Silicon the forgotten macronutrient?

[Bjorn]

You say, composting is not effective. Do you know why?
I'll have to look it up in my books, for silicon fertilizing is part of organic/bio agriculture and more so in biol/dynamic agriculture methods.

Actually, I am a bit uncertain about that one cannot quote anything right here but think I remember that decomposition has to go the whole way, not only to compost but to the mineralization stage before silicon gets available. So, on a short term it does not work. On a long term however
Of course for orchids growing, its out of question to go to the mineralization stage of the compost:rollhappy:

 

[Ray]

....the amount of sulfate, which I consider to be another important variable, is not even mentioned

No, it is not mentioned on the label, as most states do not require it, but if you consider that both the MSU & K-Lite formulas contain sulfates of copper, manganese and zinc, it's easy enough to calculate.

MSU RO contains 0.092%S and the K-Lite is about 0.102%S

 

[DavidCampen]

No, it is not mentioned on the label, as most states do not require it, but if you consider that both the MSU & K-Lite formulas contain sulfates of copper, manganese and zinc, it's easy enough to calculate.

MSU RO contains 0.092%S and the K-Lite is about 0.102%S

I guess that I don't understand how whether something is required by state agencies or not determines if it is important. Dyna-Gro lists the amount of sulfur in their formulations. In any event, it is my opinion that "K-lite", like most conventional formulations, is deficient in sulfur.

 

[Stone]

Roughly, S is required at about 10-15% of the N. In natural systems, S comes from humus and in soil, from gypsum etc. In modern p/mixes, you must provide for it in your fertilizer. I think a lot of the nutritional problems with orchids is that we don't/can't use humus and/or clay in the substrate. Just yesterday I was reading that 1 gram of humus has a surface area of around 800-900 sq. mt! That potentially, is a huge bank of reserves.

 

[Stone]

and if a fertilizer was quite a bit short of phosphorus, which would normally make things taller and stretchier, possibly, so less phosphorus might make them look 'shorter' or seem to grow and expand less, or 'not grow as good'

Its the Potassium that regulates the stretching not the Poke:

 

[Bjorn]

Why do we fertilize with phosphorous, sulfur, calcium, magnesium etc. but not with silicon although silicon is just as abundant in the plants as the rest?

I think that perhaps we should add sulphur to this listoke:

No, it is not mentioned on the label, as most states do not require it, but if you consider that both the MSU & K-Lite formulas contain sulfates of copper, manganese and zinc, it's easy enough to calculate.

MSU RO contains 0.092%S and the K-Lite is about 0.102%S

If sulphur was added in amounts corresponding to the content of the plants, the fertiliser should contain approximately the same amount as phosphorous, magnesium and calcium?

Roughly, S is required at about 10-15% of the N. In natural systems, S comes from humus and in soil, from gypsum etc. In modern p/mixes, you must provide for it in your fertilizer. I think a lot of the nutritional problems with orchids is that we don't/can't use humus and/or clay in the substrate. Just yesterday I was reading that 1 gram of humus has a surface area of around 800-900 sq. mt! That potentially, is a huge bank of reserves.

Should be at a tenfold level of today then? unless the plants have efficient "sulphur pumps" to get access to it. for some of us, the suphur supply is secured by the water we use, e.g. acid rain from industrial pollution. Personally I use water from a bog, this is, particularly during summer smelling from sulphur, so I guess I am covered:rollhappy: However, the smell is hydrogensulfide and the amounts may very well be at a too low level. Those using RO water may run into deficiency problems though:evil:
Then some notes about the high specif surface of the humus: this is the origin of cationic exchange capacity, CEC. The surface is loaded with negative sites being able to attach cations (positive ions). Over time, these sites get saturated with more or less immobile species that may not be positive for the plants, like potassium. I think the issues we have seen with CHC and salt accumulation in compost is at least partly due to this CEC. So, in order to avoid salt buildup and thereby prolong the repot intervals, my strategy is to have a compost with low CEC (like using quite a bit of sand and stone) combined with a fairly low amount of fertiliser in the irrigation(say 200ppm TDS).

