# Quick fertilizer Question - Magnesium and Calcium amounts



## silence882 (Oct 11, 2015)

Hi All,

I would like to get back to supplementing my fertilizer regimen with the occasional shot of magnesium sulfate and calcium nitrate. However, it's been so long since I did that that I've forgotten how much I used. I use R/O water and fertilize biweekly with K-lite (from Ray's) at 1/4 tsp/gallon.

Any recommendations on how much MgSO4 an CaNO3 to add?

Thanks,
--Stephen


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## Rick (Oct 11, 2015)

I wouldn't add any more calcium nitrate for sure.

The Ca Mg in K lite is already more than the old MSU fert. And the bulk of Ca is from calcium nitrate already.

If you add a dash of tap water to your mix that would give you more Ca, Mg, and sulfate to your mix. What's your water hardness?

Are you wanting to add stuff because of poor results or just for fun?

Have you tried playing with lemon juice? That has a little Ca, Mg and K, and a whole lot of citric and malic acid that the plants seem to like. Actually citric and malic acid are core organic constituents to a lot of plant activities, so this is just a boost to what's already in motion.


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## consettbay2003 (Oct 11, 2015)

How much lemon juice? Bottled or fresh lemon juice?


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## silence882 (Oct 11, 2015)

The leaves on some of my plants are too yellow and I can't seem to get them to green up. It doesn't seem to be affected by light levels or the media I use. It gets a bit better when I up the fertilizer regimen, but I don't wanna go too high on the K-lite. I remember having this problem a long while ago and it seemed like Mg supplementation helped. I just can't remember how much to add.

How much lemon juice do you use? I have never heard of that before.



Rick said:


> I wouldn't add any more calcium nitrate for sure.
> 
> The Ca Mg in K lite is already more than the old MSU fert. And the bulk of Ca is from calcium nitrate already.
> 
> ...


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## fibre (Oct 11, 2015)

I occasionally add Epsom Salt 0,3g/l to my tap water.


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## Rick (Oct 11, 2015)

I put together a Mg/PO4/SO4 supplement which is pretty close to the DynaGro Bloom boost Mag Pro stuff.

But the lemon juice is working better.

There is a thread started on "Citrate Test"

I'm using about 6 or so drops per gallon, but have gone up to a tablespoon per gal (definitely not recommended).

Please look up that thread in the culture section since I've linked a couple of good papers to it.


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## abax (Oct 11, 2015)

Does it matter if the lemon juice is fresh squeezed or the
concentrate in bottles at the supermarket?


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## gego (Oct 12, 2015)

silence882 said:


> Hi All,
> 
> I would like to get back to supplementing my fertilizer regimen with the occasional shot of magnesium sulfate and calcium nitrate. However, it's been so long since I did that that I've forgotten how much I used. I use R/O water and fertilize biweekly with K-lite (from Ray's) at 1/4 tsp/gallon.
> 
> ...



Hi Stephen,
I use RO and I also supplement Magnesium. I make a separate solution of 1/4 tsp Epsom salt/gal. Make sure you check your PH and should be between 6-6.5. I only apply it foliar. I don't trust the amount of sulfur on the roots. Effect is slow but I saw green coming out slowly. Hope that helps.


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## Rick (Oct 12, 2015)

OK 

A 1/4tsp of Epsom salts is probably close to a gram (1000 mg).

of which 9.74% is Mg.

So one gram of Epsom salt gives 97.4 mg / gram of salt.

into a gallon (3.785L) gives you 25.7 mg/L (ppm) of Mg.

This is about 4or more times higher than in many drinking waters.

Its not a scary - killer amount for infrequent spread out use, but frequent/ chronic use of Mg at greater than whatever your Calcium concentration is can cause problems.

So if you can do the math to determine final Ca concentrations then consider running the max Mg concentration to about equal the Ca. But avoid going > than the Ca concentration.


