Emergy evaluation of food production in urban residential landscapes

To transform cities from heterotrophic into sustainable ecosystems many authors have called for increased food production, including home gardening, in urban areas. We conducted an emergy analysis of four model backyard landscape plots—a conventional ornamental landscape, an intensive organic garden, an edible landscape, and a forest garden—to assess the yield and sustainability of these systems. Data were collected during the 2001 growing season and extrapolated to make a five year projection. In the 2001 season, all plots had low Emergy Yield Ratios (EYR) of between 0.0003 and 0.17 and extremely low Emergy Sustainability Indices (SI). In the five year projection, all plots still had low EYRs of between 0.0008 and 0.33 and very low SIs. These low indices are due primarily to the high levels of economic inputs required for the installation and maintenance of these plots in an urban context. Analyses performed on larger systems (households, neighborhoods and cities) containing productive landscapes such as those studied here may produce different results. Installing food-producing landscapes in urban areas without altering the networks by which such landscapes are supplied, however, may not substantially alter the heterotrophic nature of cities.