# Macroelements/microelements must be a costant ratio?



## DarioU (Dec 31, 2014)

Dear Orchid friends,
The ratio of macro and microelements in a nutrient solution must be costant? In other words a solution with 100 ppm of N must have more microelements of a solution with 60 ppm of N? Or should be better if microelements were in the same amount in both solutions? Our hobby is wonderful and interesting but very diffucult. Is not so?
Thank you


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## PaphMadMan (Dec 31, 2014)

Nature doesn't supply nutrients in a fixed ratio, and there are many successful fertilizer and nutrient solutions with very different ratios. It may depend on your purposes, but in general I would keep micronutrients constant when trying out different macronutrient levels.


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## gonewild (Dec 31, 2014)

I think the ratio between micro and macro nutrients is very important.
I don't thing anyone knows what the correct ratio is or even how much to apply.


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## DarioU (Dec 31, 2014)

Is there something written about the range suggested for each microelement in solution? A minimum and a maximum level?
Irrigation water without any fertilizer should have the same amount of microelements?


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## gonewild (Dec 31, 2014)

DarioU said:


> Is there something written about the range suggested for each microelement in solution? A minimum and a maximum level?



Yes there is a lot of research and written documents about micro nutrients.
What I'm saying is that no one really knows the correct answer. 
If you look on most complete fertilizer labels it will list the micro nutrients and those ratios are based on what is assumed to be the best.
You can copy those ratios or change them based on your on environment.
You need to know what micro nutrients are already in your water supply and media so you don't add too much of any of them.



> Irrigation water without any fertilizer should have the same amount of microelements?



No.
In my opinion the micro nutrients should be applied at the same time as the base fertilizer. And in my opinion that should be every time you water.


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## DarioU (Dec 31, 2014)

Thank you Gonewild but the problem is that on complete fertilizer label there are the micronutrients ratios but the their ppm in the final solution depend by how much fertlizer I have used.... For 100 ppm of N I have x ppm of Boron (for istance) and for 200 ppm of N I have 2X ppm of Boron ... but 2x ppm of Boron are already in a toxic amount?


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## ALToronto (Dec 31, 2014)

Given that commercially available complete fertilizers are meant to be used at 200+ ppm N, and the micros are added accordingly, you will probably not overdose the micros if you keep the N at orchid-friendly levels.


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## DarioU (Dec 31, 2014)

But if I use the same commercially available complete fertilizer at 50 ppm N I underdose micros?


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## ALToronto (Dec 31, 2014)

Probably not - otherwise we wouldn't be using RO and rain water for our plants; they'd be doing great in tap water.

My plants in pots get K-lite at about 10-15 ppm N in RO water (10-12 ppm TDS), total TDS reading is about 70. They're doing fine and are not showing any signs of nutrient deficiencies. Each new growth is bigger than the previous one, whether it's cattleyas, oncidiums or phrags. Everything is in balance, although at very low concentrations.

The plants on my living walls get ammonia-based 25-10-10 also at 10-15 ppm N, with added Epsom salts, for a total TDS reading of about 90-100. Since the walls are concrete based, the plants get plenty of Ca, and I need to add some Mg to balance it out. The actual amount of Ca is not nearly as important as the Ca/Mg ratio, which should be in the 2-4 range. The runoff water has a TDS reading of about 300, so it picks up a lot of calcium. It also picks up silicate, iron, aluminum, sulphate and a whole host of metals from the flyash component of my concrete. 

Flyash is the leftover minerals after the organic components of coal are burned off. It's about 1% of the weight of coal, so the trace minerals in coal are concentrated 100 times. Still, they're in the same perfect balance as they were in the ancient vegetation that created the coal deposits.

I'm growing phrags in the catch basin of my newest living wall, in semi-hydro conditions in lava rock, and they seem to be ok with the 300 ppm TDS water that they get. I do flush them once in a while, though.


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## gonewild (Dec 31, 2014)

DarioU said:


> But if I use the same commercially available complete fertilizer at 50 ppm N I underdose micros?



This is the part that i said no one really knows the positive answer.

The concept of using certain ratios between all the nutrients keeps things in balance. 
Think like this...
If you apply 100ppm Nitrogen as a macro nutrient and at the same time you apply 2ppm Iron as a micro nutrient the nitrogen and iron have a ratio of 100:2 or 50:1 (same ratio)

Now if you apply the same fertilizer at half strength you have 50 ppm of nitrogen and 1 ppm of iron and that ratio is 50:1 which as you can see is the same ratio as above even though you applied only half as much.

This illustrates what is meant by a balance fertilizer, the ratios between nutrients are constant within the formula regardless of the strength it is mixed.

The ratio between nutrients is probably more important than the strength.... and no one knows positively what ratios are the best. However if you compare the ratios between macros and micros of different fertilizer brands you will see they are all mostly very similar.


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## ALToronto (Dec 31, 2014)

Actually, Lance, a 'balanced' fertilizer has the macro nutrients in equal proportions, e.g. 20-20-20 or 10-10-10. I never saw the point of making a 10-10-10 fert by the same company that makes a 20-20-20, but PlantProd does. I haven't looked at the micros closely enough to see if they were in the same amounts.


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## gonewild (Dec 31, 2014)

ALToronto said:


> Actually, Lance, a 'balanced' fertilizer has the macro nutrients in equal proportions, e.g. 20-20-20 or 10-10-10. I never saw the point of making a 10-10-10 fert by the same company that makes a 20-20-20, but PlantProd does. I haven't looked at the micros closely enough to see if they were in the same amounts.



I think the term "balanced" when applied to fertilizer is just a sales prop.

I've never considered balanced as being equal numbers but rather the correct balanced ratios of nutrients for a given type of plant.

20-20-20 may be balanced for grass but it not balanced for petunias. 
When 30-10-20 was created it was touted as the perfect balance for orchids.
To me a balanced fertilizer is like a balanced diet for humans, nutrients in varying quantities that when consumed together provide ideal health.

Usually the difference between 20-20-20 and 10-10-10 would be different source chemicals...... I think!


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## limuhead (Dec 31, 2014)

Lately I hardly ever have time to fertilize. I fertilized last week for the first time in a month or so. I did notice some of my plants 'greened up' a bit, but after experimenting with different fertilizers, k-lite, MSU, organic, Miracle Grow, Peters, and countless others I have come to a conclusion.
OF ALL OF THE FACTORS CONCERNING ORCHIDS FERTILIZER IS THE LEAST SIGNIFICANT FACTOR. End of story...


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## Ozpaph (Jan 1, 2015)

I might suggest if the other factors (light etc etc) arent optimal then the mythical 'optimal' fertilizer application is not going to compensate. 
I think fertilizer is the proverbial 'icing on the cake'.


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## Bjorn (Jan 1, 2015)

No, disagree. I firmly believe that good growing is absolutely dependent on a constant and regular supply of micronutrients. Many people have sufficient of the most important in their water already, others not. That is why we add fertilisers. For some reason there seems to be a common misunderstanding that 100ppm N is good for orchids and fertilisers are often composed with this concentration in mind. Reality is of course that this is the equal of "megasize me" , remember that bloke that lived on mega sized burger meals? That was not good for him and is not for the plants either.
I and several others use far less fertiliser, around 10ppm N seems more appropriate. But then we face another challenge, the micros in the readymade fertilisers get too low.
Realising this, some of us make up their own fertilisers and for some species and growers, with great success at very low macronutirent levels.
But where the "sweet spot" is, that is another story. Suggest you read the theads by Roth regarding this, perhaps this one 
http://www.slippertalk.com/forum/showthread.php?t=23210&page=13
is the most precise additional to the culture document below
http://eurobodalla.org.au/fileadmin...012/Paphiopedilum_culture_and_propagation.pdf


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## Ray (Jan 1, 2015)

Let us not forget that we are talking MICROnutrients here, suggesting that while they may be essential, they are not needed in great supply.

Secondly, most of them are easily translocated within plant tissues - boron being an exception - so unless the plants have been getting none of a particular nutrient, it is likely there will be sufficient amounts available.

Then we also have to consider that in some cases, the micronutrients aren't really permanently incorporated into plant tissues, but act more like "catalysts" or "transfer agents" that facilitate processes, therefore they are not consumed, but remain available for future activity.

To me, the bottom line is "yes", they are important, but knowing there are "some" being provided in my fertilizer is sufficient, even at very low application rates.


Ray Barkalow
firstrays.com


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## orcoholic (Jan 1, 2015)

limuhead said:


> Lately I hardly ever have time to fertilize. I fertilized last week for the first time in a month or so. I did notice some of my plants 'greened up' a bit, but after experimenting with different fertilizers, k-lite, MSU, organic, Miracle Grow, Peters, and countless others I have come to a conclusion.
> OF ALL OF THE FACTORS CONCERNING ORCHIDS, FERTILIZER IS THE LEAST SIGNIFICANT FACTOR. End of story...




I'm with you. Least important but most time wasted discussing.


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## Rick (Jan 1, 2015)

Here's the actual in-situ concentrations (not ratios) of macros in water around the roots of Phrag kovachii:

Ca = 45.6ppm
K = 0.39ppm
Mg = 4.0ppm
Na = 1.2ppm
Cl = 14.2ppm
SO4 = 7.7ppm
HCO3 = 126.8ppm

NO3 = 0.39
No P listed but don't expect it to be greater than N or K.

Only micro listed (Boron) = 0.02ppm

These are very similar to the local surface water, and really not far from averages across the world (although the range is high).


So if you want to "feed" your plants like mother nature, applying N at 200ppm is totally un-natural.

Most N going into plants is fixed on the spot via nitrogen fixing microorganisms.

