Urban farming vs. Urban residential infill
A corn-based entryway at a house on Chillum Road in Prince George's County, Maryland.
The Atlantic Cities has a piece, "How Urban Farming Is Making San Francisco's Housing Crisis Worse," which makes the point that providing tax incentives in San Francisco for vacant lots to be urban farms/gardens, when San Francisco has a housing crisis is bad policy (a/k/a "insane").
Interestingly, I had the same kind of argument apparently 4 years ago ("Gardeners near Capitol Hill prepare to repel a Marine Corps invasion," Washington Post), with an ex-commenter, about this same issue in the context of Greater Capitol Hill and the expansion of the Marine Barracks. Said expansion will end up taking out an urban garden.
I said that the choice was easy, build.
... making the point that urban gardens are a land utilization strategy for weak real estate submarkets when there are no or limited viable alternatives for absorbing/using the land. Ironically, an Atlantic Magazine blog ("Community garden, or gardening community") argued in favor of not building on the garden, using it as a community building element. (I see the point, but in the Capitol Hill neighborhood, most people have alternatives, they just can't garden on a large scale.)
Ideally, urban gardens aren't aren't an end game, but an interim strategy--just like the sad end when artists get displaced after improving the "quality" and perception of a neighborhood so that it is repriced and becomes "valorized".
He challenged me to come up with reasons. I didn't get into it. It's all about "highest and best use."
I wasn't that great at economics in college--graphic reason and math skills (not good at calculus) did me in. But urban real estate issues make very clear how economics works.
The reason for DC's skyrocketing housing prices? Greater demand and minimal supply. So prices go up.
Limited supply of new affordable housing? New construction costs more than previously built properties (most of the time).
Because of the height limit, land supply and build out capacity is limited. This constrains the economic viability of constructing lower cost housing at a profit. So people build to the most profitable, expensive segments.
When housing demand is high, residential lots should be used for housing. If not, it's one more contributor to higher rents or property purchase prices.