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## naoki (Oct 12, 2015)

I can confirm Rick's approximate value. There are variation in the size of measuring spoons, so here is my estimated values with 5 different spoons and 3 measurement each (total of 15 measurements). I used a linear regression to get the estimate:

1 tsp of Kroger Epsom Salt (Mg SO4 7 H2O):
ave. weight: 4.76g

1 tsp per gallon:
Mg: 124.1 ppm
S: 163.7 ppm


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## gego (Oct 12, 2015)

Yes about 25 ppm. Just enough to correct the deficiency and not to use forever. You still do your normal fertilizer regiment. 

I think if you have shells or lime already in the potting and use K-lite for fertilizer, the Cal/Mag ratio really goes up to the roof.


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## silence882 (Oct 12, 2015)

Thanks everyone!

Based on feedback I think I'll switch to alternating between K-lite and MSU. Also, I'll supplement with 1/4 tsp/gal of MGSO4 every 2-4 weeks.

If I check the pH of the water+fert and find it to be too acidic, what would you recommend I use to up the pH to 6-7? ProTekt?

--Stephen


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## naoki (Oct 12, 2015)

Stephen, if you really care about the pH, measuring the pH of pour-through would be a bit more relevant (or imformative) than the fertigation pH. It is not well understood, but good pH for soil-potted plants doesn't necessarily apply to epiphytes. For example, there are scientific papers mentioning that some phals are not affected by pour-through pH of 3-4.


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## Brabantia (Oct 13, 2015)

naoki said:


> Stephen, if you really care about the pH, measuring the pH of pour-through would be a bit more relevant (or imformative) than the fertigation pH. It is not well understood, but good pH for soil-potted plants doesn't necessarily apply to epiphytes. For example, there are scientific papers mentioning that some phals are not affected by pour-through pH of 3-4.


I agree with what you write, but ... For sure your pH will decrease to low values like pH5 to 4.5 if you are not adjusting the pH of your fertilyser solution. 
This because the pH around the rots is governed not only by the pH of the fertilyser solution but also by the water in contact with a decaying substrate .
In my fertilyser solution I add always 5 to 10% of tap water (we have here a very hard water 45°F = 450 mgr/L CaCO3) in order to buffer the roots environnement. 
Remark: all the mineral fertilysers which contains Calcium nitrate and Magnesium nitrate (or sulfate) have an acid reaction in RO or rain water because they are prepared from strong acids and weak bases. These two salts are the major constituents of MSU or KLite. In RO or rain water at .5gr/L we reach a pH of around 5.5.


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## gego (Oct 13, 2015)

Thank you Brabantia.

I'm new here but I thought these principles are well understood already. My comment was based on my experiences and what you stated on your remark is so true. pH is just not a number and if one applies its importance, I suggest one should get a good meter.


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## naoki (Oct 13, 2015)

Brabantia said:


> I agree with what you write, but ... For sure your pH will decrease to low values like pH5 to 4.5 if you are not adjusting the pH of your fertilyser solution.
> This because the pH around the rots is governed not only by the pH of the fertilyser solution but also by the water in contact with a decaying substrate .
> In my fertilyser solution I add always 5 to 10% of tap water (we have here a very hard water 45°F = 450 mgr/L CaCO3) in order to buffer the roots environnement.
> Remark: all the mineral fertilysers which contains Calcium nitrate and Magnesium nitrate (or sulfate) have an acid reaction in RO or rain water because they are prepared from strong acids and weak bases. These two salts are the major constituents of MSU or KLite. In RO or rain water at .5gr/L we reach a pH of around 5.5.



In theory, you are right; if the pH of fertigation water is lower, root zone pH should be lower. There is something I don't completely understand, but from my measurement, the pH of fertigation water doesn't influence too much about the pour-through pH (at least in short term). 

Here is the method I used. I water/fertilize normally, wait for 1 hour, pour 50ml of water and catch, then measure the pH and EC of pour-through. For the first stage, I've used just rain water (pH 6.64), K-Lite+Peter's (pH 4.87), or MSU+well (pH 6.4). Regardless of what I use at the first stage, the pour-through pH is 6.2-7 (I din't do statistics, though).

