Some points:
- Plants can extract more of a specific ion than the ratio supplied. So if you supply K at half the quantity of Ca, the plant still can take two times more K than Ca. Chromium is another extreme example, plants can really become intoxicated quickly, and it is irreversible. They will take whatever they can find under the soluble form for chromium.
- Rick point, and thinking about it it matches some things I got in the past..., is that some plants cannot stop taking K from their environment, up to a detrimental level. Especially if Ca and Mg are deficient.
- Orchids have different foliar analysis than most ornamental crops, for most popular genera.
- So Rick idea was to lower the availability of K at the plant roots so they do not get intoxicated, and raise the Ca and Mg, which are divalent cations ( K is a monovalent cation).
- I think that soluble or insoluble has not much matter for most plants, as long as the insoluble compound is in contact with the root or the active root tip. Qutie a few plants are able to dissolve compounds at their roots, would be very long to explain, but that's a fact.
- Phytotoxicity symptoms charts are useless for orchids. I learned it the hard way, some 'nonmobile' compounds can move, and some mobile compounds will not move. Zinc is not supposed to move too much, but it can be translocated from the old leaves to the new ones, giving... potassium deficiency symptoms. It happened to me in the early days, and thinking of it, when I gave potassium nitrate to the plants, they were screwed at light speed. Iron is supposedly used in the new growths, but it can move to the old leaves, and make phytotoxicity symptoms in the old leaves, whilst still be deficient in the new leaves. It is very complicated, and requires many analysis. Orchids are slow growing, unlike rice or lettuces, so they can move, slowly but surely, things from the old parts to the new ones, or the opposite. Which ions they can move and which they can't remain a mystery until today...
- As for the fertilizers, they are made basically of a few chemical salts, packaged differently and that's all. Some organic fertilizers or special fertilizers can incorporate kelp, citric acid, others additives to enhance the solubility or availability of the macros and micros, or supply directly available food to the plants ( such as amino acids).
- The 'not to mix with calcium nitrate' recommendations or that style apply to professional growers who use a dosatron or similar. They mix the fertilizer in very concentrate form ( something like 1kg/10L for some nurseries) and a pump dilutes it. If you make your final fertilizer, providing the compounds are dissolved properly, you can add pretty much everything together in the final tank. This said, you better use it VERY quickly. I know as a fact too from tank analysis that calcium nitrate and Peters 20-20-20 end up in insoluble calcium and very low levels of phosphorus after a couple of days. If you mix and apply immediately, there should be a minimal loss ( especially depending on the pH. At the old 5.7 standard, there is little risk, but if you use ProTekt to raise the pH to let's say 6.5, you will have a precipitate, maybe invisible, but it will be there. Same if you tank mix calcium nitrate and a NPK fertilizer, the raise the pH. A part will become insoluble molecules, at molecular level, so there is little chance of seeing those by the naked eye)
- To raise the phosphate content, I would not use potassium phosphate ( there are 3 different ones BTW...). I use always MAP, monoammonium phosphate. In fact my use of 10-52-10 is similar to the use of MAP with a bit of potassium nitrate and oligos.
- Many people got very good results with the MSU, because at the same N concentration ( let's say 100ppm), MSU supplies way higher rates of micronutrients than a commercial standard, old style fertilizer. So when using MSU, it helped to supply the micronutrients at a proper level, whilst not overdosing the NPK... After, that's another story. I could never maintain plants with MSU alone, and they did very poorly. It is related to their all nitrate policy. Rick uses kelp, I use ammonium phosphate straight, and sometimes things like peptone, and we do not have any problems with way different setups. In both cases, we add ammonium or ammonia to the system, eventually amino acids.
- Rick should really investigate the Asian pots for orchids. In Asia, they have black plastic pots with a net at the bottom like that:
My main concern against using baskets is when it will be time to repot. Most likely there will be broken roots, etc... and a plastic pot like that would help to maintain high aeration, but with the roots inside the pot...
Overall, for the hydroponics companies ( we have many dealing in cannabis growers as well in Europe), they have some very fine product. However I would never use them, because
* First I do not know what's inside. As an example, Jerry's Grow was wonderful, but when it went out of stock, it started to be a major mess for people who used it for years. The methanol enhanced the penetrations of some ions, and changed the plant metabolism. As long as the plants were fed that way, all was fine. When it was stopped, plants could go down very quickly. Another example in Europe, some of those hydro products contains hormons, some rare compounds that are indeed enhancing plant growth for some specific crops, like spermidin, triacontanol, etc... Some plants like it, some will definitely have a very adverse reaction. In some cases it can doom the plants.
* Second I don't know if it is going to be available for long or not, or if they will 'improve' the formulation at a later point, which requires retesting, and maybe worse results for our orchids.
and when you stop using them, the plants cannot make it properly.
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