As the finishing touches go on this themed issue, evidence of widespread enthusiasm for urban farming is apparent in many developed countries. Farming in the city, commonly referred to as urban agriculture, has been put forth as a solution to multiple social problems, including the provision of new green spaces, control of runoff and provision of shade that offsets the heat of the concrete city. In cities with abundant vacant land and abandoned plots, urban agriculture promises a reduction of urban blight.

Urbandale Farm (Lansing, MI) has much in common with other urban agricultural projects throughout the US and especially those in the rust-belt cities of the Midwest. It raises food for an economically challenged neighborhood. It offers opportunities for local participation, education and job creation, and it is supported by diverse public and private institutions. By all official accounts, Urbandale Farm is good at what it does. Its acreage, production, income and entrepreneurial activities are all increasing, and it has become a poster child for urban agriculture throughout the city. However, despite its good work (or possibly because of it), Urbandale Farm, and urban agriculture more generally, may unwittingly be helping to rationalize the displacement and continued social and political inequity of urban neighbors rather than reinforcing greater place-making, neighborhood empowerment and sustainability. Using Urbandale Farm as a case in point, this paper critically explores how urban agriculture is being used by some scholars, activists, governmental offices and agencies to transform fragile neighborhoods. It questions some of the movement's underlying assumptions as well as some of its actual benefits and beneficiaries. The paper also offers suggestions—for the purpose of initiating a more nuanced conversation—on how urban agriculture can be reconfigured philosophically and practically to shed its neoliberal tendencies and contribute to a more structurally based social and political transformation.

Despite the surge of interest in urban agriculture, there have been few studies that address the biophysical challenges and opportunities of food production in urban environments. This study aims to determine the relative influence of atmospheric pollutants and microclimatic factors on the physiological response and productivity of vegetable crops across an urban-to-rural latitudinal transect in the greater Chicago metropolitan region. Data collected at each of six sites include continuous measures of atmospheric pollutants and microclimatic factors, and biweekly measures of physiological response and yield of various vegetable crops and cultivars. Preliminary data collected in early 2013 suggest that there is substantial variability in environmental factors and crop yield across this urban-to-rural transect. Results of this study will provide a scientific basis for crop adaptation to the urban environment and establish practical crop and cultivar recommendations for urban and peri-urban farmers in the North Central US.

Kitchen gardens may improve family food security and nutrition. While these gardens are the domain of women in Afghanistan, women face unique challenges accessing training and resources to maximize small-scale agricultural output. The University of Maryland's Women in Agriculture Project builds capacity among female extension educators to work with vulnerable women to implement and maintain kitchen gardens. Extension educators use experiential methods to teach vegetable gardening, apiculture, small-scale poultry production, post-harvest handling and processing, nutrition and marketing through workshops, demonstration gardens and farmer field schools. This paper explores contextual factors related to women's food security and agricultural opportunities, describes key project activities and approaches and discusses project success and challenges, sustainability and implications for future programs.

In the United States, interest in urban farms and community gardens is flourishing, yet the urban home food garden (UHFG) and its contributions to urban systems have been overlooked and understudied. To begin to address this gap, we are conducting a mixed methods study of African American, Chinese-origin and Mexican-origin households with home gardens in Chicago, IL. Study methods include in-depth interviews, participant observation, ethnobotanical surveys and analysis of the chemical and physical properties of garden soils. As of this writing, findings indicate that home gardening has an array of beneficial effects, contributing to household food budgets and community food systems, the reproduction of cultural identity and urban biodiversity. The majority of informants in the study were internal or international migrants. For these individuals, gardening, culture-specific food plant assemblages and the foodways they support represent a continuation of cultural practices and traditional agroecological knowledge associated with their place of origin. The gardens of some migrant households also harbor urban agrobiodiversity with roots in the Global South. At the same time, gardens may have less salubrious effects on urban systems and populations. A lack of knowledge of safe gardening practices may expose vulnerable populations to environmental hazards such as soil contaminants. Gardeners in this study reported using synthetic chemical fertilizers and pesticides, sometimes indiscriminately, and the repeated application of synthetic fertilizers and compost may contribute to the nutrient loading of urban stormwater runoff. These effects may be moderated by the relatively low bulk density and high porosity of garden soils due to tillage and the application of organic matter, which can be expected to enhance stormwater infiltration. While the UHFG's potential contributions to urban systems are significant, outreach and research are needed to help gardeners grow food safely and sustainably in ways that contribute to overall ecosystem health.

