Despite several current issues facing some of China’s farmland (e.g., shrinking arable land, soil pollution, toxic water), a substantial amount of progress has been made in the past three decades of reform:

The trajectory of rising agricultural productivity was similar in post-Mao China. China’s population doubled, and its GDP rose 45-fold. While the amount of land harvested for corn in China also doubled, each acre produced 4.5 times more than it did in 1960. Ausubel and his colleagues calculate that rising Chinese corn productivity spared 120 million hectares (an area more than twice the size of Texas) that would otherwise have been plowed up. The United Nations’ Food and Agriculture Organization reports that Chinese forests expanded 30 percent between 1990 and 2010.

Via: Peak Farmland?   See also: Ch 3 & 18