About 15 years ago, Jim Vansteenkiste got a phone call from Kroger that changed his life. It was 1997 or ’98, and the fourth-generation farmer had spent decades working the same land his father had worked before him, in Michigan about an hour’s drive from Detroit. In winter the land turned into icy white tundra dotted with collard green stalks spiking up through the snow, but even in the middle of a storm he could tell you which field held eggplants the year before, and which held squash. In the summer it was lush and green, and covered in four dozen kinds of vegetables, stuff he’d been selling to Kroger and Farmer Jack — two big grocery chains — his whole life. But then he got the call from a Kroger buyer, telling him he would lose the contract and, with it, half his business. Tall and trim, with the sun-creased eyes of a life worked outdoors, Vansteenkiste knew that unless he figured something out, he could lose the farm, too.