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.

缺乏关于城市农场使用的资源和生产的食物的数据。这阻碍了量化城市农业或工艺政策对城市可持续粮食生产的环境影响的尝试。为了解决这一差距，我们使用公民科学方法从 72 个城市农业地点收集数据，这些地点代表五个国家（法国、德国、波兰、英国和英国）的三种类型的空间（城市农场、集体花园、个人花园）美国）。我们用这个前所未有的数据集回答了关于都市农业的三个关键问题：(1) 它对土地、水、养分和能源的需求是什么？(2) 相对于传统农业和不同类型的农场，它的生产力如何？(3) 它对当地生物多样性的贡献是什么？我们发现参与者农场使用了数十种投入，其中大部分是有机的（例如肥料）。农场平均需要 71.6 L 灌溉水、5.5 L 堆肥和 0.53 m^2个 每公斤收获粮食的土地面积。个别花园的灌溉率较低，而使用滴灌的地点则较高。虽然变化很大，但管理良好的城市农场的产量可以超过传统农场的产量。虽然农场类型不能预测产量，但我们的聚类分析表明，单独管理的休闲花园的产量低于其他农场和花园。我们样本中的农场对当地生物多样性做出了重大贡献，每个农场平均种植 20 种不同的作物，不包括观赏植物。除了使用强大且开放的数据集阐明城市农场资源使用的重要趋势外，这项研究还提出了许多问题，即作物选择和种植实践如何影响城市种植粮食对环境的影响。