Evaluation of annual production and economic benefits of tropical rice-crayfish coculture system in China

In recent years, the rice-crayfish coculture has shown significant progress as an agricultural technology with significant economic value in the middle and lower reaches of the Yangtze River in China. Nonetheless, as the promotion of the technology expands, the unvarying co-culture method poses challenges in adapting to the diverse environmental conditions across different regions. This has resulted in regional disparities dominated by environmental factors, which have emerged as the primary obstacle to the advancement of rice-crayfish coculture. It is uncertain whether the rice-crayfish coculture model can be implemented in tropical regions due to the higher temperature and stronger solar radiation. Therefore, this study analyzes the feasibility of establishing the rice-crayfish coculture model through estimating the rice and crayfish annual production and the economic and ecological benefits in the tropical region. The growth, annual production, and nitrogen partial factor productivity (NPFP) of rice, nitrogen dynamics in the field water, as well as the economic inputs and benefits associated with the rice-crayfish coculture system over two years were evaluated in Hainan province. It was found that: 1) Even with a reduction of 33.3% in nitrogen fertilizer application, the annual production of the rice-crayfish coculture system remains equivalent to that of the rice monoculture system. Furthermore, the rice-crayfish coculture can increase the effective panicle number of rice. 2) The rice-crayfish coculture system can provide nutrients to support rice growth without polluting the water environment. The nitrogen fertilizer partial productivity in the rice-crayfish coculture system is significantly higher than that in the rice monoculture system. Crayfish culture introduced additional nitrogen in rice field at early stage, but it did not gain any form of nitrogen content in the field water at the end of the season. 3) In comparison to the rice monoculture system, the tropical rice-crayfish coculture system increased net profit by 152.82% -745.26%. 4) Comprehensive analyses of the growth, yield, and economic benefits showed that SXHN is better than YXYLS, which indicated that suitable varieties were needed for developing rice-crayfish coculture in the tropics. Rice-crayfish coculture is an economic and ecological agricultural system. However, rice-crayfish coculture encounters extensive technical challenges across various regions, because of the varied culture conditions. These challenges impede the expansion of the rice-crayfish coculture model. Therefore, this study aimed to evaluate the practicality of the rice-crayfish coculture system in the tropics to facilitate the development of the rice-crayfish coculture model.