No till is easy enough, and nearly free if you do it right. Layers:
Water + weight on top & let it sit all winter (I'm in zone 5)
mulch
compost
peat moss
compost
cardboard
mixture of soil amendments & compost, if amendments are needed
ground
I use pallet wood for bed edges if I don't have any better scrap. Use pallets marked heat treated (HT) to avoid chems. You could do something like below too, using pallets as dual purpose stabilization and mulch:
Spoiler
(https://lanailens365.files.wordpress.com/2011/05/smimg_3177.jpg)
-Companion planting or crop integration. You can use fast-maturing crops like radishes (21 days) as placeholders in the early and late season in areas you're planting summer crops. Example: In April my cucumber hills are covered in radishes with snow peas between the hills, mid-end of May radishes are harvested and cukes are in. Snow peas fix N for cukes and are done by the end of June, then it's cucumber time. You might find some other gains with maintenance things (pruning!) or choosing different cultivars.
Otherwise I don't do anything with additives, other than epsom salt for anything in Solanaceae (tomatoes, peppers, eggplant, potato), added when fruit just start to develop.
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I also keep a small flock of chickens; barred rocks & silver laced wyandottes. I feed layers garden, lawn, household waste and let broilers roam in a tractor -> process their manure through BSFL -> supplement chicken feed with BSFL -> feed BSFL frass to redworms -> redworms also supplement chicken feed -> grow mushrooms in the worm castings -> apply mushroom compost to garden.