Urban ag is a highly place-based practice. No two gardens are the same, and it's difficult to say that what you know about one garden will apply to many others. This means that the research is almost always case studies, and it's very rarely generalized to a broad spectrum of farms or gardens. To generate insights relevant to a wider variety of urban ag sites, it's necessary to put together a big sample of farms and gardens (ala FEW-meter) or to combine the insights of a bunch of case studies. Rao et al. take the second approach in their recently published systematic review, where they analyzed 320 studies of urban ag to understand the geographic and thematic trends in urban ag research to-date.

The authors tackled two major questions - where is the study of urban ag focused, and what sorts of benefits are we identifying? The answer to their first question doesn't come as much of a surprise. As is pretty typical of case study work in the academic literature, the bulk of cases took place in the global north, especially Europe. North America took a distant second, and sub-Saharan Africa hosted the third most studies. To understand what researchers were looking for in these studies, the authors used thematic analysis to identify six key areas of sustainability that urban ag research has focused on to-date. Those areas are:

1. Environmental Sustainability, which focuses on ecosystem services, ecosystem function, and preserving planetary functions;

2. Material wellbeing, Labor and livelihoods, which is a combined code that addresses the various forms of human and social capital associated with urban ag;

3. Land and Tenure Security, which highlights the importance of land tenure and security of place for the sustainability of urban agriculture as well as the sustainability of communities more broadly;

4. Food and Nutritional Security, which is possibly the most obvious benefit of urban agriculture, but which is actually a fairly contentious benefit, since the extent to which this benefit reaches the most food insecure folks in a community is often unclear;

5. Subject and relational wellbeing, which focuses on people's perceptions of their own wellbeing and the health of their relationships with others; and

6. Gender and social differentiation, which focuses on the politics of difference in the context of urban agriculture, particularly along lines of identity.

The authors found that the frequency of topics varied significantly across regions, but that work in the Global North tended to focus on Environmental and Social Sustainability (themes 1, 5, and 6), while studies in the Global South spoke more often of Economic Sustainability (themes 2, 3, and 4).

The authors dive into each of these themes in great detail, but what really stands out to me is the remarkable diversity of findings that appear in the papers they analyzed. For example, environmental sustainability and urban agriculture certainly do not have a black and white relationship, with some articles discussing at length the benefits to urban heat island and material recycling, among other benefits, and other articles pointing out the possible negative effects of additional fertilizer use in cities and the potential for environmental justice concerns with air and water pollution. In other words, we still have a lot of work to do to really understand the effects of urban ag on cities.

Rao, N., Patil, S., Singh, C., Roy, P., Pryor, C., Poonacha, P., & Genes, M. (2022). Cultivating sustainable and healthy cities: A systematic literature review of the outcomes of urban and peri-urban agriculture. Sustainable Cities and Society, 85, 104063. https://doi.org/10.1016/j.scs.2022.104063