William McDonough + Partners have designed a conceptual plan to introduce rice production on rooftops in Liuzhou, China. A.A. of Metropolis Magazine, see below, writes, “William McDonough has been at the forefront of green roofs for almost a decade now. Recently his firm unveiled a conceptual proposal to bring rooftop farms to Chinese cities that are losing cropland at an alarming rate. For example, the city of Liuzhou?a former agricultural center in southern China with an oxbow river on its border and a surging population?is rapidly running out of places to plant soybeans and sugarcane. With help from the China-US Center for Sustainable Development, McDonough has envisioned a series of buildings with bridges connecting soil-bed roofs. German green-roof manufacturer Xeroflor will analyze how much weight in tree roots and rice-paddy water the roofs can handle.?The premier of China has said that if the country continues its current pace it will lose twenty-five percent of its farmland by 2020,? McDonough says. ?The current urbanization puts pressure on the good farmland, which is around the cities?and that pressure will then transfer itself to the perimeter, where the marginal lands are. Those lands are typically the last reserves of the natural world.?