I'm guessing that this is because the fertilizer is pretty dilute (around 30ppm N or so), and the pH is dominated by the media (and possible long term accumulation of chemicals from fertilizer and root excretion in the media). As you mentioned, if I keep using low pH water for a long time, the pour-through might go down. But I've never adjusted pH of water, and the measurement is taken from paphs which has been in the same pots for 2-3 years.

I know you have been measuring pour-through, so I'm interested to hear what you think about this. It is somewhat mysterious to me that the pH of fertigation doesn't influence the pour-through much. In the study where they studied acidification of Sphagnum moss, there is influence, but their concentration of fertilizer was much higher.


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## Brabantia (Oct 13, 2015)

In order to well understood your observations I need to know the composition of the substrate you use. Do you add some dolomitic material or eggshell to these?
Just a remark and for info: It is very difficult to measure pH of solutions having low conductivity (like RO water or rain water) if you use low cost pH meter. You need meter and electrode having a very low internal resistance... very expensive.


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## gego (Oct 13, 2015)

Naoki,

I assume that we all agree that there's a range of pH that these nutrients can be easily available to plants. Right? If you don't then that's fine. 

We agree on efficiency of power supply and LEDs, I think the same principle works here. There's a certain pH that a nutrient can be available easily to plant. So a peak pH could mean 90% availability, a few points lower or higher than that could mean only 50% and may go down to 25%. On the other, the plant should also have the capability to take that nutrient. There's an exchange of energy going on here. If the exchange is not efficient, then what you feed for 30ppm N, 15 may be absorbed to your plant, the rest goes down the drain.
Well, you can tell I'm an engineer. But I really tried this concept to my vandas. The roots are just hanging, no media. The corrected pH of fertilizer solution made a huge difference. I say huge. Leaves doubled in size, spikes increase from one to three spikes. What else can I say.


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## Happypaphy7 (Oct 13, 2015)

gego said:


> Naoki,
> 
> I assume that we all agree that there's a range of pH that these nutrients can be easily available to plants. Right? If you don't then that's fine.
> 
> ...



It is true that there is a range of pH where different elements are available to plant roots at different degree. If you google up, there is a nice table.

With regard to your vanda results, I am happy that your plants are doing well, but when I see something like this said, I am worried that it will mislead some people.

Without control group and without sufficient sample size, you can't even say for sure that the results you see on your vandas is due to the change you made to your fertilizer solutions. I'm not saying it is not, but you see my point.

As plants get older, they often get larger and produce more flowers. This is a general trend for many plants, unless your vandas are already 20 years old and it never really did well the whole time, but all of sudden, you made this change, and they responded, all of them. Then, that's much safer to say that it was caused by the fertilizer change.


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## naoki (Oct 13, 2015)

Brabantia, most of them are fir bark dominated media. Some with a little bit of moss, some with a little bit of diatomaceous earth, a few were 100% dead sphag with cyanobacteria growing on the surface. Some of them were CHC. Some of them would have sprinkled with a bit of granular dolomitic lime on the top. I expected that the different media would make a bigger contribution to pour-through, but due to small samples of non-bark media, I can't quite say.

Yes, I'm aware of the issue with pH electrodes for pure water. Mine is a normal lab-grade pH electrodes from Fisher Scientific, so it is not stable with pure water. But with pour through there were enough ions.

gego, yes, pH would influence the nutrient retention in the media and uptake. For example, it is well known that pH can influence NO3:NH4 uptake ratio. When roots uptake NO3-, the enzyme also need to transport H+ into the root. So NO3 is difficult to absorb if H+ isn't around the root (high pH). The opposite occurs with NH4; uptake of NH4+ becomes more difficult with lower pH. So in the case of your Vanda, some adjustment could have influenced nutrient uptake (e.g if your N source is using only NO3 etc).

