low potassium concept is not sustained by analysis

[wjs2nd]

Just to get it said and then we can debate the trial results....

A New Zealand university does a trial funded by a New Zealand company that sells new Zealand bark and the result shows that New Zealand bark is the best media and North American bark is the worst media.

Typical corporate funded trial results.

Now when it comes to the discussion about the "low potassium concept" we don't care what brand of bark is best so Roth, how do these trial results relate to the potassium content of fertilizer?

I agree.
Xavier, you sound like your just trying to sell something verses educate. You have talked about visiting the Besgrow plant in NZ often (working for them?).

I, also, don't see how this relates to low K and fertilizers. Conducting 2 studies at the same time doesn't seem very scientific. Either your testing what is the better fertilizer or what is the better growing medium.

 

[Rick]

Actually the number for K retained in the bark mixes is part of what I was predicting with the original low K premise.

That all organic media have a cation exchange capacity. Assuming that all media were fed the same "high" levels of K, the Orchiata bark which is impregnated with lime exchanged and retained the lowest levels of K. So with respect to K buildup over time it would be the superior bark product.

With respect to K exposure to the plant, the Orchiata bark would expose the plant to the shortest duration of K since it has the lowest build up between fert applications.

That seems to be in concurrence with the actual tissue values (leaf or root) which have the lowest values in the Orchiata

 

[Rick]

Dang! almost perfectly linear


As media concentration goes from 875 to 2073, the root values go from 8,688 to 23,600 and leaves go from 35,600 to 56,000

That's perfect correlation, and definitely predicted by standard plant K uptake models.

Although all K application is higher than what I would advocate, you could easily make the statement that Orchiata bark "protects" the plant from excessive K exposures if that was the superior growth medium.

 

[gonewild]

Yes for crops, and maybe phals. But for species paphs, a large number are not likely to be beyond a couple of generations from wild-collected plants. Would the nutrient-uptaking abilities of this cultivated progeny be significantly different from their wild ancestors?

It could easily be different. Collect 100 wild plants and only one survives to be used for hybridization. The 1 surviving plant has traits that adapt to modern fertilizers and pass these genes on to the next generation. Only the seedlings that tolerate cultivation survive to reproduce so even more wild traits are eliminated. So in a few generations the cultivated progeny will be significantly different from their wild ancestors.

This is why after a few generations species produced in cultivation grow and bloom faster than the original wild collected.

 

[Rick]

I put the K data into a spreadsheet and made a chart.

The leaf and root K concentrations correlate very well to extractable K in the potting mix. Rsq values are extremely close to parity (1.0)

 

[Rick]

These pretty much parallel the results of the 1970's Cornell study results.

For their Phalea results the leaf tissue K went from 55000 to 80000 ppm as applied fert K was raised from 100 to 300 ppm (no low K trial there). Also the potting mix was the same for all fert concentration applications so exposure at the roots would parallel the fert concentrations.

As K goes up Ca and Mg in the plant tissues will go down regardless of the external Ca source. Documented in just about every green plant studied so far.

As Xavier noted the Ca concentration in Orchiata mix was the highest, but this is due to the lower overall K exposure inherent to the mix (not available Ca concentration) with subsequent reduced tissue K the plant can uptake more Ca. As he noted the plants did not pick up the Ca with increased Calcium Nitrate in other bark systems that allowed for higher tissue concentrations of K.

This work is really following the predictions of the low K system, but still operating at very high levels of K

 

[Rick]

Xavier

Do you have substrate K values at T=0 before any fert application?

It would be good to know how fast the various substrates are loading K over time.

 

[gonewild]

Let's debate this....

Honestly, it has nothing to do with the brand of the bark, and the trial was done really blinded.

No offense but to be blind the trial would need to be finded by someone that did not care what the results were.
The university absolutely knows who their sponsor was. And most likely the people in charge know what Orcidita looks like. But that is OK as far as the measurements are concerned but how the results are presented will be in question.

It was expected however that the NZ bark would perform better than the US fir bark, and this is something that is already known by the professional growers, otherwise why so many commercial pot plant nurseries, including Europe, ran internal trial and chose to use orchiata, even at an increase in cost.

Orchidita is easily the best bark media since Fir Bark is probably the worst possible media choice for orchids. But you post here is about Potassium and not bark quality.

