BACKGROUND
Rice-crayfish coculture (RC) uses 10% of the paddy field area for crayfish ditches, with rice cultivated in the remaining area, providing staple carbohydrates alongside fish rich in protein and essential oils. These systems rely on complex interactions, involving nutrient cycling, fish feeding, soil physicochemical modification, and insect-pest predation, and have important socio-economic effects. Past studies have considered only one or a few of these aspects pertinent to food system sustainability, and there remains a need for an integrated assessment of RC systems. In this mini-review, we collate data from two field experiments and three field surveys published across eight papers to synthesize the overall sustainability of RC systems in Jianghan Plain in China.

RESULTS
In deep groundwater fields, the RC rice yield was 30–55% lower than for typical rice-rapeseed (RR) rotations, while CH4 emission and pesticide use were 41–96% and 50% lower, respectively. In shallow groundwater fields, RC rice yield was similar to typical rice monoculture (RM) cultivation, while CH4 emission and pesticide use were 28–41% and 17% lower for RC cultivation. Field survey data indicated that RC can improve soil nutrient and organic matter content significantly compared with RM cultivation, and also increase the diversity of fauna and flora in the paddy field whilst reducing the incidence of chilo suppressalis (a major rice pest). Feed inputs to RC systems increased crayfish yield by 31–71% and reduced the fraction of N inputs lost to the environment from 71% to 41%.

CONCLUSION
We conclude that RC systems with feed inputs in areas with shallow groundwater can deliver improved food security, sustainability, and resilience through ecological intensification. © 2020 Society of Chemical Industry