Sudden death after using calcined DE as a soil medium?

[psi]

I've used horticultural diatomaceous earth as a soil component and liked it, but the shipping was killer and the company I got it from no longer carries it anyway. I wanted to find something similar that would be cheap and local, and I had read that similar materials were sometimes sold as oil absorbents for automotive work. The product I ended up getting was called Qualisorb, a calcined (fired) diatomaceous earth gravel. I put six ~2 year peyote seedlings into it as test subjects (placed dry followed by watering), and roughly a week later I uprooted them to see how they were doing. One had turned entirely to mush and another was mushy in all but the topmost portion. I left them all uprooted and another of the six has since gone completely mushy.

Any ideas on what kind of contaminant could have caused this? There are a bunch of other plants that I planted in a mix containing this stuff before I realized there was a problem, and I'm wondering if there's anything I can to to prevent them from suffering the same fate (aside from taking them out of it which I've done already.) I've read that some DE comes from saltwater sources so I wondered whether that was it. I haven't seen what salt contamination would do though, so I'm not sure if rapid liquification is consistent with that.

[CactusFanDan]

Sounds like they rotted to me. The effects of toxins or salinity in the soil would usually manifest as a slow dying off rather than sudden turning to mush. Sudden turning to mush is usually rot (I can't think of anything else it could be). Did you water them too soon after transplanting them? Also, isn't it a bit late in the year to be watering Loph's? Surely it's too cold for them to get any water around now.

[psi]

I keep them inside under T8s over the winter, so normally I do water them year round. They did appear to be rotten when I cut them open, yellow-orange tones in the root portion that later turned to black, accompanied by an "off" smell. If it turns out that it was just the early watering that caused the problem then overall I'd consider that good news because I'd like to be able to use this stuff. In the past I had not really encountered problems from transplanting into soil that was somewhat damp so I was not really too worried about it, but this time I gave them a real soaking.

[CactusFanDan]

In the past I had not really encountered problems from transplanting into soil that was somewhat damp so I was not really too worried about it, but this time I gave them a real soaking.

That'll be your problem then. Rot gets into plants really easily through broken roots that you get when you disturb the roots of your plants. Wet soil makes it even easier for fungus and bacteria to get into the plant and spread up through the vascular system. I usually leave plants dry for 1-3 weeks after repotting them, depending on how much I disturb the root mass.

[psi]

OK, I guess I will give this material another shot then.

[DaveW]

Try a spare "normal" plant in some since if it is toxic it will affect that too but would probably not rot as easy as cacti when just transplanted.