Christian Science Monitor: Dennis Lindsay still recalls the day four decades ago when his father, an Iowa farmer, began using nitrogen fertilizer on the family’s 160 acres. With nitrogen, the family’s corn crop suddenly grew much higher and stronger, and produced full ears and big harvests. When fed to their cows and pigs, that high-quality corn produced far more milk and meat. As a result, the family bought more livestock – and the farm grew. “I remember Dad bringing the neighbors over to see how much greener …