Ecosystem services analysis for sustainable agriculture expansion: Rice-fish co-culture system breaking through the Hu Line

• The first ES evaluation of rice-fish (RF) co-culture in the northwest of the Hu Line. • Posited three new ES indicators as to social security, saline-alkali soils and energy. • The ES value of the RF co-culture is 4.78 times as large as the cropland ES value. • Explored the driving forces to spread rice-fish culture northwest of the Hu Line. Developing sustainable agriculture in ecologically fragile areas is important. To date, the ecological service value of the rice-fish co-culture in the northwest area of the Hu Line is unclear. Based on the Millennium Ecosystem Assessment and understanding of the rice-fish co-cultures functions in the ecosystem, we construct the driving force relationship among the environment, resources, development, and social response using Yinchuan, northwest of the Hu Line, as an example. Then, we develop a multi-angle ecosystem services (ES) value assessment framework that involves 23 ES indicators. The results indicate that the ES value of the rice-fish co-culture is 266,691.89 RMB/hm 2 /year, which is 35.72% higher than that of rice monoculture. Compared with an estimated value of global ecosystem services in previous studies, the ES value of the rice-fish co-culture is 4.78 times as large as that of the cropland, slightly lower than the ES value of the wetlands. Moreover, the ES value of the rice-fish co-culture is 354.37% of its direct economic value. This doubling is mainly due to the contribution from non-economic ecological services, which may be the driving force behind the rice-fish co-culture breaking through the Hu line. This study explains the sustainability characteristics of this agricultural model in Yinchuan. Further, it expounds on the significance of the rice-fish co-culture in breaking the ecological barriers in global arid and semi-arid areas.