As a toxicologist I know that the micros (particularly the heavy metals) are toxic at low concentrations and only found in the wild at "micro" concentrations, not the "milli" concentrations we dump on our plants in fertilizer applications.

Ratios are only half the understanding of applying nutrients to plants. Need to understand the total dosing regime of concentration/amount/duration.


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## gonewild (Jan 1, 2015)

Rick said:


> Ratios are only half the understanding of applying nutrients to plants. Need to understand the total dosing regime of concentration/amount/duration.



That's the part I'm talking about that no one really knows the positive answer for.
But we are starting to learn more now that we are not just assuming the labels on fertilizer are what is correct for plants. And it's starting to look like fertilizer companies are overselling nutrients.
More is not always better. But then sometimes it is! :rollhappy:


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## PaphMadMan (Jan 1, 2015)

limuhead said:


> Lately I hardly ever have time to fertilize. I fertilized last week for the first time in a month or so. I did notice some of my plants 'greened up' a bit, but after experimenting with different fertilizers, k-lite, MSU, organic, Miracle Grow, Peters, and countless others I have come to a conclusion.
> OF ALL OF THE FACTORS CONCERNING ORCHIDS FERTILIZER IS THE LEAST SIGNIFICANT FACTOR. End of story...





orcoholic said:


> I'm with you. Least important but most time wasted discussing.



:clap::clap::clap::clap::clap::clap::clap::clap:


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## PaphMadMan (Jan 1, 2015)

As far as micronutrients... If you aren't growing hydroponically and have some complex organic material in your mix, even regular repotting with bark/moss/etc., or use an umprocessed water source once in a while, micronutrients are probably not going to be your limiting factor.


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## Rick (Jan 1, 2015)

PaphMadMan said:


> are probably not going to be your limiting factor.



:clap::clap:Limiting is the key word MadMan.

When you see what's available to very happy plants in the wild, the amounts of macros and micros we apply to our plants make for toxicology experiments because we are generally orders of magnitude beyond "limiting" in our applications.


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## Stone (Jan 1, 2015)

[


> QUOTE=DarioU;512358]Dear Orchid friends,
> The ratio of macro and microelements in a nutrient solution must be costant? In other words a solution with 100 ppm of N must have more microelements of a solution with 60 ppm of N?



Generally, when we dilute a complete fertilizer, we reduce everything as we add more water of course, but the actual amount of trace elements is so small that there is quite a lot of room for a bit more or a bit less before any toxicities will become obvious. In general horticulture (all plants grown in containers) it is far more common to see deficiencies before toxicities.

Common deficiencies (from incorrect additions) are Mg Fe, Less common is Ca, S, K, N, Mn, B.
Most classic toxicities (and they are quite rare) is due to the pH of the mix coming down below 5.

You can feel free to raise the N (mainly) but also K and even P to say double what you normally use (assuming you don't use too much in the first place!) before you will see a deficiency in micros. 
If we assume that all micros are provided, the pH of the mix and irrigation water is probably more important than increasing the micros along with the N.

So in short, don't worry about it too much but be aware that after a while, Mn and B might be two of the first to run out.
If you use bark or organic, Fe Zn and Cu will bind strongly to the organic material and will not leach out much at all.
If you use stones it's is a different story and you must supply everything the plant needs constantly. 

Anyway that's how I approach the trace element question. How much of each specific element is still a bit of a mystery...to me anyway!


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## DarioU (Jan 2, 2015)

gonewild said:


> However if you compare the ratios between macros and micros of different fertilizer brands you will see they are all mostly very similar.


The largest differences are in Boron, Fe, Cu ...


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## Bjorn (Jan 2, 2015)

DarioU said:


> The largest differences are in Boron, Fe, Cu ...



and none of them declare Na although leaf analyses frequently show significant amounts of it. Ok, sodium is very common in nature so in Natural eco-systems its always present, but what happens if we use RO water? Should we be dependent on substrate break-down in order to get the nutrients?


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## Ray (Jan 2, 2015)

To quote "my friend" Horst Marschner: "_Chlorine is a strange mineral nutrient. Its normal concentration in plants is between 70 and 700 mmol/kg dry weight (~2000 and 20,000 mg/kg dry wt), which is typical of the level of macronutrients. On the other hand, the chlorine requirement for optimal growth is between 10 and 30 mmol/kg dry wt (~340 and 1200 mg/kg dry wt), which is in the range of micronutrient levels._

He goes on to say that it is ubiquitous, and is readily absorbed from soils, rain, fertilizers and air pollution.

This is yet one more thing to not be concerned with.


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## Bjorn (Jan 2, 2015)

Ray said:


> To quote "my friend" Horst Marschner: "_Chlorine is a strange mineral nutrient. Its normal concentration in plants is between 70 and 700 mmol/kg dry weight (~2000 and 20,000 mg/kg dry wt), which is typical of the level of macronutrients. On the other hand, the chlorine requirement for optimal growth is between 10 and 30 mmol/kg dry wt (~340 and 1200 mg/kg dry wt), which is in the range of micronutrient levels._
> 
> He goes on to say that it is ubiquitous, and is readily absorbed from soils, rain, fertilizers and air pollution.
> 
> This is yet one more thing to not be concerned with.



With "natural" sources, yes I agree, but with RO? 
Another thing; not all sodium comes as sodium chloride. Potassium is commonly mined (and fertilised) as potassium chloride, so there is your chlorine source. But some sodium may come in that way as well, the potassium in fertilisers are normally not p.a. purity.
If your chlorine source is air, I would be cautious though
Since you have started the calculations Ray; what about this:
A typical fertiliser(MSU) contains 13.2% N(132000ppm) and 0.18% Fe(1800ppm). Lets assume it contains as much chlorine as Fe. How much water at 13.2ppm N to supply 340 mg (1kg dry matter) chlorine? Answer:2492 liter (658gal) Possible? Probably.
Likely? I dont know.
easier with 100ppm N.


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## Rick (Jan 2, 2015)

OK here's a time series of a plant that has gone thru (and survived) the boom and bust cycle common for me with high K feeding.

This Bulbo unitubum (mounted in wooden basket) was purchased BS multigrowth in 2006. Here in 2007 I'm pretty happy with it, and ultimately total growths got up to 20+




Some where around 2008-2009 it started crashing and I took what was left and tied it to a piece of grape vine. It straggled on and produced a bloom in 2010 (3 months into the early low K program)




Now here it is after 3+ years of low K and "impoverished" feeding.




The old growths (which were mature blooming growths) at the bottom are tiny compared to the new growths. The oldest bulbs are 1.6 cm the newest are 4 cm. The oldest growth with a leaf is 2 cm and the leaf is 5 cm. The leaves on the new growths are 9 cm. The old flower spikes are still attached, and the old growths have 1-3 spikes, while the newest growth has 5 spikes, and still healthy enough to bloom again. From 2006 to 2010 it never produced growths this big or floriferous.


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## Brabantia (Jan 2, 2015)

Interesting Rick. And about your use of KelpMax? Maybe it is not the KLite which supplies the oligos but the Kelpak. What is your current use of this laste?
Of coarse quantity and frequency. Is it exist an oligos analysis for KelpMax?


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## Rick (Jan 2, 2015)

Brabantia said:


> Interesting Rick. And about your use of Kelpack? Maybe it is not the KLite which supplies the oligos but the Kelpak. What is your current use of this laste?
> Of coarse quantity and frequency. Is it exist an oligos analysis for Kelpack?



I haven't used any kelp in several months, maybe even a full year to date. Before I discontinued altogether, it was at 1/4tsp/gal about once a month. In 2011 I used it heavier at 1/4tsp/gal once a week. But at that time I also used K lite at 30-50ppm N once a week ( now down to ~5ppm N daily).

I actually used Seaplex and not Kelpack when I used it, but the micronutrient concentrations should be similar (which there is a pretty complete analysis on Ray's site).

This is not the only plant in my collection demonstrating this growth improvement. This one is just the easiest to photograph. The small bulbo species in general are the most obvious and seem to respond very quickly to changes.


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## Bjorn (Jan 2, 2015)

DavidCampen, I know you could add valuable info to this. Why not?
B


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## gonewild (Jan 2, 2015)

Brabantia said:


> Interesting Rick. And about your use of KelpMax? Maybe it is not the KLite which supplies the oligos but the Kelpak. What is your current use of this laste?
> Of coarse quantity and frequency. Is it exist an oligos analysis for KelpMax?



If it were the Kelp making the difference the results would also have been as good before macro nutrients were reduced. Since the growth improved by using K-lite + kelp over the growth with MSU+kelp that rules out kelp being the cause of the improved growth.

I'm not saying that kelp is not good just that it is not what has caused improved growth when growers changed from MSU to K-lite.


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## Bjorn (Jan 2, 2015)

Rick,
Your bulbo is an excellent example of how plant progression should be. I normally judge performance by the size of the leaves, if they are increasing in size or constant(mature size), then everything is ok. Declining size is a symptom of something wrong. Normally that has a connection to nutrients. Additional to that comes deceases etc. which in my mind also is a symptom of some deficiency.
More is not necessarily better, the growth has to be sustainable and experience has shown that frequent additions (in all water) at tiny addition levels are preferrable to the traditional once a week feeding at relatively concentrated levels. On top of that comes of course the micronutrients that probably has to be at higher levels than you get with standard nutrients diluted to e.g. 10ppm N.


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## Bjorn (Jan 2, 2015)

Lance, an interesting point there, but think it has more to do with the accumulated nutrients than with potassium alone. What I think is that potassium poisoning may have something to do with it but if the overalllevel gets low enough the propolrtions gets less important. So MSU at 10ppm N is ok, at 100ppm its not.


