Urban agriculture is often associated with sustainable agricultural practices. However, the variety of systems qualifying as urban agriculture and the limited information available about their sustainability question this direct relationship. To better understand differences in intra-urban agriculture systems and their sustainability, this paper proposed an holistic classification of urban agricultural systems and collected knowledge about the environmental, social, and economic sustainability of these systems. Such a classification is important to evaluate sustainability claims on urban agricultural systems, anticipate potential sustainability trade-offs between urban agricultural systems and propose preventive measures to address these, and ultimately guide the sustainable deployment of these systems. Compared with existing classifications, the novel classification scheme proposed here accounts for technological, social and economic characteristics of urban agriculture systems to better distinguish between all systems. It was built on 91 scientific papers. The economic intensity of production was, for example, an important characteristic to coherently group urban agriculture systems. The intensity of cooperation between all actors was another characteristic emphasized for certain urban agriculture systems. One end of the classification scheme describes ground-based open, socially motivated urban agriculture systems with high cooperation intensity and low production intensity. The other end of the classification scheme describes building-integrated quasi-closed systems with high production intensity. In between, we find: building-integrated conditioned systems, ground-based conditioned systems, and building-integrated open systems. Mapping sustainability claims from literature in the classification scheme supported its definition along the three characteristics. For example, urban farming was associated with job creation, food safety, water savings, and higher yields while urban gardening with educational potentials, biodiversity improvements, and lower yields. Their display in the classification scheme was therefore supported. To further support the use of the proposed scheme, additional quantitative research to better understand and quantify the sustainability of urban agriculture systems is required.
