Compost is a home project (and available in some cities as part of the waste management system) and nutritious for plants; but most of the things I grow as food I don't fertilize much or any. The fruit trees once a year or so, the garden soil sometimes in between planting or when growing watermelon or squash, bigger things do need some extra fertilizer (and tomatoes like some) but most seem to do fine with good soil and crop rotation/companion planting. Farmers have to use more because they've depleted the soil with monoculture. I still don't think it's cost effective when time is factored in, but it's better fresher food and not as fussy as farming.