But my point is what would be the best compromise for rhizosphere pH of epiphytes? As Ray frequently says, the pH of 6.5 or so suggested for crop plants are unlikely to be best for epiphytes. First, the media we use don't have high CEC like soils. Second, Yen et al (2011) paper which studied the sphag acidification indirectly points a possibility that epiphyte roots could be different from crop plants. Phals seems to excrete quite a bit of chemicals to lower pH (Paph roots are probably quite different from Phals, too). Here is the quote of their concluding remark from their paper:

"The results of this study show that the roots of Phalaenopsis may be the main cause of substrate acidification, which may have something to do with how originally the epiphytic roots absorb mineral nutrients in their natural habitat. Growth of Phalaenopsis is normal in a substrate with low pH; therefore, raising substrate pH may not be needed in the production of Phalaenopsis."


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## gego (Oct 13, 2015)

Happypaphy7 said:


> It is true that there is a range of pH where different elements are available to plant roots at different degree. If you google up, there is a nice table.
> 
> With regard to your vanda results, I am happy that your plants are doing well, but when I see something like this said, I am worried that it will mislead some people.
> 
> ...



These are fairly old vandas, some of them have flowered three times already. One is about 2 feet tall. One thing my 20 years experience of growing vanda is that I know when they respond to something. The roots and the new leaf will tell you pretty fast. You will see leaves before I got them, long and thin. Stem in between leaves are short. I know my vandas very well, and I've grown them in the tropics where it was natural for them. We knew back then it was the water, so we started collecting rain. And we did not fully understand why but the rain water was not the answer. Until one of us growers stumbled into using urea with tap water. You have to understand how much junk we have in the water system there. Oh this is in the Phils, 25 years ago. There was no control of how much impurities the tap water has. In my area there, we the growers knew we have so much lime in the water. I never understood why urea worked than anything else. It wasn't the best result but way better. And then I read this article about MSU. And oh yes, the switch was turned on.

Until I learned here about the pH of the solution. One year using MSU RO and the same plants were so so. Just about six months after I started correcting my pH and yes I bought an expensive pH. Two vandas flowered three spikes, one had 33 flowers and one still in flower has 27. An asco that will only give me one spike at a time, now it has two. Leaves are getting wider and wider and firm, big roots lots of them. I have one that is in spike right now and at the same time producing three keikes. And this is a young plant, first flower. I know I could have not achieve this using my old culture.
Again, I know the clones of the plant I'm talking about, I use to grow them before.

Well, I know other conditions have to be met, humidity, water and air movement. But those inputs were not changed.

What I did was to confirm/test the available knowledge we have here. And I'm a believer. 
Please don't just believe me. Check it for yourself. You have nothing to lose, really. Just check the pH of your fertilizer, adjust it to the right range and check for yourself. It's not hard. Either you use tap water to correct or some acid you can buy. And by the way, I just read this info from one of the guys who developed MSU. It is very clear, it is how you match your fertilizer to your source of water correctly and adjust the pH accordingly.

I'm not preaching a new sermon.

Thanks for reading.


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## Stone (Oct 13, 2015)

gego said:


> > I assume that we all agree that there's a range of pH that these nutrients can be easily available to plants. Right?
> 
> 
> 
> ...


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## Happypaphy7 (Oct 13, 2015)

Good read and great point.
Thanks, Mike.


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## gego (Oct 14, 2015)

"When growth medium pH drops below 4.5, analysis should be
done to be sure deficiency of calcium or magnesium does not occur.
Likewise, when pH climbs above 5.5 to 5.7, something basic
is accumulating and should be identified. Source of the responsible
element (s) (Ca, Mg, or Na) should be located. However, once
the optimum calcium level is determined for a particular growth
medium and irrigation water source you can set the pH meter on
the shelf."

Thank you Mike. This is just validating my thinking about some of my paph plants having magnesium deficiency.

This really means knowing the pH is the easiest way for us hobbyist to know the balance. And if you make sure that what you add to the system will not make it more acidic nor basic, that micros will be always be available to the plants.

This is not really far from what Bill Argo wrote. pH reading is a condition,a symptom that a system is not balance.


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## naoki (Oct 14, 2015)

Thanks, Mike. It is interesting to think about.