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## Rick (Jan 2, 2015)

gonewild said:


> If it were the Kelp making the difference the results would also have been as good before macro nutrients were reduced. Since the growth improved by using K-lite + kelp over the growth with MSU+kelp that rules out kelp being the cause of the improved growth.
> 
> I'm not saying that kelp is not good just that it is not what has caused improved growth when growers changed from MSU to K-lite.



From a history perspective that is true that I was using the kelp with MSU before the low K trial began.

Also in the first several months of low K I was not using K lite, but MSU diluted with calcium nitrate and magnesium sulfate, and still feeding N at the rate of 80+ppm N weekly.

Also from an dosing/application perspective, the mounted Bulbo has virtually no external NPK storage between feed applications unlike a potted plant. Which I think makes the results more dramatic and due directly to the fert application rather than complications of pot conditions.


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## Rick (Jan 2, 2015)

Bjorn said:


> What I think is that potassium poisoning may have something to do with it but if the overalllevel gets low enough the propolrtions gets less important. So MSU at 10ppm N is ok, at 100ppm its not.



Yes. Actually I would stress that overall level is more important than the proportion all along (for active uptake and accumulation nutrients like K, and the trace metals).

Finding that long term dose max has been the tricky part that still keeps bringing up the proportion/ ratios question.

So 10ppm MSU will have 11-13ppm K compared to 1ppm K if K lite.

Given the good growth I'm seeing at K <1ppm. And some of the new data I've been finding on in situ conditions, I'm leaning towards K concentrations of less than 5ppm being optimal (maybe only 1ppm on sensitive species).

With MSU that's would be feeding at less than 4 ppm N, while you could still run N as high as 50ppm with K lite. 4ppm N is probably still good for what I'm seeing, but a whole separate debate. Some folks are not going to give up their N:wink:


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## gonewild (Jan 2, 2015)

Bjorn said:


> Lance, an interesting point there, but think it has more to do with the accumulated nutrients than with potassium alone. What I think is that potassium poisoning may have something to do with it but if the overalllevel gets low enough the propolrtions gets less important. So MSU at 10ppm N is ok, at 100ppm its not.



I think the proportions are important at all levels. It's a recipe that plants want followed when their dinner is prepared. What's in the food is more important that how much food is served. :wink:

Again trying to remember what has been done in the past...
We (many growers including myself) did personal trials using different strengths of what we assumed to be the best ratio of nutrients.
Everything from 0 fertilizer to 2.0ec. all results wound up with what MSU came up with, an amount around 100ppm N.

Most of the ratios were very close to MSU because that is what we (commercial growers) were already using before MSU published their results. Those ratios grew beautiful plants but there was always that random but frequent decline of different groups of plants that was assumed to be due to disease or some environmental problem. The same problems repeated whether Kelp was used or not.

The common thought was how much of what could we increase to make things better, assuming if the plants had plenty available they would take only what they needed and what was healthy. In hind sight that was kind of a big assumption to expect a plant to not be greedy and only eat what is best for it.

We don't know if K is toxic or if high ratios of K causes some other nutrient to become toxic or if "toxic" is even the correct word to use. But what we do know is that growers using the low K formulas are seeing improved growth and a reduction or elimination of the disease symptom issues. No one ever thought to trial the low K concept until Rick "invented" it, we just assumed that plenty of K was a good thing.

Now using the low K ratio growers are getting better growth with small amounts of nutrients compared to MSU. The K is the clue, but what does it do? Perhaps when K levels are high the combination of micro nutrients is the "toxic" problem and it's not the K at all? 

This thread is about micro nutrients and how much to apply and as I said we don't know the answer. The amount of micros in K-lite is a guess based on previous knowledge. So far it seems to be working at that ratio but as growers reduce the dosage of the overall fertilizer the micros are getting applied at almost "nothing" amounts. That indicated that the micros are not needed in the previously assumed amounts.

The interesting thing is that we need to test different combinations based on the new concept to determine what micros need to be added, maybe none!. Sodium may become beneficial with the reduction of K, won't know until someone tests it. Maybe silica will need to be added to the formula?


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## Bjorn (Jan 3, 2015)

Its probably inappropriate to talk about potassium poisoning, I just used that term to describe an unwanted effect by having too much of it. Plants seem to be greedy and overeat potassium. Not only potassium, also nitrate may accumulate, particularly if the micros are deficient. 

Sodium seems to be an interesting candidate, perhaps as sodium chloride? Levels? My guesstimate, 10% of the potassium? 

Silica is somewhat tricky, much water contains it and its solubility is low. I use a submicron colloidal silica that I disperse 2.5g into 10liters water and then inject that into my water supply with an injector at a 1:16 dilution rate. After that it is allowed to dissolve in my main tank that takes 1400 liters under agitation from bubbling with ozone enriched water. The output of this is entirely dissolved at some 15ppm.

My water is a bit uncommon, its surface water taken from a bog next door and smells of sulphur, hydrogen sulphide presumedly. After treatment, the sulfide is transformed to sulphate and the yellow tainted water is colorless. Conductivity is around 150microSiemens or around 100ppm if that has any significance. pH is close to 7 though. It works well for the orchids, but I do not know what causes the conductivity. Its not calcium or magnesium, probably some sort of sulphates?

The silica addition seems not to make any drastic difference and I believe its a long time thing to find out whether or not its really necessary. Silica fertilising is generally improving plants resistance to a wide range of stresses and moderates the uptake of nutrients as well. Particulaly on phosphorous it seems. With silica fertilisation, same crop can be attained at fertiliser levels down to 50% in some special cases.

What we have seen is the fabolous effect that manganese additions can have on some orchids. My own experience was particularly on Paph randsii, and I have been told that cattley rex also responds very positively to increased Mn levels. Seems that the common fertilisers contain too little or in wrong proportions of some essential micronutrients when applied at the ten ppm level.


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## Ray (Jan 3, 2015)

Bjorn, read my last line in that. I simply don't worry about it.


Ray Barkalow
firstrays.com


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## Bjorn (Jan 3, 2015)

Ray said:


> Bjorn, read my last line in that. I simply don't worry about it.
> 
> 
> Ray Barkalow
> firstrays.com



Chlorine or sodium? No reason to worry though, its probably inthe fertiliser as impurities anyhow.

The effect of the other micros particularly Manganese are real though


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## ALToronto (Jan 3, 2015)

Bjorn, if your bog water has H2S, it likely has a lot of iron. You should check for it.


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## Rick (Jan 3, 2015)

Bjorn said:


> Chlorine or sodium? No reason to worry though, its probably inthe fertiliser as impurities anyhow.
> 
> The effect of the other micros particularly Manganese are real though



Chlorine (Cl2) is oxidative (bleaching) gaseous form of chloride. In water in forms hypochlorite HClO3(also bleach). So unless your plants are burning up or turning white, you don't have significant chlorine in the system, but the anion chloride can be quite common.

Also all cations (the majors in surface water are Ca, K, Na, Mg) must be charge balanced with anions (or you are working in extreme acid, base, or potentially explosive situations).

In natural waters the major anions are chloride, sulfate, and bicarbonate ion. In RO based fertilizer systems the predominant anion will be nitrate and phosphate. The chloride and sulfate are often just balanced parts of the trace metal salts, unless special selection of chloride or sulfate salts are used to provide any of the major cations (for instance Epsom salt is Mag sulfate but you can also get chloride, hydoxal, and nitrate salts of magnesium).


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## Rick (Jan 3, 2015)

ALToronto said:


> Bjorn, if your bog water has H2S, it likely has a lot of iron. You should check for it.



Hydrogen sulfide is a toxic gas. With that rotten egg smell threshold at ppb concentrations. If you have it in water at ppm concentrations your nose should be fried and everything dead.

However, the presence of those tiny amounts of H2S often indicate substantial sulfate in the aerobic sites or metal sulfide concentrations in the anaerobic sites (deeper in the sediment).

Biology is at it again with anaerobic bacteria using generally common sulfate ion as an electron ("oxygen" source) for their respiration needs. So they strip the O's from the SO4 and release the toxic H2S as a waste product. High levels (not even1-2ppm) will generally kill everything else in the mud. I've been studying this for the last 5 years as this is a big problem in wild rice production. In the presence of iron (especially) the sulfide binds to metals as insoluble black precipitates. But this works for just about any metal not just iron (which is often the most common heavy metal in the system).


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## Bjorn (Jan 3, 2015)

Rick said:


> Chlorine (Cl2) is oxidative (bleaching) gaseous form of chloride. In water in forms hypochlorite HClO3(also bleach). So unless your plants are burning up or turning white, you don't have significant chlorine in the system, but the anion chloride can be quite common.
> 
> Also all cations (the majors in surface water are Ca, K, Na, Mg) must be charge balanced with anions (or you are working in extreme acid, base, or potentially explosive situations).
> 
> In natural waters the major anions are chloride, sulfate, and bicarbonate ion. In RO based fertilizer systems the predominant anion will be nitrate and phosphate. The chloride and sulfate are often just balanced parts of the trace metal salts, unless special selection of chloride or sulfate salts are used to provide any of the major cations (for instance Epsom salt is Mag sulfate but you can also get chloride, hydoxal, and nitrate salts of magnesium).