 

[Ray]

Back to the silicon, for a moment.... I don't understand why folks think sand is a good source. SiO2 is one of the most insoluble minerals around - unless it is in a highly alkaline environment. Why do you think that the majority of beaches are sand?

 

[Bjorn]

Back to the silicon, for a moment.... I don't understand why folks think sand is a good source. SiO2 is one of the most insoluble minerals around - unless it is in a highly alkaline environment. Why do you think that the majority of beaches are sand?

You are entirely right, Ray
Sand is definitely not a good source, since it is made of crystalline silica (quartz) and aditionally not very fine either. If silica (SiO2) is to dissolve, the Silica source has to be amorphous and very fine like submicron. Then silica may dissove, not much but perhaps up to 50-100ppm or so. It takes time though.
Btw. The dissolution is by hydrolyses to monosilisic acid.
SiO2 + 2H2O = Si(OH)4 that is the entity the plants are able to consume. By continous removal of the monosilicic acid by the plants more silica goes into solution and over time this lis responsible for the substantial silicon content we see in some plants. In orchid growing, it may very well be a growth restricting parameter

 

[Secundino]

If this is true, HOW do the plants get Si? Is there an amorphous silica source in the soil? Or the other way: how do we get monosilicic acid into the substrate? Is this part of the work the bacteria an fungi do? As well as for S, mineralizing decomposing proteins?

As I like (old) books about orchids, I found that all the old potting-mix-recipes given have a part of 'sand' - quartz sand I understand - for Paphs!

 

[Rick]

Sand is an excellent drainage material. Lot of root contact and small porosity (capillary transfer benefits) , but not water retentive. If you get micro amounts of Si moved from sand to plant via micro bacterial degradation, then so be it, but I wouldn't count on it as a significant source of Si for most plants.

Clay soils are fine mostly aluminum silicates. And many limestone's contain calcium silicates (though these are not likely any more bio available as for sand).

I would guess that most silicon in herbaceous plants is being recycled via dead plant material after being moved up in miniscule quantities via trees in contact with the local geology. Grasses growing in clay soil may access more via direct uptake from soil (???)

Maybe just chasing ghosts on this one.

 

[Rick]

If you are really scared about sulfur deficiency you could always add another 1% Mg SO4 ( or 2% epsom salt to your DI based fertilizer mix).

As noted above, most surface/tap/well waters contain several ppm of sulfate (way in excess of need).

Unless you are strict RO use and use in strict hydroponic growing (either air spray or inorganic potting materials that absolutely do not break down such as borosilicate glass marbles) then incidental sulfate will be everywhere with no problem.

And as we found out for K, plants do have super efficient uptake pumps, so it is generally not necessary to supply anything in relative percentages to what the plant contains in leaf tissue analysis.

 

[gonewild]

Maybe you should also add titanium since it is present in plant tissue?

Silica and sulfur are easily and cheaply available to plants from the media and don't need to be added in the fertilizer mix.

If you want to take plant fertilizer to a level that is based solely on the science of tissue analysis then you better also add Titanium to your fertilizer.

You can't put every mineral a plant needs into one solution that is simple enough to used by orchid collectors.

 

[Rick]

Maybe you should also add titanium since it is present in plant tissue?

Don't forget palladium!!

http://www.arbico-organics.com/downloads/maxicrop-kelp-analysis.pdf

Getting crazy guys.

Most of us also use a kelp extract, which contains just about everything under the sun. And yet another source of silicon and sulfur.

 

[DavidCampen]

If you are really scared about sulfur deficiency you could always add another 1% Mg SO4 ( or 2% epsom salt to your DI based fertilizer mix).

No, I am not "scared" why do you use such a negatively biased term. Does your attitude indicate that you do not consider sulfur a necessary element for plant growth?

If I used commercial fertilizer formulations such as K-lite I would be concerned about the lack of sulfur, especially since they don't even bother to specify the sulfur content, but I blend my own formulations.

As noted above, most surface/tap/well waters contain several ppm of sulfate (way in excess of need).

I find your attitude quite strange, you have what seems an obsessive concern about potassium levels but you flippantly dismiss sulfur as being so trivial that it does not warrant being mentioned on a label.

