Calcium and Magnesium

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consettbay2003

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If I use equal amounts (by weight) of Magnesium Sulphate and Calcium Nitrate will that give me an acceptable ratio of Mg to Ca?
 
Need to find out the waters of hydration of the materials you have access too.

Epsom salt is MgSO4.7H2O and half the weight is water. I use anhydrous MgSO4 so don't have to account for the water weight.

Same for calcium nitrate. There are probably 3 different forms available with differing waters of hydration.
 
Also what is "acceptable ratio" for you?

Are you mixing this into tap/mains water (that already has a lot of Ca in it) or in RO water?

Are you amending the potting mix with lime or dolomite?

Overall I'd like to see a ratio from 2 to 4:1 Ca:Mg
 
And then in the very next thread, someone is advocating supplementing the plants with mag sulph to 'green them up'. If the correct ratio is 2-4 : 1, then why resuppliment with mag sulph? Just asking?
 
And then in the very next thread, someone is advocating supplementing the plants with mag sulph to 'green them up'. If the correct ratio is 2-4 : 1, then why resuppliment with mag sulph? Just asking?


????? Not sure what thread is reffered to.

But since calcium is so common in the environment and many folks are adding lots of calcareous ammendments to their potting mixes, you can end up with much higher Ca:Mg ratios. That's fine for long term.

But In general it's not a poor idea to chronically apply Mg at higher concentrations to Ca. But it doesn't hurt appying a couple shots for "greening things up".
 
Rick, sorry my comment was not directed at any particular thread and not more specifically at a thread of yours. Recently there has been a lot of talk about various macro and micro nutrients and then a whole range of values which each component should be supplemented in. The values change all the time depending on who is active in that thread (we seem to have a number of different camps here, the MSU traditionalists, the K-liters, the kelp and other naturalists, the no supplement anorexors, and a few other sects beside)
I am by no means new at growing orchids, but I recently discovered two near fatal errors in my culture that have relegated me back to newbie status. Firstly I use council water for all my plants, and supplement with RO and rainwater in the hope that I am improving the water quality somewhat. I use the word 'hope', because without knowing what you are starting with, that is the best that you can do, hope! I did have a test profile from the water division web-page and took that at face value. It was only after I organised my own water test that I realised that the profiles were very different. When I phoned the water division to query the result posted on their web page I was told that if I read the whole page I would see that they said it was a representative result of water tested at the time (no claim as to which water they were testing either), and that they made no claim as to its accuracy. The most important thing about what I am trying to say is that the majority of soluble fertilizers formulated for growing tunnel and agriculture are formulated with borehole/well water as the intended water source. As has been pointed out repeatedly, you need to know what your water contains! (I thought I did know, and thought that the posted result was reasonably accurate, I know suspect that whoever sent the water sample away, sent a bottle of bottled mineral water away!). Our council water contains almost no calcium and magnesium at all. This combined with using a fertilizer with no calcium and magnesium added to them, means that for years my plants were being starved of these two important elements. My supplementing the mains water with rain water and RO was only making the situation worse, not improving it. My second error was that I did not regularly check the TDS of my water after the injector to confirm there was no 'drift'. I did check the delivered concentrations when we installed the system, but failed to check it at regular intervals and so failed to realise that the fertigator had stopped working correctly.
Two huge errors which my plants are going to take a while to recover from. It is a problem which is made worse by the fact that my collection is too large for a hobby while I have a full time job, and too small to allow me to quit my job and run it as a commercial venture.
 
Wild stuff Trithor.

I'm sure I'm totally spoiled with regards for knowing my water. For one, working in an aquatic tox lab (we get water samples from all over the country), and secondly, the US domestic water supplies are heavily regulated by local or state health departments (hence false quarterly updates would cause major legal ramifications).

In the US there is a wealth of good free data available on local domestic water supplies. Otherwise, from an orchid culture standpoint where reliable data doesn't exist, its best to start with rain or RO water and build up from scratch (as you have been doing).

Actually a 5-10% addition of Perrier water into RO would make a pretty nice base water.
 
Hello.

All the paphs must have a good supply of calcium or just a few?
And also, I'm thinking to use crushed egg shells.

What do you think about it.

THanks.
 
Hello.

All the paphs must have a good supply of calcium or just a few?
And also, I'm thinking to use crushed egg shells.

What do you think about it.

THanks.

All plants (not just orchids) need calcium and magnesium.

Unless you are watering with RO, distilled or rain water, there is plenty of Ca and Mg in your regular drinking water.

Calcium and magnesium shortages in plants are caused by excess potassium. So the best way to promote healthy uptake of calcium is to reduce potassium to environmentally realistic levels. (Less than 5 ppm).
 
