Early K-lite results

[Ray]

Dose = concentration X duration of exposure X frequency of exposure.

Let me throw out a question about the "duration" part.

Some of the reading I've done points out the unique ability of velamen to "instantly" bond with mineral ions and hold onto them, presumably an evolutionary development to take advantage of the fact that the very first part of a rainstorm will contain the most nutrients, and to prevent the deluge that follows from washing it all away.

However, that says absolutely nothing about the rate of uptake, and that is what gives relative weight to the duration of exposure. If I run my fertilizer solution over a plant's roots for two minutes, is the plant getting twice the dose as it would at one minute? I doubt it.

Any nutrient uptake dynamics studies on orchids out there to lend us a hand?

 

[Rick]

Let me throw out a question about the "duration" part.

Some of the reading I've done points out the unique ability of velamen to "instantly" bond with mineral ions and hold onto them, presumably an evolutionary development to take advantage of the fact that the very first part of a rainstorm will contain the most nutrients, and to prevent the deluge that follows from washing it all away.

However, that says absolutely nothing about the rate of uptake, and that is what gives relative weight to the duration of exposure. If I run my fertilizer solution over a plant's roots for two minutes, is the plant getting twice the dose as it would at one minute? I doubt it.

Any nutrient uptake dynamics studies on orchids out there to lend us a hand?

The duration part is really the messiest thing with regard to the variabilities in orchid culture.

Easy for SH and hydroponic culture because duration is continuous and frequency = 1 by this culture method. (barring fluctuations in stability of tank concentrations).

Duration for mounted is very short. (Splash on and thats it for the most part). Putting this into the frame of your question, you could pro-rate the duration of a mounted plant by collecting all the immediate drip off (volume) and subtracting it from the total amount applied. Obviously not all that hits the mount will hit the roots, but it would get too complex to quibble over what is going to be a very small amount in the first place.

Duration for the potted plant is very difficult since it depends on the water retentive AND CEC properties of the mix. The effect translates to that graph I posted of Xaviers work with orchiata bark that showed that even with equal application of the same kind of fert, showed dramatic differences not only in the retention of K in the various potting mixes, but the amount of K that ended up in the plants.

In comparison of Orchiata to Coir, you had over a doubling of K retention in the mix (0.8% to 2.37%) which resulted in an increase in plant tissue K that went from 3.56% to 5.6%!! ( I believe all feeding was weekly at 100ppm K).

This phenomena is why I think I couldn't grow phalaes in pots (with everything from chc to bark to moss) but did OK mounted. Even at 100ppm for concentration with a regluar weekly frequency, I had a huge duration multiplier via the potting mix.

 

[SlipperFan]

Does this put to lie the notion that one should first water the orchids with plain water, and then fertilize them?

 

[Ray]

Does this put to lie the notion that one should first water the orchids with plain water, and then fertilize them?

Hah! Like everything orchids, "it depends".

I have firmly come to believe that low-dose, frequent feeding is the best for the plants. Considering that I am not providing a lot of nutrition at a watering (it might still be high by nature's forests standards), I would think that saturating the roots with plain water first would be counter-productive, reducing the uptake substantially.

If, on the other hand, I watered heavily, infrequently, I think that saturating effect would help me prevent overdosing and "burning". When I volunteered my time (40 years ago) at what is now the Atlanta Botanical Gardens, we fed the orchids monthly at about 300+ ppm N, watering with plain water first.

While typing this, another thing occurred to me - that old practice may have been the unknowing implementation of the K-Lite concept! Think about this scenario:

Water first with tap water containing significant amounts of calcium, magnesium, and iron compared to the other minerals. Those are the ones "captured" by the velamen as it becomes saturated. Now come back and water with a fertilizer that has none of those, but substantial amounts of N, P & K, but because of the condition of the velamen, they will be absorbed in much lower rates than applied.

 

[SlipperFan]

Interesting, Ray. I water with pond water, so I suppose I give the plants something to eat every time I water. K-lite, when I give it, is that extra boost. At least, that's my very unscientific theory.

 

[Stone]

.

While typing this, another thing occurred to me - that old practice may have been the unknowing implementation of the K-Lite concept! Think about this scenario:

Water first with tap water containing significant amounts of calcium, magnesium, and iron compared to the other minerals. Those are the ones "captured" by the velamen as it becomes saturated. Now come back and water with a fertilizer that has none of those, but substantial amounts of N, P & K, but because of the condition of the velamen, they will be absorbed in much lower rates than applied

If that what was going on with the ion transfer in the roots, and I'm pretty sure it isn't, would't that make it the N-P-K-Lite concept?

