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Cattleya calcium levels

This is a discussion on Cattleya calcium levels within the Genus Specific forums, part of the Orchid Culture category; I found the paper - published by folks at Cornell University as a PhD dissertation ...

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  1. #11
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    I found the paper - published by folks at Cornell University as a PhD dissertation - and it shows a lot of signs of being a dissertation (insufficient description of method details, for one), and as it is from 1977 - meaning the work was done almost 40 years ago - the conclusions display a lot of the misunderstanding of plant nutrition that have been corrected since then. For example, in the paper it is stated that "...Ca and Mg present in old tissues are re-utilized...", when in fact, it is now well established that calcium is immobile within plant tissues - which is why deficiencies are seen right at the growth tips - the very tips of the leaves - in plants not being sufficiently supplied. It also relies a lot on dry tissue analysis for its conclusions, and it is now known that there are many nutrient uptake mechanisms within plants - some passive, and some active - that render a direct correlation between supplied nutrient and tissue analysis invalid. Potassium, for example, it actively absorbed by the plant whether it needs it or not, and it is socked away in vacuoles, so the tissue analysis will always show high levels.

    Then there's that minor detail that what's in the plant doesn't tell you what the plant needs. If that logic held, then we would conclude that high cholesterol levels are needed by man.

  2. #12
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    Missanna, a useful way to look at plant nutrients is in terms of plant response to different levels of supplied nutrients. A useful paper in this regard is by Rebecca Bichsel et al., 2008, it can be downloaded for free at Nitrogen, Phosphorus, and Potassium Requirements for Optimizing Growth and Flowering of the Nobile Dendrobium as a Potted Orchid The take-away (at least for me) from this paper is that N and K are needed in greater supply than P. The paper focuses mainly on N, P and K, but where they do mention Ca, the researchers seem to be applying it at about the same rate as N in fertilizer solution, and Mg at half that strength.

    If you have not seen them already, the St. Augustine Orchid Society St. Augustine Orchid Society - North Florida Orchid Growing makes available on its web page some good reading on orchid culture. Scroll to the bottom of their home page, There is a heading on "Orchid Culture", with topics in 5 sub-groups. In the first group, 5th star from the top, there is a section on water quality and fertilizers. Within that section you will see an article by Sue Bottom on Ca and Mg, also, a series of 5 articles by Bill Argo, the 3rd of which is on fertilizers and nutrients.

  3. #13
    Missanna is offline Cattleya lover
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    First off- thank you all so much for your responses.
    I have never used time release fertilizer and the one that I have been using is very similar to the MSU one that everyone seems to have good results with, so I don't think it's anything I have been using. Also these plants were a bit runty when I got them.
    and thank you, Ray, for reading everything and pointing out the problems with the paper.

    ALSO- Cathank you so much for telling me where to find that article. I was looking for that specific one on another website but it didn't link to it. I've become familiar with this woman from researching online and am very impressed with all of the info on that page but I have a hard time finding things sometimes.

    I was also doing more research last night and came across an article regarding temperature and it basically said that night temps that are too high basically don't let the plant "sleep" (my term), so what happens when people don't eat well and work too hard? We get sick. Same sort of thing. It also specifically said that plants can start developing calcium deficiency. Now, I know that some maximas are cooler growing than others and although all of my other ones are the shorter type, it doesn't mean that they don't have some warm blood in them somewhere. Perhaps these are full cold bloods. So I have also stuck these babies in the coolest microclimate in my area near the evap humidifier. They were being grown in Hawaii previously. When I lived there (although it was a different island), the day summer temps were 80/85 and nights were warm enough to run around naked (not that I did). So maybe Hawaii was too warm for them which caused them to not grow really well in the first place and then bringing them into a warm house under lights maybe stressed them even more. I'm still waiting for the night temps to get cooler than it already is in my basement so I can give everything a cooler winter rest. Normally my night temps in summer get to about 66, which seems pretty good, but I don't know how long it takes to get to that temperature or for how long the temp is that low. My min/max thermometer doesn't show the times of the readings. The day temperatures under 4 and 6 HO t5 fixtures however, can get kind of super hot. I recently purchased a little point and click infared thermometer for lizard cages etc. that allows me to take leaf temperatures and I discovered that the tips of some leaves were getting up to 95 degrees. They were never burning or bleaching, so I didn't worry about it too much when I would feel them and they only felt slightly warm (but I had not taken into account that our fingertips are about 90 degrees, so if a leaf even feels slightly warm, it's above that. So I moved the plants down further from the bulbs, installed an extra fan for one side do the fixture and then sort of aimed my giant humidifier near the top shelf and I'm not getting such high temp readings on the tips of leaves now, but the babies weren't getting that hot because of where they were. Still though, I suspect that they are too warm. Anyway, I created a cooler microclimate and moved my thermometer and these two babies to this area to see how cool they get and now that I am not working tonight, I can stay up late and take hourly temperature readings to see what's going on down there.

