K-lit after 6 months
- Thread starter dodidoki
- Start date
Help Support Slippertalk Orchid Forum:
- Joined
- Dec 16, 2009
- Messages
- 3,776
- Reaction score
- 4,056
This may be of some value:
Essentially, it is very hard to disentangle the nutrients from each other to perform a control experiment. But I think the central idea of the K-light philosophy is:
1. Organic media accumulate K+.
2. Plants extract cations by exporting H+ to exchange cations with the substrate.
3. The plant can't control for which cation it lets in. Whether it wants K, Ca or Mg it must take what is gets and keep pumping H+ until it has enough of what is wants.
4. This results in the excess K+ from the substrate being imported in excess.
5. Excess K disrupts the uptake of Mg and Boron (from the chart).
6. Therefore (the hypothesis): by feeding low-K fertilize the excess of K in the substrate is avoided and the plan can assimilate sufficient Mg and B.
So the critical issue is the uptake of Mg and B and the test is to see whether plants given Low-K have taken up more Mg and B than high-K plants. Mg is linked to plant health, not only chlorophyll, and a classic symptom is "ticking" (spots on the leaves) and sensitivity to infection.
Now, I write this, it dawns on me that in the formulation of the MSU fertilizers, this hypothesis was probably tested already and we are arguing over an issue which was settled long ago.
Essentially, it is very hard to disentangle the nutrients from each other to perform a control experiment. But I think the central idea of the K-light philosophy is:
1. Organic media accumulate K+.
2. Plants extract cations by exporting H+ to exchange cations with the substrate.
3. The plant can't control for which cation it lets in. Whether it wants K, Ca or Mg it must take what is gets and keep pumping H+ until it has enough of what is wants.
4. This results in the excess K+ from the substrate being imported in excess.
5. Excess K disrupts the uptake of Mg and Boron (from the chart).
6. Therefore (the hypothesis): by feeding low-K fertilize the excess of K in the substrate is avoided and the plan can assimilate sufficient Mg and B.
So the critical issue is the uptake of Mg and B and the test is to see whether plants given Low-K have taken up more Mg and B than high-K plants. Mg is linked to plant health, not only chlorophyll, and a classic symptom is "ticking" (spots on the leaves) and sensitivity to infection.
Now, I write this, it dawns on me that in the formulation of the MSU fertilizers, this hypothesis was probably tested already and we are arguing over an issue which was settled long ago.
A
ALToronto
Guest
So is K-Lite supposed to be used only on plants grown in organic media? That would be news to me...
Organic media is the major culprit. As it breaks down it holds more and more cations as the negative carbon based compounds attract them. The experiments with CHC suggests that it will preferentially hold onto K and Na over Ca and Mg. I can't think bark is much different as it is mostly the same stuff... In addition, the tannins and phenols form insoluble salts with Ca and Mg.
I would think that stone is more resistant to this but will, eventually, have the same problem as the silicates are negatively charged (but have a much higher pKa* than bark and CHC). I don't know about LECA types...
I would also think that the major benefit from K-light in inorganic medium is that the fertilizing comes more regularly in smaller doses. Also the medium is rinsed more so excesses don't build up. If you supply K-heavy ferts as per instruction (once a month) the odds are that the plant gets a massive dose of K that hinders Mg and B uptake and then all the ferts are simply washed away and the plant remains short og Mg and B.
That is at least my thinking on the subject.
*pKa is a measure of acidity. A pKa > 7 would imply an alkaline medium. A pKa < 7 is acidic. If you have two mediums of pKa 5 and 6 then the plant has to pump out less H+ to release nutrients from the 6 medium than the 5. Also, the higher acidity of the 5 medium would mean that alkali salts such as Mg and Ca would be more likely to be washed out with watering. The H+ is pumped out across an electochemical gradient. The more H+ there is outside the root the harder the plant root has to work and this means fuel and resources are taken away from growth.
I would think that stone is more resistant to this but will, eventually, have the same problem as the silicates are negatively charged (but have a much higher pKa* than bark and CHC). I don't know about LECA types...
I would also think that the major benefit from K-light in inorganic medium is that the fertilizing comes more regularly in smaller doses. Also the medium is rinsed more so excesses don't build up. If you supply K-heavy ferts as per instruction (once a month) the odds are that the plant gets a massive dose of K that hinders Mg and B uptake and then all the ferts are simply washed away and the plant remains short og Mg and B.
That is at least my thinking on the subject.
*pKa is a measure of acidity. A pKa > 7 would imply an alkaline medium. A pKa < 7 is acidic. If you have two mediums of pKa 5 and 6 then the plant has to pump out less H+ to release nutrients from the 6 medium than the 5. Also, the higher acidity of the 5 medium would mean that alkali salts such as Mg and Ca would be more likely to be washed out with watering. The H+ is pumped out across an electochemical gradient. The more H+ there is outside the root the harder the plant root has to work and this means fuel and resources are taken away from growth.
