# pH etc..



## Stone (May 25, 2016)

So lets talk pH again! :rollhappy:

Last night I was reading a report on mineral analysis of the leaves of 35 species of various plants growing on both alkaline soils (pH 7.5-8.5) and acidic soils (pH 4.5-6).

NPK did not vary substantially and neither did Mg and S. So we can forget those. (Although it is highly likely that limestone plants get higher nitrate/ammonium ratios than silicate plants)
Surprisingly, Zn also did not vary too much either. Slightly higher in the acidic soils.

The concentrations are not as important here as the difference between the 2 samples.
As expected, Cu, B, and especially Fe and Mn were much higher in the acidic soil leaves and of course Ca was much higher in alkaline soil leaves.

Mo was not included but it is well known that Mo becomes much more available in the neutral to alkaline range. (very low at about pH5 or so).
And remember too that Mo is vital for nitrate use!

Results....Mean for Calcareous soils:
B 3.4 * Zn 1.08 * Cu 0.15 * Fe 1.2 * Mn 1.7 * Ca 374.
Results....Mean for Silicate soils:
B 4.3 * Zn 1.17 * Cu 0.18 * Fe 2.1 * Mn 5.7 * Ca 208.

Below is the availability of nutrients and various pH values.




This one is better. It has nice colours to guide us 






We need to keep in mind also that in organic soils, Fe Cu and Zn are more tightly held than in mineral soils. (leaf mold and fern roots vs limestone rock face for example.) 

After wondering how I could alter my fertilizers to better meet the needs of my Paphs (calcareous vs non calcareous) Adding higher concentrations of something or removing something else is next to impossible without a lab. Especially after looking at Xavier's analysis for wild mastersianum, emersonii etc. Iron was low and sometimes vanishingly low! So removing Fe from commercial fertilizers is a major interest!
In Xavier's cultivated plant tests , Mo became almost non-existent and nitrate levels went way up! Increasing Mo would not work well in the low pH anyway. You could reduce nitrate but that doesn't solve the Iron problem.....

Avoiding things like metal toxicity especially Iron and ensuring sufficient Mo and Ca for the limestone plants, and making sure non-limestone plants are getting enough Manganese etc.etc.

I decided the easiest way is simple pH adjustment. If we keep the water and fertilizer solutions for the calcareous Paphs around neutral and acidify the solutions and water for the remaining kinds to pH 5. We should go a long way to keeping things in the correct order. At pH 7 Mo is much more available and nitrate should be utilised better. Fe becomes almost out of reach (particularly in bark). At pH 5 Fe is readily available. (think rhododendron gardenia and citrus. They need low pH to get enough Iron. Now think about henissianum, callosum and sukhakulii. pH 7 would be too high for them I would think.
I have been acidifying all my tap water to from just over 7 to about 5.5 and giving that to everything.
My plan now is to change that to 7 (rain or tap) for the C/Paphs and 5 (or even lower) for the A/Paphs. I intend to use limestone dissolved in water to adjust up and lemon juice or some other acid to adjust down.
You can always add certain nutrients (like Mn or Fe or B or whatever) separately if you want later. But changing the availability to help avoid possible problems is what I'm talking about right now.


What do you think?


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## Ray (May 26, 2016)

I think that the ONE study that generated that first chart, which used ONE fertilizer formula in ONE soil, greatly overstates things.

Soils, particularly those high in organic matter and raw clay, have a high CEC, and that's what determines what gets trapped and what doesn't, and is greatly affected by pH. If it's trapped by the soil, it's not in the solution, so is unavailable to the plant

In our - mostly-hydroponic - culture (no matter what the medium, as they all have comparably low CEC's), I believe that if it's in solution, it's available to the plants.


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## Bjorn (May 26, 2016)

Mike, 
making Your own fertiliser is not THAT difficult, I make my own and am very satisfied with it.
Btw. made a new batch with more potassium and a bit more iron. However keep ZN, Mn B and Cu higher than commonly seen and Fe lower.


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## cnycharles (May 26, 2016)

So, your plants are growing great; why is it that you want to monkey with everything? 
I know, we are human and can't help tinkering but experience has shown that if you find the sweet spot the worst thing to do is to start throwing pipe wrenches in a china shop

That said, I'm always interested in theoretical discussion and what people have to say


Elmer Nj


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## naoki (May 26, 2016)

I think it is interesting to try, Mike.

