Micro Nutrients Educate Me Please

The3rdMan said:

Just an update. I have continued to get soil tests on my soil mixes. I add a gallon of compost and a gallon of EWC to 8 gallons peat moss. Usually, Iron and Zinc are at Optimal levels while manganese, copper, and boron are sub-optimal. Sodium is also elevated. I cannot use Big 6 or TM7, but add the micronutrients separately for MN, CU, and B. Unfortunately, one cannot know this without A soil test. The macro nutrients are normally near optimal with some occasional adjustments to N, P, or K needed. Magnesium, Sulfur, and Calcium are usually fine, so most of the nutrients are coming from compost and Ewc alone.

From what I have seen, compost and EWC have more micronutrients than rock dust and much less expensive. But, the problem with both is that whatever source you use, you don‘t know if your micros are at sufficient levels unless you get a soil test.

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Whatever is added to soil must be broken down first through microbial activity in order to be available. Rock dusts take a real long time to break down so it is conceivable that adding basalt doesn’t show up right away in macronutrient form whereas compost would likely show to have much higher levels. Compost is already decomposed through microbial activity; all manner of nutrients are readily available and unlocked for absorption.
Never felt a soil test was needed myself because we always just amended a bagged soil over and over. We rely on the plants to tell you if your mix is on point ot not; many times fresh EWC and a form of fertilizer or 2 is all I ever need to add. If you had mixed up your own soil from scratch I can see how a test could show if you were missing anything.
When I first started growing in a living mix we had issues related to a lack of macro nutrients...Rust spots, etc. Soluble cal/mag was needed regularly as I give the plants stark water collected from a dehumidifier (13 ppm.) Soon after we started putting eggshells in the worm bin and began amending soil w/ minerals like soft rock phosphate, garden gypsum, D-lime, azomite, and glacial rock dust. Soluble cal/mag was no longer needed but it took about a year for everything to break down. I’m willing to bet that if you wait about 6 mo yo a year and re-test the soil there would be more available macros detected.