They barely compete now, and only for show. They divided up all the customers years ago, and don't call on each other's "accounts" with rare exception. Now every time POT announces a price increase, Mosaic follows suit the same day, at the same price. And the DoJ could not care less.
I totally agree, but that is rarely mentioned here, and many seem baffled as to why POT cannot raise prices at will, since they are such a dominant producer. Potash is as pure a commodity as corn or any other grain. Too much of any commodity results in lower prices, sometimes below production cost. If a farmer cannot pencil in a profit, even a small one, he will attempt to lower his production cost. P & K are the first to take a hit while he waits for the profitability in whatever he grows to return. It ain't rocket science.