I know, Rick. All those things are familiar to me. Just an inaccuracy that made me forget the correct nomenclature. But what is the difference between chlorine and chloride? Just one single electron, amost nothing!oke:
But I should be ashamed of this blunder, in an earlier life, I used to correct university exams in chemistry, so I should know better, shame on me!:evil:


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## Rick (Jan 3, 2015)

Bjorn said:


> My water is a bit uncommon, its surface water taken from a bog next door and smells of sulphur, hydrogen sulphide presumedly. After treatment, the sulfide is transformed to sulphate and the yellow tainted water is colorless. Conductivity is around 150microSiemens or around 100ppm if that has any significance. pH is close to 7 though. It works well for the orchids, but I do not know what causes the conductivity. Its not calcium or magnesium, probably some sort of sulphates?



It's probably not as uncommon as you think Bjorn. What is the hardness?

Sulfate is only an anion. So for charge balanced water you will have sulfates balancing with the major cations (Na, Ca, Mg, K). If the hardness (a measure of calcium and magnesium) is low you probably have mostly sodium as the predominant cation. If hardness is high then the primary salts will be calcium and magnesium sulfates.

"sulfur water" is common here in TN, and its usually very hard (calcium sulfate predominant) with some soluble iron (maybe a full ppm). But stinky with a couple hundred ppb H2S because its coming out of a de-oxygenated aquifer with plenty of sunken organic crap and metal sufides to feed the bugs. 

I could probably do an ion mass balance of your water with just a little more info (like hardness and alkalinity)


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## Bjorn (Jan 3, 2015)

ALToronto said:


> Bjorn, if your bog water has H2S, it likely has a lot of iron. You should check for it.



Guess Rick said it all, most likely the hydrogen sulfide is there at low ppb levels. Strangely, when hydrogen sulfide gets to dangerous levels, one cannot smell it anymore.
Definitely a chance that there is some sulfate in the water, what the counterions are is hard to say, but of course sodium is common in nature? And so is calcium. i do not believe in iron since the water does not give stains, the light yellow color is probably due to humic substances. Once I use the water, its crystal clear so I probably oxidise it in my tank.


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## Bjorn (Jan 3, 2015)

Rick said:


> It's probably not as uncommon as you think Bjorn. What is the hardness?
> 
> Sulfate is only an anion. So for charge balanced water you will have sulfates balancing with the major cations (Na, Ca, Mg, K). If the hardness (a measure of calcium and magnesium) is low you probably have mostly sodium as the predominant cation. If hardness is high then the primary salts will be calcium and magnesium sulfates.
> 
> ...


Thanks Rick for the offer, but it is not that straight forward. This bog thing is a genuine sphagnum moss located on my property. The bedrock in most of Norway is an ancient igneous and metamorphic rocks type gneiss dominated by plagioclase with granite inbetween. Relatively acid rocks in other words. 
To complicate, below the surface layer, and below the sphagnum, is probably a layer of marine sediments (10000years old) composed of clays with shells etc. So our well water is pretty rich in calcium and alkalinity, but the bog water is not. But there are plenty of posibilities of havings a mix of sodium calcium and perhaps magnesium sulphate and even chlorides at a few ppm levels in the bog water. Its proven good for orchids though


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## Rick (Jan 3, 2015)

Bjorn said:


> To complicate, below the surface layer, and below the sphagnum, is probably a layer of marine sediments (10000years old) composed of clays with shells etc. So our well water is pretty rich in calcium and alkalinity, but the bog water is not. But there are plenty of posibilities of havings a mix of sodium calcium and perhaps magnesium sulphate and even chlorides at a few ppm levels in the bog water. Its proven good for orchids though



Bogs are fed by either local surface water or the ground water below them. And major ion salts just don't go away. (except you can acidify bicarbonate to the point of CO2 release and gas off).

See if you can get the hardness done on your bog water Bjorn. Its a very cheap and easy test for either local health department or aquarium store.


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## Bjorn (Jan 3, 2015)

Have tried with those kits. Alkalinity and hardness is close to nil.


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## DavidCampen (Jan 3, 2015)

*My current formulation.*

This is the formulation that I am currently using:

117 g N (NO3/NH4 = 3.8/1)
21 g P2O5
83 g K2O
54 g Ca
15 g Mg
6 g S

1800 mg Fe
1600 mg Mn
800 mg Zn
600 mg B
300 mg Cu
200 mg Mo
200 mg NaCl
40 mg Co
20 mg Ni

This is diluted to 2 liters and I add 2 - 3 ml per gallon of water (Actually it is a 2 component mixture, each component diluted to 1 liter and I use 10 - 15 ml of each per 10 gallons of water). This will give 30 - 45 ppm of N.

So at 10 ml of each of the 2 solutions to 10 gallons of water gives the following ppm in the watering solution.

30 ppm N
5 ppm P2O5
21 ppm K2O
14 ppm Ca
4 ppm Mg
1.5 ppm S

0.45 ppm Fe
0.4 ppm Mn
0.2 ppm Zn
0.15 ppm B
0.08 ppm Cu
0.05 ppm Mo
0.05 ppm NaCl
0.01 ppm Co
0.005 ppm Ni


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## Ray (Jan 3, 2015)

DavidCampen said:


> This is the formulation that I am currently using:
> 
> 117 g N (NO3/NH4 = 3.8/1)
> 21 g P2O5
> ...




...and?


Ray Barkalow
firstrays.com


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## Rick (Jan 3, 2015)

Bjorn said:


> Have tried with those kits. Alkalinity and hardness is close to nil.



I've seen some water that came out of a sulfuric acid plant in Wyoming that was pretty much devoid of hardness (had just 2-3 ppm of Ca and Mg) and was nothing but sodium sulfate and sodium bicarbonate. (Conductivity was ~2000uS/cm)

Interesting that your pH is holding short of 7s.u. with 100ppm of TDS and not getting any significant alkalinity.


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## Stone (Jan 3, 2015)

Rick said:


> OK here's a time series of a plant that has gone thru (and survived) the boom and bust cycle common for me with high K feeding.
> 
> This Bulbo unitubum (mounted in wooden basket) was purchased BS multigrowth in 2006. Here in 2007 I'm pretty happy with it, and ultimately total growths got up to 20+
> 
> ...



Rick, You have convinced yourself of something that is not there.
I can show you a bulbo which has been growing on a tree fern log (high K content) for at least 8 years. It is fed with osmocote 6% K, and submerged in a high K (+Mg and Ca) fertilizer solution now and then. It also recieves dolomite a couple of times during the growing season.
I would have thought the plant and the mount were pretty saturated in K by now yet no crashing.
If I fail to notice the treefern begining to rot ( usually around 10 years or more), the plant can lose all its roots overnight.

It has not ''crashed'' and it will not crash because of high potassium or potassium blocking Calcium or whatever.
The most probable reason yours did is either because of the above cause or that the roots were too wet during a cold spell or during dormancy and died.

It takes a lot of effort to bring a plant back from that but reducing K is not what gets sets the plant back on the road to recovery. (of course you don't feed anything until you have roots)
If high K made orchids crash, then the cymbidium industry here (for example) would be long dead. 

There's an orchid nursery just down the road from me. He specialises in Australian natives but also grows Cyms and some of the best specimens of Laelia species I've seen. He only uses Peters Excell high K + Cal and Mg.
He pots in Bark lava and charcoal. No crashing just explosive growth.


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## Bjorn (Jan 4, 2015)

DavidCampen said:


> This is the formulation that I am currently using:
> 
> 117 g N (NO3/NH4 = 3.8/1)
> 21 g P2O5
> ...


Interesting David, 
I see you have an increased amount of Mn as opposed to standard, you add some sodium chloride and you add some cobalt as well. 
Also, seems as if your mix is based mostly on nitrates, the sulphur seems low to me? I just wonder, how did you arrive at this composition, by research or grow test?
I am about to set up a new fertiliser mix for my collection and I would perhaps use less nitrate with more sulphate, and less iron, more manganese copper and zinc. Perhaps something like Fe:Mn:Zn something like 1:3:2. Have to do some checks with the current fertiliser mix first. Have been running on low Fe and high urea/ammonium for a year now with increased Mn, Cu and Zn with good results and want to develop further.


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## Bjorn (Jan 4, 2015)

Rick said:


> I've seen some water that came out of a sulfuric acid plant in Wyoming that was pretty much devoid of hardness (had just 2-3 ppm of Ca and Mg) and was nothing but sodium sulfate and sodium bicarbonate. (Conductivity was ~2000uS/cm)
> 
> Interesting that your pH is holding short of 7s.u. with 100ppm of TDS and not getting any significant alkalinity.



Seems a bit similar to my water and I have been wondering whether it could have some sulphate and / or chloride, mainly sodium? Chloride and sodium coming from the marine sediments. Remember as this is a sphagnum bog, most likely there is some rather significant ion exchnage capabilities going on so if seepage water containing calcium comes into the system, it will absorb on the sphagnum releasing H+ and this will neutralise the hydrogencarbonate yielding CO2 that escapes.
Does this sound reasonable?


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## ALToronto (Jan 4, 2015)

Rick, Bjorn is right - as long as you can smell H2S, it is harmless. After all, our own bodies produce it, but no matter how toxic a bathroom may seem, the odour hasn't killed anyone yet. It's when you stop smelling it that you have to worry.

I used to work at a nuclear power plant that had a heavy water plant on the grounds, so those of us who rode bicycles to work past the heavy water plant had to carry oxygen kits. Heavy water production uses H2S for isotopic separation of water.


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## Bjorn (Jan 4, 2015)

ALToronto said:


> Rick, Bjorn is right - as long as you can smell H2S, it is harmless. After all, our own bodies produce it, but no matter how toxic a bathroom may seem, the odour hasn't killed anyone yet. It's when you stop smelling it that you have to worry.
> 
> I used to work at a nuclear power plant that had a heavy water plant on the grounds, so those of us who rode bicycles to work past the heavy water plant had to carry oxygen kits. Heavy water production uses H2S for isotopic separation of water.



