This CCTV story gives official arable land losses of 300,000+ hectares in 2006.* I question these statistics. The central government has made maintenance of arable land a priority a few years ago. The change in the numbers was immediate: subnational data that I have examined show a dramatic reduction in land losses. Two possible reasons: first, the directive was implemented successfully and made a difference; second, local governments fudged the numbers. Almost certainly both are true to a greater and lesser extent in different places.
Two final thoughts:
The data from the CCTV story are from a national survey and thus should be less beholden to local governments than the local agricultural and statistics bureaus.
Terraced farming is iconic in China. It is evocative of China’s population density, its long history, and natural environment. In terms of the arable land statistics, it leads far too many mountains to be counted as arable (that is, potentially able to be farm, not actually in use for farming).