Farmland Conversion Decreases Regional and National Land Quality in China

Maintaining sufficient farmland to ensure food security and a strong rural economy is crucial for China. At the national as well as regional levels, we compared the quality of the land converted from and to farmland during the period 1986–2005, thus quantifying the change in farmland quality directly attributable to land-use conversion. Specifically, we compared land cover maps compiled for the initial and final years of the study period at a 1:250,000 scale by institutes of the Chinese Academy of Sciences, and combined this with national land quality assessment data compiled at the beginning of the period. Comparison of the land cover maps revealed that over the 20-year period 12·9 Mha of farmland were converted to other land uses and 14·0 Mha of new farmland were brought under cultivation. Large net increases in farmland area occurred in Heilongjiang, Jilin, Liaoning, Xinjiang, and Inner Mongolia, together contributing 3·5 Mha of the net increase in farmland area. Several developed provinces, e.g. Beijing (−21·20%), Shanghai (−15·81%), Zhejiang (−9·85%), Guangdong (−7·79%), and Tianjin (−6·35%), experienced rapid farmland decreases. Although there was a net increase in farmland, the most suitable and productive farmland decreased by 1·8% while low-quality farmland increased by 1·4%. Thus, focusing solely on maintaining the total farmland area did not prevent overall loss of a substantial amount of high-quality farmland. Farmland protection policies should therefore take into account both farmland quantity and quality. Copyright © 2016 John Wiley & Sons, Ltd.