Interesting, where in the process is the hydrogen sulfide? Is it to sepaprate ot the deuterium?


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## gonewild (Jan 4, 2015)

Stone said:


> I can show you a bulbo which has been growing on a tree fern log (high K content) for at least 8 years.



Showing is good! Let's see a picture.

What is the K content of the tree fern?


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## Rick (Jan 4, 2015)

Bjorn said:


> Seems a bit similar to my water and I have been wondering whether it could have some sulphate and / or chloride, mainly sodium? Chloride and sodium coming from the marine sediments. Remember as this is a sphagnum bog, most likely there is some rather significant ion exchnage capabilities going on so if seepage water containing calcium comes into the system, it will absorb on the sphagnum releasing H+ and this will neutralise the hydrogencarbonate yielding CO2 that escapes.
> Does this sound reasonable?



If you are exchanging Ca for H ( a reasonable process in sphagnum) the pH drops to very low levels (less than 4.0 where bicarbonate, alkalinity, is truly at 0ppm).

Now pure water at conductivity 0 uS/cm can have a pH of 7 with 0 alkalinity, but at conductivity of 100uS it's hard to imagine. That sulfuric acid plant process produced a ton of sulfide, and without massive amounts of soda ash (sodium carbonate), the pH and dissolved oxygen would drop to very low levels and kill everything.

I could probably make a solution of sodium sulfate and sodium chloride in DI water with a just off neutral pH, but I suspect it would not be a stable pH and want to drop. Also even a hint of iron would drop the pH.

Could be possible that some alkali silicates are buffering the system.

Need to get your water tested at a good lab Bjorn.:wink:


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## Rick (Jan 4, 2015)

ALToronto said:


> Rick, Bjorn is right - as long as you can smell H2S, it is harmless. After all, our own bodies produce it, but no matter how toxic a bathroom may seem, the odour hasn't killed anyone yet. It's when you stop smelling it that you have to worry.
> .



Yup

The odor threshold for humans is 0.0047ppm
The OSHA 8 hour PEL is 10ppm.

I think your nose gets desensitized at 1-5ppm.

People die at 800ppm in 5 minutes, but will go unconscious at lower levels and unable to get away from it, but you'll never smell it at this level!


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## Bjorn (Jan 4, 2015)

Rick said:


> If you are exchanging Ca for H ( a reasonable process in sphagnum) the pH drops to very low levels (less than 4.0 where bicarbonate, alkalinity, is truly at 0ppm).



My suggestion was that since the calcium is supplied as calcium hydrogencarbonate, the hydrogencarbonate should react with the H+ and get transformed to CO2. This will then evaporate particularly since its pumped through an impeller type pump. The remains iare then salts of sodium..


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## ALToronto (Jan 4, 2015)

Bjorn said:


> Interesting, where in the process is the hydrogen sulfide? Is it to sepaprate ot the deuterium?



The liquid phase of H2S has an affinity for D2O, while the gaseous phase attracts H2O. It's a multi-stage process that achieves over 99% purity.


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## myxodex (Jan 4, 2015)

Interesting discussion. With some reservations, I go along with those that suggest not to worry too much about micro concentrations as even at higher dilutions you are probably still providing more than enough. I think the cationic transition metal micros (TMs) can potentially become toxic if allowed to build up in the medium. This toxicity may not be enough to kill the plant in normal practice but could harm the roots or at least be a source of continuous low level oxidative stress, which the roots would be happier without, especially in the context of sulphur-limited fertilization. If you let the medium partially dry out between waterings, then you could get an accumulative precipitate of TM-phosphates on the substrate which could then act like a timebomb if the medium pH subsequently drops. I guess that in the wild most orchids are probably more tolerant of pH fluctuations than they are in culture simply because of the high nutrient levels we traditionally throw on our plants. 

The situation could be a bit more complicated when a particular micro is provided in excess. The TM micros do compete with each other for uptake and excess of one can cause deficiencies in another. One of the most surprising is nickel, which is thus far only known to be needed for the urea cycle (urease) and is needed in vanishingly small quantities. Producing a nickel deficiency experimentally is extremely difficult, everything that goes near the plant has to be ultra, ultra pure because the smallest trace of Ni will invalidate the experiment. The real surprise is that Ni deficiencies, although rare, do occur in agriculture, and are nearly always caused by an excess of one of the other micros, or Ca, high phosphate and pH.

Bjorn pointed out Roths comments on micros, which I agree is worth reading. The difference in element analysis of leaves of wild versus cultivated plants highlighted the lower Fe to Mn ratio in wild plants. What caught my eye in this was the lower concentration of both Zn and Cu in cultivated plants and I have a (probably crazy) idea as to why this might happen. In short the culprit might just be EDTA. Most media use EDTA to complex iron as Ferric / Fe3+ because it is the more stable chelate. The chelate stabilities for the TM micros with EDTA are as follows, Fe+++ ~ 25, Fe++ ~ 14, Mn++ ~ 14, Zn++ ~ 16.5, Cu++ ~ 18.8 (couldn't find a figure for Ni). Remember that these stability constants are on a log scale. The plant is simply not going to get the Fe+++ from the EDTA unless it is reduced to Fe++, and this is what happens in the root by the activity of iron chelate reductase. The free Zn++ and Cu++ will now displace the Fe++ from the EDTA even if they are 10 to 100 fold more dilute. Some Australian scientists have demonstrated that EDTA does enter the plant root and a proportion of this moves up to the shoots. EDTA is not broken down, it is enviromentally and physiologically persistant. One bacterium species has been found to degrade it slowly under specific conditions but this is irrevelant here, the prediction is that EDTA will accumulate, mostly in the plant roots, and this will lower the available concentration of Cu and Zn. 

Just to muddy the waters even more there are the hyperaccumulator and hypertolerant plants that grow in soils that have toxic levels of say Cu, Zn, Ni etc. These are interesting because they are exceptions to the norm and have been extensively studied for the purposes of phytoremediation of metal polluted enviroments. A spin-off of this research is an increased knowledge of what "normal" is and just how variable micro concentrations and tolerances are across plant species and even between closely related species. For an extreme example, there is a hyperaccumulator in New Caledonia, Pycnandra (formally Sebertia) acuminata that produces a green latex that is up to 25% Ni dry weight. There are not many pests that will chew on that. BTW, talking of eating hyperaccumulators, there is a Mexican delicacy called "caca de luna". Not a plant, but a slime mould, Fuligo septica, (aka "dog's vomit slime mould"), can contain up to 20g/Kg dry weight Zinc and up to 15g/Kg Barium. Not high on my list of things to try.


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## DavidCampen (Jan 4, 2015)

Bjorn said:


> Interesting David,
> I see you have an increased amount of Mn as opposed to standard, you add some sodium chloride and you add some cobalt as well.
> Also, seems as if your mix is based mostly on nitrates, the sulphur seems low to me? I just wonder, how did you arrive at this composition, by research or grow test?
> I am about to set up a new fertiliser mix for my collection and I would perhaps use less nitrate with more sulphate, and less iron, more manganese copper and zinc. Perhaps something like Fe:Mn:Zn something like 1:3:2. Have to do some checks with the current fertiliser mix first. Have been running on low Fe and high urea/ammonium for a year now with increased Mn, Cu and Zn with good results and want to develop further.



The formulations that I am making and using are just based on my guesses from my observations and reading but there is no scientific testing other than that I use these formulations and my plants seem to thrive.

The nitrate to ammonia ratio is 3.8 to 1, again, just a guess at what might be most beneficial.

Most commercial water soluble fertilizer formulations don't even specify the S content. I think my levels of sulfate are significantly higher than typical single package formulations and that the low levels in commercial formulations are one reason that people see beneficial effects when supplementing with epsom salts (magnesium sulfate).

To the comment re in another post about chelates. The only complexing agents that I use in my formulations are citric acid, aspartic acid and ammonia; all are very much weaker than EDTA. I add iron to my formulations as ferric ammonium citrate (green form); the concentrate that contains the ferric ammonium citrate has to be stored in an amber bottle to prevent light from causing the iron to precipitate (via conversion of the ferric ammonium citrate from its green form to its black form).


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## Rick (Jan 4, 2015)

Stone said:


> I can show you a bulbo which has been growing on a tree fern log (high K content) for at least 8 years. It is fed with osmocote 6% K, and submerged in a high K (+Mg and Ca) fertilizer solution now and then. It also recieves dolomite a couple of times during the growing season.



This has the potential to be a wonderful low K feeding solution, but you didn't mention what type of water they use for irrigation between. 

Even if the total K content of the tree fern is relatively high (say 1% dry weight) the plant only access a tiny portion of the mount by the roots (which are not that long in this species), and they only get the K when the material is broken down . If the original mount is in good shape after 8 years then virtually no K was contributed by the tree fern. If you think tree fern has a high leachable K, then that is even more finite and short term than total K.

I can't imagine that a vertical/porous mount will hold that much osmocote (or dolomite for that matter), and osmocote is also slow release. Very little would ever be in contact with a root, and most would get washed away by the frequent misting/watering typical for a mounted Bulbo on a non-water retentive mount. 

The occasional dunks in something similar to the old MSU are probably the most significant K input, and getting closer to how I treated my plant with weekly dousing at 80-100ppm N (100ppm + K). But I was dosing weekly, and I don't know what "now and then" is. Plus I was using RO water at the time, so no additional Ca inputs beyond that in MSU.

So maybe you can do more math and fill in the blanks, but I suspect my K exposure in the good old days was way higher than your friends plant has experience over the last 8 years.

