North America’s top fertilizer producers are posting their best stock gains in years, with CF Industries Holdings Inc. leading in an industry that benefited from record high prices. CF closed at $74.32 on Dec. 28, up over 97.45 percent in 2021. The Mosaic Co. is also having a good year, with its stock climbing 70.2 percent to close at $39.96 as of Dec. 29, while shares of Nutrien Ltd. have gained 57.45 percent, closing at $76.05.