alt Hacker News> There is enough nitrogen and other nutrients in alder that the area's where they are piled and burnt will remain significantly more fertile for many years after.
My experience with burn areas is that the potash alone will do this. Are you sure that the nitrogen is what's surviving? It could be - sodium nitrate has a fairly high combustion temp of ~300C - but even then it's being boosted by the concentrated potassium left over.
That gives me a target temp for building a regenerative bio char kiln * , Thanks!
* in a regenerative kiln, volotiles are captured and fed to a burner to provide the bulk of the heat needed to char organic materials, the chared materials can do double duty as soil amendments and long term carbon storage or as fuel for a variety of uses. Also the volotiles can be condenced as liquids that have a wide variety of other uses. What would be interesting is if there might be a way to use an enhanced combustion process to capture extra atmospheric nitrogen in the bio char materials.