Investment funds have become voracious buyers of U.S. farmland, amassing over a million acres as they seek a hedge against inflation and aim to benefit from the growing global demand for food, according to data reviewed by Reuters and interviews with fund executives. Though their acreage is a small slice of the nearly 900 million acres of U.S. farmland, the pace of acquisitions by investment firms like Manulife Investment Management and Nuveen has quickened since the 2008 global financial crisis