What do you mean?
I have got compost and humus in my soil, I believe they cover me up with N-P-K (still need another source for P)
So are you saying the proper way to add fulvic acid is with watering, and not foliar spray ?
If I get you right, I need to add fulvic acid to my watering once a month, and over time the fulvic acid will make it's effect in the soil? (I plan to re-use the soil)
Compost and Humus will not hold nutrition the whole way out.....You
will need to use some form of nutrient supplementation to that soil...
Here is my favorite soil building thread I like to share with Novice soil builders - looking to go organic water only super soils...
This delivers the concept of building nutrient formula's that can deliver differing amounts for differing strain needs. YOU have to see the way they intend by reading between the lines..
I build 4-5 different bloom soils. Each delivers a different nutrient balance for specific strain needs... Available N is the most adjusted.... Some are for heavy feeders and some for light feeders. I make some adjustments on the fly with some strains - when building soils for them....Mg hog strains are another variant.
https://forum.grasscity.com/threads/easy-organic-soil-mix-for-beginners.1116550/
Your soil will last around 30 days, a bit more maybe. This will be basically true for when you up pot also...
In bloom,,your going to see a need for using a nutrient.....I guarantee you.....
Now then.....I'm not saying anything about how to apply it (Fulvic's)...
I'm telling you
the best available Humic/Fulvic product to use.
The how it's used is by the makers direction. It is the best way for that product.
Humic and Fulvic acids do the most for the plant by having them in the bio active soil, doing their job......They do more by reacting with the living bio's in the soil and the plants root activity. Then by being drawn into the plant by foliar application.