I went to a open house of a publicly funded program growing produce for resale and to supply various soup kitchens.  It is an attempt to reutilize empty lots in the city for agriculture, though the farming is currently being done on acerage provided by a community college in a more rural area.  The workers are being bused in.  Some of the inner city sites are waiting for approval from a federal agency as to the toxicity of the soil.  Pretty scary in that these are densely populated areas.

Hydroponics may be the solution.