When Ray pointed out the applicability of textbook nutrient availability figure, I looked into this a little bit. The figure is summation of several processes, which include at least the following 3 steps: nutrient leaching/retention in the media (related to CEC), nutrient retention within the cell walls, and transport rate into the cell. The 1st aspect is quite different for orchids as Ray has been pointing out. Here is a similar figure which can be used to compare the nutrient availability in high CEC soil vs hydroponic (or soilless media):





from http://www.breedbay.co.uk/gallery/data/500/Soil_PH_chart.jpg

There are some differences, but I'm not sure if it influences Mike's logic, though. But it does point out the optimum pH is generally lower in soilless media than in soil.

With regard to the leaf mineral analysis, could the large variation in the contents (e.g. Mn) indicate that it is less important? The plants have to adapt to the environment, and if they haven't come up with the mechanisms to obtain the macro nutrients, they can't survive. So the plants in acidic and alkaline soils don't differ much in NPK, Mg, S. But plants don't have to have lots of Mn, so there are some variations.


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## PaphMadMan (May 26, 2016)

Cation-exchange capacity is not a measure of what is trapped by the soil and therefore unavailable, it is a measure of cations retained by soil that are available for _exchange_ with soil solution and therefore are available to plants. High CEC represents a soil's capacity for sustaining fertility rather than allowing all nutrients to be washed away by the next moisture that passes through it. Any nutrients that are somehow trapped by soil and unavailable for plants are not related to CEC.


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## Ray (May 26, 2016)

Maybe it's just a matter of semantics, PMM. If the soil holds it and prevents it from being washed away, it seems to me that it is not allowing it to readily dissolve...


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## gego (May 26, 2016)

Naoki thanks for that soiless chart. So the media does make some difference. Nitrates pulls the ph around the roots high so maybe other N sources should be used instead. 

Mike, how do you know that high nit/ammo ratio is good for cal plants? Is this working for you in paphs?
Thanks


Sent from my HTC One using Tapatalk


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## gonewild (May 26, 2016)

Ray said:


> Maybe it's just a matter of semantics, PMM. If the soil holds it and prevents it from being washed away, it seems to me that it is not allowing it to readily dissolve...



It does not have to dissolve. The roots have their on CEC ability to reverse the ionic bond the soil holds the nutrient with and pull it in to the root.

The dissolving of the nutrients was done before it attached to the soil particles.


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## Stone (May 26, 2016)

What got me thinking about the availability factor came after a second look at Roths figures for mastersianum. I always assumed this plant came from acidic environments. I think this may not be the case. I had three small plants of mastersianum. 1 is dead the second will probably be dead soon enough. The third is growing but I cannot get it to green up. I don't think I have seen any plants of this species with good colour, yet according to Xavier, they should be dark green.

But have a look at the numbers. Compare the Fe in the jungle plants to the Fe in the ''chlorotic'' plants. The difference of a factor greater than 10!
Same with the Mo. A difference of 10.
It seems impossible that a plant coming from an acidic habitat would have such low Iron in it's leaves. Either the Fe is just extremely rare in that habitat or it's availability is very low due pH or both.
The nitrate build up is in the leaves of the chlorotic plants is extrodinary.
Something is definitely not right there.
It is possible that in the habitat the Mo just happens to be high and the Fe just happens to be very low. I suspect that more probably they are in forms which are available and unavailable respectively. A rise in pH will do this if we look at the pH charts.


Page 2. Post #19 here.
http://www.slippertalk.com/forum/showthread.php?t=7692

The same goes for the emersonii.

I'm just throwing out the questions. I don't know exactly what's going on. For example; The Mn and Zn in the leaves of the jungle plants is high yet the Fe is low. In the chlorotic plants, the Mn is not far different to the ''beautiful plants'' This possibly suggests that the form of Fe we give (usually chelates) is too readily available? and/or the high Mn in the habitat is depressing Fe assimilation?
If that is the problem, how do I go about reducing the Fe from a fertilizer?
Would a fert with Fe in the sulphate form be better? Would increasing the Mn concentration help? (that is easy! ) 
This still does not solve the Mo thing......

Iron can be extremely toxic to plants which don't tolerate it. Even very low amounts. The symptoms for Mn deficiency are similar!

@Geo, Nitrification is only very slow at a pH below about 6. If we observe the pH data from various orchid habitats, it seems that generally, volcanic or silicate type soils are quite low. Even 4 or 5 is common. For limestone areas, values of around 6 to neutral are more common. This would suggest that nitrification is higher in the limestone habitats when compared to the others.
Nitrate also depresses Fe.