I don't quite follow/understand the chemistry there. I wonder what kind of insoluble precipitate between Ca and other "micro" nutrients he is talking about. Only anion micro is B, Mo, and Cl. And CaCl2 is soluble. So does anyone know B and Mo binds to Ca to produce insoluble precipitate? I know Ca SO4 precipitates, but S is not a micro.

For Mike's hypothesis about citrate, it depends on whether calcium citrate has a stronger bind than Ca + B or Mo, right? According to this wikipedia, Calcium citrate does precipitate, so the removal of Ca by citrate does seem to work as you suggested.


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## Stone (Oct 14, 2015)

naoki said:


> > I don't quite follow/understand the chemistry there. I wonder what kind of insoluble precipitate between Ca and other "micro" nutrients he is talking about.
> 
> 
> I was wondering that too. I think both Cal borate and Cal molybdate are not very soluble. What we need is a chemist here. He also talks about other alkali such as Na, K and the carbonates. Do metal cations form carbonates? are they soluble? does Ca crowd out things like Fe and Zn etc with its stronger charge? Hell I don't know  But he did achieve similar greening with both pH 4 and pH 10 (with low Ca)


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## consettbay2003 (Oct 14, 2015)

A ph reading is not 'a condition, a symptom that a system is not in balance'. It's just a ph reading. 

This is not really far from what Bill Argo wrote. pH reading is a condition,a symptom that a system is not balance.[/QUOTE]


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## Brabantia (Oct 14, 2015)

It is here a good papier about the interaction between water_fertlyser_substrate:
http://staugorchidsociety.org/PDF/ChoosingYourFertilizerBasedonYourWaterQualitybySueBottom.pdf


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## gego (Oct 14, 2015)

consettbay2003 said:


> A ph reading is not 'a condition, a symptom that a system is not in balance'. It's just a ph reading.
> 
> This is not really far from what Bill Argo wrote. pH reading is a condition,a symptom that a system is not balance.


[/QUOTE]

Thank you for the correction. My engineering mind tells me this is something I can measure to know something, more so because it correlates to positive and negative charges. It doesn't tell me everything but adding EC and TDS to the picture kind of for me completes the picture. I just find this very useful because in my experience it is. Gives me basis on my decisions and takes away the guessing part of it. I saw good results and that is good for me.
If there is another way to know and measure what were actually absorbed by the plants, I'm all ears. I hope it's not too expensive.


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## Ray (Oct 14, 2015)

Happypaphy7 said:


> It is true that there is a range of pH where different elements are available to plant roots at different degree. If you google up, there is a nice table.


Yes, there is a nice table that shows the results of *a single test* of *a single fertilizer* pouring through *a single sample of unspecified SOIL*.

Soils have a far greater cation exchange capacity than does any orchid medium, and that graph describes which ions are trapped by the soil (hence unavailable for absorption by the plant) at specific pH values. It says absolutely nothing about the plant's ability to take it up at a specific pH.

If the ion is in solution - at any pH we'd expose our plants to - it can be absorbed. (I am discounting the likelihood that they will form huge, insoluble-, or "unabsorbable" complexes in the concentrations we apply, but even if they did form, that is making it unavailable to the plant - i.e., removing it - not having any effect on the plant's uptake abilities.)


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## gego (Oct 14, 2015)

Ray said:


> Yes, there is a nice table that shows the results of *a single test* of *a single fertilizer* pouring through *a single sample of unspecified SOIL*.
> 
> Soils have a far greater cation exchange capacity than does any orchid medium, and that graph describes which ions are trapped by the soil (hence unavailable for absorption by the plant) at specific pH values. It says absolutely nothing about the plant's ability to take it up at a specific pH.
> 
> If the ion is in solution - at any pH we'd expose our plants to - it can be absorbed. (I am discounting the likelihood that they will form huge, insoluble-, or "unabsorbable" complexes in the concentrations we apply, but even if they did form, that is making it unavailable to the plant - i.e., removing it - not having any effect on the plant's uptake abilities.)



Thank you Ray. It seems like these PhD's are all over the place about this subject or maybe we are all. I kind of understand the unavailability to plants and the plant's uptake abilities part of the discussion.