Most of my Bulbos grow year round without a defined growth season, and with all being mounted, water restriction is not an option if I don't want to crispy critter them.


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## Rick (Jan 4, 2015)

myxodex said:


> Just to muddy the waters even more there are the hyperaccumulator and hypertolerant plants that grow in soils that have toxic levels of say Cu, Zn, Ni etc. These are interesting because they are exceptions to the norm and have been extensively studied for the purposes of phytoremediation of metal polluted enviroments. A spin-off of this research is an increased knowledge of what "normal" is and just how variable micro concentrations and tolerances are across plant species and even between closely related species.



This area worries me more when I think about flasking medias, and how concentrated they are relative to the normal environment.


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## Bjorn (Jan 5, 2015)

David thanks a lot for valuable input. And Myxodex the same to you. You guys got me thinking now.
As it happens I have been feeding with a fertiliser composed to be used as a foliar feed. This has been based on urea as the nitrogen source and its pH has been higher than I wanted. So, I have been using rater high amounts of citric acid to get the pH of my stock solution down to the wanted level of approximately 4. In hind sight, I realise that much of that citric acid has been consumed to complex other components of the mix, not only to suppress the pH increase caused by the (probably enzymatic) decomposition of urea into CO2 and NH3 that I have seen in the stock solution. Now, here to the point; are there any experiences connected to such a complexation in this context? Does it make the cations more (or less )available etc?
And also, and a bit on the side but related; what does such a complexation do to the conductivity of the solution? Anyone that has experiences?
Thanks in advance.
PS Myxoydex, I'd love to hear more about your culinary specialties, where are you located?


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## Stone (Jan 5, 2015)

Rick said:


> > So maybe you can do more math and fill in the blanks, but I suspect my K exposure in the good old days was way higher than your friends plant has experience over the last 8 years.
> 
> 
> 
> ...


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## Stone (Jan 5, 2015)

Rick said:


> This area worries me more when I think about flasking medias, and how concentrated they are relative to the normal environment.



Haven't the concentrations of nutrients in flasking media been determined as optimum? Remember it's asymbiotic culture....


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## Ozpaph (Jan 5, 2015)

Stone said:


> BTW, those stonei seeds you sent (thanks again BTW) have been replated and are now ready to deflask. I'm picking them up next week. Really poor germination though. The cross gave 2 flasks. 1 with 8 plants and 1 with 4. The selfing gave 2 flasks with 4 each.



:sob::sob::sob::sob::sob::sob:


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## DavidCampen (Jan 5, 2015)

Bjorn said:


> ... As it happens I have been feeding with a fertiliser composed to be used as a foliar feed. This has been based on urea as the nitrogen source and its pH has been higher than I wanted. So, I have been using rater high amounts of citric acid to get the pH of my stock solution down to the wanted level of approximately 4. In hind sight, I realise that much of that citric acid has been consumed to complex other components of the mix, not only to suppress the pH increase caused by the (probably enzymatic) decomposition of urea into CO2 and NH3 that I have seen in the stock solution. Now, here to the point; are there any experiences connected to such a complexation in this context? Does it make the cations more (or less )available etc?
> ...


Citric acid is a very weak complexing agent for the elements we are interested in except for Fe(III).

http://george-eby-research.com/html/stability_constants.html


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## Bjorn (Jan 5, 2015)

DavidCampen said:


> Citric acid is a very weak complexing agent for the elements we are interested in except for Fe(III).
> 
> http://george-eby-research.com/html/stability_constants.html



Interesting reading, the way I interpret the table is that a relatively weak bonding should be better for plant availability than stron bonding. The complex is less stable, but its metal more available for plant nutrition. Or am I entirely lost here, pls correct if I am wrong


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## gonewild (Jan 5, 2015)

Stone said:


> Haven't the concentrations of nutrients in flasking media been determined as optimum? Remember it's asymbiotic culture....



No.
There is always room for improvement.


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## DavidCampen (Jan 5, 2015)

Bjorn said:


> Interesting reading, the way I interpret the table is that a relatively weak bonding should be better for plant availability than stron bonding. The complex is less stable, but its metal more available for plant nutrition.



That is my opinion.

Also, as was previously mentioned, the stability constants are given as base 10 logarithms. So the difference in stability of a value of 3 compared to a value of 6 is a factor of 1000.


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## Bjorn (Jan 5, 2015)

DavidCampen said:


> That is my opinion.
> 
> Also, as was previously mentioned, the stability constants are given as base 10 logarithms. So the difference in stability of a value of 3 compared to a value of 6 is a factor of 1000.



Yes in a sense logK is similar to pH (just that pH is the negative log). I used to be quite familiar with these things earlier. I assume the brackets are for concentration(Molar) although the text just says amount. Checked citric acid and found thatit improves availability of iron as opposed to iron sulphate when applied to citrus. Seems as if chlorosis is a big problem for citrus.


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## myxodex (Jan 5, 2015)

Bjorn said:


> Interesting reading, the way I interpret the table is that a relatively weak bonding should be better for plant availability than stron bonding. The complex is less stable, but its metal more available for plant nutrition. Or am I entirely lost here, pls correct if I am wrong



I wouldn't worry too much about stability constants and availability in plants, although it would probably be better if the stability constant was lower than that for nicotianamine, which is the main chelator used for transporting these metal ions in plants and has quite high constants for transition metal ions. See following papers;
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC32093/
http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2004.01209.x/full


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## myxodex (Jan 5, 2015)

Bjorn, I'm located in London, UK. Actually I grew up in Kwazulu Natal, South Africa before moving to London in 1982 and I'm really a bit squeamish about eating some of the unusual delicacies out there. For instance, I do like a bit of biltong (dried spicy meat) on occasion and visit a South Afican shop in London that sells some of better quality. They also sell mopani worms (another African delicacy) and I was encouraged to try them, but I just could not bring myself to eat them, despite having previously eaten fried flying ants (termites actually). I did do a course in mycology at university in SA and I do sometimes forage for wild mushrooms in late summer/autumn. One august during the late eighties I went walk-about, i.e. hiking/camping in Wales and found lots of chanterelle mushrooms in the woods. They were abundant and delicious, fried up with some garlic butter on my camp stove, and I couldn't understand why the locals didn't eat them. Later I found out that chanterelle is an accumulator of caesium, and that there was measurable (although not high) fall out of caesium-137 in Wales from the Chernobyl disaster the previous year. So I might just have eaten radioactive mushrooms ?

The information I stumbled across about "caca de luna" which means "**** of the moon" , brought back some memories of working with slime moulds for my MSc thesis project in SA. I would go out collecting them in the bush and bring them back to the lab and attempt to cultivate them axenically,... I only had success with two species, but I was unaware at the time that they are, or can be, hyperaccumulators. This group of acellular slime moulds are called myxomycetes (or at least were) ... and my pseudonym here is a nick name I had acquired from my friends at this time. For those with curious minds, a nice video of a slime mould eating fungi and of sporangia formation: https://www.youtube.com/watch?v=GY_uMH8Xpy0
Also slime moulds as self organising systems and computing research: https://www.youtube.com/watch?v=oEyWwUNj_es

BTW, the S/N ratio of David C's fertiliser is well within range, any more would most likely just be excess and not assimilated. I found the differences between different reports when doing some literature research on this were sometimes due to different conventions in expressing concentrations (S is sometimes expressed as SO3). I really dislike the oxide convention for fertilisers because it is so inconsistent. I recently dabbled in making up my own pottery glazes, and looked into ceramic glaze calculations where everything is expressed as the oxide, and in this context it makes perfect sense and is consistent, but for fertilisers, not so much.


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## Brabantia (Jan 5, 2015)

Just for your information. When I compare oligo's at equal concentration of Nitrogen the KLite have a contain two time higher in each element (and for some a little bit more) than in Cal Mg Everris (ex Peters). So I think it is enough (in KLite) also at high dilution.


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## PaphMadMan (Jan 5, 2015)

Stone said:


> Haven't the concentrations of nutrients in flasking media been determined as optimum? Remember it's asymbiotic culture....



I would assume that few media formulations have actually been optimized - maybe for major nutrients but only for one or a few test species. HUGE amount of work even then - just 3 nutrients at 5 concentrations each is 125 combinations to test, with replicates of each. And especially for micros, anything in a broad range above deficiency is probably indistinguishable.


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## myxodex (Jan 5, 2015)

PaphMadMan said:


> I would assume that few media formulations have actually been optimized - maybe for major nutrients but only for one or a few test species. HUGE amount of work even then - just 3 nutrients at 5 concentrations each is 125 combinations to test, with replicates of each. And especially for micros, anything in a broad range above deficiency is probably indistinguishable.



Exactly! ... very good point, not to mention getting the funding for orchid research.

I've been doing a lot of head scratching about this of late. I think that some of the ideas behind flasking media have been brought across from plant tissue culture/biotechnology studies mostly focused on crop plants (just a guess ... follow the money as they say). 
In general for the formulations I've looked at, the replating media are more concentrated than the germination media in cases where different media are used. I guess the thinking is that you have to supply nutrients for a year or more growing time. The alternative, short of using some slow release (zeolites perhaps ?), is to use liquid culture with some suitable support for the seedlings that would allow for regular medium changes, ... although this would likely increase contamination rate and require a well equipted lab.


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## ALToronto (Jan 5, 2015)

Rick said:


> This area worries me more when I think about flasking medias, and how concentrated they are relative to the normal environment.



And what's the germination rate in nature? Flasking is probably the one area where emulating nature is not the best practice.


