Consider U.S. farmers happy. They are exporting record volumes of products to China. Shipments of soybeans, corn and pork are bringing smiles back to the American heartland. Or, to put this another way, Beijing is effectively acknowledging it cannot feed the Chinese people. China's leader, Xi Jinping, recently made such an admission. Last August, he announced what became known as the "clean your plate" campaign to end what he called a "shocking and distressing" waste of food. Just about everyone saw this effort, to get the Chinese people to eat less, as a warning of food shortages to come. Chinese...