Brix is not something I know much about. One needs a special instrument to know anything about brix levels, right?
It does when you say it, though I'm not confident I could repeat it in my own words. I'm way behind in specific knowledge like you're sharing here.
I usually topdress with a nice thick layer of leaf mold which I imagine would be better than the coco what with all of the trace minerals it contains. That would supply the carbon as well as some nutrients.
I also add biochar to my mix, though I imagine that doesn't count toward what you describe as that carbon is supposed to last thousands of years in the soil (at least from studies done on Amazon Basin soil from long ago civilizations) so the microbes don't seem to be breaking that down in any appreciable manner.
I'm not sure how molasses can be a good carbon rescue given the minute amounts used at any given time. Maybe as a food source for the microbes it results in a population explosion and die off and it's actually the newly dead microbes that add the carbon?
Azi always asks the tough ones lolol
To read brix you need a refractometer. They are fairly cheap and very simple to use.
They show you the sugar levels of the plant, which is an indicator of overall plant health plus they show you in general how your calcium sits, although they don't actually measure calcium, just indicate high or low. High brix is high health.
Once brix is over 12 or 13 then the sugars in the plant are too high for pests. Plant eating pests don't have pancreas's so the sugar inside them turns to alcohol as it ferments and kills them. They know this and stay away.
Your leaf mold is an excellent carbon. I'm not sure about biochar, I've never used it.
Molasses is sugar. Sugar is a very strong form of carbon in a bioavailable form. Plants create it thru photosynthesis, use it to power cells, and send extras out the root as an exudate, for microbes and fungii eat it.
They then breath out co2 which the plant breaths in. When the plant is young it doesn't have enough sugars to share so the microbes eat only the carbon in the soil.
I use coco because they love it and it gets consumed quickly which is important in a 5 month life cycle such as a weed plant.
If the soil runs low of carbon so the microbes run low on carbon, then they breath less co2 out so the plant runs low and the sugar flow slows or stops.
The plants brix levels drop and pests move in.
Nature has decided the plant is weak and must be culled. Pests are the culling crew.
Plant exudates are a treat, not a survival tool for the microbes and mainly go to phosphorus collection, (fungii bribes certain microbes with it to fill specific needs at specific times) which is a main player in raising brix. The rich get richer.
Once the soil runs out of carbon the system crashes as there isn't enough co2 being produced for the plant to feed the system with exudates alone, so adding mollases to the soil supplies fuel to the microbes for co2 production to continue.
The problem with molasses is the microbes can harvest it directly, not having to chew thru nutes to find the carbon, so once the microbes get a steady supply of molasses for co2, nute production slows.
If you rely on molasses to finish, your weed is lesser than if the soil had the carbon in it. Molasses is for the microbes not the plant.
The biggest mistake (maybe not the best word here) organic growers make is failing to realize that everything they put in the soil isn't directly for the plant.
The microbes and fungii need tending to or they go dormant, and the soil itself needs structure, often refered to as "soil conditioning" such as how calcium helps tilth by opening hallways for air, water, nutes, microbes, etc.
Also proper calcium makes the static electricity levels proper, so when a plant pulls say a magnesium molecule off the colloidal serving tray it doesn't have to tug to get it as there is another charged molecule not yet on the tray waiting to hop on.
Its electrical field makes it so the colloid can actually toss the magnesium to the plant as it sucks the new one on, all thru electromagnetism.
Its called flow.
When food is abundant and processed from a microbe its pushing to try to get on the platter so things being taken from the platter hop off really easy.
Your additives also effect this process.
None of all that works very well with poorly conditioned soil. It all works extremely well with well conditioned soil.
Nature takes care of the tricky stuff, you just need the basic parts in a pot with some water and microbes and fungii. And light to drive the whole thing. Its solar powered.
In the human gut biome that carbon that our gut micromes eat is supposed to comes from fibre.
In perfect compost on a molecular scale carbon (browns) outnumber proteins (greens,nitrogens) 30:1, so you can see carbons importance.
Fungii needs about 20:1 carbon to nitrogen just to stay healthy, not nescessarily thriving.
Carbon is carbs, and nitrogen is proteins. If you think of it as carbs and proteins a balanced diet is easier to understand.
Humans require 2/3 carb and 1/3 protein. So do plants
Carbs are dense, proteins aren't so a 2:1 ratio on your plate translates into a 30:1 at the molecular level. Or in the ballpark. All you need for perfect weed is to be in the ballpark.
Now you need nutrients, so make sure that by eating 2:1 carbs to proteins that the carbs and proteins contain all the nutrients.
Nitrogen in the soil will find carbon in the soil causing hot composting so you must cook the soil 1st before roots touch it.
If you balance your diet and still don't lose weight your calcium is low so mag has locked your proteins( nitrogen lockout) and now carbs can't burn.
Your brix are low and the culling crew is coming for you. McDonalds has no fibre.
Processed means " we took the fibre out, now microbes don't want it so it has a longer shelf life, as no one wants to eat it except you"
When they GMO a seed to make it "pest resistant" they have made it so the pests don't want the plants fibre so they stay away, but then we eat it and our biome doesn't want it either.
When the crop stubble gets tilled in it won't decompose, as the microbes don't like it, so the field gets carbon deficient really quickly. Then they sell you carbon too.
Understand the carbon and nitrogen cycles, and calciums value in the soil and you now have carbon,nitrogen,O2, and H2O covered.
All thats left is nutrients, so make your carbs and proteins supply them.
The microbes and fungii will take it from there.
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Hopefully theres 40 tomatoes in there...