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## Stone (Jan 6, 2015)

PaphMadMan said:


> I would assume that few media formulations have actually been optimized - maybe for major nutrients but only for one or a few test species. HUGE amount of work even then - just 3 nutrients at 5 concentrations each is 125 combinations to test, with replicates of each. And especially for micros, anything in a broad range above deficiency is probably indistinguishable.



Hi Kirk, Yes I agree with that. Perhaps ''optimum'' was the wrong word. My point was that we cannot use nutrient availability in nature to determine correct concentrations in the lab. Particularly when we are dealing with asmybiotic germination.
Eg: I often wonder just how much copper or zinc or whatever a twig epiphyte on the tip of a branch overlooking a revine recieves. No throughfall from the canopy only what is in rain or dust. Probably close to undetectable. Yet somehow they manage. We cannot use these tiny amounts with success in the flask (that I know of). Rather than optimum, maybe ''the best we have come up with so far''


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## Bjorn (Jan 6, 2015)

Myxodex, good stories you tell, but you should be careful With eating mushrooms that you are not 100% familiar with. Not that they contain caesium (they still do), we got a lot of that from Tsjernobyl 29years ago and mushrooms are still full of the caesium. But as long as you do not eat it every day there is no worry.
Generally, at least in Norway, there has been a reluctancy in the population to eat mushrooms. Traditionally it has been regarded as dangerous and people do not take the risk. Nonsense of course if you know what you are doing. But there is one precaution, most of the poisonings in Norway happen with immigrants. Particularly from far east but also from eastern Europe. It seems that some of the common culinary mushrooms in Eastern Europe (does not grow here) are mixed up with a rather similar but poisonous species growing in Norway. So, be careful in new countries.


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## gonewild (Jan 6, 2015)

Stone said:


> Eg: I often wonder just how much copper or zinc or whatever a twig epiphyte on the tip of a branch overlooking a revine recieves. No throughfall from the canopy only what is in rain or dust. Probably close to undetectable. Yet somehow they manage.



They don't manage only on what is in the rain or dust they get nutrients from the living organisms that grow associated with them.



> We cannot use these tiny amounts with success in the flask (that I know of). Rather than optimum, maybe ''the best we have come up with so far''



This is the reason to consider nutrient amounts and ratios that don't conform with previously published knowledge. It is the reason to consider that some common nutrients may cause problems when used at previously accepted levels. We do not yet know the optimum levels in-vitro or in-garden and we can come up with better than we have so far.


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## Ray (Jan 6, 2015)

I have to question whether the discussion about complexing agents is even relevant to this discussion, if for no other reason than the extreme dilution levels we're dealing with in our solutions.

You can mix fertilizers and stuff like potassium silicate (Dyna-Gro ProTekt) in dilute solutions with no issue; mix them up in their concentrated forms, and they'll "complex" themselves into insoluble compounds quite readily.


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## gonewild (Jan 6, 2015)

Back to the original question....



DarioU said:


> Dear Orchid friends,
> The ratio of macro and microelements in a nutrient solution must be costant? In other words a solution with 100 ppm of N must have more microelements of a solution with 60 ppm of N? Or should be better if microelements were in the same amount in both solutions?



As you see one knows the positive answer.



> Our hobby is wonderful and interesting but very diffucult. Is not so?
> Thank you



The hobby is very complex because of the complexing agents that complex themselves when we make it too complex.

:evil:
:sob:
:noangel:


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## Bjorn (Jan 6, 2015)

To answer Ray; preparing stock solutions necessitates stable solutions not too diluted. This applies for those of us that use proportioners. For others, it may be beneficial to have a homogenous solution instead of a powder mix, particularly when addition levels get down to low three digits ppm levels. E.g. 300mg/gal.


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## DavidCampen (Jan 6, 2015)

Bjorn said:


> To answer Ray; preparing stock solutions necessitates stable solutions not too diluted. This applies for those of us that use proportioners. For others, it may be beneficial to have a homogenous solution instead of a powder mix, particularly when addition levels get down to low three digits ppm levels. E.g. 300mg/gal.



Also, the discussion in this thread about complexing agents had nothing to do with using them in an attempt prepare non-precipitating concentrated solutions. 

The discussion in this thread had started as someone wondering if the citric acid that he was using to adjust pH would significantly affect the bioavailabilty of micronutrients. My response was that, in my opinion, citric acid was a sufficiently weak complexing agent that it would _not_ significantly affect the availability of the micronutrients.

Then there was a bit of a discussion about if very strong chelating agents such as EDTA would significantly affect the bioavailabilty of the micronutrients. It is my opinion that very strong chelating agents such as EDTA likely do reduce the bioavailabilty of the micronutrients. I believe that someone else also made a similar comment.

I gave up trying to make a single bottle liquid concentrate to use with a Dosmatic injector (for use at something like 1:50 or 1:100). I did not want to use strong chelating agents like EDTA and so I could not get enough calcium and sulfate in my concentrate without precipitation. I gave up on using the Dosmatic pump and now prepare a two bottle liquid concentrate that I add to a stock tank to make the final diluted watering solution.

Many commercial fertilizer formulations do provide the minor elements as chelates with very strong chelating agents (some even stronger than EDTA). I think that this not necessary for fertilizers that will be used on epiphytic orchids (or even Paphiopedilums) and is likely counterproductive.


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## Bjorn (Jan 7, 2015)

David, that is why I bought a second Dosmatic a couple of years back. Then I can inject Ca to the water without precipitation. I use the miniDos, at 1:100 and 1:500. Guess the ideal would have been to have Three; one for macro elements except Ca, one for Ca and one for micros 
But that gets excessively expensive.
There seems to be results in literature that citric acid helps iron to enter the plant through the epidermis, at least for citrus.


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## myxodex (Jan 7, 2015)

Ray said:


> I have to question whether the discussion about complexing agents is even relevant to this discussion, if for no other reason than the extreme dilution levels we're dealing with in our solutions.
> 
> You can mix fertilizers and stuff like potassium silicate (Dyna-Gro ProTekt) in dilute solutions with no issue; mix them up in their concentrated forms, and they'll "complex" themselves into insoluble compounds quite readily.



Interesting point that raises for me a tangential question. I wonder how much silicate precipitation goes on in the medium during the drier part of the watering cycle? Given that Ca is the cation with highest concentration (of those with insoluble silicates) , I wonder whether a small amount Ca silicate precipitation occurs and could then act as an antacid in the media, could be a potentially useful side effect of using proTekt ? I have wondered whether there are any insoluble or conditionally (pH) insoluble minerals that would buffer pH only when it drops into the low 5's ... that could be very useful.


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## Ray (Jan 7, 2015)

myxodex said:


> I wonder how much silicate precipitation goes on in the medium during the drier part of the watering cycle?


When the medium is dry, ALL dissolved solids have precipitated.

Which drops out of solution first is dependent upon their relative solubilities and interactions with other species as the concentration increases with evaporation of the solvent.


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## gonewild (Jan 7, 2015)

Ray said:


> When the medium is dry, ALL dissolved solids have precipitated.
> 
> Which drops out of solution first is dependent upon their relative solubilities and interactions with other species as the concentration increases with evaporation of the solvent.



Along this though path...
As the soil moisture dries up different nutrients drop out of solution leaving an imbalance of nutrients in solution. That imbalanced solution is what the plant has access to. As well, as the compounds are close to dropping out of solution aren't they supper saturated in solution at that point?
As the moisture dries what are the ppms of each remaining nutrient?


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## Ray (Jan 7, 2015)

gonewild said:


> Along this though path...
> As the soil moisture dries up different nutrients drop out of solution leaving an imbalance of nutrients in solution. That imbalanced solution is what the plant has access to.


I hadn't thought of that...


> As well, as the compounds are close to dropping out of solution aren't they supper saturated in solution at that point?


Not necessarily, as that means the concentration has actually exceeded the normal solubility limit, which is unlikely in all but undisturbed systems, but yes, that normal limit is approached.


> As the moisture dries what are the ppms of each remaining nutrient?


It's going to approach the percentages of the solute, less whatever has been absorbed already. If you dissolve a 30-10-10 fertilizer in pure water, then let the water evaporate without any other interaction, you end up with your 30-10-10 again.


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## DavidCampen (Jan 7, 2015)

Bjorn said:


> David, that is why I bought a second Dosmatic a couple of years back. Then I can inject Ca to the water without precipitation. I use the miniDos, at 1:100 and 1:500. Guess the ideal would have been to have Three; one for macro elements except Ca, one for Ca and one for micros
> But that gets excessively expensive.
> There seems to be results in literature that citric acid helps iron to enter the plant through the epidermis, at least for citrus.



I had thought about buying a 2nd MiniDos but then I discovered that I was having trouble getting consistent metering from the MiniDos (and a MicroDos was even more problematic). I use a watering wand with a very fine spray head (made from a pesticide applicator spray wand), with the spray head removed so that the solution could flow freely I would get the metering rate that I expected but with the spray head on (which would increase the backpressure and reduce the flow rate) the proportion of concentrate being injected would be greatly reduced. So I decided to abandon using an injector and instead use a stock tank (where I mix the ready to use watering solution) and electric pump. As a bonus I can now use the stock tank with electric pump for pesticide and fungicide applications.

Yes, iron is the one element that has to be complexed. Fe(II) sulfate is water soluble but it quickly oxidizes to insoluble Fe(III) oxide/hydroxide but Fe(III) ammonium citrate (green form) is nicely soluble and stable if it is not left standing in sunlight and additional citric acid improves the stability.