    I found the article on the Florida site and the photo of the magnesium deficient leaf is EXACTLY what one of these seedlings looks like. From what I understand, these two minerals work together and if there is a mg deficiency, it seems like the plant can be Ca deficient as well.

    Is this logical or am I missing something?

    Also, I know certain minerals (if supplied in the wrong ratios) can sort of block or interfere the uptake of others. (Is it uptake or something else?) I'm not talking about when they precipitate in solution. Do you know what I'm asking here? I'm trying to remember what this process is called so I can search for it.

    ALSO- I was kind of confused when I read Sue's article when she said you can add calicium nitrate and Epsom salts as a supplement "though you would never add the Calcium and Magnesium supplements concurrently because they will react and precipitate into a sludge." I think she meant concurrently with your regular fertilizer, but it sounds like she means "don't add the Ca and mag together" which seems weird to me because there are cal mag fertilizers and, from my understanding, the two work synergistically.

    Is it possible that the S in Epsom or the N in cal nitrate or some combination causes precipitates?

    More research...

    Ok, so upon actually looking at a cal mag fertilizer, I see that they don't just have Ca and mg , but they have all the other stuff in there as well. One label said that there is no precipitate because of the combination of calcium and sulfur and the S is some special form of S. So maybe since Epsom doesn't have this special form of S, it will cause precipitates. So, I answered some of my own questions there.

  4. #14
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    Quote Originally Posted by Missanna View Post
    thank you, Ray, for reading everything and pointing out the problems with the paper.
    It's easy! All I have to do is go back and read my own dissertation. LOL

    ALSO- I was kind of confused when I read Sue's article when she said you can add calicium nitrate and Epsom salts as a supplement "though you would never add the Calcium and Magnesium supplements concurrently because they will react and precipitate into a sludge." I think she meant concurrently with your regular fertilizer, but it sounds like she means "don't add the Ca and mag together" which seems weird to me because there are cal mag fertilizers and, from my understanding, the two work synergistically.
    Calcium and magnesium should always be used together, as that's how the plants tend to use them.

    Sulfur, or the so-called "form" of it, plays absolutely no role.

    The issue with mixing can be avoided by controlling the concentration. Calcium nitrate is 40% Ca, and sodium sulfate is 20% Mg (Epsom salts is lower, as each molecule has 7 water molecules attached in the crystal structure, but that's irrelevant in solution). In a fertilizer, they are lower- but still in reasonably strong concentrations - 9% Ca and 3% Mg in MSU RO - but when mixed with water, even a concentrate for use with a metering pump, their concentrations in the liquid are low enough that no reaction takes place.

    If you were to take pure calcium nitrate and Epsom Salts and add them one at a time to water in amounts that would be usable on plants, there would be no precipitation. When we were developing the K-Lite formula for orchids and epiphytes in general (12-1-1-10Ca-4Mg), some folks used the two 50/50 as their only fertilizer for more than a year to "detox" their plants of potassium overload.

  5. #15
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    Thanks Ray. Excellent information. I am thinking of using pure calcium nitrate and mgs04 as is. I was thinking to use them separately and now I can add them together ~20mg per gallon per salt.

  6. #16
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    Regarding the "sludge" mentioned in Sue's article, that is precipitated gypsum (think of it simply as "calcium sulfate"; the mineralogy is a bit more complex in real life, but this will do for our purposes). Epsom salts can be thought of as magnesium sulfate (again, somewhat simplified). You really only need to worry about this sludge forming when you are mixing a nitrate and a sulfate in concentrated solutions (such as a feeder tank that doses fertilizer into a large watering system).

