Like any plant, marijuana saplings need fertilizer. Potash Corporation of Saskatchewan Inc. (TSX:POT)(NYSE:POT) is North America's largest provider of potash, which ultimately gets made into all sorts of different fertilizers. There are a couple of issues with Potash, however. First of all, the company has proposed it will merge with Agrium to create a huge crop-input powerhouse. We're still waiting for regulatory approval on that deal. And second, even if marijuana growing becomes a big deal in Canada, it's still going to take an awful lot of pot plants to really make an impact. Think about how much wheat, canola, and other crops get grown in Canada.