I'm in a place where buying baking soda is proving to be quite difficult*, so I was looking for substitutions, and it seems there really aren't any. So this got me thinking: Baking soda is made (or otherwise harvested from nature) in some way.
How can I do this?
I realize the answer is likely to be so involved or expensive that I won't want to undertake the project, but for the determined baker, how would it be done?
*I eventually found some.