A price war in the potash market is pushing down profits and inciting political tension, making for a difficult investment environment at least through the end of next year. With a small number of players controlling a large swath of global potash sales, Citi Research analysts Andrew Benson and Tina M. Fordham think it’s only a matter of time before the sector returns to oligopolistic pricing, but most companies are better avoided in the short term. Potash market share problem Problems started when Uralkali OAO (LON:URALL) (OTCMKTS:URALL) exited Belarusian Potash Co on July 30, most likely in reaction to its plummeting…