The EU nurseries that made trials and are using Orchiata now pay nearly double price for orchiata compared to their old media, mostly due to transportation costs, but they are happy to do so because they see a tremendous improvement in the growth quality). So it has nothing to do with corporate funded results.

Would Besgrow have done the trial if they knew ahead that Fir bark would perform better than orchidita? Of course not, so it has something to do with corporate funding, that how the world functions.

In fact, the background of the study, and what will be made public at a later time ( the analysis have been extensive, including arsenic, chromium, even lithium...), was not to promote the Orchiata or New Zealand sphagnum moss, but to try to explain why they perform better than US bark or Chile sphagnum moss.

OK.

There are some elements of reply in fact in the remaining of the data. There are analysis of fresh media before potting, then media being used, then media at the end of the trial.

results about the media and not plant nutrition.

For the trial, it started with flasks of clone from Clone Biotech, until the plants bloomed, so it is pretty extensive.

How many generations of hybridization is involved to make this clone? How many generations of this clone have been developed growing using commercial forcing techniques?

How well do the physical growing tolerances of this clone relate to plants in private collections? Has this clone been bred and grown with an addiction to Potassium? (OK not addiction but rather a higher tolerance than wild plants)

The basis being that the sphagnum moss from New Zealand had nearly 2000ppm potassium, coir the same, yet the NZ plants were growing considerably better than the ones in coir.

I am a pretty experience grower and I pay very close attention to plant nutrition. But my personal growing experience has exact opposite results from this. So I am curious where this "basis" originates from?

Orchiata had a low level of potassium, yet, the plants were identical to the NZ Sphagnum moss plants. Another media ( Dutch blend) produced good plants, and was even higher in potassium content.

So low level Potassium produces just as good a plant as does higher levels.
But what determines "good plants"?
Fast growers until bloom?
Lush dark green leaves?

Is a good plant one that blooms at a young age or one that lives and blooms for 40 years?

Who determines what shade of green is the most healthiest and not just the most pretty?

For the fertilizer, it was a standard 6-3-1 20-20-20 Ca(NO3)2 MgSO4 blend, typical of the Dutch style of feeding. We decided to use that one because it is the most used type of fertilizer in the pro phalaenopsis growers, with reverse osmosis.

But it is common knowledge that Phals produced under forced growing conditions are not the healthiest plants and live a short life unless they go through rehab after leaving the mass market shelves.

The potassium content of the media has indeed very little effect on the foliar tissue content, and was not related to the plant appearance and quality ( on a grower's point of view, not as a disposable plant).

Thaat is because Phalaenopsis roots in Nature don't extract nutrients from dead wood. They grow on living bark tissue and get what nutrients the can from the surface.

On one side, Rick is right, because the load of the leaves of the plants does not depend so much of the potassium concentration in the media. so at a point, too much potassium is just a total waste.

Or toxic.

We did the analysis for the calcium, and orchiata had much more calcium in the leaves than the others, due to the added lime. Yet, it is very interesting to note that a little bit lime was more effective in increasing the calcium foliar content than lots of calcium nitrate, providing the fertilizer was an acidifying one.

How often were the plants repotted to refresh the media during the trial

All of this has been done on a pH for the fertilizer of 5.7, which is again the standard for phalaenopsis. The fertilizer used, the 3x20, is nearly only urea with some ammonium, + the calcium nitrate, which brings some nitrate, so it is an acidifying fertilizer.

Standard for forcing growth.

Now, to sum up a bit further about the fertilizer. I think K-Lite performed better than the MSU for some growers because in the MSU, the all nitrate ( the percentage of ammonium is ridiculous) force the plant to take up a cation, which is easier to take if it is potassium, a monovalent one. In this case, the MSU could well cause problems that the K Lite solved.

Then the "low potassium concept" is a valid concept?

Rick solved the problem by lowering the potassium, and increasing the calcium and magnesium. But this still has the risk of potassium deficiency, and we force calcium and magnesium.

From the trial results it seems Orchidita forces Calcium doesn't it?