So Rick if I understand you correctly, you're are stating that a proper regular feeding amount of 5 ppm Potassium is important to reduce calcium and magnesium deficiancies when using distilled water, such as in my case?

Or is 5 ppm what you would suggest for all Paphs?
 
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I am curious to know how one decided the contents in Calcium and Magnesium in K-Lite fertilyser (same for MSU which as the same content for these two). At 65 ppm N for these two fertilysers we have a solution having a content of 15 and 50 ppm Ca and Mg respectively. Here in Belgium the AKERNE society sells a substitute for MSU (AKERNE RainMix) which gives respectively 40 and 9 ppm of Calcium and Magnesium at 65 ppm N. Discussing with the seller he said me that it is risky to use a hight concentration in these two elements because we can have an exaggerated leaves hardening and in the case of plants such as Masdevallias a difficulty for leaves to go out of their shield. This is the reason why they have decrease a little bit the content in Ca and Mg of the AKERNE RM. Your comments about this subject will be very appreciated.
Thank you in advance.
 
Calcium and magnesium shortages in plants are caused by excess potassium.

But if you are using a fertilizer without these 2 elements and rain water, then the shortage is due to lack of these elements not K. Also many plants (as discussed elsewhere) can take high K amounts without the Ca/Mg becomming deficient. Without going over the same ground again, as an example, my lowii, philippinese, roths etc are doing great with 'normal' K (about 0.5:1 K/N)
 
I am curious to know how one decided the contents in Calcium and Magnesium in K-Lite fertilyser (same for MSU which as the same content for these two). At 65 ppm N for these two fertilysers we have a solution having a content of 15 and 50 ppm Ca and Mg respectively. Here in Belgium the AKERNE society sells a substitute for MSU (AKERNE RainMix) which gives respectively 40 and 9 ppm of Calcium and Magnesium at 65 ppm N. Discussing with the seller he said me that it is risky to use a hight concentration in these two elements because we can have an exaggerated leaves hardening and in the case of plants such as Masdevallias a difficulty for leaves to go out of their shield. This is the reason why they have decrease a little bit the content in Ca and Mg of the AKERNE RM. Your comments about this subject will be very appreciated.
Thank you in advance.

The MSU and AKERNE formulations were based on leaf tissue analysis of plants exposed to "traditional agricultural usage levels" of K. Upon examination of these leaves (which is pretty much the same for the Cornell study done in the 1970's, and just about any agri study with food crop plants) the amount of Ca and Mg was reduced relative to N and K. Also as K exposure increases the Ca and Mg goes down. At what point you will experience acute symptoms of Ca and Mg "deficiency" symptoms will vary based on the tolerance of the plant. However, I have also suggested that a lot of sublethal effects (such as general slow growth, susceptibility to disease, and bud blast) can also be symptomatic of low tissue Ca and excess K.

Now if you pull leaves from jungle grown plants (not exposed to agriculture levels of K) you generally find that the amount of Ca is considerably higher than K and sometimes higher than N.

Ca is almost always more available in the environment than K.

I have pointed to a handful of successful growers that have never used supplemental feed using irrigation water with hardness in excess of 200ppm (as CaCO3).

With very elevated levels of Ca (especially as carbonates) there is a possibility of magnesium and phosphate deficiency. So if you run systems with lots of calcareous buffer you should probably be concerned with supporting a bit extra Mg and Phosphate (a bit more sulfate probably wouldn't hurt either).

I don't grow a lot of pleuros and masdes, but I have been getting some good results lately since reducing light in my pleuro box. I'm also about to get blooms on my first Masdevalia ever (an infracta). Leaf growth has been excellent. I would say that ratios aren't that important when the conductivity of the total feed mix is around 50 uS/cm.

I have been feeding at the rate of about 5ppm N with a hardness of ~ 25-35 ppm (as CaCO3). Phosphate about 5ppm, and K is probably less than 1ppm. The pleuros (genus Pleuro, Resptrepia, Masdevalia, Stellis) are doing good.
 
Also many plants (as discussed elsewhere) can take high K amounts without the Ca/Mg becomming deficient. Without going over the same ground again, as an example, my lowii, philippinese, roths etc are doing great with 'normal' K (about 0.5:1 K/N)

Especially if you flush the heck out of them with low K water between feedings to wash it all away:wink:
 
Especially if you flush the heck out of them with low K water between feedings to wash it all away:wink:

K is continually being released from the osmocote in the pots :poke:
But I admit I still try to keep the K from dominating the fert mix by adding dolomite and straight N occasionally (and/or blood and bone).
 

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