Roxanne Christensen is co-creator of SPIN-farming, or Small Plot Intensive farming.
"Several years ago, she set out with the Philadelphia Water Department to prove that a half-acre of urban land could yield crops worth $50,000. She planted 60 types of vegetables on a tiny PWD plot and raised only high-value crops that grow quickly. In its fourth year, the parcel produced gross sales of $68,000. 'The only way for urban agriculture to establish itself on any scale is to be a viable business proposition,' says Christensen, who has written a book on small-plot farming."