I am certain, even looking at how many growers are successful, that increasing a bit the potassium ( a high K fertilizer would seem to be foolish, because it seems that the plants have a maximal uptake level,

Even though you look at how many growers are successful with the low K level you still recommend to increase it. Why, to avoid possible K deficiency? After we see one case of K deficiency using K-lite then we should recommend increasing the K level.

and they cannot be intoxicated by the potassium truly),

Truly? Based on what?

and using ammonium nitrogen instead of nitrate, at least 50/50, or using urea, would solve the whole problem.

This is not true. Over the years all different combinations of Nitrogen has been tried but no one really tried decreasing the potassium so low before. This was because science said we need high K levels for healthy plant growth. (results of university trials funded by fertilizer companies).

I can assure you personally from the use of tons and tons Of Ammonium, Urea and Nitrate fertilizers that no combination has shown the improved growth as is being seen using K-lite.

If anyone reads on the forum other posters, many report increased growth by using ammonium and urea fertilizers, and the growth will not be soft and weak.

Of course you see increased growth when Nitrogen is increased. But increased growth is a commercial forcing concept of what is good. in this case increased growth is the same as rapid growth.

We made a trial of an all nitrate MSU vs. the Dutch formulation given above, in several potting mixes. This is another study. And it appeared that the MSU plants looked really crappy compared to the Dutch formulation ( 202020 calcium nitrate magnesium sulfate, lots of urea and ammonium).

Crappy? If the trial produced crappy looking plants using MSU then either they purposely mis applied the MSU or know nothing about growing orchids. MSU is a very good formula.

They looked weak and starved. The only noticeable difference was the nitrogen contents of the leaves and the nitrogen source... Apparently nitrate does not so good a job to supply nitrogen compared to ammonium or even urea.

The fertilizer results were not related to the pH or whatever, because Orchiata has lime and is buffered, the sphagnum mosses we tested had a low pH, standard for sphagnum, US bark was of low pH too, and no carbonate contents for the last 3.

You say the results are not pH related yet the media results were all different and the pH of each was different. How do we assume the results are not pH related?

To another interesting notice, some bacteria and microorganism can make up ammoniac and ammonia therefore in the potting mix. Rick plants are indeed in excellent shape, but it could well be related to the microflora present around his greenhouse.

But the good results are not limited to Rick's greenhouse. I doubt that Aunt Martha's windowsill has a great microorganism population. But even if the results are from the improved microflora doesn't that just prove that low K increases beneficial microflora? Doesn't it also prove (suggest) that potassium is toxic to beneficial microorganisms?

(Post too long continued)

 

[gonewild]

(Continued)

Seaweed is being investigated, and it is a source of nitrogen, no matter the low analysis. Most of the nitrogen is available as amino acids in the seaweed ( and the potassium content is quite high in the Ascophyllum nodosium seaweed extract, like Maxicrop), and the plant takes those up readily.

I think seaweed replicates what orchid plants get from Lichens and mosses in the wild.

So the K Lite could well benefit from increasing the potassium a bit, and adding at least 1/3 ammonium, it would be worth testing, even a K-Lite:ammonium nitrate blend at 1:1 or 2:1 if anyone wants, to see how the results are...[/QUOTE]

OK I get your point about adding ammonium, in fact we have talked about that recently in some thread here. But why increase potassium until we see a reason to? No one has dis-proven the toxicity theory and how it related to plant disease (rot).

 

[Ray]

I still have to wonder what role classic physics play in these ion absorption rates, referring back to my "enthalpy of hydration" Comment elsewhere.

What the data could be demonstrating might be nothing more than a demonstration of what is taken from the solution most easily, rather than necessarily an indicator of the plant reacting differently to the substrate.


Ray Barkalow
Sent using Tapatalk

 

[Rick]

Plants have to expend energy to convert nitrate to ammonia before it can be used to make amino acids (which requires phosphorus, via ATP for currency)

Subsequently the plant will always find it energetically expedient to uptake ammonia if phosphorus is tight, and the pH is in a poor range.

However its even cheaper for the plant to uptake amino acids, and no synthesis required at all at that point.

Also like K, Ca, P, Mg..... the plant only needs a miniscule amount of N to take care of business. Given that N accounts for about 1 percent of the tissue dry weight in a healthy plant feeding much more than 10 or so ppm of N is still mostly feeding the bacteria in a pot rather than the plant. If you have cultured a huge bacterial colony in your potting mix, then the plant always be in competition with the bacteria for ammonia, and will still be relying on the nitrate reductase system for what little N it needs.


