From the Guardian:

China's ability to feed a fifth of the world's population will become tougher because of land degradation, urbanisation and over-reliance on fossil-fuels and fertiliser, a United Nations envoy warned today as grain and meat prices climbed on global markets.

With memories still fresh of the famines that killed tens of millions of people in the early 1960s, the Chinese government has gone to great lengths to ensure the world's biggest population has enough to eat, but its long-term self-sufficiency was questioned by UN special rapporteur on the right to food, Olivier De Schutter.

"The shrinking of arable land and the massive land degradation threatens the ability of the country to maintain current levels of agricultural production, while the widening gap between rural and urban is an important challenge to the right to food of the Chinese population," said De Schutter at the end of a trip to China.

China's ability to feed its people questioned by UN expert