How Much Food Can We Grow in Urban Areas? Food Production and Crop Yields of Urban Agriculture: A Meta‐Analysis.

Urban agriculture can contribute to food security, food system resilience and sustainability at the city level. While studies have examined urban agricultural productivity, we lack systemic knowledge of how agricultural productivity of urban systems compares to conventional agriculture and how productivity varies for different urban spaces (e.g., allotments vs. rooftops vs. indoor farming) and growing systems (e.g., hydroponics vs. soil‐based agriculture). Here, we present a global meta‐analysis that seeks to quantify crop yields of urban agriculture for a broad range of crops and explore differences in yields for distinct urban spaces and growing systems. We found 200 studies reporting urban crop yields, from which 2,062 observations were extracted. Lettuces and chicories were the most studied urban grown crops. We observed high agronomic suitability of urban areas, with urban agricultural yields on par with or greater than global average conventional agricultural yields. "Cucumbers and gherkins" was the category of crops for which differences in yields between urban and conventional agriculture were the greatest (17 kg m−2 cycle−1 vs. 3.8 kg m−2 cycle−1). Some urban spaces and growing systems also had a significant effect on specific crop yields (e.g., tomato yields in hydroponic systems were significantly greater than tomato yields in soil‐based systems). This analysis provides a more robust, globally relevant evidence base on the productivity of urban agriculture that can be used in future research and practice relating to urban agriculture, especially in scaling‐up studies aiming to estimate the self‐sufficiency of cities and towns and their potential to meet local food demand. Plain Language Summary: By growing crops in cities and towns directly for urban consumers, we can make the food system more sustainable and resilient, and we can help to improve human health by increasing the accessibility to freshly grown foodstuffs. However, we lack information and evidence about what we can grow in urban areas, what quantity we can hope to produce, and which urban spaces could and should be used for urban food production. In this study, we aim to quantify the global crop yields of urban agriculture and see how they compare with those of conventional agriculture. We also investigate whether yields vary based on the urban spaces and growing systems where the crops are grown. We found that urban settings are productive places and can welcome a wide variety of crops (such as vegetables, legumes, cereals, soft fruit, orchard fruit, oil crops and fiber crops). Some spaces are more suited to specific crops than others, such as hydroponics for tomatoes, for instance. Findings from this paper allow us to draw a more accurate picture of the role urban agriculture could play in meeting global food demand alongside rural agriculture and contribute to increasing food security. Key Points: A meta‐analysis was conducted to quantify crop yields of urban agriculture and investigate how they compare with conventional agricultureUrban areas have high agronomic suitability, with urban agricultural yields on par with or greater than conventional agricultural yieldsYields differ significantly between certain urban spaces and growing systems where crops are grown, which shows varying crop suitability [ABSTRACT FROM AUTHOR]