 

[Stone]

Does this put to lie the notion that one should first water the orchids with plain water, and then fertilize them?

Dot, The Japanese bonsai masters say ''If you fertilize dry soil it is giving strong fertilizer'' or something like that. Which actually means that there should be some moisture at the roots before you feed. Watering the day before should therefore be fine. (unless your fertilizer is so weak as to be inoccuous (spelling?) then any time will be ok.

 

[Rick]

Hah! Like everything orchids, "it depends".

I have firmly come to believe that low-dose, frequent feeding is the best for the plants. Considering that I am not providing a lot of nutrition at a watering (it might still be high by nature's forests standards), I would think that saturating the roots with plain water first would be counter-productive, reducing the uptake substantially.

If, on the other hand, I watered heavily, infrequently, I think that saturating effect would help me prevent overdosing and "burning". When I volunteered my time (40 years ago) at what is now the Atlanta Botanical Gardens, we fed the orchids monthly at about 300+ ppm N, watering with plain water first.

While typing this, another thing occurred to me - that old practice may have been the unknowing implementation of the K-Lite concept! Think about this scenario:

Water first with tap water containing significant amounts of calcium, magnesium, and iron compared to the other minerals. Those are the ones "captured" by the velamen as it becomes saturated. Now come back and water with a fertilizer that has none of those, but substantial amounts of N, P & K, but because of the condition of the velamen, they will be absorbed in much lower rates than applied.

Partially.

Plants grow and transfer materials with the environment 24/7 not just on feed day. So yes a monthly versus weekly feeding cuts the monthly duration of exposure by at last a factor of 4.

But:

If the potting mix is dry between feedings then the plant uptake only occurs at the feeding time. There must be a fairly decent aqueous interface between the root and the media for nutrient transfer. K is not a gas and doesn't crawl as a solid, so needs an aqueous pipeline for transfer. In a potting mix the porous materials act as a sponge. If roots are in contact they can transfer from the pores when wet, but not at some level of dry.

Those spongy materials extend the exposure duration beyond what a plant on a mount experiences. As you noted water over roots 1-2 -3 minutes on a mount. In comparison try 10,080 minutes of exposure duration over the coarse of a week if you load up a pot of wet moss with 100 ppm K.

Then add the CEC multiplier to the concentration regime. So if you are adding 100ppm K per week, and the potting mix selectively keeps the K and lets the Ca go through, then you get the effect Xavier's study shows with the K concentration going up through time even though applied K is constant. The Orchiata people are proud of the low CEC of their material and in that data supplied by Xavier its pretty obvious that it lets more K run through the pot compared to the other comparison materials. That pushes the duration figure closer to the mounted condition again.

Now heavy flushing intervention with a strong solution of Ca and Mg between the weekly or monthly K feedings will drop the exposure dose over the coarse of the week back down. but if you use RO water then the CEC of the material will not be overcome, and your mix will still be saturated with high K.

 

[Rick]

Let me throw out a question about the "duration" part.

Some of the reading I've done points out the unique ability of velamen to "instantly" bond with mineral ions and hold onto them, presumably an evolutionary development to take advantage of the fact that the very first part of a rainstorm will contain the most nutrients, and to prevent the deluge that follows from washing it all away.

Actually from a toxicity test protocol the mechanics of what happens inside the organism are not part of the basic dose considerations. That gets into the body burden/physiology issues of toxicity.

The study of velamen with regard to uptake efficiency doesn't change the basic equation of concentration X exposure duration rather than validating that orchids do efficiently pick up ions from the environment. Probably more efficiently than passive osmotic transfer.

But duration is based on the duration of time the organism is exposed to the chemical in the external environment not its internal environment per se.

Now if the material actually has a clearance time within the organism you can subtract that off from duration for pulsed dose studies. But I don't think there is efficient discharge of excess K in plants to consider this in the equation.

 

[Ray]

.


If that what was going on with the ion transfer in the roots, and I'm pretty sure it isn't, would't that make it the N-P-K-Lite concept?

Probably right - unless the fertilizer used was high in nitrogen (30-10-10 was used on all orchids in that Atlanta collection I mentioned earlier).

According to what I've read, (Marschner or Benzing, maybe both), velamen has the unique ability to instantly trap and hold cations. It stands to reason that 1) it will trap whatever is in the water supply, and 2) being that there are a finite number of "capture sites", if they are predominately filled with Ca, Mg, etc., there will be fewer sites available to capture the fertilizer cations, not to mention that the presaturation of the velamen would already lower the number absorbed and able to be captured.

All of that assumes, of course, that the absorption of the captured ions is slow enough that the originally-occupied sites haven't been "opened up" before that second application.

