title: Phosphorus cycling in Montreal's food and urban agriculture systems.
abstract: Cities are a key system in anthropogenic phosphorus (P) cycling because they concentrate both P demand and waste production. Urban agriculture (UA) has been proposed as a means to improve P management by recycling cities' P-rich waste back into local food production. However, we have a limited understanding of the role UA currently plays in the P cycle of cities or its potential to recycle local P waste. Using existing data combined with surveys of local UA practitioners, we quantified the role of UA in the P cycle of Montreal, Canada to explore the potential for UA to recycle local P waste. We also used existing data to complete a substance flow analysis of P flows in the overall food system of Montreal. In 2012, Montreal imported 3.5 Gg of P in food, of which 2.63 Gg ultimately accumulated in landfills, 0.36 Gg were discharged to local waters, and only 0.09 Gg were recycled through composting. We found that UA is only a small sub-system in the overall P cycle of the city, contributing just 0.44% of the P consumed as food in the city. However, within the UA system, the rate of recycling is high: 73% of inputs applied to soil were from recycled sources. While a Quebec mandate to recycle 100% of all organic waste by 2020 might increase the role of UA in P recycling, the area of land in UA is too small to accommodate all P waste produced on the island. UA may, however, be a valuable pathway to improve urban P sustainability by acting as an activity that changes residents' relationship to, and understanding of, the food system and increases their acceptance of composting.
authors.affiliation: Department of Natural Resource Sciences, McGill University, Sainte Anne de Bellevue, Montreal, Quebec, Canada.
authors.forename: Geneviève S
authors.initials: GS
authors.lastname: Metson
authors.affiliation: Department of Natural Resource Sciences, McGill University, Sainte Anne de Bellevue, Montreal, Quebec, Canada; McGill School of Environment, McGill University, Montreal, Quebec, Canada.
authors.forename: Elena M
authors.initials: EM
authors.lastname: Bennett
mesh_terms: D000383:Agriculture; D005504:Food Analysis; D010758:Phosphorus / Q000737:chemistry*; D011792:Quebec; D014504:Urban Health
chemical_list: D010758:Phosphorus
references.citation: Geogr J. 2011;177(4):311-20
references.pmid: 22180921
references.citation: Environ Technol. 2012 Oct-Nov;33(19-21):2383-93
references.pmid: 23393981
references.citation: Waste Manag. 2013 May;33(5):1113-8
references.pmid: 23481343
references.citation: Ecotoxicol Environ Saf. 2014 Mar;101:233-9
references.pmid: 24507151
references.citation: Environ Pollut. 2014 Apr;187:162-9
references.pmid: 24502997
references.citation: Chemosphere. 2011 Aug;84(6):747-58
references.pmid: 21414650
references.citation: Chemosphere. 2011 Aug;84(6):735-6
references.pmid: 21724236
references.citation: J Environ Qual. 2001 Mar-Apr;30(2):275-81
references.pmid: 11285887
references.citation: Nature. 2002 Aug 8;418(6898):671-7
references.pmid: 12167873
references.citation: Science. 2008 Feb 8;319(5864):756-60
references.pmid: 18258902
references.citation: Trends Ecol Evol. 2009 Apr;24(4):201-7
references.pmid: 19246117
references.citation: Proc Natl Acad Sci U S A. 2011 Feb 15;108(7):3086-91
references.pmid: 21282605
references.citation: Environ Pollut. 2011 Aug-Sep;159(8-9):1965-73
references.pmid: 21084139