One thing I have proven to myself though, that by just adjusting the pH of my fertilizer solution (all the time, I was using MSU RO, I got from you), before and after results were very dramatic. I wish I can say something I did differently or something I came up with. But no, I just adjusted the pH as what was intended in the first place.


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## gego (Oct 14, 2015)

naoki said:


> Brabantia, most of them are fir bark dominated media. Some with a little bit of moss, some with a little bit of diatomaceous earth, a few were 100% dead sphag with cyanobacteria growing on the surface. Some of them were CHC. Some of them would have sprinkled with a bit of granular dolomitic lime on the top. I expected that the different media would make a bigger contribution to pour-through, but due to small samples of non-bark media, I can't quite say.
> 
> Yes, I'm aware of the issue with pH electrodes for pure water. Mine is a normal lab-grade pH electrodes from Fisher Scientific, so it is not stable with pure water. But with pour through there were enough ions.
> 
> ...



Thank you Naoki, yes that's what I have learned from reading. The change was very dramatic to my Vandas. I am doing my experiment right now, by any means not very scientific, but I could definitely tell if my plants are getting better, so I'm just going to use my eyes to gage. I have about 10 paphs right now of varying sizes and species on orchiata barks and maybe more than ten in S/H. Yes, I'm only using nitrite for N. I'm using 75 ppm of MSU RO. Some plants on bark have eggshells and probably some dolomite too. So I added some eggshells also on the S/H plants. In a brief period, I can see slight yellowing of the older leaves on S/H but not on barks. I'm on my fourth month now and I have a gut feeling the yellowing is due to Mag deficiency. When I started this, I was using tap water to adjust my pH. My line of thought is that I might have caused the Ca/Mg ratio too high that it caused Mg deficiency. So I reverted back to a base solution pH adjuster.
Then I added foliar sprays of the Epsom salt I mentioned above to the S/H plants with yellowing leaves. Slowly I could see greening on the older leaves, the greening seems to start at the tip of the leaves or at the edge. Very interesting. I find this very fascinating. I stopped the foliar feed and just add about 12 ppm of Mg to my fertilizer solution. And the greening to a few plants happens on one leaf then next. Very exciting for me as I watch this slowly changing.

There could be more scientific reasons that you guys can describe what really happened here but for me it's all about pH adjustment.

Talking about Phals, don't know what kind of Phals they use in the study but I can say this, most butterfly type species used for breeding came from the Phils. They are very easy to grow and they are mostly grown in gardens, on tree branches, on charcoal, moss or fern bark. You can see them planted on a whole coconut husks with out even cleaning the husk. They add eggshells on top of it, pour diluted urine and some would pour water use to rinse rice before cooking. Water them with tap water that has so much minerals in it mostly lime. pH probably up more than 9. They seem to grow like weeds. Since they are very common, people tend to ignore them. I had a hard time growing Vandas than Phals. I didn't actually grew them but my mother had a good collection.


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## Stone (Oct 14, 2015)

With some small paphs in particular I often find it a bit of a pain trying to get good colour in the leaves. It's probably due to a poor root system. Larger plants seem to get by with next to nothing. I haven't fed the larger ones yet this season and we're into the second month of spring and they look fine. 
But anyway rather than worrying too much about the trace elements in the fertilizer and whether they are actually being absorbed, I have started foliar spraying once per month with this product. It was designed for Citrus and as some of you might know, getting good leaf colour in Citrus plants can be extremely difficult sometimes.

I'm using it at one quarter strength.




It also has a ''sticker'' so it's water fast in 2 hours. A good product I think.





They also have one for Mn and Zn fans.


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## silence882 (Oct 14, 2015)

Guys guys guys - I said a _quick _fertilizer question...


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## Bjorn (Oct 15, 2015)

Like to add my twocents; I have been using citric acid for some years now, and the reason for me to use it is as a chelating agent. Citric acid forms chelates which render else insolubles in solution. The citrate complex is weakly bound (as compared to the more common EDTA) which probably makes the micros easier obtainable for the plants. In my own fertiliser mix, I have reduced the iron while increased the manganese, zinc and boron and use citric acid to prevent precipitation of insoluble iron. Been using it all 2015, and leaf color is exactly what I want it to be- that is not too dark nor too yellow; more like grass.