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## gonewild (May 26, 2016)

It might be a mistake to assume that plants growing on limestone have their roots receive water with a high pH. 
I've measured pH of water trickling over plant roots attached to limestone and the pH was 7.0. In these habitats maybe the majority of water moving to the roots is close to being pure rainwater still.
So first you need to decide what pH is more important to the roots the solid media or the free water.


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## Stone (May 26, 2016)

gonewild said:


> > It might be a mistake to assume that plants growing on limestone have their roots receive water with a high pH.
> > I've measured pH of water trickling over plant roots attached to limestone and the pH was 7.0.
> 
> 
> ...


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## gonewild (May 26, 2016)

Stone said:


> gonewild said:
> 
> 
> > Btw, You are in Peru yes? Do you happen to know the general geology of the Phrag caudatum habitat?
> ...


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## Stone (May 26, 2016)

Ray said:


> > I think that the ONE study that generated that first chart, which used ONE fertilizer formula in ONE soil, greatly overstates things.
> 
> 
> 
> Ray, this was a field study of natural plants. The same species growing in BOTH acidic AND alkaline habitats. Therefore the differences in leaf nutrient concentrations are due to differences in availability and/or concentration in the soils.


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## Stone (May 26, 2016)

gonewild said:


> Stone said:
> 
> 
> > Yes I do, caudatum grows in my area.
> ...


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## Stone (May 27, 2016)

Says here that the Fe EDTA is 50% unavailable at above pH 6.5!
http://www.smart-fertilizer.com/articles/iron


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## Bjorn (May 27, 2016)

Stone said:


> Says here that the Fe EDTA is 50% unavailable at above pH 6.5!
> http://www.smart-fertilizer.com/articles/iron



That is why I use citric acid as chelant
But of course I keep my water below pH 6.....Stable chelates may also render the iron unavailable to plants....


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## Ray (May 27, 2016)

Lance, my understanding is that plants do not take in atoms, they take in ions, which means, in solution.


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## gonewild (May 27, 2016)

Ray said:


> Lance, my understanding is that plants do not take in atoms, they take in ions, which means, in solution.



Yes the ions move from the soil to roots in solution, water between soil and root...very close distance. But they don't have to be "dissolved" to be released from the ionic bond to the soil. They were already dissolved from salt form and turned into ionic form before CE with the soil occurred. The nutrient salts are first dissolved into solution then they bond to the soil particles as ions. 

It's a little difficult to write the explanation, maybe I did not word this correctly?


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## gego (May 27, 2016)

Stone said:


> Says here that the Fe EDTA is 50% unavailable at above pH 6.5!
> http://www.smart-fertilizer.com/articles/iron



"In this respect, choice of the form of nitrogen fertilizer is significant. Ammonium nitrogen increases proton release by roots, thus lowering pH and facilitating iron uptake. 

Nitrate nitrogen enhances the release of hydroxide ions that increase pH in the root zone and counteract efficient iron uptake."

That is stated in the article above and that is what I meant. So to minimize iron uptake use more of nitrate and calcium. You want more, use ammonium.

Also, I want to say this again, in nature potential balance must be achieved and so is the charge between the roots and its surrounding in contact to it. So the charge between the roots and media or solution must be neutral to promote healthy growth. Any uptake of anion or cation by the roots, the roots/plants have to provide an ion to neutralized the charge between them.

The question is how do we provide in ratio to make sure the availability of these nutrients will be more our less balanced, meaning more or less balanced supply of anions and cations?


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## PaphMadMan (May 27, 2016)

Ray said:


> Maybe it's just a matter of semantics, PMM. If the soil holds it and prevents it from being washed away, it seems to me that it is not allowing it to readily dissolve...



A thorough technical explanation of the chemistry is beyond me without consulting references, and I'm an analytical chemist by profession. But the short answer is: Cations held by soil CEC definitely ARE readily available to plants, and that is the relevant point. Clay and humus compounds have net negative charge and hold onto cations to balance charge, but essentially those cations are still in solution even though the anions may not be. Uptake by roots is mostly an active process by swapping cations and the ones held by CEC are largely available for that process just as if they were free in solution.


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## gego (May 27, 2016)

Here's an article from the same website about anion-cation balance.
http://www.smart-fertilizer.com/articles/Cation-Anion-Balance


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## Ray (May 27, 2016)

Hey, Kirk.

As a ceramic engineer, I studied a lot about clays, but admittedly that was a LONG time ago. However, edges of clay particles - they are plate-shaped - can be positively-, or negatively charged, depending upon the pH. If too acidic, they tend to bond face-to-face, in a "stack" like a deck of cards, but if you raise the pH, you get edge-to-face bonding, like a house of cards. That's why we add lime to clay soils to "open them up".

