The present work, focusing on the theme of food production and consumption in urban areas, analyses the relationships among three factors: city, human well-being and ecosystems. A case study was carried out addressing the quantification of the potential of rooftop vegetable production in the city of Bologna (Italy) as related to its citizens’ needs. Besides the contribution to food security of the city, the potential benefits to urban biodiversity and ecosystem service provision were estimated. The methodology consisted of: 1) experimental trials of potential productivity of simplified soil- less systems in rooftop gardens (RTGs); 2) detection of all flat roofs and roof-terraces and quantification of the potential surfaces that could be converted into RTGs; 3) identification of the city’s vegetable requirements, based on population and diet data; 4) calculation of the proportion of vegetable require- ment that could be satisfied by local RTG production; 5) identification of other benefits (improvement of urban biodi- versity through the creation of green corridors and estimation of carbon sequestration) associated with the increased area of urban green infrastructure (GI). According to the present study, RTGs could provide more than 12,000 t year−1 vegeta- bles to Bologna, satisfying 77 % of the inhabitants’ require- ments. The study also advances hypotheses for the implementation of biodiversity roofs enabling the connection of biodiversity rich areas across and close to the city: these would form a network of green corridors of over 94 km length with a density of about 0.67 km km−2

Abstract:In recent years, urban agriculture has been asserting its relevance as part of a vibrant and diverse food system due to its small scale, its focus on nutrition, its contribution to food security, its employment opportunities, and its role in community building and social mobility. Urban agriculture may also be a tool to re-appropriate a range of abandoned or unused irregular spaces within the city, including flowerbeds, roundabouts, terraces, balconies and rooftops. Consistently, all spaces that present a lack of identity may be converted to urban agriculture areas and, more specifically, to urban horticulture as a way to strengthen resilience and sustainability. The goal of this paper is to analyse current practices in the requalification of vacant areas as urban gardens with the aim of building communities and improving landscapes and life quality. To do so, the city of Bologna (Italy) was used as a case study. Four types of vacant areas were identified as places for implementing urban gardens: flowerbeds along streets and squares, balconies and rooftops, abandoned buildings and abandoned neighbourhoods. Six case studies representing this variety of vacant areas were identified and evaluated by collecting primary data (i.e., field work, participant observations and interviews) and performing a SWOT analysis. For most cases, urban horticulture improved the image and quality of the areas as well as bringing numerous social benefits in terms of life quality, food access and social interaction among participants. Strong differences in some aspects were found between top-down and bottom-up initiatives, being the later preferable for the engagement of citizens. Policy-making might focus on participatory and transparent planning, long-term actions, food safety and economic development.

Urban horticulture is increasingly popular for social and economic benefits. However, edible urban crops may be contaminated by airborne pollutants, thus leading to serious health risks. Therefore, a better understanding of contamination risks of urban cultivation is needed in order to define safe practices. In particular, whereas it is commonly accepted that the contamination of urban-grown food comes from airborne pollutants, little is known on a possible contamination by soils. Here, we studied trace metal risk in horticultural crops grown in an experimental urban allotment garden in Bologna, Italy. Seven experiments were conducted between June and November 2015 on tomato, sweet basil, onion, lettuce, kale, bulb fennel and radish. Treatments included two growing systems, soil and soilless, and two fertilization managements, mineral and organic. Trace metal concentrations were measured in soils, substrates and edible plant tissues. We identified preferentially translocated metals by partitioning analysis of tomato, sweet basil and kale. Results showed that crops grown in a soilless system have a lower metal content of −70 % for Cr, −61 % for Cu, −45 % for Cd and −81 % for Ni, compared with those grown in soil. This finding demonstrates that the major contamination risk in an urban area is unexpectedly related to soil pollution.

Abstract:In the expanding urban agriculture phenomenon in Europe, home gardens are a traditional form that have kept agriculture within cities, even becoming crucial in certain historical periods (e.g., war periods). However, horticultural practices in home gardens can also have negative consequences. The goal of this paper is to assess the eco-efficiency of home gardens as a type of urban agriculture. To do so, a case study in Padua (Italy) was evaluated following life cycle assessment and life cycle costing methods. A home garden of 30.6 m 2 and 21 crop cycles were evaluated. The functional unit of the assessment was 1 kg of harvested fresh vegetable at the consumption point, and the ReCiPe method was employed for impact assessment. Environmental assessment indicated that organic fertilization, use of tap water, mineral fertilization and pesticides were the most contributing elements of the entire life cycle. Furthermore, the relevance of garden design and crop selection was a determinant in the eco-efficiency results. The assessed home garden could satisfy the food requirements of between 1 and 2 members of the household. Crop management and design recommendations are provided to improve eco-efficiency and food security potential of home gardens.