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## fibre (Oct 15, 2015)

silence882 said:


> Guys guys guys - I said a _quick _fertilizer question...



just my thoughts


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## gego (Oct 15, 2015)

Bjorn said:


> Like to add my twocents; I have been using citric acid for some years now, and the reason for me to use it is as a chelating agent. Citric acid forms chelates which render else insolubles in solution. The citrate complex is weakly bound (as compared to the more common EDTA) which probably makes the micros easier obtainable for the plants. In my own fertiliser mix, I have reduced the iron while increased the manganese, zinc and boron and use citric acid to prevent precipitation of insoluble iron. Been using it all 2015, and leaf color is exactly what I want it to be- that is not too dark nor too yellow; more like grass.



Good input Bjorn, so any suggestion on the amount of citric acid to add say per gallon of fertilizer solution?

More than the flower, I like my plants green.


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## gego (Oct 16, 2015)

Stone said:


> With some small paphs in particular I often find it a bit of a pain trying to get good colour in the leaves. It's probably due to a poor root system. Larger plants seem to get by with next to nothing. I haven't fed the larger ones yet this season and we're into the second month of spring and they look fine.
> But anyway rather than worrying too much about the trace elements in the fertilizer and whether they are actually being absorbed, I have started foliar spraying once per month with this product. It was designed for Citrus and as some of you might know, getting good leaf colour in Citrus plants can be extremely difficult sometimes.
> 
> I'm using it at one quarter strength.
> ...



Hi Mike, where can we get this?
Thanks


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## gonewild (Oct 16, 2015)

silence882 said:


> Guys guys guys - I said a _quick _fertilizer question...



You did ask a quick question but you did not ask for a quick answer.


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## gonewild (Oct 16, 2015)

gego said:


> Good input Bjorn, so any suggestion on the amount of citric acid to add say per gallon of fertilizer solution?
> 
> More than the flower, I like my plants green.



Yes Bjorn how much Citric acid do you add?


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## Bjorn (Oct 16, 2015)

Its fairly much, normally what is necessary to bring the pH of the water with fertiliser (at 50-60ppm) Down to pH5.5 or so. But cannot really say HOW much. Sorry for that. The fertiliser solution itself (10% remember I make it myself) approaches a pH of around 3.5 which is close to the lowest pH attainable with citric acid.


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## phraggy (Oct 16, 2015)

silence882 said:


> Hi All,
> 
> I would like to get back to supplementing my fertilizer regimen with the occasional shot of magnesium sulfate and calcium nitrate. However, it's been so long since I did that that I've forgotten how much I used. I use R/O water and fertilize biweekly with K-lite (from Ray's) at 1/4 tsp/gallon.
> 
> ...



Calcium nitrate and Magnesium sulphate are not compatable and will precipitate if mixed together. Always mix them seperately before adding together.

Ed


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## gego (Oct 16, 2015)

Bjorn said:


> Its fairly much, normally what is necessary to bring the pH of the water with fertiliser (at 50-60ppm) Down to pH5.5 or so. But cannot really say HOW much. Sorry for that. The fertiliser solution itself (10% remember I make it myself) approaches a pH of around 3.5 which is close to the lowest pH attainable with citric acid.



Thanks again.

So your target is around 5.5pH? Do you use this on barks? Organic media or both organic and in-organic?


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## Happypaphy7 (Oct 16, 2015)

So, according to that article, adding lime stone and other similar stuff in the potting mix will worsen the conditions where micronutrients are not readily available to the plants??

Does leaching do any good I wonder??
The Ca ion that tightly bond with certain potting mix ingredients and other elements, do they ever leach out or not??

Now I'm rather puzzled about the purpose of leaching then if the leaching does not get any leaching done? 





Stone said:


> gego said:
> 
> 
> > I wonder if the results Rick is seeing from citric acid is it's bonding with Ca forming insoluble citrate and making micros more available?
> ...


