Environmental challenges threatening the continued growth of urban agriculture in the United States

Background/Question/Methods

Urban agriculture, though often difficult to define, is an emerging sector of local food economies in the United States. While urban and agricultural landscapes are often integrated in countries around the world, the establishment of mid- to large-scale food production in the US urban ecosystem is a relatively new development. Many of the urban agricultural projects in the US have emerged from social movements and non-profit organizations focused on urban renewal, education, job training, community development, and sustainability initiatives. While these social initiatives have traction, critical knowledge gaps exist regarding the science of food production in the urban ecosystem. Developing a science-based approach to urban agriculture will be essential to the economic and environmental sustainability of the movement. Drawing on scientific literature in the disciplines of agroecology, horticulture, plant physiology, and soil, water, and atmospheric sciences, this review seeks to characterize the limited state of the science on urban agricultural systems and to identify research questions most relevant to urban farmers, agroecologists, land-use planners, and environmental consultants.  

Results/Conclusions

Three primary environmental challenges were identified as most problematic to plants and humans in urban agroecosystems including, soil contamination, atmospheric pollutants and altered microclimatic conditions, and water contamination and conservation. Several research questions were identified and two projects have been initiated to address these environmental challenges. To address the issue of inorganic soil contamination (e.g., Pb) in urban soils, a study has been launched to compare crop productivity and ecosystem services provided by common soil remediation strategies for urban agriculture (e.g., cap-and-fill) with less expensive strategies (e.g., compost and cover crop soil amendment). Because so many atmospheric factors known to influence plant growth (e.g., CO₂, O₃, NO_x, and temperature) have been shown to vary in and around urban ecosystems, a second study seeks to quantify crop physiological response to atmospheric conditions across six sites positioned on a latitudinal gradient in the Chicago metropolitan region. Many urban farms are not economically self-sustaining and rely heavily on external grants to supplement farm income. However, as the movement grows and external funds become scarce, it will become increasingly important to develop science-based approaches to urban farming that maximize productivity per land area without jeopardizing the safety of farmers and consumers.