Substantial K in rainforest through fall.

[Rick]

The Wang study of K in Phals (and please spare the ''but their hybrids bred for high K'' and ''this study is flawed'' bunkum) found K/N ratios of 0.5 still showed K deficiency and I'm not surprized as stemflow is typically K/N of 1 or higher!

No the Wang study was flawed because they overdosed ammonia (one of the few things that actually controls K uptake).

Given their salt selection there was no way to make a low K soup without using a ton of ammonia for N (not nitrate)

Also the "K" deficient plants died in less than a year. Why are my Phalaes flourishing with even less?

 

[gonewild]

Maybe I don't understand your perspective. The ratios in the studies are clear but how do the ratios you present relate to formulating a complete fertilizer formula?

Annual litterfall in a NG rainforest in kg/ha.

N 91, P 5.1, K 28, Ca 95, Mg 19

Annual throughfall in the same forest.

N 30, P 2.5, K71, Ca 19, Mg 11.

Both combined
N 121, P 7.3, K82, Ca 115, Mg 25.5.

Why are you combining them? The leaf litter would already have the through fall minerals mixed with it.

(annual nutrients plants growing on the ground leaf litter layer will have access to) These are the 2 major nutrient pathways as determined by the P. J. Edwards NG Study. Are we agreed on this at least? ??

There are other major nutrient supplies besides leaf litter and through fall. You acknowledge them but don't include them?

Once again... the above figures are the ANNUAL EXCHANGABLE AVAILABLE nutrients to the ground plants.

Are you still talking about epiphytes or now just ground plants?

Now.....To explain again what ratios actually mean and how they are determined.... And please just for one second forget about concentrations!

The ratios ( quantaties of nutrients in relation to each other) are worked out like this: (and yes you are right about my dislike for maths but I have a calculator)

Phosphorus divided by Nitrogen. (in this case) 7.3 divided by 121 gives us...
P/N of 0.06 Remember N = 1.
K/N of 0.6
Ca/N of 0.9 (please check what I wrote about Ca application above)
Mg/N of 0.2

K-lite ratios:

P/N of 0.1....No problem there!
K/N of 0.1....You tell me???
Ca/N of 0.7....No problem as there is also no such thig as Ca toxicity (interference-yes)
Mg/N Well as long as its less than half the Ca also fine.

These ratios only include the N that comes from through fall and leaf litter. When N is also supplied from other sources the ratios would change drastically.

The stemflow figures for ''bark epiphytes'' Eg Dendrobiums Phals Catts etc. have nuch higher K/N ratios

Are the stemflow figures actually taken from stems where Dendrobiums Phals Catts etc actually grow? Can you please point to the reference I don't remember it.

To determine the actual mineral ratios the "bark epiphytes" actually have available the bark moisture must be analyzed and not the larger volume of water flowing over it. What is the mineral ratio and concentration content of the water that remains on the bark after stem flow? (the water that does not flow) That ratio/combination is what the plants have contact with for the great majority of the growth cycle. When the stemflow stops there is water still on the bark that no longer flows down and remains in contact with epiphytes. As that water sits "still' in contact with bark minerals are dissolved (leached) out of the bark surface and become available for the epiphyte roots. The concentration and ratio will be very different from the diluted stemflow numbers. As bacteria, fungi, lichen release N on the bark surface the N/P/K/Ca ratio changes drastically with N becoming much higher.

 

[TyroneGenade]

Going back to Mulder's Chart, if you reduce K you increase Mg availability which in turn increases N availability etc... A simple dilution of a "balanced" fertilizer could be just as effective as K-light (if, as Rick points out its the K concentration that is the problem).

Again, we are blurring two separate issues: nutrient interactions and chemical toxicity. Too much K will kill you regardless of its ratio to other ions in your blood stream; but at the same time small imbalance of K relative Na will cause heart arrhythmia, muscle cramps, kidney problems etc... Same for the plants. Too much K will mess with osmolarity, ion uptake etc... which can be fatal; while an imbalance will disrupt nutrient utilization.

In this debate, I think, we have to conscious of the two separate issues we are dealing with: nutrient interactions and mineral toxicity.

