'What Orchids Eat', importance of calcium

[tucker85]

Taking this thread back to where it originally started. After reading an article in the St. Augustine Orchid Society newsletter I finally realized why my orchids improved when I started giving a calcium/magnesium supplement. During most of the year I water my orchids with municipal water that has plenty of calcium and magnesium in it. But I grow my orchids outdoors in South Florida and during the summer most of the water they get is rain water. It rains almost every day during the summer. So I realized the plants aren't getting any calcium because of the rainwater. I could use a cal/mag fertilizer, like many South Floridians do, but for now I'm going to keep using my cal/mag supplement twice a month. Most of you Northern growers don't run into this problem but for anyone interested here's a link to the article that clarified it for me. Bottom line, if your water doesn't contain calcium and magnesium, then it must be provided in the fertilizer or a supplement.

http://www.staugorchidsociety.org/PD...ps-Calcium.pdf

[Ray]

I don't think any of us has the wherewithal to conduct a truly scientifically-valid experiment, so we're left with anecdotal observations.

Personally, over the last six-to nine months, I have seen plants bloom for me that have not done so for a while, but I have not-, and will not claim that has anything to do with K-Lite, because I simply cannot say one way or another. In the 40+ years I have been growing orchids, I am confident that changes are often subtle, and sometimes subtle changes can have a major influence on how well things grow, so how can I, in a scientifically uncontrolled environment (despite my efforts to control what I can) make a call one way or another? The end result is often nothing more than a "gut feel".

Going into this experiment, I knew I was taking a risk with my plants, and the folks that developed the "MSU" fertilizers warned me what to look for in both phosphous and potassium deficincies. So far, I have seen none.


Let me also add that it appears to me that a lot of folks are forgetting how a lot of discoveries come about:

1. An observation is made that leads to a hypothesis. That observation need not be in the same field - that's where "free-thinking" and "creativity" come in.
2. Potential scientific theories are put forth to try to explain the observed phenomenon, and how it might be applicable to the specific field of interest.
3. Testing is begun in an attempt to prove or disprove those theories. Sometimes that initial testing can be nothing more than "Let's give it a shot.".
4. The testing is assessed for its validity.
5. The results of that testing is analyzed and a conclusion reached.

Having done product- and process development, as well as process problem solving and optimization for a living, to my mind it is very clear that we are very early in that process - no more than step 3 - yet some folks are treating it like we are past step 5.

Give it a rest, folks. Nobody is forcing anyone to use the product, or saying you're stupid if you don't.

[Discus]

Originally Posted by ALToronto

I have no control - what would the control be - pure RO water? That would mean certain death for the control group. The grower from whom I bought the flasks (Kingfisher Orchids in BC) told me that he used fish/seaweed for his flasklings, so that is really my control. I'm testing K-Lite against it.

I guess the control (in the overall "k-lite" debate) would be as similar a formulation as you can manage that has a "normal" level of K in it (perhaps something like MSU vs K-lite, or "commonly used normal fertiliser" vs k-lite) I haven't read the labels, but I suspect they're (RO MSU vs K-lite) quite close to each other aside from the level of K and the chemicals used to get to the respective levels of K. That said, I believe MSU is relatively low P compared to most "regular" fertilisers*...

I guess you should ideally have an overall similar level of EC too, but I'm not certain as to how you'd achieve that without skewing the results (there may be something you can use to affect the EC or "osmolarity" of the solution which would have no other effect). Certainly, the levels of the non-K parts of it should be as similar as possible (N,P, micro, pH, using the same water source).

Basically, if possible, your "test" should be the effect of the level of K on the plants, and nothing else should change (i.e. micronutrients, level of N and P, and not then adding other "non-specific" factors like the contents of organic fertilisers or seaweed growth supplements).

Obviously the control can't be pure RO, but your treatments are (in the opinion of someone who has done some science and a couple of undergraduate courses on experimental design, even if not done experimental design for a living) a bit too "variable" to really be determining if it's just the K that's what is affecting the plants - indeed it's not really any improvement over an anecdotal "we tried some k-lite here and we like it a lot" (or "hated it" depending on your outcome). I don't mean to discourage you in any way, nor disparage your professional skills.

At the moment, your experiment is "which of these two treatments produces "better" growth in phalaenopsis", *not* "what is the effect of K".

*so the "trend" here, with the first "revolution" being lowering P (MSU) and the next then possibly K, when will we get a Low N hypothesis, and then realise what we should have done all along is simply used much less of a normal fertiliser...? New! Improved! LESS IS MORE(tm)! (aka weakly-weakly weekly)

---------- Post added at 03:43 PM ---------- Previous post was at 03:37 PM ----------

Originally Posted by tucker85

After reading an article in the St. Augustine Orchid Society newsletter I finally realized why my orchids improved when I started giving a calcium/magnesium supplement.

