Cargill Inc. said Wednesday that profits for the third quarter grew 30 percent despite an unsteady commodity market. The Wayzata-based agribusiness giant said profit for the quarter ending Feb. 28 was $763 million, up from $588 million in the same period a year earlier. Sales for the period rose 21 percent to $30.5 billion, the private company said in a news release. Those numbers excluded any earnings from The Mosaic Co., the publicly held fertilizer company that Cargill is spinning off.