Boulder County is looking at some kind of county-wide sustainability program, with an associated tax which will be on the ballot this fall. The City of Boulder is revising its Climate Action Plan, looking toward a goal of climate neutrality in 2050. An extension of the tax which supports our climate work will also be on the ballot in the fall. One thing that none of that money should go toward? Urban farming.
I know — that’s an unpopular thing to say. People here love the idea of urban farming. We’ve got Growing Gardens and a huge community garden in North Boulder, and just a block away from my house is the Flatirons Neighborhood Farm, a micro CSA. I like these organizations too, and I enjoy being exposed to the miraculous process of food production — taking air, sunlight, water, soil and seeds and from them creating a feast. Everybody should experience it at some point, especially children, so they know where food really comes from. But at the end of the day, in the context of a city, or even a town, this can only be an educational tool. A spectator sport. A part time hobby for a few of us. It can never scale up to feed even a small fraction of the citizenry. Any serious attempt to do so would utterly destroy the city, and there are many very, very good environmental and climate related reasons why we should not want to do that. Why we should be building the best possible cities, not disassembling them. They need to be dense and durable, beautiful, livable, and humane.
To understand why urban farming can never scale up to feed us all, let’s look instead at Boulder County as an example. Can even the county feed itself? If not, then the city certainly cannot. The county has a population of 300,000, and an area of 2,000 km2. However, the western two-thirds of the county’s area is mountainous, and unsuitable for food production, so that means we’ve really only got about 667 km2 to work with, or 66,700 hectares. On average, it takes about half a hectare to produce food for one person with a typical US diet. Half a hectare per person, times 300,000 people is about 150,000 hectares, which is more than twice the arable land in the county. Okay, fine. Say we all go vegetarian and fat-free then. Cutting out all the meat and fat from a typical US diet reduces the required land area by half. A quarter hectare per person, times 300,000 people is about 75,000 hectares, which is roughly the amount of potentially arable land in Boulder County. So, within the county, if we’re all fat-free vegetarians, we might just barely be able to grow enough food for everyone. That is, if we had the water resources required to intensively cultivate all of the somewhat flat land in the county, which we don’t really — not without bringing it to the Front Range from the Western Slope through tunnels that pass under the Continental Divide. Not without bringing it south from the Laramie River Valley too. But let’s ignore the water issue (and Denver) for the moment, and assume we could import enough from the nearby mountains if we wanted to. It’s maybe just barely feasible, on an order-of-magnitude basis, to feed the county with its own produce.
Maybe we could improve on that with much more intensive farming practices, and much more water efficient irrigation methods (both of which would increase the cost of food production).  How much more productive would we have to make our agricultural system (on a food per unit area basis) to be able to feed the 100,000 Boulder residents using only the land area within the city of Boulder? Boulder’s area is about 6600 hectares, so that means we’ve got about 0.066 hectares per person to work with. That’s about quadruple the productivity of the above scenario (with 0.25 hectares per person, eating no meat or fat). Is that attainable? Maybe… but it would mean dedicating every last square meter of space within the city limits to intensive food production! This scenario is not a solution!
Furthermore, Boulder is far from being a dense city. Urban spaces which are dense enough to obviate automobile usage, making walking and transit convenient for most of the population and dramatically reducing transportation related energy usage, have at least several times as many people per unit area as we do. For those cities, no plausible increase in farming intensity can hope to feed the population, even if every square meter of the city were dedicated to food production.
Cities import food. They have always imported food. So long as we use air, sunlight, water soil and seeds to make food, cities will import food. To argue for “urban agriculture” as a way to produce a significant portion of our food is to argue against cities altogether, and cities are good for the environment. Very good in fact, as demonstrated in this EPA study (and many others) looking at the effects of development patterns on energy usage. Putting people close to each other and the things they want to have access to every day dramatically reduces transportation energy use. Attached dwellings can be made far more energy efficient more cost effectively than detached dwellings. Putting people close together means they can more effectively share resources which would otherwise languish most of the time, if each and every person or household had to own their own copy. Furthermore, life in cities — especially good cities — is generally better. Social and economic opportunities are greater in cities, and cities are much more culturally diverse, more cosmopolitan.
Now, do cities need to import their food from other continents? No, we do not need to airlift asparagus from Argentina to Boulder in November. Can we reduce GHG emissions and energy consumption from the food production system? We have to, but transportation is only a small part of that problem. Synthetic fertilizers, pesticides and the fuel used in tillage, not to mention the intrinsic caloric inefficiency of meat production, play larger roles. Can we create more sustainable food economies, with fewer unaccounted for externalities by localizing a significant chunk of our food production and enjoying seasonal cuisine? Enthusiastically yes! But when it comes to food, “local” means it came from somewhere in the county, or even the state. If it’s all going to come from your backyard, then you’re going to live on a farmstead, and you’re either going to live in isolation, or, more likely, you’re going to use vast quantities of fossil fuels and public infrastructure to assuage that geographic isolation.
So please, for the love of the Earth, stop pitching “urban agriculture” as a way to feed our cities. It’s an important educational tool and an enjoyable hobby, but it’s not a means of large scale production, and it never will be.
More than anything, what I’m trying to get at here is the utility and importance of being able to do order of magnitude reality checks before you get too excited about anything being The Solution. One person who read this article suggested that in 2017 when the Valmont coal plant shuts down, we’d have a lot more water to work with. Valmont uses about 2.5 million cubic meters of water every year. That’s a lot of water! Except that, the city of Boulder uses 25 million cubic meters of water every year, and the water that goes into all the agricultural products we consume in the city is probably something more like 100 million cubic meters every year (based on the 1:4 urban:ag water use ratio in California anyway). So the water from Valmont is maybe 2.5% extra to work with, not 25% extra, not 250% extra. Being able to pencil this kind of thing out really helps sort serious solutions from fluff… and there’s unfortunately a lot of fluff.
