ABSTRACT
Food supply is a major factor in shaping cities (Steele, 2010) and determining their relationships with surrounding (close or distant) rural territories. The agricultural development in the city hinterland as well as the construction of large transport infrastructures has been largely dictated by the requirements of urban food markets (Keene, 2011; Charruadas, 2011; Billen et al., 2011). Because cities consume most of the final products of agriculture and dictate its specialisation and location, urbanisation is a major driver of the human perturbation of the nitrogen cycle (SvirejevaHopkins and Reis, 2011). As shown by several authors, the anthropogenic introduction into the biosphere of reactive nitrogen, which subsequently
cascades through a number of environmental compartments until it is finally denitrified back to the atmosphere, causing multiple harmful effects, is nowadays among the most severe environmental threats (Galloway et al., 2002; Sutton et al., 2011). Any attempt to eliminate or reduce the source of the nitrogen cascade should take into account the urban food supply issue.
