Gauging the environmental impact of urban farms and gardens
“Working closely with the people implementing these practices, we can better understand what drives the environmental performance of urban agriculture,” Dr. Cohen says.
By The City University of New York
Phys.org
Agronomy for Sustainable Development (2023).
Food production and resource use of urban farms and gardens: a five-country study
Erica Dorr, Jason K. Hawes, Benjamin Goldstein, Agnès Fargue-Lelièvre, Runrid Fox-Kämper, Kathrin Specht, Konstancja Fedeczak, Silvio Caputo, Nevin Cohen, Lidia Poniy, Victoria Schoen, Tomasz Górecki, Joshua P. Newell, Liliane Jean-Soro & Baptiste Grard
(Must Read. Mike)
Excerpt:
Urban agriculture is rapidly growing in cities across the global north, but without data on its environmental impact, it’s all but impossible to craft policies for sustainable urban food production.
To address this gap, an international team of researchers including Associate Professor Nevin Cohen studied a large, diverse sample of urban farms and gardens in five countries and generated a uniquely powerful dataset for understanding the relationships between urban farm and garden yields, resource use, and urban farmers and gardeners.
The researchers used a citizen science approach to collect data from 72 urban agriculture sites in France, Germany, Poland, the United Kingdom and the United States. They found that resource use and yields varied widely, and that climate and location could not explain most of the differences.
Farm type, such as collective garden, individual, garden or urban farm, could explain differences in several dimensions of resource use, but failed to predict production potential. The most important differentiator appeared to be collective versus individual management.
Yields at many well-managed urban farms exceeded those of conventional rural farms, and the farms in the sample contributed significantly to local biodiversity, with an average of 20 different crops per farm not including ornamental plants.
Read the complete article here.
Abstract:
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.
