So I've found by experiment that Chacruna seeds will sprout in the aluvial soil of the lower mississippi river. Can they also sprout in upland soils, Say in the hills outside of the lower mississippi flood plain. Do they grow naturally in alluvial Amazonian soil, in uplands or both? And what about Caapi?

I would suggest you take a look at this growing guide for P. viridis. Altough the information is somewhat scattered along the Nexus, there is still a bunch of information about growing here.

I think one of the most important factors is soil pH and organic content. But from my experience the available light (they prefer halfshadow) and humudity (70-90%) are the determining factors to let these plant thrive...