# Komplex or free ions????



## dodidoki (Jan 30, 2013)

I'd like to interest, what is better for plants: EDTA komplex celated formulas or free ions in relation of MG2+, Fe2+ and micros?


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## Rick (Jan 30, 2013)

With regard to Mg, I don't think it matters to the plants at all.

Free Mg ion is generally present at multiple ppms in normal surface waters, and Epsom salt (Mg SO4) is readily soluble and cheap if you wanted to add it to RO water.

Plants need a little sulfate too, so I don't see a benifit to using chelated Mg.

Fe can go to insoluble oxides fairly easily, so chelated iron tends to be more bioavailble to the plant over time.


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## DavidCampen (Feb 1, 2013)

*EDTA too strong.*

I compound my own nutrient formulations. I use aspartic acid (in the form of ammonium aspartate) instead of EDTA as the chelating agent in my formulations. It is my opinion that EDTA is too strong of a chelating agent, the plants are likely to not be able to extract the essential element from the EDTA complex. Aspartic acid is a weaker chelating agent than EDTA but is still strong enough to keep the chelated elements in solution. 

EDTA is, after all, what is used in medicine to _remove_ excess metallics from organisms. EDTA may be warranted in fertilizer formulations that are being applied to crops grown if fields of dirt but not for orchids. 

I use a fairly large amount of ammonium aspartate with the intent of also chelating the calcium and magnesium so that I can get adequate amounts of phosphate, sulfate and borate in my formulations without those anions precipitating as insoluble calcium and magnesium salts. I use ammonium aspartate at the rate of about 0.2 grams per liter of ready-to-use nutrient solution and apply nutrient solution each time I water.

As an added bonus to using ammonium aspartate, it seems that it also causes thickening and branching of the roots similar to what people report from the use of kelp extract supplements.

As a caveat, I grow mostly laeliinae and catasetinae.


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## Ray (Feb 1, 2013)

DavidCampen said:


> EDTA is, after all, what is used in medicine to _remove_ excess metallics from organisms.



That is true, but I believe this is a common, but false extension of the technology. Chelation therapy is intended to take metals that are already precipitated and accumulated in the body, and make them more soluble so the body may excrete the solutions. It says absolutely nothing about the availability of metal ions to plants.

I don't recal the reference, but I have read that EDTA solublized ions have been proven to be taken up by plants when they are the only known source of the metals.


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## Rick (Feb 1, 2013)

We do a lot of toxicity tests with unicellular algae.

There is a differential in the EPA protocols when metals are suspected as a toxiciant (copper for instance is a potent algicide) for the amount of edta that can be used in the basic nutrient broth for the algae.

So its apparent that the algeae can pick up micro metals with and without the metals being chelated. But the non chelated solutions have to be made up fresh and used quickly. In some ways the EDTA is really acting more like a preservative or solution stabilizer in this case.

Also the effective copper (or nickel, cadmium, cobalt...whatever the toxicant of concern is) dose that causes toxicity is increased dramatically in the presence of EDTA. So it does reduce the bioavailability of the metal to the metabolism of the algae.

This is a subject of great complexity. There are certainly differences in chelating binding strenght of different organic compounds. Humic substance also chelate metals. Also differnt metals bind with different strenghts to EDTA. Iron and aluminum are relatively weak binders to EDTA compared to copper and nickel.


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## SlipperFan (Feb 1, 2013)

Welcome to Slippertalk, David. Please tell us a little about yourself in the Greetings and Salutations section.


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## Ozpaph (Feb 1, 2013)

SlipperFan said:


> Welcome to Slippertalk, David. Please tell us a little about yourself in the Greetings and Salutations section.



Please do David. You sound like you do some interesting things.


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## DavidCampen (Feb 2, 2013)

Ray said:


> I don't recal the reference, but I have read that EDTA solublized ions have been proven to be taken up by plants when they are the only known source of the metals.


Oh certainly, if the plant is desperate for the ion and the only source is an EDTA chelate then it will find a way to extract the ion.

Aspartic acid also chelates the same minerals as EDTA but the stability constants are not as great as the EDTA chelates. 

So what are you saying? Is it your opinion that the stability of the EDTA chelates make them a superior source of essential ions compared to aspartic acid chelates?

It is my opinion that the EDTA chelates may be superior when the nutrients are being applied to soil, to help prevent the essential ions from being lost by binding to the soil; but when growing orchids, especially the epiphytic orchids that I grow, and even more so in semi-hydro, there is much less to compete for the binding of the essential ions and so aspartic acid chelates should be superior. Additionally, orchids can utilize aspartic acid as a nitrogen source while it is likely that they have to dispose of EDTA unchanged as nothing more than a burdensome and useless waste.