That's why I believe that the pH can affect the availability of nutrients in soils moree than it does in solutions.


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## Stone (May 28, 2016)

But pH adjustment of nutrients solutions for hydroponic systems is fundamental.
The reason for the pH reduction from about 6.5 to 5.5 in soiless media is because the metals become bound to organic particles. This is especially true for Fe. That is why when growing in mainly bark, a increase of between 1/2 and 1 unit back to say 6.7-7 should make Fe less available.
(which is what I am interested in)
At the same time Mo becomes more free.
The link to the Fe paper says that the EDTA is a stable chelate for metals EXCEPT Iron which means that if I use a fertilizer where all the micros are EDTA (which I have) and keep pH above 6.5, I effectively reduce Fe availability to the plant by 50%.
Whether this is a good thing for limestone Paphs or not I don't know but I think it may be some kind of starting point to get figure closer to the mastersianum and emersonii in Roth's post. No doubt hangianum, cahnii, sanderianum etc etc would be the same.
Maybe even 6.7 would be enough (barely acid). I remember many years ago growing big plants of parishii and micranthum very well with a water pH of 9-10 and osmocote which was mainly urea, and that's it! No chelates at all.


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## Happypaphy7 (May 28, 2016)

I've been wondering about pH quite a bit recently since pretty much all my henryanum seedlings started to grow nice big leaves but all has chlorosis leaving only the veins darker green.

I checked the run through pH on all my plants and there were two groups regardless of the type of mix (I have mostly orchita based mix or coconut husk chips based), and they were 5-5.5 and 6.0 group.

I thought the first group had it a bit too acidic, and now the second table makes me wonder if those seedlings are suffering iron overdose.

I did some search and it says under iron toxicity, manganese deficiency symptoms appear first. 
I looked up some images and perfect match! 

Now, can someone advise me how to best increase pH??

I'd like to have it around 6.0-6.5 ideally.
I grow at home, so no special equipment. 

Thanks!

Oh, and another thing is some of my bulldog hybrids tend to have their tips brown when old, which always bothered me, and while doing the above mentioned search, it may also be related to iron toxicity. hmmm...
I know they definitely do not match any diseases I can think of.


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## Happypaphy7 (May 28, 2016)

gonewild said:


> It might be a mistake to assume that plants growing on limestone have their roots receive water with a high pH.
> I've measured pH of water trickling over plant roots attached to limestone and the pH was 7.0. In these habitats maybe the majority of water moving to the roots is close to being pure rainwater still.
> So first you need to decide what pH is more important to the roots the solid media or the free water.



Adding on to that, many of these plants do have some moss blankets and many other vegetations growing near or over their roots, not to mention some of these plants may excrete enzymes and such that creat acidic root zone for better nutrient uptake.

I remember reading about pH measurement of Paph. armeniacum on their habitat. The pH of the root area was between high 5 to low 6.


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## Stone (May 28, 2016)

Happypaphy7 said:


> I've been wondering about pH quite a bit recently since pretty much all my henryanum seedlings started to grow nice big leaves but all has chlorosis leaving only the veins darker green.
> 
> I checked the run through pH on all my plants and there were two groups regardless of the type of mix (I have mostly orchita based mix or coconut husk chips based), and they were 5-5.5 and 6.0 group.
> 
> ...



Funny you should say that hp. My henryis are the same. Growing well but the same weird mottling. My charlesworthii seedlings are beautiful dark green. (My flasker told me when he sows limestone Paph seed they won't grow if the pH is much below neutral. (Make of that what you wish)
Anyway, to increase my pH, I put about a teaspoon of finely ground dolomite in 1lt of water, mix and let it sit for a couple of days. When everything has settled, I decant into another container leaving most of the solids behind - apart from those suspended. I use that water to add to my solution (or rain water of pH6) 1 tablespoon at a time until I get to about 7 or a bit under. (or whatever you want) It might pay to set aside some of the solution and re-test it 2 days later to see if it has changed. If it does, most likely it will go up. In that case just add less of the alkaline water next time. You can do it many other ways but I'm keeping it natural 
Also I'm going to stop Fe chelate for a while or at least cut down as much as possible.. and perhaps spray Mn sulphate once in a while.
Hey nothing ventured nothing gained!


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## Happypaphy7 (May 28, 2016)

Thanks, Mike. 

The thing is where I could find powered dolomite. lol
I think I have seen a bag of dolomite chips (big like pebble size) Home Depot, but I would think they are too hard to crush without machine? 

