Identifying eco-efficient year-round crop combinations for rooftop greenhouse agriculture
Rufí Salís, Martí (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Petit Boix, Anna (University of Freiburg. Chair of Societal Transition and Circular Economy)
Villalba, Gara (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Ercilla Montserrat, Mireia (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Sanjuan Delmas, David (Ghent University)
Parada, Felipe (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Arcas Pilz, Verónica (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Muñoz Liesa, Joan (Universitat Politècnica de Catalunya)
Gabarrell Durany, Xavier (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)

Data:	2020
Resum:	Purpose: Rooftop greenhouses (RTGs) are agricultural systems that can improve the food supply chain by producing vegetables in unused urban spaces. However, to date, environmental assessments of RTGs have only focused on specific crops, without considering the impacts resulting from seasonality, combinations of crops and nonoperational time. We analyze vegetable production in an RTG over 4 years to determine the crop combinations that minimize yearly environmental impacts while diversifying food supply. Methods: The system under study consists of an integrated RTG (i-RTG) with a hydroponic system in Barcelona, in the Mediterranean region. By using life cycle assessment (LCA), we evaluate the environmental performance of 25 different crop cycles and 7 species cultivated during the period 2015-2018. Three functional units are used: 1 kg of edible fresh production, 1 unit of economic value (€) in the wholesale market and 1 kcal of nutritional value. The system boundaries consider two subsystems: infrastructure (greenhouse structure, rainwater harvesting system and auxiliary equipment) and operation (fertilizers and their emissions into water and substrate). In addition, we perform an eco-efficiency analysis, considering the carbon footprint of the crop cycles and their value at the wholesale market during their harvesting periods. Results and discussion: Spring tomato cycles exert the lowest impacts in all categories, considering all three functional units, due to the high yields obtained. In contrast, spinach and arugula have the highest impacts. Regarding relative impact, the greenhouse structure presented a large impact, while fertilizer production had notable relative contributions in tomato cycles. Moreover, nitrogen and phosphorus emissions from fertigation are the main causes of freshwater and marine eutrophication. By combining the most eco-efficient cycles, we can see that growing two consecutive tomato cycles is the best alternative with the functional unit of yield (0. 49 kg CO2 eq. /kg), whereas a long spring tomato cycle combined with bean and lettuce cycles in the autumn/winter is the best scenario when using market (0. 70 kg CO2 eq. /€) and nutritional value (3. 18·10−3 kg CO2/ kcal). Conclusions: This study shows that increasing the diversity of the system leads to better environmental performance of greenhouse urban agriculture if suitable crops are selected for the autumn/winter season. The functional unit involving the economic value and the eco-efficiency analysis are useful to demonstrate the capability of the growing system to produce added-value vegetables under harsher conditions while categorizing and classifying the crops to select the most suitable combinations based on economic and environmental parameters.
Ajuts:	Ministerio de Economía y Competitividad CTM2013-47067-C2-1-R Ministerio de Economía y Competitividad CTM2016-75772-C3-1-R Ministerio de Economía y Competitividad MDM-2015-0552
Nota:	Unidad de excelencia María de Maeztu CEX2019-000940-M
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Urban agriculture ; Rooftop greenhouses ; Eco-efficiency ; Crop combinations ; Life Cycle Assessment ; Industrial ecology ; Urban metabolism ; Sustainability
Publicat a:	The international journal of life cycle assessment, Vol. 25 (January 2020) , p. 564-576, ISSN 1614-7502

DOI: 10.1007/s11367-019-01724-5

Postprint 20 p, 1.1 MB

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