Potash, evaporating, from space, land and air. Potassium is a vital ingredient of fertilisers, without which the sustainable world population may be something like 2 billion humans, and areas where it can be obtained in a form easily used by plants such a salt are at a premium. Much of the USA gets its stock from mines like the Intrepid mine in Moab, Utah (depicted in the photos) which produces 60% of its supply.









