Grewal's solution to increase the output from urban agriculture is based on converting vacant lots into farms, and residential lots producing crops.
"In the first scenario, Grewal found that if Cleveland converted 80% of its vacant lots into farms it could produce 22% to 48% of the city's demand for fresh produce (vegetables and fruits) depending on the type of farming. It could also produce 25% of poultry and shell eggs, and 100% of honey.
"In addition, if Cleveland used 80% of every vacant lot and 9% of every occupied residential lot, the city could generate between 31% and 68% of the needed fresh produce, 94% of poultry and shell eggs, and 100% of honey."
"Growing food in the city would also keep $29-115 million in the local economy."
Comments
Not practical
Why on earth would anyone think that retrofitting an existing commercial building to support the additional weight of a green roof for local food production is a good idea? If you want to be eco-friendly, put solar panels up there instead, where anybody falling off is going to be an insured installer rather than a volunteer with the local CSA.
All this local food movement stuff tends to ignore grain. I have yet to see any small scale wheat, oat, or rice cultivation in an urban area, even though grains make up a large portion of average daily caloric intake in this country.
Focus on perishable foods
I would never recommend grain. It is low-cost. It stores and transports very well. An urban location offers no real advantage.
Highly-perishable foods offer a much greater advantage. Minimizing the transportation and reducing the amount of handling allows for higher quality produce, while the lower spoilage improves the cost. Think berries!