Canada’s two largest fertilizer makers, Potash Corp. of Saskatchewan and Agrium, say they are negotiating a potential merger of equals. The two firms caution that the “preliminary discussions” won’t necessarily yield a transaction. PotashCorp had $6.3 billion in sales in 2015. It is the world’s largest producer of potash, with about 20% of global capacity, and a sizable maker of nitrogen and phosphate fertilizers. In fact, it derives a majority of its sales from those products. Agrium also manufactures the three main fertilizers. However, more than 80% of its $14.8 billion in sales last year came from its retail outlets. It operates more than 1,200 of them in North America alone. PotashCorp has been on the hunt for a major deal. Last year, Germany’s K+S rejected an $8.7 billion unsolicited takeover offer from the Canadian firm.