According to the United States Census, California is the most urban state in the nation. Although there are many outstanding examples of urban farms in California, in general, urban agriculture (UA) has been slower to gain momentum here than in some other states with large urban populations. Over the past several years, urban agriculture's popularity in California has begun to escalate, with strong emerging interest in San Francisco, San Jose, Oakland, San Diego, Los Angeles and other metropolitan communities. One challenge for urban farmers and municipal decision makers engaged with UA in California has been limited availability of relevant information and technical assistance. A new project team at the University of California Cooperative Extension, part of the Division of Agriculture and Natural Resources (UC ANR) is working to develop web-based educational resources that will be grounded in a needs assessment that is currently underway. The needs assessment includes a literature review, an internal survey of UC ANR personnel, and community clientele interviews. This paper will report on preliminary findings and analyses of the needs assessment, particularly how UC ANR personnel are engaged with UA, and what tools they think would best serve urban farmers. We suggest implications for those involved with UA, such as personnel of land-grant universities, local governments and non-profits seeking to address the needs of urban farmers in an environment of constrained resources.

Considering global trends such as climate change and resource scarcity, a major challenge of future cities will be to reduce urban footprints. Moreover, cities have to become or remain livable for their inhabitants and offer social and economic opportunities. Thus, reconnecting food production and cities offers promising potential. The diffusion of urban farming reflects a rising awareness of how food and farming can shape our cities. A growing number of urban farming projects exist in and on urban buildings, including open rooftop farms, rooftop greenhouses and indoor farming. These projects are characterized by the non-use of land or acreage for farming activities. We use the term ‘Zero-Acreage Farming’ (ZFarming) to represent these farms. The objective of this paper is to: (1) illustrate and systemize present practices of ZFarming and (2) discuss specific novelties of ZFarming in the wider context of urban agriculture. We analyzed 73 ZFarms in cities of North America, Asia, Australia and Europe using a set of criteria, and developed a typology of ZFarming, complemented by in-depth interviews with pioneers in rooftop farming in New York. The results illustrate that ZFarming generates innovative practices that may contribute to a sustainable urban agriculture. Besides growing food, it produces a range of non-food and non-market goods. It involves new opportunities for resource efficiency, new farming technologies, specific implementation processes and networks, new patterns of food supply and new urban spaces.

Although interest in integrating agriculture into the urban landscape in the USA is increasing rapidly, there is a shortage of guidance for agricultural production in this context as well as a unique set of significant biophysical constraints. A common constraint is not being able to grow directly in the soil, making raised-bed gardening a necessity. Subirrigated planters (SIPs) are a style of raised bed with a subsoil reservoir that provides aeration and allows growers to irrigate below the soil where water is pulled up via capillary action. This bed design has vocal advocates; anecdotally, growers find them to be high yielding, water efficient and easier to maintain than standard raised beds. Given their apparent promise, there is interest in promoting SIPs and in utilizing them in larger-scale urban gardening operations but no rigorous tests compare these beds relative to standard raised beds. At one location and for one season, we compared yields for three crops: cayenne pepper (Capsicum annuum), sungold cherry tomatoes (Solanum lycopersicum) and lacinato kale (Brassica oleracea), crop quality and labor input for two styles of SIPs, as well as a sack garden, a variation of a SIP that does not require lightweight soil, with two conventional raised beds (one with a compost and topsoil mix and one with the soilless growing medium ideal for container gardening). Results from our first year of data indicate that both the SIP beds and the conventional beds with the soilless growing medium were more productive overall than conventional raised beds with topsoil and compost (P<0.01). Tomato production in the SIP without the root barrier was greater than both the conventional bed with the compost and topsoil mix (P<0.01) and the conventional bed with the soilless growing medium (P<0.05). The majority of the higher-cost beds had a positive revenue stream in the first summer season; given these results, investing in SIPs or in soil appropriate for raised beds appears to be worth the higher initial cost.

