I certainly do not want to restart a firestorm of crap-posting, but using tissue analysis to determine what a plant needs is not particularly valid. If that were true, my blood work indicates I need extra cholesterol! Tissue analysis tells what the plant has been getting, not what it should be getting.
That said, it does seem logical that tissue analysis of wild collected plants will tell you what they’ve been getting, and if they’ve been doing well in the wild and have evolved to be there, it must be some indication of what is adequate.
Such analyses I have seen suggest that roughly 99% of the tissue is C, O, H, & N, 0.9% is P, K, Ca, Mg, & S, and the remainder is all of the trace elements, combined.
I will not refute Xavier’s claimed expertise, but there are several growers in tropical areas whose plants are growing quite well with K-Lite, others I have spoken to who only feed calcium nitrate most of the time, supplementing with the “minor” elements quarterly and trace elements annually.
There is also the case to be made that a very important factor in fertilizer selection for large-scale growers is cost, and urea is far less expensive than are nitrate and ammonium-based formulas, so that makes me wonder if that isn’t the more important factor for “why 100% of all the growers from Taiwan to Indonesia use urea-based fertilizers...”.
By itself, I know that statement to be untrue, as I used to do business with a cymbidium nursery in Taiwan that exported about 10,000 plants weekly to Japan. Their complete nutritional package consisted of fermented milk.
To me, after doing a lot of reading and having discussions with scientists and manufacturers of fertilizers, it seems that “we tried it and it works” is fairly common in the industry, when it comes to the hobby grower, there are far more variables than just the chemical components and ratios in the feed that play a role in success or failure, and that the fertilizer component ratios are not all that important. The plants are slow-growing compared to most others, the majority of nutrient ions are stored and recycled within a plant, so fertilizers end up being very low on the plants’ “Maslow’s pyramid of needs”.
It is much more complicated than that unfortunately.
Wild plant analysis, that depends when they were sampled, and which leaves. Old ones ' not to disturb the plant' wil have typically a very low potassium content if they start to be senescent. Roots need to be sampled aside ( we do that in industrial production), because there are some huge surprises in the needs and contents of the roots vs. the leaves.
If you go to make blood samples in the refugees camps with 35kg adults in Africa, you get a result, and 'it must be what human needs', as people are still alive. It is not a reasoning. To make something that is really realistic for the analysis, one needs to sample a specimen in the wild or in sustainable culture, that is really doing very well. It must be sampled properly, which leaf, and which root. Not old leaves or just random....
Foliar analysis after using a fertilizer or new one can point to a problem, like why is the potassium going down after 3 months, is it normal or not ? Why does it crashes after blooming (low K will eventually induce a total plant crash in Phalaenopsis, chlorotic leaves, becoming reddish, and eventually plant death, that's documented, even in published research) ?
People are scared of leaf or root tissue analysis because it costs money, they have most of the time no clue as to what to do with them, and they could contradict their belief as well. As well, many do not grow enough plants to sample 100g of leaves per test x X test... so better to forget that step.
Looking at the plants is as well something that does not work. Phosphorus deficiency makes beautifully green and compact plants to start with. In fact P deficiency is used to dwarf plants in ornamental production, and give them a dark green lush color... at the beginning. The yellowing and chlorosis will happen later, once they are sold/used. Yet, with a very low P fertilizer, the plants will 'green up' at first for a few months... Where orchids need massive amounts of phosphorus, and it can be proved by analysis of certain tissues ( not the leaves...).
Urea fertilizers of quality are more expensive than nitrate or ammonium-based ones, if you want to be certain there is no phytotoxic biuret inside....
The Japanese use mostly an ammonium/nitrate or full ammonium system ( many use Nitrocote/Molcoat, that are ammonium with some nitrate, others with great plants use MagAmp-K, only ammonium nitrogen...)
sour milk/fermented milk is as well conceptually very good as a nitrogen source, because it contains both ammonium and aminoacids that can be absorbed directly by the plants. I saw some cultures like that in China, the 2 problems were that you need to mix it with streptomycin/tetracyclin every couple of months ( widely available and very cheap in China and Taiwan...), and yes I had to advise nurseries in Taiwan and China, so I saw that...
For what people consider a good culture, and how successful a fertilizer is, well that depends on the standard of culture. I could listen to people that present plants as good as mine ( see my many posts on Facebook as SelectOrchids...), I won't if the plants are yellowish or if the guy takes 7 years to flower a rothschildianum, or 2 for a Phalaenopsis, from flask.
We tried and it works does not exist in reputabled fertilizer companies or larger scale nurseries, whether in Europe, Taiwan or Japan. They have massive stockpiles of trials, metrics, tissue analysis. Even the fertilizer companies usually have a in-house department with analysis standards for specific crops, and advisor to send to their larger customers, who will do... analysis before advising anything. Been there, worked that... Fertilizer components ratios are essential, with some variations, as well as the potting mix current pH, pH when feeding, and residual pH after a couple days, etc...
Most of the obvious failures in orchids, or slow growth, can be traced down as well to a pH issues related to the fertilizers and soil composition.
K-Lite or Calcium Nitrate will be the less worse fertilizers in sphagnum moss as an example, especially Chile one. Why? Because their residual effect will be to tend to raise the pH, which can become too acid in sphagnum. They are not the best fertilizers if you correct the pH of the sphagnum with lime as an example, by far, which is what I advised the Phalaenopsis nurseries in Taiwan to do, and what most are now doing on a large scale. Otherwise they were using a high urea 20-20-20 or 30-10-10 year round in sphagnum and problems appeared after 6-8 months. Now, no more problems, and no more rots due to low pH.
There are many variables, and that's why large companies employ people like me too...
