Canada, Russia, Belarus and China are the major players in potash mining and production. The US doesn't mine or produce any in a substantial number. The US has huge import tariffs on China, and can't currently buy from either Russia or Belarus.
Canada needs to put a 50-70% export tariff on potash. That would crush US farming.
If Trump wants to play, let's burn them to the ground. Here is your 51st state you cunt.
I don't think Americans have it in them to do a general strike. Too much apathy and cowardice.