Thanks Tucker - I think in one of my earlier contributions to this thread, I mentioned the need to understand whether or not particular growers were using "well water" or "pure water" formulations. (as well as other aspects of their "culture" whether intentional or not, like heavy rain on their plants).

You could certainly expect to ultimately see Ca and Mg deficiencies in rainwater irrigated plants if using "well water" forumlations - certainly if you used rainwater to fertigate with, and possibly through "leaching" if you used your normal water to fertilise, but the rain "washed it out". It's plausible that such deficiencies might be "subclinical" (i.e. you don't see the leaf effects) but do affect the overall vigour of the plants, which you see as increased vitality and flowering when you supplement.
Good luck with your plants

---------- Post added at 03:56 PM ---------- Previous post was at 03:43 PM ----------

Oh, and if anyone is wondering how a plant can grow happily in the rainforest on rain and then suddenly be "sad" when subjected to "rain" in cultivation, I would posit the answer lies in the need for a "balanced" diet - if you're spurring your plants on with N fertilisation but not keeping up the other essential micronutrients (like Ca Mg etc) then you'd expect some sadness. Such "unbalanced" fertilisation presumably doesn't happen in the wild, and I suspect many plants are much more vigorous in cultivation than they are in the wild because of our increased nutrient regimes.

Giving a plant an "unbalanced" diet (like feeding yourself pure protein and nothing else) might work for a while (you may even "grow" for a while), but you'll get sick in the end.

The most common cause of this would probably be using "well water" formulations (which often are low in Ca & Mg in particular) with pure water supplies (rain/RO/distilled).

Thinking about it a bit further, it's interesting that all the rain doesn't in general reduce the vigour of your plants even with Ca/Mg supplementation - I doubt that the other elements of fertilisers are that much less "labile" than Ca & Mg (more resistant to being "flushed out"). I wonder if orchids are just very bad at "grabbing" those out of the media or simply "greedy" for them (relative to NPK and other micronutrients)?

---------- Post added at 04:07 PM ---------- Previous post was at 03:56 PM ----------

And on the comparison between MSU and K-lite, Ray helpfully publishes some of the info one might like to know on his site:
Fertilizer for Pure Water
http://www.firstrays.com/images/product/K-Lite.jpg
The ingredients are the same (at least as listed); clearly it's the relative amounts that vary between formulations.

It's interesting to note that K-Lite is also P-lighter in comparison to MSU RO:
K-Lite: 12-1-1-10Ca-3Mg
MSU RO: 13-3-15-8Ca-2Mg
...and it also has a bit more Ca and Mg and a smidge less N. And you'll note that the k-lite is also a little less conductive overall (i.e. less ionically/osmotically "concentrated" for a given ppm of N) which could, I suppose, play a role?

This will considerably complicate amateur attempts to sleuth this out in experiments (because at minimum it's hard to definitively prove that the effect was due to the K levels, rather than to reduced N or P or increased Ca or Mg, or even EC, because these all vary) :/

---------- Post added at 04:12 PM ---------- Previous post was at 04:07 PM ----------

Also, it's interesting to note in klite that the "micronutrients" Ca and Mg appear to be given in larger quantity than the non-nitrogen "macronutrients"! (again, is this an indication that orchids really love them some serious Ca and Mg for whatever reason?).

[Leafmite]

I find I have to add calcium, too. We have been having a ton of rain...nearly every day. The calcium really goes a long way in preventing problems with orchids.

[Ray]

I wish I could find more about this, but in going through Benzing's Vascular Epiphytes, there is a comment soemthing to the effect of "orchid root velamen having a unique ability to trap ions", suggesting that there is more to to it that merely being the "sponge" many of us have thought.

If you think about how the plants basically get fed when rainfall cascades through the forest canopy, and its in the first few moments that the nutrients would be the most concentrated, it would seem to make sense that "trapping" would be better. If the velamen was just a sponge, continued rainfall would dilute the concentration of minerals available to the plant.

That suggests to me that "weakly-weakly-weekly", coupled with "frequently" is probably the better approach to feeding. There are some I know of that are down to as little as 5 ppm N applied daily.... Personally, I'm running a bit under 10x that, applied about every 3 days.

[Discus]

I suspect Benzing's JSTOR: An Error Occurred Setting Your User Cookie might have some additional details. Damn thing wants me to pay $14 to access it though, which would be fine if I knew the info was there, but I don't.