 

[Trithor]

In this debate, I think, we have to conscious of the two separate issues we are dealing with: nutrient interactions and mineral toxicity.

My thinking too

 

[gonewild]

In this debate, I think, we have to conscious of the two separate issues we are dealing with: nutrient interactions and mineral toxicity.

I agree.

Nutrient interactions in that certain levels of K will inhibit other minerals.

Mineral toxicity in several concepts such as K being toxic to micro organisms that may make other nutrients available to the plant roots. So high K levels may indirectly reduce the availability of N for plants.
As well as the obesity concept that plants consume excess K and get fat....much like fast foods are bad for human health, this is toxicity....slow death.

 

[Rick]

I agree.

Nutrient interactions in that certain levels of K will inhibit other minerals.

Mineral toxicity in several concepts such as K being toxic to micro organisms that may make other nutrients available to the plant roots. So high K levels may indirectly reduce the availability of N for plants.
As well as the obesity concept that plants consume excess K and get fat....much like fast foods are bad for human health, this is toxicity....slow death.

http://www.ipipotash.org/udocs/Chap-3a_K_and_cl_in_higher_plants.pdf

Here's some lite reading on plant physiology (cellular level) as related to K interactions with other minerals. Note it's from the International Potash Assoc.

 

[Rick]

I agree.



So high K levels may indirectly reduce the availability of N for plants.

Read the posted link please.

It's not a matter of "may".

K is directly competitive with NH3, Ca, Mg (all cations).

Any impact to Nitrate (an anion) uptake is indirect.

Ammonia uptake is actually able to block K uptake (not the opposite we've been focusing on that K blocks Ca and Mg uptake).

So you can cause K deficiency with ammonium application.

Maybe this is a reason why so many Euro slipper growers were having good results with supplementing ammonia?? (controlling K toxicity from the backside of the concentration regime?????).

 

[Stone]

"A good balance" of Ca Mg K in soils is:
60-80% Ca
10-15% Mg
2-5% K
Of the total exchangeable sites occupied by the above cations.

I can't find that in my book. Maybe its a different edition?
Anyway on page 142 of mine:

''For soils, the level of exchangeable Mg should be between 15 and 50% of the level of Ca. K should make up 2-5% of exchangeable cations''. There is no mention of the total exchageable Ca.

Note: ''these guidelines do not apply to soiless potting media''. Determine the best balanace from the recommendations in chapter 16 (best K/N between 0.5 and 2)



Pg 179

"Pine bark has enough K to make it unnecessary to add more"

As a pre plant admendment. This assumes the correct balance of nutrients are added after planting. ie fertilization.

"No pre-planting K is needed if DTPA extract of the media contains more than 50 ppm of K."

You left out....''Assuming that a fertilizer program will start soon after planting''

Sounds like your man Kevin is pushing on the verge of a low K philosophyoke:

From the above N/K ratios recommended, sounds like he isn't

 

[Stone]

No the Wang study was flawed because they overdosed ammonia (one of the few things that actually controls K uptake).

From my reckoning ( and I'm not exactly sure of the ammonium to nitrate ratio of NH4NO3), They used a 38% Ammonium to 31% nitrate ratio (aprox)
Hardly what I would consider overdosing ammonium. But yes I agree ammonium plays significant role in reducing K uptake but all other cations as well.

Also the "K" deficient plants died in less than a year.

Because you cant give so much N and P without K to balance.

Why are my Phalaes flourishing with even less?

Are they? Compared to what?

 

[Stone]

Maybe I don't understand your perspective. The ratios in the studies are clear but how do the ratios you present relate to formulating a complete fertilizer formula

I can't think of another way to say that hasn't already been said :sob:

Why are you combining them? The leaf litter would already have the through fall minerals mixed with it.

Because that would be roughly what the plants would recieve during the rainy /growing season.

There are other major nutrient supplies besides leaf litter and through fall. You acknowledge them but don't include them?

Look up ''major'' in the dictionary.

These ratios only include the N that comes from through fall and leaf litter. When N is also supplied from other sources the ratios would change drastically.

See the ''major'' reference above.... What other sources? The data on nutrient imput includes rain, exudations from tree leaves, exudations from the epiphytic biomass (which includes lichens, mosses etc. dead insects and their excretions) any dry depositions from dust, N from N-fixing bacteria and algae.