Anyways, Bjorn reports that his plants green up nicely after spraying mancozeb, which has manganese and zinc. 
I'm not sure if it's legal in NY but I know it is rather low toxic ( to humans) spray. 

I have heard different like stone or dolomite degrade at different rates.
I wonder where this dolomite sold at garden stores fall under? 
Hmmm


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## Ray (May 28, 2016)

Mike, the reason pH control is so important in soilless hydroponics systems is not so much about the availability of nutrients in the solution, but because in the recirculation process the plants deplete the solution of nutrients, and dump plants wastes into the solution. Both of those processes can cause significant swings in the solution pH, so it becomes a good way to monitor that, so that it can be adjusted.

One thing that seems to have been missed (or at least, I missed it) is the fact that we should focus on the substrate pH, more than the solution pH. Both the potting medium ingredients and the plant itself affect that. Even in the case of plants in semi-hydroponics, in which (in the case of PrimeAgra, anyway) the medium has no effect, I have seen reservoir solution pH change significantly overnight. It has been a long time since several of us were measuring it, but using MSURO at an adjusted pH=6.0, I have seen the solution pH dip to upper-3's to low-4's (with no plant damage or precipitation).


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## gonewild (May 28, 2016)

I don't think the substrate/media pH is as important for orchids as it is for other plants. The reason being the specialized roots orchids have. I dont think orchid roots interface and relate to the substrate as dependently as "normal" plants do.
I don't think orchid roots have the same CEC function as other plants and don't remove nutrients from soil as do other plants. Orchid roots gain the nutrients when the nutrients flow freely on and into the root velum.

This is just what I think, I have not read a published report relating to the subject. Probably the main reason that I think this is true is because of what I see in pots of Phals. The pH of the media becomes very acidic from whatever Phal roots release into the media. Now the reason I am using this as an example of why the pH of the irrigation water is more important than that of the media is because..... I have Phals growing beautifully that have a flow through pH that can read as low as pH3.9. I have my fertilizer mix at pH 6.5 trying to keep the media pH up closer to 5.0. The point is the media pH is 3.9 and if I were to apply fertilizer water with a pH 3.9 it would destroy the roots really fast. So..... In this case it seems media pH is not important but the water pH is.


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## DarioU (May 29, 2016)

In the "Soilless Mix." graphic of Naoki the phosphorus behavior is strange .. phosphorus is assorbed better with very low pH? It is the opposite then in the graphic reported by Stone. Isn't it?


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## Stone (May 29, 2016)

Ray said:


> > Mike, the reason pH control is so important in soilless hydroponics systems is not so much about the availability of nutrients in the solution, but because in the recirculation process the plants deplete the solution of nutrients, and dump plants wastes into the solution. Both of those processes can cause significant swings in the solution pH, so it becomes a good way to monitor that, so that it can be adjusted.
> 
> 
> 
> ...


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## myxodex (May 30, 2016)

These nutrient availability versus pH profiles are necessarily very generalised and are really only a rough guide. 
For example the presence of charged soluble organic compounds like amino acids, dicarboxylic acids or humic substances will generally tend to broaden these availability profiles by suppressing precipitation reactions between the components in our fertilisers. Then there is another issue, changes in pH effect different species differently in terms of how efficiently they take up nutrients at different pH's so there is a genetic component. For example; increasing soil pH decreased uptake of NPK in rice, but increased it in wheat and corn. http://www.tandfonline.com/doi/abs/10.1080/00103629809370142

As for the practical issues of controlling pH, I found dolomite lime to be a difficult one to get right, although I know a nursery that uses it routinely without problems. As others have said above, acidification of the medium depends a lot on the NH4 level in your fertiliser more than the pH at which you apply it. I found the Bill Argo article most useful. I use a rule of thumb; I add bicarbonate in ppm, at roughly 4x the NH4 level in my fertiliser. So if I'm feeding at 5 ppm NH4, I add 20 ppm bicarbonate. I simply use my tap water (260 ppm HCO3) because it's easiest. Obviously it depends on other factors, so when I switched from my previous bark to orchiata I noticed that the pH was drifting up a little, so I'm now reducing the amount of tap water I add into my mix.


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## Happypaphy7 (May 30, 2016)

This is for Aussie Mike. 

A couple of pictures, first one is of Doll's Kobold, the second henryanum.

Both had very dark green leaves for a while after deflasking.
Then earlier this year as they started to grow new leaves, they looked terribly light green, some even yellow with only vein left green.

