Something I thought was really cool is that in Korean Natural Farming [1] there is a technique where you go to the forest near your farm and gather a bunch of decomposing leaves and other matter from the forest floor, then take it at home and throw it in a tub of I think starchy water to feed the microorganisms in the material you collected. You incubate this for a while and then spread this water over your soil. The motivation for this practice is the idea that your local forest has self-selected to grow well in your particular location, and those bacteria will be very helpful. I think it's an excellent innovation. It is both very simple for poor farmers all over the world to do and based on good scientific principles.

[1] https://en.wikipedia.org/wiki/Korean_natural_farming