    At low concentrations, the gypsum does not precipitate. I actually provide Ca to plants by dissolving gypsum in water (it dissolves slowly at levels up to 1 teaspoon per gallon). Dissolve gypsum and Epsom salts together, 1 tsp each/gal, and you provide three important plant nutrients (Ca, Mg, and S) in one solution. You can use this as-is, or mix a small amount of the solution in with your dilute fertilizer water when you supply fertilizer (this is what I usually do).

    Regarding the temperatures, I do not have experience growing C. maxima specifically. I do have many Cattleya hybrids and related intergeneric hybrids. They seem tolerant of a wide range of temperatures, mine do just fine at high temperatures in the summer (90 to 100 F day, 70 - 90 F night), intermediate in the winter (70 F + or - daytime, a bit cooler at night). I have found that some other genera that are reported to require cool temperatures (Coelogyne cristata is one) actually can tolerate much warmer temperatures if you can keep the roots cool and manage water to keep the roots from drying out. Catts, of course, seem to prefer their roots drying out before you water again.

  7. #17
    Missanna is offline Cattleya lover
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    So, I did yet more research (I love reading and learning and spend ridiculous amounts of time doing so)

    Ray- thanks for clearing up the precipitate confusion, but since cal and mag are both used by the plant together, does it make sense that a plant with a mg deficiency is also likely to have a Cal deficiency? For example, if the plant doesn't have enough mg and mg (for instance) helps the plant use or take up Ca, it can't do so very well because it doesn't have enough Mg in its tissues. I know that's grossly oversimplified, but it's like how people vitamins come in calcium plus D because without enough D, your body can't absorb the Ca very well and you would just poop it out (or in this case, it gets flushed out of the pot).

    Also- can you tell me where you you got the 40% figure Ca of cal nitrate? All the labels on the fertilizer grade say it's 15.5 and 20 (speaking of which, what makes up the rest of the 80 percent? I've never understood how the percentages on fertilizers never add up to 100)

    Anyway, for those in the future who may come across this post, I'll list the recommended dosages in tsp/gallon of Epsom and calcium nitrate from Sue's article and try and make this post as complete as possible so if websites change or you're just lazy, you don't have to go searching all over the internet for the info (you know who you are, me in two years or whenever you see this issue pop up again and you forget that you wrote it in your notes in your blue orchid binder, by the way, I hope you've had a chance to bloom your new s/a maxima and I hope it's a good one. Also don't forget that the black root tips don't respond to t-methyl. Use the A fungicide for pythium instead)

    Calcium nitrate .25 = 50ppm N; 62 Ca
    .5 = 101ppm N. 124 ca
    Epsom salts. 1/8 = 16ppm mg
    Then as follows respectively : .25, .5, 1 =33,66, 130 (ppm mg)

    The article says a "megadose" of Epsom is 1tsp/gallon

  8. #18
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    Not sure where Ray's 40% came from, but calcium nitrate, Ca (NO3)2, is a little over 24% calcium. It's an atomic weight, molar mass thingie.

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    You all are right - I mistakenly used CaNO3, not Ca(NO3)2. Also, for the most part, "greenhouse grade" calcium nitrate is most often 5Ca(NO3)2∙NH4NO3(10H2O), which is 15.5% Ca.

    Missanna - with two exceptions, in the US, the ingredients of all fertilizers are expressed as weight percentages of elemental materials - pure nitrogen, calcium, magnesium, iron, etc.

    The exceptions are P & K, which are expressed as the oxides, P2O5 and K2O - a remnant of old testing methods that required the chemicals be burned to ash (oxide) for analysis. As the P in P2O5 constitutes roughly 44% of the weight of that molecule, and the K is about 83% of K2O, a 10-10-10 fertilizer is actually:

    10% nitrogen, by weight
    4.4% phosphorus, and
    8.3% potassium.

    The reason that the ingredients on a fertilizer label don't add up to 100% is similar - some are carbonates, and the carbon and oxygen are not included in the total, sulfates where the O - and sometimes the S - is ignored, some are hydrated species, and the water of hydration is likewise ignored, etc.

  10. #20
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    I never looked up the reason why the P and K results were always expressed in term of phosphorus pentoxide and potassium oxide. Good to know! Thx Ray.

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