Advances and Challenges Between Urban Agriculture and the Circular Economy to Promote Sustainable Cities

In this study, we examined the literature on how urban agriculture under a circular economy (CE) model contributes to the development of sustainable cities. Through bibliometric and factorial analyses of the conceptual structure of the publications indexed in Scopus, we provided a brief overview of the scientific trends, impacts, and barriers. The results indicated that research on the intersection between the three themes is still in its early stages. The CE promotes networks of urban resources for their recovery and reuse for nutritional, water, and energy purposes in urban agriculture. Urban agriculture has been proposed as a nature-based solution where CE can play a vital role in enhancing the ecosystem services it provides. Although CE has not been investigated as a transversal system in the productive cycle of urban agriculture, we identified assessments of the reuse of agricultural resources. Composting, hydroponics, and vertical agriculture are the urban agriculture techniques that have been most closely associated with CE through strategies such as the use of recycled fertilizers, the incorporation of renewable sources, and the establishment of industrial symbiosis processes. Moreover, urban metabolism and life cycle assessment are crucial tools for material and energy flows. In conclusion, the synergy between CE and urban agriculture can trigger regeneration processes that transform cities in a sustainable way. Efforts toward holistic and measurable approaches to the multiple sustainable benefits generated by this synergy for cities are needed.