On a separate note, the leaf tissue concentrations of K in this potting mix study are equivalent to the K concentrations in Cattleya in the Cornell Study.
The value for the Orchiata bark (3.56%) is still more than 3.5X the value for your average epiphytic orchid in Panama.

Comparing Phales in this study to Phales in the Cornell study, even the highest K (5.6% for Coir) is just tickling the bottom end of what the Cornell researchers put Phales through in terms of K exposure. So the results are not unexpected.

I think this study demonstrates the dynamics of both dose concentration/duration with respect to CEC capacity of the different materials.

 

[Secundino]

At the end all comes down to atmospheric pressure...
byebye folks, and good night!

 

[Ray]

There has been a lot about K-lite on this site and all the results seem to have been very good. This may be due to the users paying more attention to their fertilizer regime than they did before they went to K-lite. It also could be due the amount of N is increased relative to the P & K.

I agree that the "suddenly paying attention aspect" is fairly common in the introduction of almost anything. The casual grower can get pretty complacent, with many cultural aspects slipping, but then with the addition of something new, that interest level is rekindled, and ity's amazing what happens! However, I think many of us here are beyond the "casual grower" stage. I know that in my own case, the "diligence" aspect is pretty steady, as I feed at every watering.

When I switched from MSU to K-Lite, I also maintained the same nitrogen loading, so while the mass of that may be the same, the P & K are much lower, so maybe that does have something to do with the improved growing & blooming I've seen.

 

[Rick]

Here's the Cornell study results for K Ca and Mg with increasing feed K



Here's the Cornell study results for K Ca and Mg with increasing feed K. In this chart I added a 5ppm K to show about where wild epiphytes in Panama end up on the scale.



In both studies the Ca was held constant at 200 ppm while the K was ramped up as per the lower scale.

BTW 1% = 10,000ppm if you want to convert.

 

[Ozpaph]

are there 'p values' for these lines or 'box and whiskers' plots? looking at graphs can be deceiving without statistical analysis telling us if the change is 'significant' (as I'm sure you know).
My point? Perhaps there is no real change in Calcium and magnesium with change in K+. (whatever that means)

 

[Stone]

The numbers you are posting are so far into the range of non environmentally relevant that I would not expect any normal foliar or root ratios of Ca Mg or K. Incidentally you didn't present any values of Ca and Mg to compare with tissue K. That's been the problem with all past GH studies in that they start out at already high levels of K and go on from there.

The point is though (and I brought this up many moons ago from another trial), that doubling the K did not show a huge drop in Ca and Mg. and whether the leaf K levels where very high or not, uptake of Ca and Mg was still taking place and growth was normal even though there was a slight reduction in Ca and Mg. This shows that there is huge plasticity in the plants and they can operate equally well. It also showed a leveling out of K uptake as more was provided, meaning there is a definate limit to how much K can be taken up in the first place. The adaptation for orchids and most other plants to take up ''luxury amounts'' of K is obviously a natural one and possibly due to scarcity in nature? But there does not seem to be any adverse effect to the plant (that I can see) until massive amounts of K are given AS WELL as too low a level of Ca and Mg (possibly 3 or 4 to 1 K/N) which will finally tip the scale. I still like the idea of reducing K a bit to say 1/2of the N but I'm STILL not convinced if even that is really necessary. It is pretty obvious from Rick's plants that feeding low K still works but I feel the need to give more K and as Roth said, ammonium has a way of regulating other cations anyway. In my opinion the best and ''safest'' fertilizer is 50/50 ammonium and nitrate and with K at 30 to 50% of the toal N.

 

[Ray]

Mike, I'm still not convinced it's necessary, either, but I think that proving - or disproving - the concept is a very long-term thing, and none of the data shown is of a long-enough term to tell us anything, making these debates rather senseless.

I think that if one really wanted to put some "meat" in this, it would involve raising a number of clones of different plants on diets in which the ONLY variable would be the K content, and raising them for many years.

To my mind, having fed my plants nothing but K-Lite for 19 months now and not seeing any negatives is a good thing, but not evidence that the concept is correct, even if I feel, based upon my readings and background education, that there might be something to it.

