Tue, 23 Oct 12 at 16:15 |
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Living Off The (How Much?) Land
Real mixed use
How much land does a typical, four-person family need to grow all their own food? Everything included — vegetables, wheat, dairy, meat — the answer is not that much: about two acres.
(That’s 1.5 football fields, or a square plot 200 feet on a side.)
As it happens, the US supports a population of 310m people on 1.2bn acres of cropland, rangeland and pasture — about four acres per person, or sixteen per family. Yes, we export a lot of food, and yes, some of the “pasture” component is probably not in productive use. But this rough comparison does suggest that industrial agriculture is not as efficient as usually thought.
(That’s perhaps not too surprising. Small-scale agriculture is far more efficient in terms of physical inputs, though it does require greater labor.)
The photo above is from Japan, where archaic land-use regulation has long kept small farm plots in use throughout the highly urbanized Tokyo-Osaka megapolis. When I lived there twenty-five years ago, one room I rented looked right out onto a quarter-acre rice paddy — not an unusual juxtaposition.
What about closer to home?
Detroit, poster child for contemporary de-urbanization, has 40 square miles of vacant, unbuilt land within the city line. That’s more than 25,000 acres — or enough to support almost 13,000 families. But with 700,000 people still living in the city, this means that urban gardening could feed only about an eighth of them. (Of course, if city parks and public open space were taken over as well, the figure would be higher.)
On the other hand, most suburbs have lots of room yet. Looking at entire metro areas, rather than just the smaller, denser cities proper, the proportion of people who could be fed hyper-locally is sure to be higher. Include intensive operations like vertical gardens and aquaculture, and 100% might not be unachievable.
Perhaps the next Green Revolution will take place — literally — in our own back yards.
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