D
DavidCampen
Guest
I don't remember seeing any experiments that suggested this. Which are you talking about?
Stone
Well-Known Member
Looks like I'm going to have to trial Klite for myself. (Its the only way I'll be satisfied
) The trouble is to find a fertilizer with the same P levels for the controls. I have an insigne which I can divide into 6 equal parts. 2 for Klite, 2 for MSU type and 2 for a general Urea based feed over 1 and 2 years. (I think I should use divsions of one clone as there is too much variation in seedlings unless you have 20 or 30 of each to cover it?)
Ray, have you sent any of this stuff downunder?
) The trouble is to find a fertilizer with the same P levels for the controls. I have an insigne which I can divide into 6 equal parts. 2 for Klite, 2 for MSU type and 2 for a general Urea based feed over 1 and 2 years. (I think I should use divsions of one clone as there is too much variation in seedlings unless you have 20 or 30 of each to cover it?)Ray, have you sent any of this stuff downunder?
Stone
Well-Known Member
Well Rick defines K toxicity as its atagonistic ability which leads to deficiency.
I totally agree. My point was that the closer we can get to the natural nutrient concentrations which orchids see, which are exceedingly low but constant, (especially for some epiphytes), the less we need to worry about ratios and antagonism between ions. But thats just my take on it....And thats why I would love to see a thourough nutrient and pH analysis of the substrate were some of our paphs grow. But there are so many variables such as light, temp, humidity, air movement and rainfall that I'm begining to think it's a wild goose chase. So many people grow paphs really well with a low EC of any general plant food you can buy at any harware store with no signs of deficiency. Look at some of these and probably grown with ''normal'' K levels ): http://www.google.com.au/search?q=C...jBiQeWyYG4Dg&ved=0CAcQ_AUoAQ&biw=1024&bih=545 For example, what did Piping Rock use to grow that heryanum?
And some plants still going strong after 40 years! I still have some that were imported from India in the 50's and 60's.
Hmm... It will take a while to dig up the reference but that was the reason why loading the CHC with CaNO3 was suggested. I think this was discussed in the following thread: http://www.slippertalk.com/forum/showthread.php?t=28491 and also http://www.ladyslipper.com/coco3.htm and http://www.aquaculture-hydroponics.co.uk/hydroponics-advice/growing_media/growing_in_coco_coir.html (search for "Potassium" to find the relevant bit of info).
Stone
Well-Known Member
I think the CaN03 and Mgso4 wash was to help remove the native very high K and (sometimes) Na already in the chc and to help with its low Ca Mg an S content. But once that's rectified somewhat, ( if it can be ) are chc any different to sphag or bark when it comes to K loading? If so how?
The Antex and hydroponics links both imply that CHC releases K slowly but doesn't release Ca and Mg readily. High Ca concentrations push the K and Na from the CHC matrix. In essence, this is the same idea as softening water with a resin that releases K and Na but takes up Ca and Mg. But the chemistry would be the same all woody organic substances like bark. The ion exchange is occurring on a medium of cross-linked lignins, tannins, cyanins etc... which tend to chelate divalent cations (Ca, Mg, Fe, Mo etc...) but also hold on to K and Na via direct ionic interactions. To force the K and Na off those negative groups on the CHC you need a high concentration of Ca.
Looks like I'm going to have to trial Klite for myself. (Its the only way I'll be satisfied
Ray, have you sent any of this stuff downunder?
Sure have.
Go to the USPS.com website and check the "calculate rates" button. I can repackage 2# into a plastic bag and fit it into a small, flat rate box.
Ray Barkalow
Sent using Tapatalk
D
DavidCampen
Guest
The Antec paper does not present any evidence to suggest that "CHC ... will preferentially hold onto K and Na over Ca and Mg" as you stated earlier. And in fact, as you stated above, ion exchange resins tend to bind divalent ions (such as Ca and Mg) more strongly than monovalent ions (such as K and Na).
Well spotted, David, but I didn't say that was the reference to the claim, only supporting testimony.
You misunderstand the issue of the K/Ca resin effect. When the plant pumps out H+ from the roots it can either displace a K or a Ca. But there is a lot more K present (from the fertilizer and the medium) so there is an increased probability that a K comes loose over a Ca. In addition, the organic medium holds onto Ca and Mg more readily than K and Na because: (1) the phenolics chelate divalent cations and (2) Ca and Mg form insoluble precipitates with phenolics (tannins etc...). So the probability of that H+ displacing a Ca is very small compared to it displacing a K.
