Should Mosaic Stock Holders Look At CF Industries Instead?

Mosaic (MOS) stock has lost 42% over the past twelve months, while CF Industries stock has returned 32%. Investors buy both fertilizer makers for the same reason: farmers need the product and the global supply of nitrogen and phosphate is tight. Yet their underlying businesses differ. Mosaic sells phosphate and potash, while CF sells nitrogen. Which of the two is actually earning more from short supply.