Are the stemflow figures actually taken from stems where Dendrobiums Phals Catts etc actually grow? Can you please point to the reference I don't remember it.

Don't know, don't care

To determine the actual mineral ratios the "bark epiphytes" actually have available the bark moisture must be analyzed and not the larger volume of water flowing over it.

The only thing that would change in the moisture available to the plants is that
the consentration would increase as evaporation takes place.

What is the mineral ratio and concentration content of the water that remains on the bark after stem flow?

Ratio remains the same, concentration increases

As bacteria, fungi, lichen release N on the bark surface the N/P/K/Ca ratio changes drastically with N becoming much higher

See above.

 

[Stone]

A simple dilution of a "balanced" fertilizer could be just as effective as K-light (if, as Rick points out its the K concentration that is the problem).

This statement is self contradictory

Again, we are blurring two separate issues: nutrient interactions and chemical toxicity. Too much K will kill you regardless of its ratio to other ions in your blood stream; but at the same time small imbalance of K relative Na will cause heart arrhythmia, muscle cramps, kidney problems etc... Same for the plants. Too much K will mess with osmolarity, ion uptake etc... which can be fatal; while an imbalance will disrupt nutrient utilization.

I know little about human physiology but I think comparing plants with animals is totally wrong.

In this debate, I think, we have to conscious of the two separate issues we are dealing with: nutrient interactions and mineral toxicity

Agreed

 

[Stone]

I agree.

Nutrient interactions in that certain levels of K will inhibit other minerals.

No one is suggesting otherwise. The debate is about what levels of K are detrimental to plants.

Mineral toxicity in several concepts such as K being toxic to micro organisms that may make other nutrients available to the plant roots.

So high K levels may indirectly reduce the availability of N for plants.
As well as the obesity concept that plants consume excess K and get fat....much like fast foods are bad for human health, this is toxicity....slow death.

Plants don't get ''fat''

 

[TyroneGenade]

The chemical osmotic physiology of plants and animals are identical. It is only the organs that differ. K and Na are hydroscopic salts that, if not regulated, will mess with osmosis. Once you mess with osmosis you get water balance and circulation issues. Our hearts can largely overcome some of the issues by forcing the fluid along (though our kidneys suffer greatly). Plants have a largely passive circulation system that relies on the manipulation of ions and other dissolved solutes to create pressure in one location and drive fluid movement to another.

You will have to explain why the statement is contradictory for me to reply. I see a big difference between talking about NPK balance and K concentration. It doesn't much matter how much you increase N and P to balance out the K if the K is at a toxic concentration. Alternatively, giving 1 ppm NPK every day may have no consequences compared to giving 10 ppm* NPK once a week (assuming the 10 ppm K is safe).

I'm happy to read you at least agree that we are conflating separate issues: optimum N:K and too much K.

*Yes, I know we don't give 10 ppm NPK but I' too lazy to look up the actual values as it is irrelevant to the nature of explanation.

 

[DavidCampen]

The chemical osmotic physiology of plants and animals are identical. It is only the organs that differ. K and Na are hydroscopic salts that, if not regulated, will mess with osmosis.

K and Na are not salts but metals. Many salts of K and Na are not hygroscopic. Whether or not a substance is hygroscopic has no bearing on its effect as a solute on osmotic pressure. Your comments about osmosis have no basis in science.

 

[Trithor]

In animals/humans, K and Na are involved in membrane stability and flux which is the basis of neural impulse transmission and muscular contraction. Sudden increase in K disrupts this, which is the reason for death/heart attack. Slow loading of a similar amount of K has no such effect as it is moved into the intra cellular space. Extended loading has a different effect and toxicity, a part of which is related to renal ion exchange. I doubt that the pathways are the same in plants, however that toxicity exists to a specific ion in most plants and animals is logical as we have all 'evolved' in a similar environmental 'soup'. Metallic ions which exist in nature in minute concentrations naturally are almost all universally toxic in raised concentrations, so we would expect disease to follow extended exposure to concentrations of more common ions which are drastically different from normal environmental concentrations that the life form has adapted to survive in.

