Spectrum analytic tests are about 25. I work with an agronimist. The package he told me to use was $53. Previous tests with logan and Intl ag lab were about the same.
Re K. I consult with farmers and have been a life long gardener. Most of the farmers i work with and almost all of the MJ gardeners I discuss plant health with, agree that high K is a quality killer. I understand that it can drive highest yields. But it certainly doesn't drive highest nutritional content. I doubt it drives best genetic expression either.
This site is packed with info
https://www.spectrumanalytic.com/
First off, meant to say USDA.
Your correct. Use of extra K does add yield, if done right. I like to add a cpl of points in bloom after the 2nd week. Minor P increase and reduce some later. Use of more K late can influence color expression in plants that are able. Higher K in veg? Haven't found that to be exactly productive down the road.....Years ago when I was experimenting with finding my "best's" with differing synthetic ratio's. Found the line between good and overdose to be very fine, as once you go over. the plants stunt's and a clear sign is color expression in veg. Once you get that, too late!
As for MJ and reducing quality....Just started some experimenting with specific synthetic lines again. Friends and others in our little Co-op have done some eyeopening work with them. Thought I might give synthetic a shot again....May have to do some at what I
liked to supplement to and not From the past synthetic use. Test the difference and see...
For the most part, build my soils (organic water only's) to recipes that came from years of building them. Your quoted amounts/methods (for Mn and Fe) and the testing has me rather interested in actually testing my different bloom formulas out. I could learn a lot from actually doing that. Being satisfied with what has been achieved, never sits well if I think I might do better....
I farm but, it's organic and don't express any supplementation of K in any of the tea's or mineral applications done to the soil. Our soils tend to be a tic over in K from normal/surrounding farm lands anyway (in USDA tests). In the final year of certification on the "new" dairy farm to the co-op. We set that up for the organic manure for use in other locations due to the cost/water reductions and other benefits of some moving away (somewhat) from AACT's.
Never much of a flower grower per-say, More of a tropical interest. Learning the ins and outs of succulents from seed....Something new to me..... My wife has absconded with some of my used and not replenished MJ soils for use with some of her squash and tomato's as an up-pot this year. You could see the very early coloring and when they went out. Got that classic light tan edge necrosis that signals K tox, after she put them out into full sun.....She came in and asked what happened. Took one look and told her that was from the increase in transpiration and there for the increase in up-take of the available nutrient in the soil.
Looked at her and said, "Now you understand why I told you not to use that soil for veggies? That soil has higher med./slow release P&K then you needed.....? It's about all that's left in that soil after the Long running Sativa's that were in it.... As soon as you added your first feeding, you over did the K....
So, anyway. This and your information have me looking to do some tests on fresh, used and re-amended soils to see exactly where those are.....I'll be better able to re-amend that way.....
All these years and I didn't think to try that......You've taught an old dog a trick he didn't consider. Even for a farmer...
Damn local USDA branch closed too.....I'll have to send to labs.....Might try friends at my college too....
GREAT INPUT!