Wednesday, July 30, 2008

Sustainable Ballard: Local Food Production and Population

CORE GIS is located right on the edge of the Ballard neighborhood in Seattle. The non-profit Sustainable Ballard has been active in numerous sustainability and environmental issues, and each year at this time they ramp up their "Eat Local" campaign by promoting the 100 mile diet.

This seems like a great idea, for a number of reasons--it supports local farmers and local economies, reduces fossil fuel consumption, builds community, and encourages all of us to think about where and how our food is grown.

I decided to take this idea to its logical extreme--what if everyone in Seattle decided to follow the 100 mile diet? Do we have enough agricultural land to support that many people?

I started with 2000 U.S. Census data, specifically the SF1 100% population count at the block group. Then I used 2001 NLCD land cover data and extracted the two agricultural classes--cultivated crops and hay/pasture. I arbitrarily chose a spot in the middle of Seattle, created 50 mile and 100 mile buffers, then counted up the number of people and the acres of agricultural land within the two distance bands.

As it turns out there is far less acreage in cultivated crops than in hay/pasture, and within 50 miles, each acre of cultivated crops would need to feed 172 people! If we assume that all of the hay/pasture can be converted into cultivated crops, the number of people supported by one acre drops to 22. Moving out to 100 miles improves the situation, with just under 31 people per acre of cultivated crops and just under 7 per acre for all agricultural land. (The cartographic and tabular results are shown in the thumbnail image to the right; if you'd like to download a screen-resolution PDF of the 30"x36" poster, just click here. Please contact me if you'd like a printed version).

However, according to one study, a meat-based diet requires 9 acres per person! A diet that is primarily plant-based (with some milk, cheese, and eggs) requires 3/4 of an acre. Clearly, we still have far too little agricultural land within our 100 mile radius to feed our entire population.

This suggests to me that our region has a lot of thinking to do about our food security and food sovereignty. What happens if there are shortages of fossil fuels, in particular diesel, for transporting food across the vast distances it currently travels? Are there areas within our region that have prime agricultural soils that are not being cultivated? What policies can/should be put in place to ensure that we have the capacity to feed a much larger proportion of our population from local farms? How should our food distribution network change to make it easier and more efficient for local farmers to get their produce to market?


Anonymous said...

Wow! Thank you for your enlightening work,Matt.

Ingela Wanerstrand
Garden & Environment Guild Coordinator
Sustainable Ballard

Julianne said...

Very impressive! And an excellent idea to begin to look at those kinds of issues relative to eating locally.

The one thought that comes to mind however, if I'm understanding your work correctly, is that you've only looked at the larger parcels of land, as opposed to also factoring in people's own yards as a (potential) significant source of food. And not only those people who have yards themselves, but also the idea of people sharing yards in order to grow food - an idea that Vancouver has perfected in their "Sharing Backyards / City Farmer" program, vancouver.BC&welcome_box=3

Our own City Council, vis-a-vis the leadership of Richard Conlin, is also now looking at, through the Local Food Action Initiative, how to transition people off a lengthy waiting list for a P-patch into just such a "yard sharing" situation.

It would be interesting to know what percentage of land currently devoted to "grass yards" would need to be converted to food cultivation to tip the balance in favor of being able to successfully feed our community ala' the 100 mile diet.

Thanks again for your ideas and work - very stimulating!

Julianne Jaz

Anonymous said...

Fascinating! Some 10 percent of public land in Seattle is in planting strips. A fledgling local effort,, is promoting edible gardens on that land as well as the yard sharing. Help us spread the word!
Julie Whitehorn

Julianne said...

I agree that parking strips can yield a wealth of arable land, and I've certainly had gardens on them myself. The one consideration I'd like to mention about that, however, is the need to measure the volume of traffic on any given street where gardening on the parking strip might be a possibility. There are real concerns about pollution (not only exhaust, but also small pieces of rubber off the tires) to be taken into account as they could easily render what would otherwise be organic produce potentially toxic instead. There have been studies done about this - the two things you'd be looking for are traffic volumes (over a 24 hr period, as well as seasonally), and a measurement of the distance from the roadway to the actual produce in the garden. Re: traffic volume - the reason I mention over a 24 hr period as well as seasonally has to do with things like whether or not a street is quiet most of the time, but might be a fairly main thoroughfare during commuter hrs, or seasonally - e.g., during the fall when the UW has football season you've got 70,000 people coming to the stadium half a dozen times over a 3 mos period (Sept/Oct/Nov). If I were growing fall/winter crops out on my parking strip, they might easily become contaminated during that period, whereas at other times of the year the traffic in the neighborhood might not reach a volume that would be considered hazardous...

Anyway, just more food for thought on the subject - and kudos to you, Julie, for your project and what you're hoping to accomplish!