 

[orcoholic]

When I switched from MSU to K-Lite, I also maintained the same nitrogen loading, so while the mass of that may be the same, the P & K are much lower, so maybe that does have something to do with the improved growing & blooming I've seen.

Ray,

Did you continue to water with the same TDS as before you changed to K-lt.? If so, by decreasing the P & K isn't that, in effect, the same thing as increasing N and keeping the TDS the same as before?

 

[Roth]

So far, to make a reply over the whole thread:

- The background of those studies is simple. Many growers are using Orchiata and NZ Sphagnum moss around the world. Those are the majority of the growers in Hawaii and Japan in fact. Growers made a lot of internal trials, especially the pot plant growers, and at the end said that they are using Orchiata or NZ Sphagnum moss because their own results were far superior to the other potting mixes. Good. However some growers said that, as an example, plants in the Dutch mixes were growing very fast, then stopped growing after a while. Some other growers need technical advise to change from, let's say, fir bark (yes, some still do use it on a very large scale) to Orchiata. So we needed to have a background for the real differences, in terms of chemistry and growth, assessment. It is not a advertisement campaign at all...

- As for studies being paid by private companies, well, most studies in this world are, directly or indirectly. Many universities and research teams will do the studies in a fair way ( they have to water Orchiata or fir bark when the moisture content is such and such, etc...), so even if they know where are the Orchiata plant, they don't care, and no one can change or tamper the results. Add to that that New Zealand is one of the least corrupt countries in the world as well. I cannot think of any studies made by universities that are not done for commercial applications, or for private companies/on behalf of them/sponsored. Public money is rarely used for such studies, and the money involved is usually not spent on orchids, in that Pacific Wide did sponsor the study, to get chemical data information.

- I am technical adviser for Besgrow, indeed, and that's not a secret. I shared those results here pertaining to the potassium level. Rick found out that in Cornell they had even higher values, and no toxicity noticed at the end of their trial so far. I think the Cornell values are too excessive however, but indeed there are no 'toxic' effects.

- The results would be that people must not be afraid of potassium as an evil evenement, and the low K benefit lies mostly in a problem due to the use of an all nitrate fertilizer. In fact we found that the all nitrate fertilizer does not perform well at all. I cannot disclose more, because some are our customers for pot plant, including non phalaenopsis and quite fragile plants ( miltoniopsis), but indeed they tried nitrate as a source of nitrogen, with Orchiata, with NZ Sphagnum moss, even with coir, and even with mixes not related to Besgrow. I advised them all, and they are really huge nurseries, some of the biggest even. Their problems vanished as soon as they added ammonium. Strong, long lasting plants.

- Floricultura is growing a lot of mother plants, including masdevallias, paphs ( they have a very large collection, trust me, with some dream plants...), and many more. They apply the same feeding schedule for those as for their pot plants. Superb plants, some being decades old.

- Gonewild said * Over the years all different combinations of Nitrogen has been tried but no one really tried decreasing the potassium so low before. This was because science said we need high K levels for healthy plant growth. (results of university trials funded by fertilizer companies)*

Well, I agree that the high K formulations such as the 15-10-30 and such are not promoting anything good... However, not all different combinations of nitrogen have been tried, etc... over the years. Only very few, and it was a butchered job.

In Europe, we had nurseries with 40-50 years old plants. Using TAP water ( high in calcium), nitric acid to lower the pH, and an ammonium nitrogen source. The fertilizers used ( Hakaphos and similar...) were cheap ones, but included magnesium. There was actually nitrogen, ammonium, calcium, magnesium. Great plants. Floricultura used that feeding schedule.

Then, many nurseries changed for ALL their plants to using lime, and still an urea or ammo-urea fertilizer. Great plants. In fact many nurseries in Europe had a growth far superior to the US nurseries of the same time. names like Wichmann in Celle, Floricultura themselves, but Rohl, etc... had amazing growths.

The trials and university trials went from a NPK like a Peters, all urea, used in reverse osmosis water, and no calcium/magnesium found anywhere, to using an all nitrate calcium magnesium fertilizer, through various things, that were missing some elements.

As Ray pointed out, it is clear that the plant metabolism is not really a stupid ion uptake. Plants with lime ( I showed the Orchiata ones, but we had in the trial a Dutch blend with lime, and the calcium was really increased) always have much calcium in their tissues than plants supplemented with calcium nitrate. This is really weird...

