N2O emissions from protected soilless crops for more precise food and urban agriculture life cycle assessments
Llorach-Massana, Pere (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Muñoz Odina, Pere (Institut de Recerca i Tecnologia Agroalimentàries)
Riera Riera, M. Rosa (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Rieradevall, Joan (Universitat Autònoma de Barcelona. Departament d'Enginyeria Química, Biològica i Ambiental)
Gabarrell Durany, Xavier (Universitat Autònoma de Barcelona. Departament d'Enginyeria Química, Biològica i Ambiental)
Montero Camacho, Juan Ignacio (Institut de Recerca i Tecnologia Agroalimentàries)
Villalba, Gara (Universitat Autònoma de Barcelona. Departament d'Enginyeria Química, Biològica i Ambiental)

Date:	2017
Abstract:	Due to population growth and the subsequent increase in the demand for food, low carbon food chain production systems are a necessity to reduce the effects on climate change as much as possible. Urban agriculture is of great interest because of its potential in reducing the indirect CO2 emissions of a city's food supply by reducing transportation distances, the packaging required and the food losses that occur during transportation. However, intensive urban agriculture production, which often relies on the use of soilless substrates, requires synthetic fertilizers rich in nitrogen, resulting in N2O emissions. Presently, there is a lack of studies that determine the generation of N2O from soilless crops to properly account for their global warming potential. In this study, an open chamber system was used to quantify N2O emissions from lettuce crops with perlite bags as their substrate in a Mediterranean rooftop greenhouse located in the metropolitan area of Barcelona (Spain). N2O generation, through nitrifying and denitrifying reactions, was limited by assuring an aerobic environment, negligible water retention, the absence of NH3, and controlled dosage of NO3− in the most favorable pH conditions for plant assimilation. The emission factor (EF) measured for the soilless lettuce crop (0. 0072-0. 0085 kg N2O−1 per kg N−1) was half the EF of the IPCC method (0. 0125 kg N2O−1 per kg N−1) for soil crops, which is commonly used in life cycle assessment (LCA) studies to approximate direct N2O emissions, for lack of a better method. Using a more appropriate EF for an LCA study of a tomato crop grown under similar conditions to those used to generate the EF resulted in a 7. 5% reduction (0. 06 kg CO2 eq. per kilogram of tomato production) in total global warming potential. This study shows that soilless crops reduce N2O emissions when compared to conventional crops, making urban agriculture an attractive practice for reducing GHG emissions. The results highlight the need to determine a standard method for determining an EF applicable to soilless protected crops, which, based on the parameters described here, such as the type of substrate, fertilizers and irrigation system, would allow for a more accurate environmental evaluation of soilless conventional and urban crops.
Grants:	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 CTM2016-75772-C3-2-R Ministerio de Economía y Competitividad CTM2016-75772-C3-3-R Ministerio de Economía y Competitividad MDM-2015-0552
Note:	Altres ajuts: La Generalitat de Catalunya, for awarding a research scholarship (FI-AGUAR 2015) to Pere Llorach Massana.
Note:	Unidad de excelencia María de Maeztu MdM-2015-0552
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Subject:	N2O emissions ; Soilless crops ; Low carbon food chain ; Nitrogen balance ; Urban agriculture ; Carbon Footprint ; Roof top greenhouses
Published in:	Journal of cleaner production, Vol. 149 (April 2017) , p. 1118-1126, ISSN 1879-1786

DOI: 10.1016/j.jclepro.2017.02.191

Post-print 19 p, 1.3 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Institut de Ciència i Tecnologia Ambientals (ICTA) > Sustainability and Environmental Protection (Sostenipra)
Articles > Research articles
Articles > Published articles