I tried Cal/Mag a few times in a row at first, but nothing changed. 
Then I poured some vinegar solutions, which I think helped with color almost immediately, but not very good result still as you can see.

Henry seedlings are slowly recovering, but Doll's Kobold seedlings still look terrible.
In the second picture, all the seedlings had two upper most leaves looking terrible, but as the leaves further develop and mature, green slowly returned.
This has not yet happened, or very little on the DK.


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## gego (May 30, 2016)

So it was the vinegar? Cal Mag is base an prob with nitrates which if taken by the roots will make the media attached to the roots go up in pH. So what do you think happened here? 

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## gego (May 30, 2016)

Hh7, what other fertilizer have you applied other than the Cal Mag? What Cal Mag is this? 

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## gonewild (May 30, 2016)

gego said:


> So it was the vinegar? Cal Mag is base an prob with nitrates which if taken by the roots will make the media attached to the roots go up in pH. So what do you think happened here?
> 
> Sent from my HTC One using Tapatalk



Vinegar is not just a simple acid, it contains a lot of different compounds. So an effect by adding vinegar may not be simply because of the pH change.
Complicated.


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## gego (May 31, 2016)

let's go back to Mike's interpretation, he thinks that those cultivated plants that have too much Fe and showed unhealthy were supplied with too much Fe. 

Below could be the reasons why:

1. If Fe was supplied in good amount, then for the plants to be able to get a large amount, then we can assume the pH of the solution and around the roots is low enough for that amount to be available.

2. pH was low and Fe was abundant but other micro like Mn and Zinc were in small quantity so that Fe was taken more as an exchangeble ion. No competation with other micros. 

3. Fe could be just the right amount but plant was not able to use it efficiently. May need an organic acid like citrate. 

1a. The data also showed Mo being low so if pH was that low then Mo could have been unavailable to the plant assuming it was being supplied but was in low quantity. And if pH was low then very likely that urea/ammonium were the main source of N. The accumulated nitrates were probably due to low Mo so the plant was not able to use it efficiently.

Remember the article "Ecology of Paph rothschildianum at the type locality in Kinabalu Park"? The soil chemistry of the rhizosphere of one roth loc 1 has 87mg/g of Fe and 2.4 mg/g of Mn. The foliar concentration showed an Fe of 0.03 mg/g and 0.024 mg/g, almost the same, although Fe is more than 400% more than Mn. Looks likes Fe in this location is way harder to take up than Mn. The pH was 6.7.

The article also showed from the same locality above that the Ca, Mg and K exchangeables were 1339, 2223, and 44 ug/g correspondingly but the foliar concentrations were 6.9, 3.7 and 5.8 ug/g. With such a very low supply of K the plant was able to uptake even higher than Mg. These are all cations but it does show that K are easily absorbed compared to the other two.

I have been talking about charges and the only difference between these three cations are the number of (missing) electrons. It seems it's easier to extract and uptake a K than the two. It is probably true that Na is just as easy as K. And that K,Na and ammonium having only one electron missing, are equally competing each other.

To solve the problem of having too much Fe and low Mn and Z, one option could just be adding more chelated Mn and Z at the same time raise the pH around 6.5 so Mo will be more available and Fe less.


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## Bjorn (May 31, 2016)

gego said:


> To solve the problem of having too much Fe and low Mn and Z, one option could just be adding more chelated Mn and Z at the same time raise the pH around 6.5 so Mo will be more available and Fe less.



Spray with some Mancozeb. plus, reduce fertiliser level. Remember, Huntington (Brandon Tam , Lance Birk) fertilises with Ca-nitrate only. And they get good (sometimes fabolous) results.


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## Ray (May 31, 2016)

Be careful with vinegar. It's a great herbicide.


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## gego (May 31, 2016)

Bjorn said:


> Spray with some Mancozeb. plus, reduce fertiliser level. Remember, Huntington (Brandon Tam , Lance Birk) fertilises with Ca-nitrate only. And they get good (sometimes fabolous) results.



Bjorn, I'm not convinced that nitrate is the native source of N with Paphs. In high altitude and almost wet all the time environment, nitrification is very minimal and with rain water flowing most of the time, this form easily get leached. Even my vandas don't like it. Leaves are yellowish and short. Spikes are short, stem in between flowers are short. Even the color of the flower is different, lighter and bland. 

With just nitrates, it would be impossible to get the sizes these plants are capable of. If using inorganic, a mix of ammo/nitrate is better. Or urea/nitrate combo. But I'm seeing amino acids/urea/nitrate mix is very promising.