Urban agriculture, a current trend in many US cities, is purported to bring enhanced food security, reduction of food waste, community building, open green space in cities and higher property values. However, the literature lacks an understanding of whether urban farming has extended beyond a compelling concept into the practice of farming in the city and peri-urban areas. The exact definition of an urban farm is challenging, since many urban farms have a primary mission of supporting social goals rather than providing food. Use of the USDA definition of farm omits many self-identified urban farms, but the most consistent measure of agriculture is the Census of Agriculture. Using census data, this paper finds that urban farms are smaller than the typical farm, and while the amount of urban and peri-urban farmland declined between 2002 and 2007, the total number of farms increased. Growth in farmland is positively related to land values, suggesting that increases in urban farmland are more likely to take place in population dense, land scarce areas. Spatial analysis of urban and peri-urban farms in the Northeast finds fewer clusters of farms in areas with high land costs. In the most populous Northeastern cities, the farms are more likely to be located in the peri-urban area than in the urban core. Urban farms in the Northeast were more likely to produce vegetables, eggs and goats. Significant levels of vegetable farm clusters were detected surrounding Providence, Boston and Hartford Metropolitan Statistical Areas, which are regions that had no significant level of clustering of total farms. Future analysis, incorporating data from the 2012 census, should provide insight into whether local policy changes have resulted in growth in urban farms and farmland.

Although discussion of the role of urban agriculture in developing nations has occurred over the past decade, dialogue relating to urban agriculture in industrialized countries, including the United States (US) has only recently begun to attract significant attention. The unique factors that influence urban agriculture, including limited and non-traditional land access, use of reclaimed soils and alternative growing mediums, local legal and political environments, social and community-based missions, and involvement of non-traditional farmers, create a production system distinct from rural agricultural enterprises. In many cases, specific local environmental and external factors drive urban farms to develop unique innovations for space-intensive production systems, often creating a dominant paradigm for urban farming for a given location. Furthermore, non-production-related organizational goals are often the primary focus of urban agricultural operations, with the food production becoming a secondary objective. In order to address this information gap regarding the status of urban agriculture in the US, our project, centered at the University of Wisconsin-Madison, gathered data through site visits to and interviews of organizations in seven cities, examining how structural and strategic food system factors shape urban agricultural efforts. A broad range of operations are considered, including diverse business and production models based on both commercial and community-based management strategies and production in parking and vacant lots, warehouses, public land and peri-urban locations. Based on these observations, the unique innovations in space-intensive agricultural production that have arisen in response to urban food system factors are discussed. We conclude with an assessment of the most significant challenges continuing to face urban agriculture.

Throughout the USA, urban agriculture is expanding as a manifestation of an emerging American food politics. Through a case study of Brooklyn, New York, I used mixed qualitative research methods to investigate the political possibilities of urban agriculture for fostering food justice. My findings build on the existing alternative food network (AFN) literature by indicating that problematic contradictions rooted in the neoliberalization of urban agriculture limit the transformative possibilities of farming the city as currently practiced in Brooklyn. I suggest that longstanding agrarian questions—concerns over the relationship between agriculture and capitalism and the politics of small-scale producers—are informative for critical interrogation of urban agriculture as a politicization of food.

Many urban agriculture programs, and the organizations that run them, require substantial resources to remain viable and provide the multifunctional benefits that practitioners and supporters hope to achieve. As urban agriculture activity expands, practitioners and supporters face significant challenges, including how to match resources to the needs of practitioners and expectations of municipalities, and how to distribute those resources effectively and equitably so that communities, and the city as a whole, capture the benefits of these projects. This is particularly important as cities face increasing pressure to reduce costs and maximize the return on public expenditures. A 2-year study called Five Borough Farm documented the goals and objectives of urban agriculture projects in New York City and the resources for their success. The data showed that resource needs go beyond the material and financial needs discussed in the urban agriculture literature (e.g., land, soil, money). Interviews documented that urban agriculture projects have broader goals than merely producing food, and that attaining these goals (e.g., environmental improvements, community development, social justice) requires the support of government and networks of practitioners, non-profit organizations and philanthropies. Moreover, interviewee comments suggested that significant disparities in access to resources make the urban agriculture system in New York unequal and constrain the efforts of some farms and gardens. This paper, based on the Five Borough Farm research, examines the resource needs of urban agriculture operations in terms of farm and garden viability and equity among practitioners. It describes the goals, expectations and resource needs of New York City urban agriculture from the perspectives of farmers and gardeners, and from the views of city officials, funders and supporting non-profits. It discusses the need for attention to the political and social structures that create disparity and precariousness to ensure a sustainable and just urban agricultural system, in addition to the financial and technical assistance resources that enable farmers and gardeners to produce food. The paper concludes with recommended strategies to align resource needs and urban agriculture goals and expectations in New York and other cities.