O`okala soil is volcanic ash.
As far as huglekultur goes, I listen to Paul Wheaton's podcasts all the time. My understanding is that the hugelkulture bed is permanent, should be at least 6 feet high, and are used as terriscaping features to alter water and temperature patterns on a micro scale (farm).
They had the expert, Sepp Holster, come to Montana last year and build a big one. They planted tons of potatoes, berries and other shrubs, and then broadcast the entire mound with mixed vegetables of all kinds. Supposed to be better every year but sounds like they plant it as soon as they build it.
Sounds a lot like a french intensive method my immigrant grandfather taught me, but on steroids.
Would love to hear peoples' experiences.