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## DavidCampen (Feb 2, 2013)

Ray said:


> That is true, but I believe this is a common, but false extension of the technology. Chelation therapy is intended to take metals that are already precipitated and accumulated in the body, and make them more soluble so the body may excrete the solutions. It says absolutely nothing about the availability of metal ions to plants.



Yes, I should not have made that comment as my argument stands without it.


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## Brabantia (Feb 2, 2013)

If I remembers me well, Roth ( Xavier) had written that he used some citric acid as chelating agent. One of met problem when we use EDTA ( Na2EDTA) to prepare a solution of chelated metal is that it is necessary to adjust the pH around 5.5-6. We use completely logically some Potassium hydroxide what still adds some potassium ions to those brought by the fertilizer.The quantity of potassium hydroxide added is not unimportant because we use a mole / mole ratio Na2EDTA/metal. Remarke: In order to chelate Iron it is made use more often at present of the less expensive EDDHMA than the EDTA and more stable in wider pH range. 
Curious to read the Xavier's preparation for chelated metals using citric acid and his experience and opinion about this.


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## Ray (Feb 2, 2013)

DavidCampen said:


> So what are you saying? Is it your opinion that the stability of the EDTA chelates make them a superior source of essential ions compared to aspartic acid chelates?
> .


You need not be confrontational, David. My opinion is that the application of chelating agents is different in fertilizers than it is in human medical therapies, and that in fertilizers, the choice of agents is not crucial.


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## Rick (Feb 2, 2013)

DavidCampen said:


> I compound my own nutrient formulations. I use aspartic acid (in the form of ammonium aspartate) instead of EDTA as the chelating agent in my formulations.



Do you add enough aspartic acid to chelate all your metals (including Ca and Mg) or just the micros?

Typical feeding formulations just use some chelated forms of the micros, which are a very small percentage of the total formulation, and subsequently (INHO) insignificant with regards to the pot biology. But more important as a means of preserving material integrity of the stored bulk material.

But if chelators are used for the major metals as well, then the selection of form is much more significant. Factors such as supplying a second source of nitrogen, and binding coefficients will be important to the biology of the system.

As noted earlier there are some parallels in kelp extracts with aspartic acid.


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## DavidCampen (Feb 2, 2013)

DavidCampen said:


> So what are you saying? Is it your opinion that the stability of the EDTA chelates make them a superior source of essential ions compared to aspartic acid chelates?





Ray said:


> You need not be confrontational, David. My opinion is that the application of chelating agents is different in fertilizers than it is in human medical therapies, and that in fertilizers, the choice of agents is not crucial.



My Goodness, simply asking you to clearly state your opinion is confrontational?

Sure, in plant nutrient formulations the choice of chelating agent is not _critical_, just as adding kelp extracts is not critical. The plants are not going to die because you use EDTA instead of aspartic acid just as the plants are not going to die if you do not use kelp extract supplements. Still, I think there may be some benefit to the deliberate choice of chelating agent just as there may be some benefit to the use of kelp extract supplements.

And actually, in the nutrient formulations that I am compounding I think that there is a significant reason for the deliberate and carefull choice of chelating agent. I am preparing liquid nutrient concentrates with large proportions of calcium and magnesium while also maintaining the typical concentrations of phosphate and increased amounts of sulfate. To make this possible with a reasonable pH, I am using enough aspartate to chelate 1/2 of the calcium and magnesium. I would not want to use such large amounts of EDTA as its high affinity for iron and copper etc. might create deficiencies of those elements.

If I were to add a 2nd chemical metering pump to my system so that I could use a 2 component nutrient system where the phosphate and sulfate (and borate and molybdate) could be kept separate from the calcium, magnesium, iron etc. until the moment they were diluted to the ready-to-use concentration then I would not need to be so concerned about the formation of phosphate (and sulfate and borate and molybdate) precipitates. And I had considered purchasing a 2nd chemical pump but the aspartic acid chelate method seemed interesting and was less expensive. As a result of having tried this approach of using aspartic acid in large quantities I have also discovered that the aspartic acid seems to cause substantial root growth with root thickening and branching in the same manner as I have seen described from the use of kelp extract additives.


