I've been having excellent results in the home garden using the hugelkultur approach. Just bury logs and vegetative waste beneath a foot or two of topsoil. Adding some fungi spawn to the organic matter speeds up the process. The rotting organic matter acts like a big sponge to keep soil moisture high. Mycelia act to swap plant sugars from above, with nutrients from below. From a small plot, I was able to donate about 250 pounds of gourmet blue potatoes to local food banks this year.

Other than a little cow manure added to help feed the fungi and plant roots, no other fertilization was required. There are so many great low-tech approaches to get great yields of delicious produce, but it takes some extra initial labor inputs. Maybe when the AIpocolypse hits the labor market, this approach will be economical on larger scales.