Lanx
<Prior Amod>
where do you even buy just soil in a bag? cuz the lowest quality soil i've seen is top soil, and i saw that potting soil is really just different amounts of top soil + peet moss.The short version is - if you’ve been fertilizing with any frequency and/or your lawn is old (even if not well maintained) then a couple applications of humic acid on its own will have a visible impact on turf growth and health. Beyond that though, you’ll really only benefit by applying the humic with or alongside whatever else you’re applying.
The longer version is that humic acid basically creates a weak molecular bond with nutrients (in your case, nutrients that are already existing in the soil) and this bond makes them bio-available to the plant. An oversimplified analogy is the difference between supplementing iron by eating iron shavings versus eating vegetables high in iron. Your body can’t do anything with the iron shavings because it’s not chelated (bio-available in that form). But the vegetable has already processed its iron and made it organic and bio-available so when you eat the vegetable you can actually absorb its iron and benefit from it.
It looks like humic acid alone isn’t nearly as effective as I originally thought, but that’s not to say it’s not effective. Keep doing the things that encourage your grass to grow (mow frequently, water regularly, and fertilize the soil) and the humic acid will allow for more robust and vigorous growth. This in turn will cause more frequent root cycling (where the plant’s roots die and it grows new roots), which leads to bio-available nutrients and carbon in the soil, which leads to increased microbiotic activity, which leads to more robust and vigorous plant growth, which leads to... you get the idea
This guy goes all in and says buying top soil is a waste of money because you can take any regular old soil and turn it into rich top soil in as little as two months by using humic acid and practicing the methods described above.