 

[Bjorn]

Probably right - unless the fertilizer used was high in nitrogen (30-10-10 was used on all orchids in that Atlanta collection I mentioned earlier).

According to what I've read, (Marschner or Benzing, maybe both), velamen has the unique ability to instantly trap and hold cations. It stands to reason that 1) it will trap whatever is in the water supply, and 2) being that there are a finite number of "capture sites", if they are predominately filled with Ca, Mg, etc., there will be fewer sites available to capture the fertilizer cations, not to mention that the presaturation of the velamen would already lower the number absorbed and able to be captured.

All of that assumes, of course, that the absorption of the captured ions is slow enough that the originally-occupied sites haven't been "opened up" before that second application.

Ray, I find this very interesting, can you supply me with some background references?

 

[Ray]

Bjorn, it was either in Mineral Nutrition of Higher Plants by Marschner, or more likely, Vascular Epiphytes by Benzing. Sorry I cannot be more specific right now - doing two jobs - purchasing manager for Total, and manager of everything for First Rays.

 

[Bjorn]

Found it, in Benzing. Thanks Ray!

 

[naoki]

Bjorn, have you seen a recent paper by Zots and Winkler?

http://www.ncbi.nlm.nih.gov/pubmed/23292456

Email (or PM) me your email address if you want to take a look at it.

 

[Bjorn]

Bjorn, have you seen a recent paper by Zots and Winkler?

http://www.ncbi.nlm.nih.gov/pubmed/23292456

Email (or PM) me your email address if you want to take a look at it.

mailed you

 

[cnycharles]

Though there might be science stating that watering before feeding doesn't get as many nutrients into the roots, if your plant us too dry you're preventing the chance of burning the roots and plant. Old days may have been more chance of burning if they used more bark and higher periodic feeding instead of weakly weekly. Better to lessen risk of burning plant


Sent from my iPhone using Tapatalk

 

[Ray]

That paper confirms the almost-instantaneous saturation of the velamen, and the trapping of ionic species, making me think that first watering with "hard" water might lead to boosting of Ca, Mg, and probably Fe in the plants' "diet", compared to watering once with that water supply plus fertilizer. Of course, a great deal depends upon preferential trapping and absorption dynamics.

Personally, I think that a little nutrition, applied frequently, is preferred over less-frequent, heavier feeding - it's what the plants have evolved to expect, after all.

 

[Brabantia]

Though there might be science stating that watering before feeding doesn't get as many nutrients into the roots, if your plant us too dry you're preventing the chance of burning the roots and plant. Old days may have been more chance of burning if they used more bark and higher periodic feeding instead of weakly weekly. Better to lessen risk of burning plant

.

Interesting for me what you say Charles, because during many years I tried to feed my plants at 125 ppm N as Ray recommended (in former days). Of cause I have burned many time the roots of my plants (Cattleya, Dendrobium, Oncidium and there hybrids ...) and for sure when I changed the substrate of my paphio's it remained no roots. Thought when I read scientific papers on the optimization of some orchids culture I see that some researchers are able the feed at high concentration. What is the trick? Are fertilizers made with urea as nitrogen source as "agressive" than the one made with ammonium and nitrate salts? Professional producers of Phalaenopsis are also feeding at high concentration 1000 µS is usual!

 

[Ray]

...during many years I tried to feed my plants at 125 ppm N as Ray recommended (in former days). Of cause I have burned many time the roots of my plants...

125 ppm N is the recommendation of the folks that developed the "MSU" fertilizers - that's what was published in the AOS article many moons ago. One of those folks has since told me (my paraphrasing) "You know how we arrived at that? We tried it and it worked. There was no scientific basis for it."

There is a lot more to this than just concentration. I used the MSU RO formula @ 125 ppm N at every watering for about 5 years, and never experienced any burning or root loss. What I did notice was a lack of blooms due to overdosing nitrogen.

 

[Brabantia]

There is a lot more to this than just concentration. I used the MSU RO formula @ 125 ppm N at every watering for about 5 years, and never experienced any burning or root loss. What I did notice was a lack of blooms due to overdosing nitrogen.

Thanks for your response Ray. Have you also used the 125 ppm N for paphs?
I ask you this question because since more than one year I am now feeding my Paphs at 30 ppm N ( from 4/0.64/0.64 Ca and Mg same ratio as in KLite) one time per week and I observe that effectively the roots are in very good health (...and the plants also) but there growth is very slow. The substrate I use is 1/3 bark - 1/3 CHC - 1/3 hydroton (Gold Label for hydroponic culture).