Chelated Mineral Sources

[Allen Repashy]

In my never ending research of nutrients, I have found my way back to chelated minerals. Chelated minerals are often used to provide minor nutrients in fertilizer formulas. Chelated minerals are minerals bound to an organic acid such as citrate, malate, fumarate, lactate, or gluconate; Or they can be bound to amino acids such as aspartate.

So for you experts out there, what do you think is the best product compound to use to provide these minerals...... Organic acids, as Tim points out could provide nutrients to bad guy fungus as part of the Krebs cycye.... gluconates form gluconic acids, which are also listed as organic acids but I can't figure out if it is also part of the Krebs Cycle..... amino acids maybe... I don't know anything about what effect they might have.....

Anyone have an opinion?

Allen

[Matt Maggio]

Before considering the use of chelates one should avoid the conditions which may warrant their use... in my opinion. When discussing chelates we are concerned with micronutrients available as cations, notably Fe, Zn, Cu, and Mn. The availability of these is adversely affected by pH <6.5, so assess what steps could be taken to maintain optimum pH.

Chelates are measured by their stability constant K value. The higher the K value, the stronger the bond, and the least likelihood of a micronutrient being supplanted by another on a binding site. The same chelating agent can have a different K value per nutrient. Some of the strongest associations are with EDDHA or Gluconate coupled with Fe3+... other nutrients not so much. Calcium competes strongly with micronutrients on binding sites, and since we need lots of calcium in our our cultivation of succulents, I doubt most chelates of Zn, Cu, an Mn, would be very applicable. In studying plant tissue analyses of some succulents, I also notice that relatively high levels of iron may be required. Iron chelates could be of merit, especially those with synthetic agents like EDTA, EDDHA, and HEEDTA. Again, these tend to have stronger K values than compounds like citrate, but they are relatively expensive.

Going back to this issue of microbial metabolism, I would assume that most synthetic chelates would be a safer bet. They are more complex molecules to utilize and/or may not be recognized by the microorganisms... though some have acetate in the name. This assumes there could be a real problem, as further research has elevated my skepticism. I have no doubt simple metabolites like acetate and citrate are usable... but are the users necessarily bad? I found how bacteria are the most likely consumers and are first on the scene when such a food source abounds. Fungi make efficient use of more complex organic substances like cellulose. Most plant pathogens are fungi. Furthermore, the bacteria could consume the substances quickly before anything else has a chance.

Enough on my part for now... let's hear from someone else.

[Kerino]

Allen, it doesn't state the minerals are chelated, but I always sprinkle a little of this when repotting:
http://www.ussoil.net/pdf/PlantersIIspecs.pdf

You may have a local source, but I get mine from these guys:
http://www.bes-tex.com/products.php?kei=1003

[agavemonger]

Hey Allen!
Almost all professional growers have experimented with different formulas of fertilizer for most of their careers, thinking that there's got to be a better way. The resulting horror stories are legion. Not to burst your bubble or anything, but Bottom line is that the best and most proven way to grow plants is to buy a professionally pre-mixed balanced blend of solluble fertilizer that already contains your chelated micro-nutrients. Apply through an injector. I buy mine from Fallbrook fertilizer (20-20-20 with micronutrients) in 25 pound bags at around thirty dollars a bag. Tell Brad I sent you in. But more importantly; (and this is the CRUX of the issue: ALWAYS monitor the output of your injector with an electrical conductivity meter at a concentration rate of 1.0-1.25 mmhos (millimhos) on the guage at the business end of your hose. The hardest lesson I've repeatedly had to learn is that MORE is not BETTER. I'm also turning away from greenhouse type soils. They work fine in a greenhouse for tiny plants but the BUFF STUFF on this forum mostly prefer full sun and organics. The combination of organics and low-dose fertilizer acids is truly the best of both worlds. 50% decomposed granite mixed with 50% compost makes a wonderful potting mix for outdoor container-grown Aloes & Agaves. (Bet you have plenty of D.G. right there on your property) If this soil is too heavy for you then amend with 50% pumice or scoria (ground lava). Forget the chemistry experiments and get down to growing some killer plants!
Most Sincerely, the Monger

[Turtile]

Most fungi have no negative effect on plants. Most of them are decomposers. Regardless of the nutrient or the form of the nutrient, soil organisms will always absorb the nutrients before plants. When these organisms are dead, the plants can absorb the nutrients.

