Abstract:

Changes of rice production in Southern China are crucial to national food security. This study employed Landsat images to map the distributions of paddy rice cropping systems in Southern China in 1990 and 2015, and then explored the impact of rice multiple cropping index changes on grain production capacity. The results indicated that: (1) From 1990 to 2015, the multiple cropping index of rice decreased from 148.3% to 129.3%, and the loss area due to conversion of double cropping rice to single cropping rice ("double to single") was 253. 16×10⁴ hm². The area with most dramatic changes was located in the Middle-Lower Yangtze Plain. The rice cropping systems in Southern China showed a change pattern of "double cropping rice shrinkage and single cropping rice expansion" from north to south. (2) From 1990 to 2015, "double to single" led to a reduction of 6.1% and 2.6% in rice production and grain production, respectively. Hunan and Jiangxi, located in the main rice producing areas, as well as Zhejiang with better economic development, had a large reduction in rice production due to "double to single", all exceeding 13%. (3) The grain production capacity of "double to single" paddy field is equivalent to that of 223.3×10⁴ hm² of newly reclaimed cultivated land. The equivalent newly reclaimed cultivated land is 54% of the total newly reclaimed cultivated land through the land consolidation project during 2001-2015, as well as 1.7 times the target of the newly cultivated land goal for the national land consolidation plan (2016-2020). Making full use of the "double to single" paddy field can save approximately 167.44 billion yuan newly reclaimed cultivated land costs. Therefore, instead of pursuing low-quality "new" arable land, it is better to make full use of the existing high-quality "old" arable land. The government should change the assessment method of cultivated land balance, and incorporate the sown area increased by improving multiple cropping index into the cultivated land compensation indicator.

Key words: rice multiple cropping index, food security, double-cropping rice to single-cropping rice, Southern China, policy implications