The US produces most of their own nitrogen, but the same is not true of potash.
The US does have potash mines for example around Carlsbad New Mexico. But these cover only a percentage of domestic need. Perhaps they could be scaled up not sure.
alt Hacker News
The US does have potash mines for example around Carlsbad New Mexico. But these cover only a percentage of domestic need. Perhaps they could be scaled up not sure.