Silicon the forgotten macronutrient?

[gonewild]

especially in places I didn't care to have it improved.

You must not be from California?

 

[cnycharles]

I happen to agree but......
In tropical South America the "local" timber cutters don't like to cut trees growing on sandy soils because they say the trees contain too much sand in the wood and it dulls their saws. They say the trees suck up the sand grains for the first 2 logs and then it won't go any higher. Now this might sound a little strange but the wood is high in silica as they say. Obvious the trees are not sucking up grains of sand but there are Silica deposits throughout the wood.
I really would like to understand why these trees have silica deposits.

well, if it's a transport thing because there's so much of it in the soil and it just is taken up with the water unselectively, it could be that it's getting stored in 'waste' vacuoles and such. I don't know if pear fruit 'stones' are also silica; you know when you bite into a pear it has the gritty bits in it? I can't remember if this is something 'precipitated' into a vacuole or exactly what the mechanism and compound was for that

 

[ALToronto]

In forage plants on the plains grazed by big herbivours high silica was an adaptive feature. But high silica is not universal for many plants. I attached an article early on that showed that a lot of flowering plants tended to be on the low side of Si. Also Ca is responsible for a lot of cell wall integrity issues that effect diisease and pest resistance.

Since high K inhibits the induction of Ca and Mg, I wonder if it does the same thing to silica.

Ca and Si are very synergistic in inorganic chemistry - it's essentially how we get concrete (yes, there are aluminum compounds involved as well). In people, both elements are necessary for strong bones, and too many people overdose on Ca supplements to no avail because they don't get enough Si. I wonder how this works with plants.

 

[Ray]

I was reading more about that earlier today.

As Lance stated many pages ago, stuff like rice have a huge demand for silicon, but it seems that the higher the plants are in the evolutionary tree, the less and less they need.

One might also argue (I'm not - just throwing it out for the discussion) that the silicon absorbed from the Si-rich soil by terrestrial plants is converted into insoluble forms within the plant, so unlike most of the other minerals, it will not be appreciably exuded by the plants, to be cascaded down on the epiphytes during rainstorms.

 

[Stone]

I was reading more about that earlier today.

As Lance stated many pages ago, stuff like rice have a huge demand for silicon, but it seems that the higher the plants are in the evolutionary tree, the less and less they need.

One might also argue (I'm not - just throwing it out for the discussion) that the silicon absorbed from the Si-rich soil by terrestrial plants is converted into insoluble forms within the plant, so unlike most of the other minerals, it will not be appreciably exuded by the plants, to be cascaded down on the epiphytes during rainstorms.

Yes an example is the ''needles'' on stinging nettle are (for all intents and purposes) glass! Which would not be readily soluble? But since glass is (I heard) not a solid but a super cooled liquid, then it would be a matter of time before it broke down again???

 

[Rick]

http://cccryo.ntr.io/sources/files/medien/fwDiatom.pdf

Here's one of the proven culture medias for freshwater diatoms (unicellular algaes that have a silicon case).

I've used something similar in some diatom culture work I did in the late 90's

They generally use sodium silicate as the silicon source, and the diatoms seem to have no problem utilizing it.

 

[DavidCampen]

Here is an interesting silicic acid paper. It states that aqueous monomeric silicic acid solution is in equilibrium with solid amorphous silica at a concentration of 0.002 molar. Since silicic acid has a formula weight of about 100 then 0.002 molar would be 200 ppm.
http://eprints.nwisrl.ars.usda.gov/318/1/373.pdf

 

[Stone]

Just an interesting side note. Apparently all the silica in the millions of tons of diatomite deposits ended up in the sea from the s**t of grazing animals..

 

[Ray]

But since glass is (I heard) not a solid but a super cooled liquid, then it would be a matter of time before it broke down again???

Glass is sort-of an "in-between" solid.

Due to the melting, the crystal structure is mostly disrupted, but the viscosity is so high that it really cannot full recombine into lattices upon cooling.

 

[lepetitmartien]

Glad to see someone brought up the biogenic silica. Other genera use/produce silica glass beside diatoms, in plants and animals (sponges) so the bio-availability mechanisms are studied there (especially diatoms, as their glass is very interesting for applied science : how to make a cristal clear glass without heat…) so there's papers certainly in the literature.