Many moons ago, when I was experimenting with developing my own, better-but-much-cheaper SuperThrive (abandoned, due to EPA regs), I began using humic acid as an additive to the formulation.
I am quite certain of its benefit in soils, as it helps release otherwise-sequestered nutrients, but I questioned its applicability to orchid-growing.
I know this is quite unscientific, but about 4 months ago - just before the time I had to start mostly "ignoring" my collection due to the various surgeries I endured - I added a liquid humic acid concentrate to my fertilizer feed tank, so have been feeding with it (it ends up being about a teaspoon per gallon), and it "looks" like it may be a "plus" after all, as I am seeing more growth and blooms than I had been (again I'll state - it's quite an unscientific assessment).
IIRC Superthrive is vitamin B-1 with some other plant hormone, but the real ingredient is the B-1. So, just as B-1 softens transplanting shock so Superthrive will help wiht repotting shock.
IIRC humic acid is the acid that makes tropical river water dark, its from broken down plant material. Sure there's some plant hormones in there too, but in general its acidity is what hold back or causes decline in potted plants, the salts and acids build up in old potting soil - soil I hastens to add!! I'm talking about house plants here, not orchids - and the plant fails to thrive. You repot and voila, better blooms growths etc. Less burning of those delicate root hairs.
Now what humic acid may or maynot provide to *orchids* is another horse entirely, IMHO. There have been any number of peopel who like use of a variety of natural fertilizers. Alan Koch liked using the algae additive (of course I'm blanking on its name.... some sort of Icelandic algae, has a variety of plant hormones which increases rooting, growth, etc.) I used to use it and did see improvement. Of course, as Wellenstein says, you never know whether the plants are responding to 1) repotting 2) better watering because you are paying better attention 3) or the stuff you are using.
So its a double edged sword. Ray, I think what you are seeing is just the usual increased solubility of inorganic micronutrients that any acidification/fertilizer would bring to solution. Marschner ( "Mineral Nutrition of Higher Plants") doesn't have an index listing for Humic acid, or even humus. There's nothing in the old AOS Bulletin under Humic Acid and the only 2 possible articles are in regard to CAM.
Here's a link to humic acid and follow the link to Leibig:
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.