Life cycle environmental impacts of integrated rice-crayfish farming: A comparative study of coculture and rotation...

Integrated aquaculture-agriculture farming has gained popularity in China due to its high economic returns, efficient nutrient utilization, and low pollutant emissions. However, life-cycle environmental impacts vary depending on the choice of functional units (FUs), which define the reference units used for comparison among product systems. In this study, life cycle assessment (LCA) is employed to evaluate the environmental impacts of two typical systems, rice-crayfish rotation (RCR) and rice-crayfish coculture (RCC), using four kinds of FUs: per unit area (ha), per unit energy content (100 kal), per unit Nutrition Density Unit (NDU), and per unit revenue (RMB). The results show that RCC exhibits greater environmental impacts than RCR only when assessed per unit area (ha), primarily due to additional material inputs such as feed and fertilizers. Under the other three FUs, however, RCC demonstrates 5.8-76.9% lower environmental impacts compared to RCR. Feed, fertilizers, electricity, and diesel are the main contributors to the environmental burdens, accounting for 63.4-72.0% for GWP, among others. For the RCC system, GWP is primarily attributed to field emissions and feed, with electricity playing a relatively minor role. Thus, reducing feed redundancy and developing alternative proteins can support the sustainability of rice-crayfish systems.