https://www.greenhousemag.com/article/gmpro-0610-silicon-plant-growth/
I also see it first hand. I now let my plants go completely dry before watering, without any worries of them shriveling up. Maybe not the best example. But the secret of silica has been known to farmers way before the science. Surprisingly, since there are many myths in growing, such as flushing, watering your plants with ice water at the end to bring out trichomes.
That's how it often goes, those on the front lines see things first hand, and others come along later to take measurements and call it official :P
But SiO2 doesn't seem to be a nutrient (something used in biochemical processes). I think what is probably happening is the plants are taking up some of the SiO2 and using it as structural reinforcement. Quite brilliant, really. Several types of plants are known to be able to do this. I think the SiO2 deposits found in plants are called phyoliths. They aren't nutrients, and the plant can survive without them (if there's no SiO2 around), but they can definitely be advantageous. Maybe that's what you've experienced first hand? Are the plants even more strong than normal, even once they're harvested and dried out?
If that's what's happening, then cannabis must be one of those species with the ability to create SiO2 phyoliths. I had no idea! I'm going to give it a shot.
How much per unit of water? Spoonful per watering jug? I'll give it a shot. I've already got some in my soil mix, but I got enough DE now to play around with some in the water, too ;D
EDIT: Just saw your link, haha. Checking it out, thanks.
EDIT2: Unfortunately, that's a non-scientific and non-peer-reviewed study, conducted by a magazine for a story. Their results might be legit, but we can't know from reading that article. And even if what they're saying is true (that stem thickness increases under the conditions they used), we have to remember that they gave their plants a very different form of Silicon, specifically, a soluble form. As we were saying earlier, DE is insoluble. Think of DE as tiny flakes of glass. They're small, but they're still glass, so they can't dissolve in water. They can't even dissolve in most acids. Long story short, more research and experimentation required!