Besides evident urban problems - waste, pollution, etc. - there are an urban system dynamic's problem it is interesting: growing productive ecosystems appropriation destining to satisfy urban metabolism requires in Tandil city, Argentina. We use for calculating it, Ecological Footprint concept (Rees 1996a; Wackernagel 1996), it allow us assess in superficial terms -hectares- food, combustible, forestall products required as well as, direct soil occupation necessary to wastes and dissipate warm absorption. Ecological Footprint there has a deficit around 77.708,9 ha. And it will be 17, 2 times city area to cover urban metabolism requires in the considered period.