Loading the CHC with CaNO3 removes a lot of the K from the CHC (etc...) so the probability that the H+ will displace a Ca or Mg is now greater. In addition, you have precipitated out the free phenolics as well as saturated the chelating sites. So there is more Ca and Mg free to be absorbed by the plant.
Until I can recall the reference for the preferential binding of monovalent cations can you propose an alternative hypothesis for why K-light works (particularly with CHC). There is a lot of evidence for K-light being better with CHC than others. Read the thread I mentioned previously.
I do not believe that my hypothesis is necessarily correct in every way, but from the evidence presented, I believe it is the better hypothesis. If you wish to supplant it, provide your evidence.
You misunderstand the issue of the K/Ca resin effect. When the plant pumps out H+ from the roots it can either displace a K or a Ca. But there is a lot more K present (from the fertilizer and the medium) so there is an increased probability that a K comes loose over a Ca. In addition, the organic medium holds onto Ca and Mg more readily than K and Na because: (1) the phenolics chelate divalent cations and (2) Ca and Mg form insoluble precipitates with phenolics (tannins etc...). So the probability of that H+ displacing a Ca is very small compared to it displacing a K.
Loading the CHC with CaNO3 removes a lot of the K from the CHC (etc...) so the probability that the H+ will displace a Ca or Mg is now greater. In addition, you have precipitated out the free phenolics as well as saturated the chelating sites. So there is more Ca and Mg free to be absorbed by the plant.
Until I can recall the reference for the preferential binding of monovalent cations can you propose an alternative hypothesis for why K-light works (particularly with CHC). There is a lot of evidence for K-light being better with CHC than others. Read the thread I mentioned previously.
I do not believe that my hypothesis is necessarily correct in every way, but from the evidence presented, I believe it is the better hypothesis. If you wish to supplant it, provide your evidence.
Trithor
Chico (..... the clown)
Wheweee! just been offered the post of assistant Prof, and already argues like one. I wait with baited breath for the next installment, or perhaps I should just wait for everyone to resolve the issue so that I dont have to take a Doctoral Post-Grad in chem to distill the salient facts?
As interesting as the results on the insigne study will be, I am afraid to point out that they will apply to insigne only, and at a streatch those which are similar in geographical location, habitat and type. Unfortunately it will be impossible to extrapolate the results to other species. Perhaps other ST members will conduct similar trials on other species and so spread the load and give a broader base?
D
DavidCampen
Guest
OK, then what is the reference that provides evidence for your statement that "experiments with CHC suggests that it will preferentially hold onto K and Na over Ca and Mg"? It is my opinion that that statement is incorrect. I don't see that the Antec paper supplies even supporting testimony.
I don't see how you can say I misunderstand the above since I did not comment on the above. I said only that your statement that "experiments with CHC suggests that it will preferentially hold onto K and Na over Ca and Mg" is not correct.
Your previous statement was "The experiments with CHC suggests that it will preferentially hold onto K and Na over Ca and Mg" Now you are saying the opposite.
This has nothing to do with your statement that " (CHC) holds onto Ca and Mg more readily than K and Na".
How about you first providing the reference for your statement that "(CHC)holds onto Ca and Mg more readily than K and Na. "
Where are the specific posts that provide "evidence for K-light being better with CHC than others" our do you intend to send me on another wild goose chase like you did by supplying the Antec reference for your first statement?
How about you supplying your reference first.
Can you succinctly state your hypothesis and the supporting data? Is it the potassium toxicity thesis as stated in the AOS article? Whether potassium or calcium bind more strongly to potting media, I don't think that that provides any evidence for the AOS article potassium toxicity thesis.
D
DavidCampen
Guest
Here you have gotten things backwards. In a water softener small amounts of Ca or Mg in the water readily display the K or Na. To recharge the water softner you have to flush it with high concentrations of K or Na because the cation exchange sites on the water softener media hold the Ca and Mg much more strongly than they do K or Na.
Stone
Well-Known Member
Trithor
Chico (..... the clown)
Mike, I agree with you, that a controlled study would be benificial. I think you are being overly sensitive to what was intended as a constructive comment. We all know that not all paphs have the same nutritional requirements (FACT), so my suggestion that perhaps other ST members would consider helping out with a similar study to yours using different species would give us a broader understanding of the effect of K-lite, benificial or otherwise.
can we stop bitching about who said what, and decide whether or not that something seems to work or not? instead of always trying to poke holes in something, come up with statements that are backed by refuting evidence. getting tired of the usual blather about 'you said this and that and contradict yourself'. either make your own statement about how something does or doesn't work, which is productive, or please refrain from being a dart-thrower. I am only asking politely, not telling anyone to do anything. supplying something that actively supports or refutes something is much more forward-moving and thinking and results in supportable conclusions
Similar threads