You shouldn't worry about micronutrients pushing soil organism populations since there are already more than enough already present in the soil. They are mainly limited by nitrogen as are most plants.

As for the best compound, the only way to know which one works best is to test it out.

[Matt Maggio]

So much to say here, so little time...

Plant nutrition is a damn tough one...if one cares to delve and learn from their mistakes. I don't recommend custom blending fertilizers without exercising extreme caution. The margin for error with some micros is <10 ppm. As the Monger suggests, restraint is key. However so is tenacity. I'm a tinkerer myself... always will be. I don't believe in a one-size-fits-all approach, and cringe at the thought of using 20-20-20 on many succulents. Beyond the problems I've obsevered with this formulation over years of experience, I have several plant tissue analyses as evidence that this is not the best choice in many cases. Where's the calcium, for example?... and the tap water is not enough.

One final thought for all growers struggling with this... don't acquiesce to growing by luck, grow by skill!

[Tim Harvey]

I have never worried about micronutrients. Maybe you can tell. However, when the winds are blowing in Southern California I think there's more than enough in the dust. Thereagain, I use commercial fertilizer formulations ...

T

[Matt Maggio]

I use commercial formulations too...and have the added daily benefit of airport soot

[agavemonger]

I have to agree with you on the calcium part Matt. Most agaves prefer a higher calcium level in the soil. Amending with calcium at different concentrations would make for a most interesting study. Perhaps at certain levels we could obtain cross-banding and pink coloration in plants such as A.colorata, A. marmorata and A. zebra. It would also be fun to tinker with different formulations of fertilizer in different concentration levels of Nitrogen, Potassium, Phosphorus. I find that in outdoor growing that the 20-20-20 combination gives the maximum balanced concentration possible for a general purpose fertilizer that can be used safely on all plants save for acid lovers. I prefer liquid feed because there is no need to worry about overfertilization due to pelletized fertilizer buildup in the soil. You cannot leach out pelletized fertilizer, so there is the ongoing problem of fertilizer buildup and resulting high toxicity levels. The only way to leach out pelletized fertilizers is by completely repotting the plant in new soil. Certainly a scientifically controlled blind-testing would offer most interesting results on these plants. However, most afficianados simply don't have the number of plants necessary to undergo these type of studies. In the meantime, I'm finding that soils with high organic levels tend to balance out most conditions that would normally be detrimental as far as toxicity. These organically amended soils have a myriad array of biological checks and balances and constantly are adding plant-usable trace elements, hormones, complex vitamin trains, etc, as well as the more generic fertilizer constituants to boot. Very controlled amounts of supplemental "chemical" fertilizer at low concentrations in soluble form is very helpful and aid the plant in building up resistance to the plethora of bacteria, viruses and other bad guys inherrent in organic soils. Greenhouse growing exacerbates the bad effects of these little monsters, sometimes horrifically fast. Phytophora, Rhizoctonia, spider mites, etc., can all literally explode in growth in a greenhouse environment, so I advocate sterile, soil-less growing with pasteurized potting mixes for the high heat and humidities inherrent in a greenhouse environment. Certainly a large part of the joy in growing rare plants in a unique garden setting is the constant fun with "experimenting". But when it comes to fertilizers one must be extremely cautious not to overdo it. It is all to easy to ascribe a plants renewed vigor to the trace element, hormone, or vitamin you just overdosed it with; this is very seldom a logical conclusion and is usually due to other factors such as the onset of spring, a lower toxicity level due to rainwater leeching, a better concentration of auxins in the nuclear makeup or what-have-you. Without large blind-testing experimentation most conclusions reached are really only assumptions and we all know what a little hyphenation can do to assume. An amateur would be far better off by concentrating on efforts to improve water quality by investing in rain-water capturing efforts or water purification technologies. When used with pure water, fertilizer concentrations can be doubled as compared with our standard, salty, Southern California water which generally measures out at .5 -.8 mmhos. This is roughly half the maximum allowable concentration of salt that most plants can tolerate without root damage. It's a wonder our plants don't drop dead from heart attacks! Happy growing! the monger

