China produces cheap manufactured goods. But the U.S. is the world's largest producer of cheap agricultural goods. In fact, China's largest sources of meat source much of their feed from the U.S. The U.S. also pretty much only produces soy for export to China, as does Brazil. My point is that people thing the global economy would collapse if China stopped exporting manufactured goods, but China would starve without the rest of the world feeding their people.

China may be able to feed its people with its arable land, but the reality is that it would be only at a sustenance level. This is why China is investing so heavily in African agriculture.