 

[Stone]

You will have to explain why the statement is contradictory for me to reply.

If as Rick points out K concentration (in general ''balanced'' fertilizers) is the problem then a simple dilution of a ''balanced fertilizer'' could NOT be just as effective as k-lite. You would be diluting all other nutrients thereby reducing what is available to the plant.

It doesn't much matter how much you increase N and P to balance out the K if the K is at a toxic concentration.

Assuming we agree that we are feeding plants here, not fresh water inveratrates and not making chemical weapons, ( and we are dealing with very dilute formulations...say between 25 and 100ppm ),as has been said, K is NOT toxic to plants. Too much leads to interference with uptake of other elements. Obviously if we put a plant into a bag of potassium nitrate it would die. From salinity not poison.

I'm happy to read you at least agree that we are conflating separate issues: optimum N:K and too much K.

I am aware of the two seperate issues but I am not conflating. I'm trying to point out the differences.

Some people feed at full strength concentrations some at 1/8. This could give a difference in K concentration of (for example) 200 mg/L and 25 mg/L of K. Little immediate difference will be noticed except for slowed growth if 1/8 or full strength was not optimum. However if you change the concentration of one element in isolation by 200% the effect would be profound. This is why determining the right ratio first is vital. Thereafter you can play with concentrations.
The way to determine ratio (balance) is from habitat data or trials in the nursery. None of the habitat data which I have seen comes close to K-Lite K/N. The all nitrate N is also a worry but that's another issue.

 

[naoki]

In addition to Poole and Sheehan (1982, I added the book name to my post in p.12), this one seems to show that not much detrimental effect of high K on Dendrobium: Determining the Nutritional Requirements for Optimizing Flowering of the Nobile Dendrobiium as a Potted Orchid. M.S. thesis by Rebecca G. Bichsel (2006) I haven't had time to read it in details, but she seems to have used up to 400ppm of K, and her data seem not to show a strong detrimental effects. Has anyone read this, and noticed if there were some issues (i.e. something which doesn't apply for hobbyist culture) with this set of experiments??? (I didn't post this originally because I wasn't sure if it was accessible from non-academic internet. Anyone should be able to access it.)

 

[gonewild]

In addition to Poole and Sheehan (1982, I added the book name to my post in p.12), this one seems to show that not much detrimental effect of high K on Dendrobium: Determining the Nutritional Requirements for Optimizing Flowering of the Nobile Dendrobiium as a Potted Orchid. M.S. thesis by Rebecca G. Bichsel (2006) I haven't had time to read it in details, but she seems to have used up to 400ppm of K, and her data seem not to show a strong detrimental effects. Has anyone read this, and noticed if there were some issues (i.e. something which doesn't apply for hobbyist culture) with this set of experiments??? (I didn't post this originally because I wasn't sure if it was accessible from non-academic internet. Anyone should be able to access it.)

I can't access the book. But most likely the difference between her trials and "hobbyist culture" is time. Her trial where she used 400ppm K with no detrimental effect may have lasted only one year. In one year you would not likely see any negative effect from excess K depending on the frequency of application. However in hobbyist culture where plants are to be grown for a "lifetime" the accumulative effect of excess K manifests itself as poor plant health and reduced vigor. Data from short scientific trials does not apply well to long term culture.

Aside from my comment above, in the trial you reference D.nobile was used as the subject and since it is a deciduous species how it handles excess K can not be applied to the majority of orchids in a hobbyist collection.

 

[gonewild]

Read the posted link please.

It's not a matter of "may".

Reading it now...slowly!

I used "may" to be polite, but it did not help.

 

[Ray]

If as Rick points out K concentration (in general ''balanced'' fertilizers) is the problem then a simple dilution of a ''balanced fertilizer'' could NOT be just as effective as k-lite. You would be diluting all other nutrients thereby reducing what is available to the plant.

"Lowering the relative concentration ratio", yes. "Diluting", probably not, as even in the lightest concentrations most of us apply, they are still many times what the plants have evolved to take up in nature.

I don't think we can assume that the ratios provided in the solutions we apply can be equated with what is taken up, just as we know that what's in the tissues don't match what's available.