My thought on the matter is that there are a couple of (slightly useful) options:
1. If you’re going to live somewhere with a lawn and aren’t going to try xeriscaping, you might as well replace much of the useless grass with something edible (if you’re planning on using the water anyway…)
2. You may have some benefits with roof-top gardens as a means to provide insulation without seriously sacrificing space.
Either way, the food you get is fairly supplementary, but at least there are some gains made in efficiency. Mostly I advocate the death of the private lawn (and the promotion of parks instead) if natural rainfall is insufficient to keep the grass alive.
Grist has an article: “Counting the Harvest: How Numbers Can Save Urban Gardens” about efforts to quantify the productivity of urban agriculture, and turn urban gardeners into a unified constituency. Unfortunately, it doesn’t actually provide any useful numbers. “67 gardens” in NYC generated 87,000 lbs of food, worth $200k. But how much space do 67 gardens take up, and what is the value of that land — both monetarily, and in terms of providing low-carbon real-estate. To know whether urban farming is a good idea, we need, for example, food quantity and dollar value per unit area, and we need to be able to compare the GHG emissions avoided (by having food produced nearby) to the GHG emissions created, by pushing things in the urban landscape further apart.
This entire article makes no sense. Clearly the author has little understanding of urban agriculture. The point of urban farming is NOT to “feed an entire city” (I would think this is common sense). It’s to supplement our food production with locally grown fresh produce. I live in NYC and grow a lot of vegetables/herbs on my farm, it has saved me a ton of money and is a fun hobby to boot! I think urban farming should be encouraged. We could use more green space and less concrete here in the city.
In big chunks of NYC, I’m sure you could do with more green space, but in most of sprawling America, intermixing yet more green space to create a kind of agri-burbia only serves to make our cities more auto-dependent than they already are, by spreading destinations yet further apart. And in some of these contexts, it is (unfortunately!) not clear that people understand you can’t feed a city from within its borders. Or to put it another way, it’s not clear people understand that the sustainability benefits of encouraging compact, walkable, auto-independent cities far outweigh any possible benefits from hyperlocalization of food production. If you take it for granted that everyone is going to have a front and back yard… then sure, they might as well be growing food. But it’s far better from a livability and sustainability point of view to question the assumption that we should all have yards at all…
All urban agriculture is not taking down buildings to turn them into farms. In NYC they have vast, expansive rooftop farms and gardens, utilizing what is otherwise dead space and it even helps with limiting the need for heating and AC in the buildings. Urban agriculture can also be done through vertical farming indoors or out with hydroponics or even aquaponics. As Serena said, the point of urban agriculture is not to feed everyone, the point is to generate local produce which does a number of great things for everyone. Less food needs to be imported which lowers transportation emissions, food deserts in cities will be able to sell fresh, healthy food to customer who would otherwise be required to live off what they can get at a local quick-stop. Processes like aquaponics even remove the need for synthetic fertilizers and pesticides through a closed-loop system. This article is completely the wrong point of view and isn’t helping anyone, urban farming is definitely a positive.
I’m using the calculation of how much land is required to feed everyone as a way to set the geographic scale required for food production. Not only will we not feed everyone with urban ag, we won’t even feed a substantial fraction of any city. Vertical farming also doesn’t really pencil out — it’s expensive and can’t scale up in production without artificial light, which is a GHG emissions disaster, relative to growing food in the countryside and transporting it into cities — the emissions from moving food around just aren’t that big (unless you’re flying it, which is totally nutso). Rooftop gardens are great — if you’ve got a flat roof, and it’s structurally sound, then by all means, use it for something, whether it’s greenhouses or outdoor patio living space, but that doesn’t change the plausible scale of urban food production. And of course closed loop resource systems that don’t required mining non-renewable agricultural inputs are great! And that’s totally independent of where you put the farm. And of course urban food deserts are bad… but why would growing food in them be the best solution? Given the limited amount of food you can produce relative to demand in an urban context, they can only ever provide healthy whole foods to a small fraction of the food desert’s population. Wouldn’t it be better to actually get some healthy grocery stores or farmer’s markets into those neighborhoods, with enough real food to give everyone access?
Of course, if one is replacing lawns with gardens, one is not pushing the city further apart. I don’t think it is in any way realistic to imagine bulldozing all the neighborhoods with yards and rebuilding; think of the energy this would require!
We will have to work with the cities we’ve got, more or less; so replace small swatches of lawns, pavement, and rooftop with food.
And I think any city can and should grow all of its own vegetables; they are some of the hardest items to transport.
Infill is far more energy and material and space efficient than greenfield development. New housing is going to get built *somewhere* and if it’s not within existing cities, where it can make use of all the existing infrastructure, and be made up of more energy efficient, compact, attached dwellings, it’s likely going to be built at the margins of our cities, requiring all new infrastructure, auto-dependence, and taking the form of larger, detached, inefficient single family homes. Most of the world’s cities will be built or re-built in the next 50 years. We should do it well. Look up how much area it takes to produce the foods a household eats in a year — even just the fruits and vegetables — it’s far more than the area available per household in any city — especially in a city that’s walkable, supports mass transit, and houses people in space and material, and energy efficient dwellings. Cities will always import their food, water, and energy. And that’s okay — because they make it possible to live wonderful lives that use drastically less resources overall.