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## DavidCampen (Feb 2, 2013)

Rick said:


> Do you add enough aspartic acid to chelate all your metals (including Ca and Mg) or just the micros?
> 
> Typical feeding formulations just use some chelated forms of the micros, which are a very small percentage of the total formulation, and subsequently (INHO) insignificant with regards to the pot biology. But more important as a means of preserving material integrity of the stored bulk material.
> 
> ...



Yes, exactly, I am using enough aspartate to chelate a substantial amount of calcium and magnesium and so all the considerations that you mentioned are important.


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## Rick (Feb 2, 2013)

DavidCampen said:


> Yes, exactly, I am using enough aspartate to chelate a substantial amount of calcium and magnesium and so all the considerations that you mentioned are important.



Cool, So what is the final N and ratio of ammonia to nitrate in your system?

Do you have it designed for a specific alkalinity level?


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## DavidCampen (Feb 3, 2013)

*My most recent formulation.*

I am not familiar with the term "alkalinity" but here is my most recent formulation:

50 g Calcium Ammonium Nitrate
25 g Magnesium Nitrate
10 g Potassium Nitrate
20 g Potassium Dihydrogen Phosphate
25 g Ammonium Aspartate
2 g Ammonium Sulfate
3 g Diammonium Citrate
plus minor elements
diluted to 2 liters with RO water and then metered into my watering wand feed at a ratio of 1:100 with RO water.

This gives an N-P-K-Ca-Mg-S ratio of 14.6-10.4-11.4-9.5-2.4-0.5 with a nitrate/ammonia ratio of 4.3/1. I include the ammonia from the ammonium aspartate in the Nitrogen total but not the aspartic acid amino nitrogen.

The diammonium citrate is to adjust pH. It is still more acidic than I would like, 5.0 to 5.5. In my next batch I will add perhaps 0.5 g of potassium acetate to raise the pH. I would like to be able to raise the pH to 6 without any precipitates forming in the concentrate. If I can do that then next I will increase the amount of sulfate.

Since the formulation includes a bioavailable source of carbon from the aspartic acid, it readily supports microbial growth. So I filter the concentrate solution through a sub-micron filter, made for hikers to use to purify drinking water, into an aseptic container that is then connected to the intake of my chemical metering pump.


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## Ray (Feb 3, 2013)

Sorry about the misunderstanding, David. I interpreted the tone of your response to be a bit defensive-turned-aggressive. 

It's very interesting work you're doing there, and I can now see where you're coming from on the choices of specific chemical entities.


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## Rick (Feb 3, 2013)

DavidCampen said:


> I am not familiar with the term "alkalinity" but here is my most recent formulation:
> 
> This gives an N-P-K-Ca-Mg-S ratio of 14.6-10.4-11.4-9.5-2.4-0.5 with a nitrate/ammonia ratio of 4.3/1. I include the ammonia from the ammonium aspartate in the Nitrogen total but not the aspartic acid amino nitrogen.
> 
> .



Interesting. There is no bicarbonate in this system at all (unless you have pot supplements). So why the high percent of ammonia?


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## Rick (Feb 3, 2013)

DavidCampen said:


> diluted to 2 liters with RO water and then metered into my watering wand feed at a ratio of 1:100 with RO water.



What is the concentration of N at the wand, and what is your frequency of watering?

I can see this working for species that are deciduous and have fast seasonal growth spurts.

The "ant associates" seem to handle higher K levels than Ca


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## DavidCampen (Feb 3, 2013)

This ratio is also the number of grams of each component in 2 liters of concentrate:
N-P-K-Ca-Mg-S ratio of 14.6-10.4-11.4-9.5-2.4-0.5 

ppm is milligrams/liter

So at the wand I have 14.6 grams of nitrogen in 200 liters = 
14600 mg/200 liters = 73 mg/liter = 73 ppm.

Converting everything to ppm at the watering wand and also giving values for the minor elements, I have:

73 ppm Nitrogen
52 ppm P2O5
57 ppm K2O
48 ppm Ca
12 ppm Mg
2.5 ppm S
0.9 ppm Fe
0.45 ppm Cu
0.45 ppm Mn
0.45 ppm Zn
0.18 ppm B
0.5 ppm NaCl
0.01 ppm Mo
0.01 ppm Co

I plan to increase the amount of sulfur 4 fold, double the amount of iron and halve the amount of copper.


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## Rick (Feb 3, 2013)

Are you going to use some mix of calcium and magnesium sulfate to pick up the S?

Is this a hydroponic tank mix, or do you apply intermittently?


