Nope, not at all relevant.
1. Fertilizer effects have changed, check wiki for agriculture page where the new values (some) are listed.
2. Hay is much easier to get, spam haystacks and it'll be easier on your soul than hammering at your fields with humus for a week and a bit.
3. Long initial post was long. I mean I respected Martinuzz for being part of the nerd team theorycrafting salem for the newbies
But perhaps my lack of patience makes me want to describe it more as .. "Either raise the influence bars in one go, or divide it into as many sessions as you feel comfortable with. Keep in mind it's easy to speed up a field to make it be ready in a day, and splitting it up into more harvests will save you hay as the first uses have more effect. Other than that, do what fits your playstyle most."
Exactly 6.022 x 10^23 worth of Lach molecules.