Agribusiness and trading company Cargill Inc. posted a 59 percent drop in quarterly profit on Thursday, dragged down by plunging earnings at fertilizer maker Mosaic Co, in which Cargill is the majority shareholder. Cargill, one of the world’s largest private corporations, said it earned $489 million in the second quarter ended Nov. 30, compared with $1.19 billion a year earlier. Cargill, which operates in dozens of countries, is a leading U.S. grain exporter, a major producer of ethanol, and a top energy trader, among other businesses.