February 2023 -- Food production and resource use in urban ag

One of the most important contributions of the FEW-meter project is the large-scale tracking of inputs and outputs for urban agriculture. We recently published the results of this work in Agronomy for Sustainable Development, an effort led by Erica Dorr. One of the most interesting challenges of this work, which I think is worth thinking about here, is the diversity of urban ag sites we see around the world today. Our work focused on work in industrialized nations, specifically the US and Europe, and we were tasked with figuring out how to meaningfully bin those farms and gardens into categories that were both useful and insightful. 

To do this, we collected input from practitioners and academics, and we analyzed the goals of each site as well as its material inputs and outputs. From this, we identified three key types of UA sites represented among our sample: Urban farms - sites managed professionally for food production; Urban collective gardens - sites managed communally, often with volunteer labor, for social good; and Urban individual gardens - sites managed by individuals or a family unit. These are relatively consistent with some of the other attempts to classify UA, though it's difficult to say that any two systems are identical. We had a pretty extensive discussion of this in the motivations paper, though it also included some content about participant roles, since we were using individual-level surveys instead of site-level data for that. 

What's interesting is that, although we found differences across these types, we didn't end up finding that the typology itself was predictive of yield. We conducted a cluster analysis to try to figure out what was going on beneath the hood of these farms and gardens, and the most important thing we found for predicting yield was experience. Experience might come in the form of training, or it might come in the form of years in the dirt, but one way or another, those with more experience managed to grow more field. Not much else seemed to drive it. This sort of finding is particularly useful for cities looking to maximize food output at sites they support - at the end of the day, it might not be necessary to pay for the fanciest equipment. Instead, just pay for folks to go through a few trainings a year and grow as a gardener. 

Figure 5 (see citation below, credit Erica Dorr and copyright Agronomy for Sustainable Development) shows some of the nuance in these yield findings - for more discussion see the full text! 

Lots of other interesting results in there, but I wanted to share some of the intricacies of that typology assessment and the resulting findings. Here's the abstract as one last hook for you to check out the full text: 

There is a lack of data on resources used and food produced at urban farms. This hampers attempts to quantify the environmental impacts of urban agriculture or craft policies for sustainable food production in cities. To address this gap, we used a citizen science approach to collect data from 72 urban agriculture sites, representing three types of spaces (urban farms, collective gardens, individual gardens), in five countries (France, Germany, Poland, United Kingdom, and United States). We answered three key questions about urban agriculture with this unprecedented dataset: (1) What are its land, water, nutrient, and energy demands? (2) How productive is it relative to conventional agriculture and across types of farms? and (3) What are its contributions to local biodiversity? We found that participant farms used dozens of inputs, most of which were organic (e.g., manure for fertilizers). Farms required on average 71.6 L of irrigation water, 5.5 L of compost, and 0.53 m2 of land per kilogram of harvested food. Irrigation was lower in individual gardens and higher in sites using drip irrigation. While extremely variable, yields at well-managed urban farms can exceed those of conventional counterparts. Although farm type did not predict yield, our cluster analysis demonstrated that individually managed leisure gardens had lower yields than other farms and gardens. Farms in our sample contributed significantly to local biodiversity, with an average of 20 different crops per farm not including ornamental plants. Aside from clarifying important trends in resource use at urban farms using a robust and open dataset, this study also raises numerous questions about how crop selection and growing practices influence the environmental impacts of growing food in cities. We conclude with a research agenda to tackle these and other pressing questions on resource use at urban farms.

Dorr, Erica, Jason K. Hawes, Benjamin Goldstein, Agnès Fargue-Lelièvre, Runrid Fox-Kämper, Kathrin Specht, Konstancja Fedeńczak, et al. “Food Production and Resource Use of Urban Farms and Gardens: A Five-Country Study.” Agronomy for Sustainable Development 43, no. 1 (February 1, 2023): 18. https://doi.org/10.1007/s13593-022-00859-4