The lede: Potash has no substitute in row-crop agriculture, and Russia and Belarus together control roughly a third of global supply — a chokepoint Washington has weaponized before and could again. Belaruskali and Russia's Uralkali sit alongside Nutrien and Mosaic as the world's four dominant potash suppliers. If the U.S. reverses course and slaps new tariffs or duties on Russian- and Belarusian-origin potash (mirroring the escalating EU duty schedule, which ramps toward roughly €430/tonne by 2028), the effect isn't a uniform "fertilizer stocks up" trade. It's a reallocation of pricing power toward whichever North American producer has the most exposed potash tonnage and the least offsetting business elsewhere — and that split is exactly where Nutrien and Mosaic diverge.