They are being shut down for maintenance, but also to reduce supplies.
It announced a few weeks ago that it will be closing a big mine in New Brunswick.
The company is reacting to a sharp decline in prices – from a peak of $900 a tonne in 2008 to about $300 now.
The decline began when a cartel between Russia and Belarus fell apart and both increased production and cut prices.
There is an export cartel for Canada’s three major potash miners – Potash Corp. of Saskatchewan, Agrium and Mosaic.
It's probably a good time for farmers to stock up the potash content of their soils. When prices peaked, many farmers were able to sharply reduce or even eliminate applying potash because they could rely on inventories in the soil for the short term.