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## gonewild (Oct 16, 2015)

Happypaphy7 said:


> Now I'm rather puzzled about the purpose of leaching then if the leaching does not get any leaching done?



Irrigate to "leach' out harmful soluble salts like Sodium and other chlorides.


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## gego (Oct 16, 2015)

So tap water with high pH with all the minerals will not be effective, RO or Rain with low pH maybe better but RO/rain with citric acid will do it. I use this solution to remove salt deposits on my vanda leaves. But never thought using it to leach.
I have plants on S/H and I can see deposits on the media. I may have to select a guinea pig.


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## Rick (Oct 16, 2015)

naoki said:


> gego, yes, pH would influence the nutrient retention in the media and uptake. For example, it is well known that pH can influence NO3:NH4 uptake ratio. When roots uptake NO3-, the enzyme also need to transport H+ into the root. So NO3 is difficult to absorb if H+ isn't around the root (high pH).



The sweet spot for NO3 uptake seems to be around 5.8s.u. I really wouldn't call that "high pH).

It's really not the plant having problems picking up NO3 at high pH, but having a feedback loop from the nitrate reductase system overloading the roots with OH- , and not being able to expel the hydroxide from the plant without an acid sink. 

This is where the citratic and malic acid comes in.

The organic acids have a second level duty to keep the rhyzosphere pH around 5.8 to increase Fe and phosphate uptake.

(phosphate is difficult for plants to extract from calcareous environments when the pH is >6.0).


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## Rick (Oct 16, 2015)

Stone said:


> gego said:
> 
> 
> > I wonder if the results Rick is seeing from citric acid is it's bonding with Ca forming insoluble citrate and making micros more available?
> ...


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## Rick (Oct 16, 2015)

http://www.researchgate.net/publica...s_calcifuge_and_acidifuge_behaviour_of_plants

This one is pretty cool Mike

With the exception of lactate the calcareous species kick butt on siliceous species for organic acid production.

That in its self is kind of interesting in we use lactate to promote certain types of microbial growth to erode silicaceous materials.


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## gego (Oct 17, 2015)

Thank you Rick, very interesting. Cool stuff. I like reading about this subject.


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## Rick (Oct 17, 2015)

gego said:


> Thank you Rick, very interesting. Cool stuff. I like reading about this subject.




Your Welcome.

It looks like there's a lot of work in this area and I won't be able to post all the links.

What I end up doing after finding one good paper is go to the references and start googling them up. Often you can't get the whole paper for free, but if the abstract looks promising it might be worth the investment or subscribe to a certain research site. I just noted something weird searching for the paper in my next post. Using my internet from work and key words from the title brings up the article from the free ResearchGate site automatically. Trying the same search from my home service yields only pay versions. If I include ResearchGate into my search engine then it brings up the result (that I ultimately posted). So not sure why my google engine from work brings up different stuff from my google engine on my home line.

The more stuff I come across generally indicates that plants have amazing abilities or relationships to regulate the environment they grow in (rather than passive existence). And when we throw them chemical conditions not likely observed in nature we end up creating antagonistic systems to compensate for.


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## Rick (Oct 17, 2015)

http://www.researchgate.net/publica...Implications_for_rhizosphere_nutrient_cycling


This one compliments/expands Mikes paper pretty nice.


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## NYEric (Oct 19, 2015)

Chem. Nerds! :evil:


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## Stone (Oct 19, 2015)

Rick said:


> http://www.researchgate.net/publica...Implications_for_rhizosphere_nutrient_cycling
> 
> 
> This one compliments/expands Mikes paper pretty nice.



Interesting. However does it just mean that in a slightly alkaline pot environment with a bellatulum will be modified by the plant and we don't really need to do anything? Or do we need to add the organic acids to help it fuction or get it kick started if it is languishing?


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## Stone (Oct 19, 2015)

gego said:


> Hi Mike, where can we get this?
> Thanks



Try to find a similar product over there. Start with the Citrus people. If you have trouble let me know.


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