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## DavidCampen (Feb 4, 2013)

This is what I use every time I water. I do not grow hydroponically. I grow in fir bark, spaghnum or some mixture thereof depending on the plant. For plants that call for bark then for pots over 4" diameter, for improved drainage, the bottom of the pot will have a small inverted plastic mesh pot with hydroton (now hydrocorn) around the periphery. My watering wand was taken from a pesticide sprayer, the water comes from my pressurized RO tank and goes through a chemical injection pump (Dosmatic brand) where the nutrient concentrate is added.

I would probably use ammonium sulfate to increase the sulfur, in part because I already have a stock solution of this. When I prepare a batch of nutrient concentrate I don't work with dry materials but use stock solutions. Calcium ammonium nitrate and magnesium nitrate stock solutions contain 400 grams/liter, potassium dihydrogen phosphate solution is 100 g/liter, all the others are somewhere in between except for the minor elements which are much more dilute.


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## myxodex (Feb 10, 2013)

Very interesting thread. I really like the idea behind this approach; better uptake = lower nutrient concentrations needed, which chimes with what I'm getting from all the fert threads here. I do have a little concern about aa's causing excess bacterial growth. I came across this US patent that some of you might find interesting that fits nicely with David's use of both aspartate and citric acid http://www.google.com/patents?id=wysgAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false
Unfortunately it's annoying full of legalese and the experiments don't answer questions I have (e.g. no comparison with EDTA or EDDTA).
Anyhow thanks for posting.


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## DavidCampen (Feb 10, 2013)

Rick said:


> Interesting. There is no bicarbonate in this system at all (unless you have pot supplements). So why the high percent of ammonia?



Less than 20% of the nitrogen as ammonium doesn't seem high to me.

By bicarbonate I guess that you mean buffer capacity. You don't particularly need buffer capacity; to take up a cation the plant releases H+ and to take up an anion the plants releases OH- (in the form of bicarbonate). The H+ from the uptake of cations and the OH- from the uptake of anions neutralize each other producing water. But that said; the ammonium, aspartate, citrate and phosphate provide buffer capacity.


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## Rick (Feb 10, 2013)

DavidCampen said:


> You don't particularly need buffer capacity; But that said; the ammonium, aspartate, citrate and phosphate provide buffer capacity.



http://www.firstrays.com/PDF/Part 3 - Fertilizers.pdf

Check this out. Bill Argo is pretty much the one who came up with MSU ferts (high and low alkalinity use versions). 

I'll dig up the link showing uptake models in plants that show the use of bicarbonate ion to move other ions in and out of plants.

OH (rather than bicarbonate ion) measure is really a poor surrogate for understanding buffering capacity in plans and soil systems.


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## Rick (Feb 10, 2013)

http://www.verdegaalbrothers.com/ph_meters/Uses_of_sulfuric_acid_as_water_admendment.pdf

Here's another fun play paper.


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## DavidCampen (Feb 10, 2013)

Rick said:


> http://www.firstrays.com/PDF/Part 3 - Fertilizers.pdf
> 
> Check this out. Bill Argo is pretty much the one who came up with MSU ferts (high and low alkalinity use versions).
> 
> ...



Yes, the _plant_ produces bicarbonate (HCO3-) from OH- and CO2. You don't need bicarbonate in your nutrient solution. Yes, OH- is not a buffer.

In fact, Bill Argo states on the 1st page of the link you gave:
" ... uptake of nitrate nitrogen increases substrate-pH because *OH- or HCO3- (bases) are secreted by plant roots* in order to balance nitrate uptake."

That would be a good paper to study.


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## DavidCampen (Feb 10, 2013)

Rick said:


> http://www.verdegaalbrothers.com/ph_meters/Uses_of_sulfuric_acid_as_water_admendment.pdf
> 
> Here's another fun play paper.



That paper talks about how to get _rid_ of carbonates from irrigation water using strong acids. I don't use water from an irrigation ditch for my orchids. I use RO water.


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## Rick (Feb 10, 2013)

DavidCampen said:


> That would be a good paper to study.



Yes, read on. There is a section in there about alkalinity of feed water. There is also a good table in there that shows fert selection (and %N from ammonia vs nitrate) based on alkalinity in the system.


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## DavidCampen (Feb 10, 2013)

Rick said:


> Yes, read on. There is a section in there about alkalinity of feed water. There is also a good table in there that shows fert selection (and %N from ammonia vs nitrate) based on alkalinity in the system.



Um, actually, I was suggesting that other people should study the paper. I already know everything that is there.


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