Silica

[PaphMadMan]

Certainly any terrestrials would have abundant silica available to them. Epiphytes as well from rain etc.

I just want to make it clear that the above quote is NOT from me, though the quote function somehow seems to think it is.

 

[gonewild]

I just want to make it clear that the above quote is NOT from me, though the quote function somehow seems to think it is.

You are being framed!

 

[AdamD]

So would DE contain silica in available form to the plant? Either foliage or roots?

 

[gonewild]

So would DE contain silica in available form to the plant? Either foliage or roots?

If the silica in Diatoms were soluble it would not make them a very good exo-skelton since the lived in water. So answer must be, no.

 

[AdamD]

So, I guess the follow-up would be, is potassium silicate the best available option? If pH were adjusted?

 

[Stone]

And how wold silica get in rain?

The same way as all the other minerals do.
Tillandsias contain silica and they survive on rainfall exclusively.

 

[Stone]

So would DE contain silica in available form to the plant? Either foliage or roots?

Yes.

 

[Stone]

So, I guess the follow-up would be, is potassium silicate the best available option? If pH were adjusted?

There is (or was) a product in the US called ''Pyroclay'' which does not have all the negative qualities of Potassium silicate.
It is not available here but I try to regularly add silica to the plants in the form of ''diatomite water'' or from composted bamboo leaves and fibrous grasses etc. I have no idea if it makes a difference. Silica certainly makes a big difference with some crops. Stronger and taller flower stems in Gerbera, higher yeild and bigger root system in Strawberry etc. etc. etc.

 

[troy]

Rain water washes down the hill through the trees and bushes over roots

 

[ALToronto]

I use soluble silicates in the production of my mineral composites. The most common ones are sodium, potassium and lithium, but there are others (magnesium, titanium, zirconium, etc). The alkali component is the carrier for the silicate component.

These are generally referred to as metal silicates and are written as M2O:SiO2, where M is the metal (Na, K or Li). The most important property of metal silicates is the molar ratio of the M2O component to the SiO2 component, i.e. how many molecules of M2O there are for every molecule of SiO2. The higher the ratio, the less silicate it contains, and the higher the pH. Cost goes up dramatically as the ratio decreases.

Most industrial grade metal silicates have molar ratios between 2.0-3.5. These correspond to pH levels of 11-12. Lower ratio silicates are used in concrete production, higher ratio ones are put in laundry detergents and used in the oilfields. In prepared liquid products, the solids content is 25-30%, but you can buy crystals and dissolve them yourself. It takes a long time with continuous stirring to get even 30% solubility.

In spite of molar ratio being the important property, silicates are graded and sold by the weight ratio - molecular weight of M2O:SiO2. This is because the molar ratio of the most common liquid silicate, Sodium, is the same as its weight ratio. Potassium is heavier than Sodium, so the same weight ratio = lower molar ratio. Lithium is lighter, so you get a lot less SiO2 for the same weight ratio.

Which brings us to Pro-Tek, which has a molar ratio of 0.25. This is extremely low, and I don't even know who makes liquid silicates with such low ratios. Certainly not PQ Corporation, the world's biggest producer of soluble silicates. Pro-Tek is also very dilute, with 7% solids. Even so, it's a significant pH booster, so I can only imagine how much industrial liquid silicate will raise the pH. You will also be adding 8-12 times more hydroxide salts for the same amount of SiO2 added as with Pro-Tek.

I don't use Pro-Tek because my plants get silica from other sources. Those that grow on my living walls get plenty from the wall material and the chopped hemp stems I use for the surface layer. I have a few plants in pots, in lava rock, with hemp stems mixed in. Bark and CHC also contain soluble silica, and LECA doesn't. This might be why my plants growing in LECA are doing worse than the rest.

 

[troy]

Thank you altoronto, very detailed explanation of the moleculuar breakdown of silica, yur an intellegent person, do you have a science degree? Protekt or such is nonsoluble

 

[Bjorn]

I think come of it is semantics, and some inconsistent use of terms.

"Silica" is SiO2 in the materials industry. To me, amorphous silica is pure silica glass, which is still highly insoluble in almost anything but HF.

So a question, Bjorn: do plants contain SiO2, or Si, which is incinerated and oxidized in the analytical lab? I can see the metal more than the oxide.

Ray, we have both a past in ceramic science so you are right, silica is SiO2. Si is absorbed by the plants though monosilicic acid Si(OH)4 which could be described as a (monomeric) hydrated silica. This monosilicic acid tends to polymerise, and then it cannot get adsorbed anymore. Polymerisation also takes place in the plant resulting in aggregates of polysilicic acid eventually aggregates of silica gel. These silica structures (amorphous) can be seen in the microscope. In phalaenopsis they appear as beads on a string like structures if I remember correctly. It is speculated that the silica-gel aggregates serves as catalysts (similar things are used in Chemical industry) for sythesis of stress related chemical compounds. At least some scientist believe that this could be the role. But these are new ideas and may not be easy to verify.
Amorphous silica can be glass but is actually any silica that has no crystallinity. E.g. silica gel, silica glass, fumed silica etc.

 

[Bjorn]

So would DE contain silica in available form to the plant? Either foliage or roots?

That is one of the main silica fertilisers.

 

[Bjorn]

So, I guess the follow-up would be, is potassium silicate the best available option? If pH were adjusted?

Higher pH gives more silica in solution. If you lower the pH, silica gel will be condensed. You might not see it it transparent and probably nano-sized.

 

[Ray]

Thank you, Bjorn. I can wrap my mind around the acid, more than the oxide for absorption and transport!

 

[troy]

My only question is could good humidity stiffen up leaves? Bcuse....

 

[gonewild]

My only question is could good humidity stiffen up leaves? Bcuse....

Of course it can. leaves become more turgid (holding more water pressure) with humidity and water on roots. As leaves loose water pressure they become softer.

 

[gonewild]

Higher pH gives more silica in solution. If you lower the pH, silica gel will be condensed. You might not see it it transparent and probably nano-sized.

So in acidic conditions such as fertilizer solutions below pH6 used on orchids or orchid growing media that is normally below pH7 is silica soluble?

 

[Bjorn]

So in acidic conditions such as fertilizer solutions below pH6 used on orchids or orchid growing media that is normally below pH7 is silica soluble?

It certainly is soluble, but only to some ppm. May be repeating myself, but soil often contains around 10-20ppm dissolved silica. Some may regard it as insoluble, but certain plants accumulate it to yield more than 50%of dry matter. Quite impressing taking into account what diluted solution it is (not orchids)

 

[Bjorn]

My only question is could good humidity stiffen up leaves? Bcuse....

I have been adding silica to my water for almost a year now. Not the pro-tekt type though initially I thought that I saw stiffening, now I am not so certain anymore. Was it wishful thinking or some intermittent situation?