Spatial optimization and zoning guidance strategy of rice-aquatic coculture system in Jiangsu Province, China

Abstract: A rice-aquatic coculture system is of great significance to explore the paddy field resources for the food supply security in the green development of agricultural industry. It is very necessary to identify the priority areas for the industrial decision-making on the overall planning and layout. Taking Jiangsu Province of China as the research area, this study aims to comprehensively evaluate the spatial priority level of industrialization development. A quantitative evaluation index system was also constructed from two dimensions of natural suitability and industrial dominance. Four indexes were selected for the natural suitability, including the water network density, water source abundance, soil sandiness, and terrain. The hydrology, terrain and soil data were applied using the grid unit in the paddy field. The priority rating of natural suitability at county level was assessed to transform from the comprehensive scores of the above indexes of natural space units to the score of county unit through scale conversion. Alternatively, the priority rating of industrial dominance was evaluated directly at the county level, where nine indexes were selected from three aspects of labor force, infrastructure and industrial soft environment, according to the production statistics data of key demonstration areas that issued by the agricultural administration department. The evaluation results showed that 13.8% of the total paddy field area in the study area was highly suitable for the rice-aquatic coculture systems, and 57.0% was the moderately suitable space; The high-score areas of natural suitability were mainly distributed in the Lixia River area and extended to the North Jiangsu irrigation canal in Northern Jiangsu, as well as the eastern Yangtze River plain south of the Yangtze River to the Tai-Lake Plain, indicating two concentrated distribution areas to the periphery. There was the high industrial dominance level around the hinterland of Lixia River plain in the north. By contrast, the high-score areas in the south were mainly distributed in the suburban counties adjacent to the metropolis of Shanghai and Nanjing. The development types were classified among all county-level administrative units, according to the combination characteristics of the priority rating of natural suitability and industrial dominance level. Four types with 16 squares at county level were then identified, corresponding to four development strategies: the key development, moderate support, optimized adjustment, and control development. Specifically, the key development areas were represented by the Lixia River plain area in the north and Tai-lake Plain water network area in the south. Differentiated industry can be orientated in the center of the industrial development of rice-aquatic production system, according to the dislocation competition strategy. The rest agricultural areas can turn the resource advantages into industrial ones, according to the development strategy of "one land, one aquatic product and one industry". The emphasis can be shifted from the quantity-based expansion to quality-based promotion in the areas around Hongze Lake, in order to strengthen the intensive and efficient utilization of paddy field resources for the industrial upgrading. These findings can provide references on the rice field resource for the high quality and efficiency in the rice-aquaculture industry.