This article is pretty informative, hoping she'll also post some more details there or here:
http://www.yesmagazine.org/planet/four-ways-mexico-indigenous-farmers-agriculture-of-the-future-20150810
Leah Penniment of Soul Fire Farm went to Mexico this winter and studied with a lot of different farmers up in the poor-soil, steep slope areas. Milpa, or three-sisters-type thing, is one of their practices, but I remember her telling me that it had five seeds (peppers were involved too) and also that it all gets planted in a single hole instead of just nearby.
Other lessons to be learned from this environment.
It's great yhow they're rebuilding the oil and re-implementing ancestral knowledge.