---------- Post added at 05:32 PM ---------- Previous post was at 05:21 PM ----------

This paper (Brazilian Archives of Biology and Technology - Comparative anatomy of the absorption roots of terrestrial and epiphytic orchids) suggests Benzing 1982 discusses nutrient access by velamen. Benzing 1982 is JSTOR: An Error Occurred Setting Your User Cookie

If we can find my wife's university library card this evening, I'll see if I can't persuade JSTOR to give me the goods.

---------- Post added at 05:33 PM ---------- Previous post was at 05:32 PM ----------

Aerial roots of epiphytic orchids: the velamen radicum and its role in water and nutrient uptake - Springer looks like it will be interesting too:

The velamen radicum, a spongy, usually multiple epidermis of the roots, which at maturity consists of dead cells, is frequently described as an important adaptation of epiphytic orchids. Yet, quantitative evidence for the alleged functions, e.g., efficient water and nutrient uptake, nutrient retention, reduction of water loss, mechanical protection, or the avoidance of overheating, is rare or missing. We tested the notion originally put forward by Went in 1940 that the velamen allows plants to capture and immobilize the first solutions arriving in a rainfall, which are the most heavily charged with nutrients. In a series of experiments, we examined whether all necessary functional characteristics are given for this scenario to be realistic under ecological conditions. First, we show that the velamen of a large number of orchid species takes up solutions within seconds, while evaporation from the velamen takes several hours. Charged ions are retained in the velamen probably due to positive and negative charges in the cell walls, while uncharged compounds are lost to the external medium. Finally, we demonstrate that nutrient uptake follows biphasic kinetics with a highly efficient, active transport system at low external concentrations. Thus, our results lend strong support to Went’s hypothesis: the velamen fulfills an important function in nutrient uptake in the epiphytic habitat. Most of the other functions outlined above still await similar experimental scrutiny

[ALToronto]

Discus, I'm not trying to test the isolated effect of potassium. That's a trap that too many scientists have fallen into. In any biological system, the balance of factors is often more important than the level of each factor. So just like in the Phal paper quoted by David and Fabian, giving plants absurdly high doses of N and P, and then withholding K, will lead to problems.

I have no stake in K-Lite, and I don't care if it's the absolutely perfect standalone fertilizer for me. Like any other fertilizer, it's part of an overall culture I'm providing for my plants. I'm trying to find out if it will work better than another fertilizer, that's all.

I have offered to design a scientific study to evaluate the isolated effect of K, but no takers yet. And I don't think an isolated effect study is appropriate in this case,because it fails to look at the plant environment as a complete system.

As a comparison, look at fat in people's diet - everyone tells us to reduce fat, but what happens when we eliminate it completely? Insulin skyrockets, we gain weight, we get sick easily, have no energy, etc. It's not a linear relationship - nothing in nature is. Yet every study tests factors in isolation, in a linear progression. It's also why vitamins tested in isolation show detrimental effects.

[Discus]

Originally Posted by ALToronto

In any biological system, the balance of factors is often more important than the level of each factor.

Thanks for your feedback - I agree that plant culture is ultimately going to be about balance, but I can't envision any sensibly scaled experiment that would replace the tendency to design experiments where one alters just one factor at a time (hence the "common trap" for scientists effect?). I think most people tend to shy away from designing or analysing multivariate experiments for fairly obvious reasons (perhaps not least of which may be math-o-phobia).

That said, your experiment to compare two fertiliser regimes will lead, as you surmise, to reasonable information on which of those two work better for you - but as you say, probably won't help that much in the "Kontroversy".

[isurus79]

Originally Posted by orchidsarefun

after all this is it still ok for me to eat Special K occasionally ?

Yes, but absolutely no bananas!

[palm521]

i have heard that bananas are good source of K. and milk gives you calcium.. hmm.. special k (with bananas) for orchids ? maybe?

having special K without bananas is like going to the beach without beers...

---------- Post added at 12:39 AM ---------- Previous post was at 12:33 AM ----------

Originally Posted by Discus

Thanks for your feedback - I agree that plant culture is ultimately going to be about balance, but I can't envision any sensibly scaled experiment that would replace the tendency to design experiments where one alters just one factor at a time (hence the "common trap" for scientists effect?). I think most people tend to shy away from designing or analysing multivariate experiments for fairly obvious reasons (perhaps not least of which may be math-o-phobia).

That said, your experiment to compare two fertiliser regimes will lead, as you surmise, to reasonable information on which of those two work better for you - but as you say, probably won't help that much in the "Kontroversy".

orchids are slow growers so whoever does a controlled experiment , it is going to take time.

balance is a good word, there is also different species that will require more or less of any given nutrient. so this is really complex,

for example a P. kovachii that i own, i ended up doing a different nutrient regime based on the information i gathered from mr Mantique when i visited Peru. meaning (Maybe) a fertilizer might be outstanding for some groups and deficient for others?