In "And the Lawn Won" (Back Page, June 6) writer Joe Essid claimed that "much fertilizer is made from petroleum." He corrects himself: "In fact, natural gas is more widely used than liquified petroleum in the process of making ammonia for fertilizers. Given projections for rising use of natural gas and its finite supply, however, I stand by my larger claim that we are entering an era when higher energy costs will cause fertilizer prices to rise. Readers wanting more information should search online for the United Nations' document 'Mineral Fertilizer Production and the Environment.'"
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