Reserves of potash in million tonnes by country (2011)

In 2013, almost 70% of potash production was controlled by two cartels, Canpotex and the Belarusian Potash Company. The latter was a joint venture between Belaruskali and Uralkali, but on July 30, 2013 Uralkali announced that it had ended the venture.

Reference 1: Production and Reserves.

Reference 2: Canada, Russia, Belarus, Germany, China, Israel, Jordan, United States, Chile, Uzbekistan, United Kingdom, Spain, Brazil, Other countries and World total.

Source: http://en.wikipedia.org/wiki/Potash