet Turface compacts a bit and does not breathe. I have used this with Pachypodiums and also found that growth was stunted compared to mixes using perlite, scoria or pumice. I suspect that since clay has a higher Cation exchance capacity, that there may be some binding of nutrients to the surface of the Turface. Normal clay has a high CEC, but calcined clay, well some sites state that during the vitrification process, these characteristics are eliminated as the surface charge changes as does the cation exchange. Clay is not always clay.

The higher moisture retention also created some issues with dudleya rotting during the wetter fall and winter months. Plants grown in the open using my standard mixes didn't miss a beat and grew as they normally would. Turface based plants rotted at the base and suffered lots of root rot. Its higher water carrying capacity needs to be considered when used as a soil additive in my opinion. It also seems that plants that have been treated with a systemic insecticide such as Imidacloprid, required more treatments to gain the same control as those in a standard soil mix.

Still looking for more experiences out there, so share with the group.

In my humble opinion, Turface receives a

[Steve Steward]

I use the turface stuff as an occasional top-dressing only. It seems to have been a growth inhibitor of sorts when I tried to make a media with it. I believe it was something like 30% compost 40% pumice 30% turface. Everything I tried in that mix seemed to suffer. From Pachypodium, to Ferocactus etc.
Just one man's experience though.

steve

[Boo Hollow]

Folks - here is a link to an interesting article that discusses soil mixes and additives and has a blurb on Turface. It has been around quite a while and there are other items referenced that may be better suited to our collective needs that are still a calcined clay product.

http://edis.ifas.ufl.edu/cn004

[Matt Maggio]

I pray each and every day that the pumice mines never run out... the yellow-tinged killer death pumice notwithstanding. Its dust holds levels of boron toxic to most plants and contains high levels of elemental sulfur, enough to engender catastrophic levels of sulfuric acid.