The article is quite long, but here's an excerpt:
There are a few cities in the world that grow and provide about half their total food supply within their urban and peri-urban regions—Dar es Salaam, Tanzania; Havana, Cuba; Hanoi, Vietnam; Dakar, Senegal; Rosario, Argentina; Cagayan de Oro in the Philippines; and, my personal favorite, Cuenca, Equador—all of which have much longer growing seasons than Detroit. However, those cities evolved that way, almost unintentionally. They are, in fact, about where Detroit was agriculturally around one hundred and fifty years ago. Half of them will almost surely drop under 50 percent sufficiency within the next two decades as industry subsumes cultivated land to build factories (à la China). Because of its unique situation, Detroit could come close to being 100 percent self-sufficient.
First, the city lies on one hundred and forty square miles of former farmland. Manhattan, Boston, and San Francisco could be placed inside the borders of Detroit with room to spare, and the population is about the same as the smallest of those cities, San Francisco: eight hundred thousand. And that number is still declining from a high of two million in the mid-nineteen fifties. Demographers expect Detroit’s population to level off somewhere between five hundred thousand and six hundred thousand by 2025. Right now there is about forty square miles of unoccupied open land in the city, the area of San Francisco, and that landmass could be doubled by moving a few thousand people out of hazardous firetraps into affordable housing in the eight villages. As I drove around the city, I saw many full-sized blocks with one, two, or three houses on them, many already burned out and abandoned. The ones that weren’t would make splendid farmhouses.
As Detroit was built on rich agricultural land, the soil beneath the city is fertile and arable. Certainly some of it is contaminated with the wastes of heavy industry, but not so badly that it’s beyond remediation. In fact, phyto-remediation, using certain plants to remove toxic chemicals permanently from the soil, is already practiced in parts of the city. And some of the plants used for remediation can be readily converted to biofuels. Others can be safely fed to livestock.
Leading the way in Detroit’s soil remediation is Malik Yakini, owner of the Black Star Community Book Store and founder of the Detroit Black Community Food Security Network. Yakini and his colleagues begin the remediation process by removing abandoned house foundations and toxic debris from vacated industrial sites. Often that is all that need be done to begin farming. Throw a little compost on the ground, turn it in, sow some seeds, and water it. Water in Detroit is remarkably clean and plentiful.