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## Stone (May 31, 2016)

Happypaphy7 said:


> This is for Aussie Mike.
> 
> A couple of pictures, first one is of Doll's Kobold, the second henryanum.
> 
> ...



I would not discount the possibility that the coco chips are playing a part with the leaf colour there!


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## Stone (Jun 1, 2016)

gego said:


> > Remember the article "Ecology of Paph rothschildianum at the type locality in Kinabalu Park"? The soil chemistry of the rhizosphere of one roth loc 1 has 87mg/g of Fe and 2.4 mg/g of Mn. The foliar concentration showed an Fe of 0.03 mg/g and 0.024 mg/g, almost the same, although Fe is more than 400% more than Mn. Looks likes Fe in this location is way harder to take up than Mn. The pH was 6.7.
> 
> 
> 
> ...


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## Bjorn (Jun 1, 2016)

gego said:


> Bjorn, I'm not convinced that nitrate is the native source of N with Paphs. In high altitude and almost wet all the time environment, nitrification is very minimal and with rain water flowing most of the time, this form easily get leached. Even my vandas don't like it. Leaves are yellowish and short. Spikes are short, stem in between flowers are short. Even the color of the flower is different, lighter and bland.
> 
> With just nitrates, it would be impossible to get the sizes these plants are capable of. If using inorganic, a mix of ammo/nitrate is better. Or urea/nitrate combo. But I'm seeing amino acids/urea/nitrate mix is very promising.



No, I am not convinced either that nitrate is the chosen N-Source, actually one of my first postings on this forum was an appraisal how well urea(pure) worked in greening up things
the Cal-nitrate used by Huntintons is however not a pure Calciumnitrate, there is some ammonium in it as well (though jubelow 10% of N) Personally I use ammonium/ nitrate mix approx 2/1 so pretty high in ammonium.
Problems with nitrates could be connected to lack of molybdenum?


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## myxodex (Jun 1, 2016)

Bjorn said:


> No, I am not convinced either that nitrate is the chosen N-Source, actually one of my first postings on this forum was an appraisal how well urea(pure) worked in greening up things
> the Cal-nitrate used by Huntintons is however not a pure Calciumnitrate, there is some ammonium in it as well (though jubelow 10% of N) Personally I use ammonium/ nitrate mix approx 2/1 so pretty high in ammonium.
> Problems with nitrates could be connected to lack of molybdenum?



Yes, Bjorn and gego, I've been wondering about the same thing. 

It also ties in with pH management issues. I think someone here previously posted the link (see below) to this paper on Catasetum fimbriatum, an acid growing species that uses glutamine and NH4 efficiently, but NO3 poorly. This research was conducted in in vitro culture, which is not ideal, but at least it was done with an orchid species.

The bit I found most interesting in this paper was that this plant acidifed the medium down to a pH in the 4.6 to 3.5 range depending on N source. With the nitrate and glutamine as N source the pH ended up at 4.6, but with NH4 it went to 3.5 ! The point is that the glutamine was less acidifying than the NH4, and comparable to the NO3. This makes sense as uptake of acidic and neutral amino acids involves proton symport, i.e. a H+ is taken up with the amino acid (same as with NO3). So maybe if we are looking for a non-acidifying source of reduced N, some amino acids could be the answer. The question then is whether the limestone paphs will use amino acids as efficiently as acid loving epiphytes ?

https://www.researchgate.net/public...idaceae_grown_with_different_nitrogen_sources


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## Bjorn (Jun 1, 2016)

Amino-acids have been (and is) used amongst other sources is kelp extract being rich in amino-acids. So, I am convinced that amino-acids might be ideal, in many respects. One source of amino-acids could be lichen, moss and some cyano-bacter etc, which have been advocated for by Lance earlier.


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## Stone (Jun 1, 2016)

I'm also a believer in organic N. It's part of the natural system and it's only natural that orchids use it. Especially those that grow like this!:
http://www.slippertalk.com/forum/showthread.php?t=40573&highlight=appletonianum+situ
I think there would be little in the way of nitrification going on there. I could be wrong....


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## Happypaphy7 (Jun 4, 2016)

Stone said:


> I would not discount the possibility that the coco chips are playing a part with the leaf colour there!



Can you tell me more?
I am aware of coco chip being a cation exchanger. 

Btw, others of the same cross in orchiata mix look the same.


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## Happypaphy7 (Jun 4, 2016)

Stone said:


> I'm also a believer in organic N. It's part of the natural system and it's only natural that orchids use it. Especially those that grow like this!:
> http://www.slippertalk.com/forum/showthread.php?t=40573&highlight=appletonianum+situ
> I think there would be little in the way of nitrification going on there. I could be wrong....