In my 2 component concentrate formulations, Solution A contains calcium and magnesium nitrates along with all of the cationic trace elements - Fe, Mn, Zn, Cu, Co, and Ni which are also added as nitrates with the exception of the ferric ammonium citrate and the solution is then buffered to pH 5.5 - 6.0 with the addition of citric acid and citric acid salts. Solution B then contains potassium and ammonium nitrates along with phosphate, sulfate, borate and molybdate. Solution A is stored in amber bottles (actinic glass) to prevent light from converting the ferric ammonium citrate into a less soluble form.


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## Bjorn (Jan 7, 2015)

Yes, injectors need a certain minimum flow to work properly. According to the manufacturer data that flow is rather high, cannot remember exactly, but think I found out that I made it with my half inch hose. Checking fertiliser level with the conductivity revealed that at least it was working approximately correct. Approximate is the right term dealing with mixture of citric chelates and urea trying to assess ppm by conductivity. Its not straight forward, but probably good enough knowing the compsition?


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## DavidCampen (Jan 7, 2015)

Bjorn said:


> ... Checking fertilizer level with the conductivity revealed that at least it was working approximately correct. Approximate is the right term dealing with mixture of citric chelates and urea trying to assess ppm by conductivity. Its not straight forward, but probably good enough knowing the composition?



What I would do is prepare a known concentration by, say for a 1:100 ratio, diluting 10 ml of concentrate measured using a small graduated cylinder to 1 liter using my RO water and a 1 liter graduated cylinder. Measuring this conductivity would give me the value that I would expect to see coming from the injector.


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## Bjorn (Jan 7, 2015)

Sure that is a way to calibrate things. Should be more accurate, being away from analytical chemistry does these things to man. Unfortunately my lab conditions are far from beiing perfect, more like non existing for the time being. That is why I have not started with seed propagation i assume....


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## Rick (Jan 7, 2015)

Stone said:


> Rick said:
> 
> 
> > BTW, those stonei seeds you sent (thanks again BTW) have been replated and are now ready to deflask. I'm picking them up next week. Really poor germination though. The cross gave 2 flasks. 1 with 8 plants and 1 with 4. The selfing gave 2 flasks with 4 each. How did Troy do with them??
> ...


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## Rick (Jan 7, 2015)

Stone said:


> Rick said:
> 
> 
> > There is no point or need to do the math. Best judgement is made by looking at the plant.
> ...


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## myxodex (Jan 8, 2015)

Ray said:


> When the medium is dry, ALL dissolved solids have precipitated.
> 
> Which drops out of solution first is dependent upon their relative solubilities and interactions with other species as the concentration increases with evaporation of the solvent.



So from the time of watering to the next watering the concentration of nutrients is obviously increasing. The idea of chelating all the cationic micros is to lengthen the time that they are available by reducing their propensity to precipitate as phosphates, increase their mobility in the medium and thus, hopefully, allow lower concentrations to be effective for longer. That is the idea at least, whether it actually works out this way in practice is another matter. There is a company that produces freeze dried amino acid chelates of micronutrients that they claim to be soluble and compatible with fertilisers. I'm not entirely convinced that the amino acid chelates that I use are necessarily going to stay intact that long in the medium as the microbial population in the mix is probably going to gobble up the amino acids anyway. Nonetheless, I'm trying this approach which is very similar to what David Campen has been doing, which I think is a good enough idea at least to try out.

We tend to focus on the inorganic compounds when looking at natural systems, but there is accumulating evidence that both the organic acids (eg. citric, malic, succinic, fumaric, oxalic) and amino acids (eg. aspartate, glutamate, histidine, and others) are present in easily detectable amounts in aboreal forest soils. Not much work on tropical forests that I could find. Fungi, including mycorrhizal fungi, are known to excrete organic acids to increase the availability of cationic nutrients, and some plants have genes that are involved in the export from roots of malic or citric acid. I seem to remember that mosses do something similar. So chelation is a natural strategy for both plants and fungi in the acquisition of cationic nutrients. Subsequent to uptake in plants, chelation of the cationic micros is essential to protect the plants from oxidative damage. A tomato mutant that is defective in the gene that synthesizes nicotianamine, an essential chelator for metal ion transport in plants, has all sorts of problems and can only be kept alive by application of chelated micros. Hyperaccumulators of Ni have constitutively high levels of histidine in their xylem, and their resistance to Ni toxicity can be partially conferred on sensitive plants by feeding histidine. The point I'm making is that chelation is not some exotic unnatural mechanism dreamt up by chemists in a lab (EDTA is, for sure, but that has been mentioned above). In what form do wild orchids get their micros from mycorrhizal fungi? I'm not sure this is known, but I'm willing to bet that due to toxicity issues the fungus is going to be transporting these as chelates of one form or another. It is likely that fungi growing in our orchid pots are excreting organic acids anyway and whether you are applying chelates or not, some of the micros being assimilated by your plants might well be in chelate form anyway. It's back to the story of beneficial micro-organisms and the interactions between the micro-ecology of the pot and the nutrients we apply.

So as the question about the relevance of chelation at high dilution, I would say chelation could just be a way of getting effective feeding at even higher dilutions, maybe even approaching that in natural environments by using a mechanism that exists in these environments.


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## gonewild (Jan 8, 2015)

myxodex said:


> So from the time of watering to the next watering the concentration of nutrients is obviously increasing.



Sounds like you just described "accumulated salts".



> There is a company that produces freeze dried amino acid chelates of micronutrients that they claim to be soluble and compatible with fertilisers. I'm not entirely convinced that the amino acid chelates that I use are necessarily going to stay intact that long in the medium as the microbial population in the mix is probably going to gobble up the amino acids anyway.



And as the microbial population gobbles up the amino acids they may very well excrete the exact nutrients that the plant needs.



> Nonetheless, I'm trying this approach which is very similar to what David Campen has been doing, which I think is a good enough idea at least to try out.



Yes, try it to find out.



> We tend to focus on the inorganic compounds when looking at natural systems, but there is accumulating evidence that both the organic acids (eg. citric, malic, succinic, fumaric, oxalic) and amino acids (eg. aspartate, glutamate, histidine, and others) are present in easily detectable amounts in aboreal forest soils. Not much work on tropical forests that I could find. Fungi, including mycorrhizal fungi, are known to excrete organic acids to increase the availability of cationic nutrients, and some plants have genes that are involved in the export from roots of malic or citric acid. I seem to remember that mosses do something similar.



Exactly what I have been saying but you have used bigger words! The living organisms are what provide orchids with most of their nutrients in Nature.



> The point I'm making is that chelation is not some exotic unnatural mechanism dreamt up by chemists in a lab (EDTA is, for sure, but that has been mentioned above). In what form do wild orchids get their micros from mycorrhizal fungi? I'm not sure this is known, but I'm willing to bet that due to toxicity issues the fungus is going to be transporting these as chelates of one form or another.



This is why we need to look at unconventional nutrient sources and not assume all nutrients come from rain or dust or leaching leaves.



> It is likely that fungi growing in our orchid pots are excreting organic acids anyway and whether you are applying chelates or not, some of the micros being assimilated by your plants might well be in chelate form anyway. It's back to the story of beneficial micro-organisms and the interactions between the micro-ecology of the pot and the nutrients we apply.



Yes, and to have the orchids grow well we need to give them some form of artificial nutrient supply until the natural organisms establish themselves in the growing media or on the orchid roots and foliage. When an orchid is put into fresh growing media there are no organisms present to produce nutrients so we need to use fertilizer as a form of artificial life support. The growers that are lucky enough to have beneficial organisms populating their cultures are the ones that say fertilizer content is not important.


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## Ray (Jan 9, 2015)

myxodex said:


> So from the time of watering to the next watering the concentration of nutrients is obviously increasing. The idea of chelating all the cationic micros is to lengthen the time that they are available by reducing their propensity to precipitate as phosphates, increase their mobility in the medium and thus, hopefully, allow lower concentrations to be effective for longer.



Sounds reasonable, but we must keep in mind that that is good and well with only very low doses; in the commercial nursery world, it is well established that one of the best ways to screw up plant nutrition is by overdosing the micros. Most feed N-P-K only, and apply soluble trace elements only if there's a recognized issue.


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## DavidCampen (Jan 12, 2015)

Ray said:


> ... in the commercial nursery world, it is well established that one of the best ways to screw up plant nutrition is by overdosing the micros. Most feed N-P-K only, and apply soluble trace elements only if there's a recognized issue.



Really, most commercial orchid growers using RO water use N-P-K only?

Or are you talking about commercial growers who grow in soil, use tap water and do not use greenhouse grade (water soluble) nutrients?

Most people here use RO water, do not grow in soil and use greenhouse grade nutrients.

After all, it was you who said: "_Don't let knowledge (or mythology, in some cases) about nutrition in terrestrial plants "contaminate" your thinking about orchids. Sometimes the info applies, but in some cases, it doesn't._"


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## cnycharles (Jan 12, 2015)

I believe the statement was specific and didn't mention ro water. In the commercial nursery world (general horticulture world of plant production) plain bagged fertilizer is used unless there is a known deficiency or general need of certain plants or a certain feed used is lacking in a known needed micro. Some nurseries may toss in stem or something like that but usually it's done when a need is perceived. Again generally... 
There is often pH adjustment and feeds are often chosen which will tend towards a needed pH, but the micros in that particular feed may not be enough for a particular crop


Sent from my iPhone using Tapatalk


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## Ray (Jan 12, 2015)

DavidCampen said:


> Really, most commercial orchid growers using RO water use N-P-K only?
> 
> Or are you talking about commercial growers who grow in soil, use tap water and do not use greenhouse grade (water soluble) nutrients?
> 
> ...



Right you are, David. I never stated RO, and I wasn't thinking in those terms, but my assertion that overdosing trace elements can screw things up still stands.


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