Unless you are strict RO use and use in strict hydroponic growing (either air spray or inorganic potting materials that absolutely do not break down such as borosilicate glass marbles) then incidental sulfate will be everywhere with no problem.

So you are saying don't be concerned about sulfur even if you use RO water because enough will be obtained from the air or media. That seems a rather flippant and, in my opinion, probably erroneous comment

And as we found out for K, plants do have super efficient uptake pumps, so it is generally not necessary to supply anything in relative percentages to what the plant contains in leaf tissue analysis.

So what you seem to be saying is that any proportions of any nutrient will be optimal (except, or course, for potassium which has to be strictly controlled).
I find your position to be quite odd.

 

[DavidCampen]

Maybe you should also add titanium since it is present in plant tissue?

Silica and sulfur are easily and cheaply available to plants from the media and don't need to be added in the fertilizer mix.

If you want to take plant fertilizer to a level that is based solely on the science of tissue analysis then you better also add Titanium to your fertilizer.

You can't put every mineral a plant needs into one solution that is simple enough to used by orchid collectors.

You equate sulfur to titanium with respect to plant nutritional requirements? That is an ignorant statement.

 

[gonewild]

A little side tracked from discussing the benefits of Silica?


The idea that Silica should be added to fertilizers is not new (orchids and other ornamentals). It has been tried many times and the results are not dramatic one way or the other. They may actually show some positive results and really don't show any negative result.

Sulphur has been tested and manipulated for a long, long time. The idea that fertilizer should contain more has been tested and as with Silica the results are positive but not dramatic. Personally I have tried all sorts of different uses of sulfur on plants and the results were not very exciting one way or another.

Basically plants are able to forage what they need from what is available and both silica and sulfur seem to be available from many different places for the plants in most growing conditions.

The idea with K-lite and lowering the potassium is to restrict a mineral from availability because the plants over-indulge on it causing a nutritional imbalance. The benefit and likely success of K-lite is because it gives better results with less fertilizer. If anything K-lite does increase the ratio of Silica and Sulfur without actually needing to add it to the fertilizer mix. The reason being is that with the reduction of the contained K-lite minerals that creates an increase in the ratio of naturally available Sulfur and Silica.

 

[gonewild]

You equate sulfur to titanium with respect to plant nutritional requirements? That is an ignorant statement.

Thank you.

 

[Rick]

So what you seem to be saying is that any proportions of any nutrient will be optimal (except, or course, for potassium which has to be strictly controlled).
I find your position to be quite odd.

Odd and heretical. Go ahead and read the references in the paper.

 

[Bjorn]

Maybe you should also add titanium since it is present in plant tissue?

Silica and sulfur are easily and cheaply available to plants from the media and don't need to be added in the fertilizer

OMG,:rollhappy: in water in soil there is some 3-15ppm Silicon available and that is enough, in typical compost there is 10-25ppm extractable Silicon, in shoots there can be 30-500ppm Si.
Ok, my gut-feeling tells that sooner or later the available silicon is depleted and growth stops. Then its time to repot; or perhaps wait for compost-decomposition?

Don't forget palladium!!

http://www.arbico-organics.com/downloads/maxicrop-kelp-analysis.pdf

Getting crazy guys.

Most of us also use a kelp extract, which contains just about everything under the sun. And yet another source of silicon and sulfur.

Let us assume that there is no more available silicon in the compost and that there is no silicon in the water(RO). All silicon has to be supplied with kelp extract having 0.16% silicon according to the above link. If 5ppm silicon is a good number(enough), then the irrigation water must contain 3125ppm kelp. A reasonable number?. BUT you have to do it in every watering, always! Gets pretty expensive if you ask meoke: and if the right number is 0,5ppm, then 313ppm has to be added to the water, still quite expensive. Of course, this is just playing with numbers, but keep in mind that the plants absorb just as much silicon as many of the other elements like phosporous and calcium. And for that sake potassiumoke: So why do you not care about Si fertilizing what if silicon deficiency makes the plants prone to infections?

 

[keithrs]

What ever happen to folks using pro-tek?