[Matt Maggio]

I use gypsum in many cases. Chalky echeverias (lilacina, laui, colorata, cante, etc.) noticably thrive on elevated calcium as well many agaves. Succulents native to limestone soils seem to either require large amounts in their biomass, or have perhaps adapted as inefficient users of calcium resulting from excess in their soil environment. Nutrient analyses have already shed light on the former. Interestingly, some calciophiles can secrete root exudates which lower the pH in the imediate rhizosphere, thereby facilitating uptake of other nutrients with low availability in high Ca (pH <7) environments - iron and phosphorus, for example. I've had Aloe dichotoma tissue tested for a tip necrosis problem. The results suggested a potassium deficiency, but in the process I discovered even these contain levels of Ca in their biomass on par with N-P-K... I remember 2-3 % Ca of dry weight. In addition, I should underscore that phosphorus tends to be the primary nutrient of least % incorporation across the succulent spectrum. Potassium was always the highest in healthy baseline samples, with the narrowest gap in Aloe. These tissue analyses SUPERFICIALLY translate to N-P-K in the neighborhood of 10-5-20 for many succulents... much can happen between the end of a hose and actual biomass incorporation! So, I'd at least think about keeping P on the low side, and watch for possible Fe, Mg and Ca deficiencies as a result of excess P. Since I've started using high K fertilizers, many of my tip necrosis problems on Aloe and Agave have subsided. Watch for the form of Nitrogen as well. Some of my necrosis problems may have resulted from excess ammonical N, which also competes with K+ for uptake. My current formulations contain mostly nitrate N. Anything else? oh yes, I agree with the warning about granular materials. Case in point, I experimented with some granular Scott's Ironite on a variety of Echeverias because some dry weight analyses showed a curiously high proportion of Fe. This product also contains a host of other micros. The results were positive with agavoides types, but disatrous with others. Some of the black necrotic lesions actually shimmered metallic in the sunlight! Lessions learned!

Finally, a general understanding of what these nutrients are used for in plants coupled with our knowledge of succulent's developmental habits should steer growers in the right direction. Potassium = carbohydrate/water storage = fat plants.

[Tim Harvey]

Maybe I'm missing something, but what is the relationship between calcium and the thickness of leaf cuticle? White cuticles are the result of wax deposits, which are rather organic.

Unless you mean hard water stains?

T

[Matt Maggio]

Since when are you concerned about Echeverias Tim? No seriously, excellent point, and perhaps the word "chalky" is a tad misleading. All I can point towards is a positive correlation based on my experience growing the farinose types. There could be some other biological cost which the calcium pays for. Interestingly, I did a trial with E. nodulosa - which is about as chalky as a watermelon - where gypsum was used over the control. The gypsum sample demonstrated much accelerated growth (mostly roots) over the control which had typical root rot. What nodulosa has in common with many farinose types is the relatively high susceptibility to root rot. Perhaps the calcium helps in suppressing certain soil-borne pathogens.

Yes, the cuticle is comprised of mostly long chain polymers(hydrocarbons). I think in the case of farina, they form flakey scales. If calcium is actually present, the only compound I can think of would be crystalized calcium oxalate, but isn't that poisonous?