BEREZNIKI, Russia—In the foothills of Russia’s Urals mountains, a new potash producer is looking to lay claim to around a 10th of the global market for the fertilizer by the middle of the next decade.

EuroChem Group AG, a maker of nitrogen and phosphate fertilizers, is getting into the potash-mining business, in a move that could shake up a market dominated by a handful of producers in North America and the former Soviet Union.

By James Marson