Now I agree that Rick solved the MSU problem, and his solution is indeed good. I worry, myself, and I suggest to use a slightly higher potassium value, because different levels of potassium at the roots did not make a sharp increase in the leaves, and we failed to see anything that could be locked up, WITH THE USE of an urea/ammonium/calcium nitrate/magnesium sulfate fertilizer. That fertilizer produced stunning plants compared to the MSU.

According to my experience as a grower ( and not really a bad one ) I strongly advise to have much more ammonium. Why no one wants to make a test...

I think in fact that the seaweed could help a bit with the amino acids, too, and clearly I have seen improvement using seaweed on the plants. One of the best ( the best ?) growers of paphs I ever saw was using fern roots (don't tell me I am making the promotion of Orchiata), big charcoal, polystyren, seaweed and bat guano. Never seen before or since such massive plants... No mineral fertilizers, and the plants were really old.

As for what's a good growing plant, I would say that if the plant grows at the same speed or faster than in the wild, glossy juicy leaves but not weak or soft, then that's a good growing plant...

I am not really impressed by most of what is published in terms of feeding schedules or results. In fact, I sometimes advised growers to use this and that kind of recipe for their crop. Sometimes they made foliar or run off analysis ( some are big hydroponics growers), and the lab comments ' too much' 'not enough' blabla... Even some graphs show an arrow outside of the page, because the value is way too high. Well they have one of the best crop possible, so they have a big laugh, so do I.

Back to the main problem, potassium toxicity was not found to be a problem in general, and the plant clearly takes up what it needs up to a certain point.

I think however that ammonium would be a very welcome additive to the K Lite, as well as the use of lime in the potting mix with a 50-50 ammonium-nitrate nitrogen source. There are other unpublished results from the study, and my experience on top of that.

The potassium levels in our study were about half the ones of Cornell ( what the hell did they use ???), and this shows even further than potassium is not toxic through accumulation. It could be that, using a nitrate nitrogen fertilizer, a problem appears due to the potassium, but on a general sense, there is no problem.

My trials with MSU or the K Lite, ( and the ones of several massive nurseries, some having got real problems with the MSU type fertilizers, and even the calcium nitrate use vs. using lime in the potting mix...) were a total failure, compared to the growth standard I expect, dark green leaves, no premature leaf drop, increase in size, long roots, and long lasting, not weak or soft plants.

In our study too, the plants with the lower K content had higher contents of sodium and lithium... so it seems that those three guys can be interchanged. Maybe Rick low K pushes more sodium in the plant ( this is not detrimental, plants need sodium anyway... and plants can be deficient in sodium clearly), or??? But definitely not a K toxicity problem per se.

I use a lot of insecticides, being in Vietnam, but so far most of the plants did not get fungicide for a really long while, despite the weather. If the plants are growing well, they are less prone to diseases.

The easiest way for some people to test would be to add ammonium nitrate to the K Lite and see how the plants performs after that. I am certain that they would grow tremendously better ( and not soft or forced after that...). Several people on the forum already reported so, with the use of urea or ammonium and a K Lite variation home made... Some others reported the same with MSU and ammonium added too.

 

[Rick]

are there 'p values' for these lines or 'box and whiskers' plots? looking at graphs can be deceiving without statistical analysis telling us if the change is 'significant' (as I'm sure you know).
My point? Perhaps there is no real change in Calcium and magnesium with change in K+. (whatever that means)

Correct. Mike originally linked this study (though everything was in table form and not graphical) a year or so ago now. I think I relinked it in subsequent debates.

To answer your question, the drops in Ca were statistically significant and some of the Mg drops were significant (but not always). The K increases are also significant (but not surprising given the magnitude change compared to the Ca drops).

In this study they also trialed the effects with a Cymbidium hybrid. Similar results

The trial duration was short (9 -12 months can't recall exactly). Nothing died, and everything was rated as "unimpaired". But they did see reduced growth in Catts over the 3 dose regimes, and leaf tip burn in cymbidium (but they chalked it up as a normal phenomena anyway).

They also trialed changing N with everything else "constant". (Really hard to do since cations are always paired with anions, so something else must change). It's really a pretty good study of orchid response under basic cultural conditions. There was no 0 control though.