Me, too!

The problem is how to apply it in home culture without too much smell. lol
In the past, Maudiae type hybrids did very well in the "rotten" mix. 
I was never sure, of course, if it was because they were old and stronger, or if it was the natural fertilizer from the breakdown of the mix. 
I'm talking no repotting for several years. 
Then, you miss the perfect timing for repotting and the roots get all mushy. lol


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## Stone (Jun 4, 2016)

Happypaphy7 said:


> Can you tell me more?
> I am aware of coco chip being a cation exchanger.
> 
> Btw, others of the same cross in orchiata mix look the same.



Then it's probably something else but as I understand it, the fresh (or even treated) CHC can be extremely high in K and Na and very low in Ca and S.
High enough to cause imbalances with other elements. I'm testing some some which are now 3 years old and have had ferns growing in them. But not alone. They have the fern roots in them and I will add a bit of that to sphag and hard treefern. I think it could be a good product but not in the new/fresh state.
Try spraying your plants every few days with very weak Mn sulphate for a month and see if they green up.


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## Stone (Jun 5, 2016)

I wouldn't recommend this but I have the time and space (and craziness) to do it.
This is the CHC which has been in a pot with the fern for about 2.5 years. (after the usual 3 month soaking in water with gypsum)
The fern grows very well in it. It is fed with osmocote and blood and bone.




The centre of the root ball.





It separates quite easily but most chips have fern roots penetrated through them.





After washing 3 times to remove a build up of humus along with the odd worm and other bugs.





The pH has now stabilized at about 5.8 from the original 7. (on the surface as well as inside the chips)




Theoretically, after 3 years of bacterial - and especially fungal action, it should now be quite safe to use. All of the easily rotted skin is gone and tannins no longer leach from it like when it is fresh.




The roots make the best of all basket lining material and is also good as a medium for many orchids too.




The fern can go back into a fresh pot of chc..


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## PaphMadMan (Jun 5, 2016)

Stone said:


> ...
> Try spraying your plants every few days with very weak Mn sulphate for a month and see if they green up.



I presume you mean Mg sulfate. Manganese (Mn) is an important micronutrient, but Magnesium (Mg) is probably what you want here.


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## Happypaphy7 (Jun 5, 2016)

I used cal mag a few weeks in a row with no effects. 

Mike, where can one get Mn sulfate???
Or should I just spray mancozeb since it's mildly toxic?
No, I don't want to use anything toxic. I would freak out worrying about myself. lol


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## gonewild (Jun 5, 2016)

Happypaphy7 said:


> I used cal mag a few weeks in a row with no effects.



A few weeks is not enough time to see results unless you used a heavy dose.


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## Happypaphy7 (Jun 5, 2016)

The label says it is.


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## gonewild (Jun 5, 2016)

Happypaphy7 said:


> The label says it is.



Well then it must be true.


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## Happypaphy7 (Jun 5, 2016)

Thanks for sharing, Mike.

I would do it, but no space. 




Stone said:


> I wouldn't recommend this but I have the time and space (and craziness) to do it.
> This is the CHC which has been in a pot with the fern for about 2.5 years. (after the usual 3 month soaking in water with gypsum)
> The fern grows very well in it. It is fed with osmocote and blood and bone.
> 
> ...


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## gego (Jun 5, 2016)

Very nice. Let us know how your plants grow on it. 

Sent from my HTC One using Tapatalk


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## Stone (Jun 5, 2016)

PaphMadMan said:


> I presume you mean Mg sulfate. Manganese (Mn) is an important micronutrient, but Magnesium (Mg) is probably what you want here.


No, I mean Manganese sulphate. Mg deficiency always shows up in the old leaves first because it is very mobile. Mn tends to show up on the new - and particularly - newly expanded leaves.
Fe deficiency is similar to Mn but have another look at the Fe/Mn ratios in wild paphs in post 14 and 19 here.http://www.slippertalk.com/forum/showthread.php?t=7692&page=2
I think a Mn supplement would be a good starting point. A very dilute drench and/or spray.


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## Stone (Jun 5, 2016)

Happypaphy7 said:


> I used cal mag a few weeks in a row with no effects.
> 
> Mike, where can one get Mn sulfate???
> Or should I just spray mancozeb since it's mildly toxic?
> No, I don't want to use anything toxic. I would freak out worrying about myself. lol


You can get it on ebay now I think. If not, get in touch with any citrus grower.
They will have it.


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