Increased Productivity, Role in Alleviating Food Insecurity Possible

First paragraphs It's true that urban agriculture may provide a modest contribution to most cities' food supply. However, Hallsworth and Wong (2013) fail to recognize the range of cities across North America as well as the numerous opportunities to increase the productivity of urban agriculture and its potential role in alleviating food insecurity. They also under¬emphasize the value of urban agriculture beyond the quantity of food produced. There are many cities — Detroit, Cleveland, and Milwaukee come to mind — with large amounts of open space and notions of incorporating agriculture into the fabric of a 21st century green city. The authors fail to acknowledge the potential for expanded productivity per unit of land beyond what is currently observed, for example with the use of passive solar, season-extension methods. In Michigan, with average low temperatures below Vancouver's, unheated hoophouses allow for at least 30 crops to be grown, many year-round (Colasanti, Matts, Blackburn, Corrin, & Hausler, 2010). The authors dismiss what can be grown in a 4-square-meter (43-square-feet) garden as "suitable only for... personal enjoyment," but during the frost-free period an extra vegetable serving for a family of four per day is easily accomplished in this space....