One of the dimensions in Western civilisation’s relentless march towards “development” has been the increasing scale of our agriculture – not just a larger footprint needed to feed our growing population, but also the larger machinery, tilling larger tracts of land, and employing fewer and fewer farmers. In Australia, the average size of a broadacre farm has almost doubled since the 1980s, during which time the number of farms has – not surprisingly – halved.
Set in stark contrast to this reality is the fact that many of our “visions” of regenerative development feature some form of urban food production: not ever-increasing acreages tended by a dwindling workforce, but rather more homely, small-scale enterprises from backyards to market gardens. What is it about urban agriculture that is so appealing?
The super-sizing of farms is part of a long urbanisation trend – in fact in Australia, the recent doubling of farm sizes is really just the tail-end of our urbanisation journey, where now roughly 90% of our population lives in cities. In South Korea over the past half-century, the urban fraction has risen from one-quarter to over three-quarters of the population, with similar trends underway in China and India. In the US, the urbanised fraction is just over 80%.
Now, at the risk of offending 80-90% of our readers, I would argue that most of what we end up being employed to “do” in cities is the economic equivalent of placing furniture in a hamster cage – it serves little purpose other than to entertain the caged animals. We might call this “degenerative” development, and that’s a whole other blog post. So maybe part of urban agriculture’s appeal is that it promises an alternative – a reconnection with productive purpose – and a chance to open the door to the cage and let the hamsters free. Lump all of this in with nature deficit disorder, the environmental push to reduce food miles, opposition to neoclassical “growth-at-all-costs” economic mantra, and a desire to reduce chemical inputs, and we perhaps see why small-scale, local organic food production is intrinsically appealing to those of us interested in regenerative development.
So if all this interest in urban agriculture continues, where might it end up? Is it plausible that cities could one day “feed themselves”? In 2014 we set out to answer this question quantitatively, starting with some dietary basics.
To survive, we all need a certain amount of energy (over 2,000 kilocalories per day for adults) and protein (50-60 grams per day, depending on gender and body weight) and our diet must contain a balance of different food groups (e.g. “MyPlate” in the US). Clearly, there are many different combinations of foods that can meet these basic nutritional requirements. When faced with a multitude of options like this, optimisation is one mathematical technique that can be used to explore the solution space. Optimisation seeks out the combination of “decision variables” that maximises or minimises a particular objective while satisfying practical constraints. In our case, we chose from a range of foods and identified the minimum total land area – assuming typical commercial agricultural yields – that would be required to deliver a diet that would meet our dietary needs.
Obtaining a theoretical minimum amount of land we need to feed ourselves is the most basic first step towards working out how much of our diet could be supplied within the city boundary.
Understandably, people growing up in cities can be blissfully unaware of the scale of our dietary footprint; we all see our “built” footprint – houses, roads, carparks, airports, etc. – but most of us are utterly disconnected from agriculture. So let’s remedy that by trying to visualise our “foodprint”.
As it turns out, it’s surprisingly hard to find a universally familiar thing that illustrates a spatial area of the right size for this experiment – so a “ballpark” estimate will have to do, quite literally. Sports fields seem to be the most widely recognisable and standardised spaces, and they tend to be in the realm of 0.5 to 1 hectare in size. So, let’s imagine a “typical” sports field, comprising 0.8 hectares (2 acres) of grass, surrounded by a crowd of say, 50,000 fans. Now imagine we wanted to grow food instead of grass to feed the fans. How many do you think we could feed?
Well, if every person in that stadium ate the amount of meat typical of countries like the US and Australia, then they would EACH need an area roughly the size of two of the sports fields, just to feed the animals whose products they consume. Even with a mathematically optimised vegetarian diet, the whole field would only provide enough space to feed maybe four of the fans. The other 49,996 would go hungry.
(Out of interest, if this was an apocalyptic disaster movie where everyone was trapped in the stadium, they could adopt a “bare minimum” survival diet and manual farming system, whereby 20 full-time micro-farmers *might* grow enough food for themselves plus about 80 fans, leaving 49,900 to experiment with cannibalism. Eesh, that got dark quickly…)
The point of that sojourn was to highlight the very significant spatial demands of our diet – even when it’s been mathematically optimised to minimise area. So the prospect of cities “feeding themselves” entirely with rooftop gardens and spare allotments is clearly nonsensical. The relatively high costs of land and water in cities further undermine the potential of urban agriculture. But I believe that urban food gardening (or farming) still has a place in our vision of regenerative development, for two main reasons.
Firstly, high-yielding, high-value, and/or perishable crops – e.g. fresh herbs, chicken eggs, and some fruits and vegetables – make great sense to grow in cities. Such foods can be grown by household gardeners, or by small-scale market gardeners, perhaps creating more meaningful livelihoods than the meaningless hamster-wheels of the growth economy. Lower-value, less perishable crops that require more space but can be transported efficiently would still be grown by rural famers in the hinterlands and beyond, where they can access greater economies of scale.
Secondly, perhaps the greatest contribution that urban agriculture can make is not through the calories or grams of protein it can deliver, or the jobs it can create, but rather through the awareness it can raise about our food system.
Anyone who has dug a vegetable patch, grown tomatoes, attempted to irrigate efficiently, dealt with pests, tried to maintain soil nutrients, kept animals alive (let alone killed them to eat!), and handled either gluts or shortages of seasonal produce, will have a greatly enhanced respect for our complex food system.
I strongly believe that urban agriculture can, and needs to, do both of these things: it should provide an efficient local production mechanism for certain foods appropriate to the urban context, and, if it does this well, it should deliver much-needed “food system literacy” allowing city dwellers to make more informed food choices.
About the Author
Dr. James Ward
Associate Head of School: Teaching & Learning
School of Natural & Built Environments
University of South Australia, Adelaide
James trained as an engineer and completed a PhD in numerical modelling in 2008. He now works as a Senior Lecturer in water and environmental engineering at the University of South Australia and has published research papers and delivered lectures on a variety of global questions such as overpopulation, limits to growth, global fossil fuel constraints, and climate change. On the solutions side, James conducts research into energy efficient buildings, sustainable urban food systems, wicking bed irrigation and industrial wastewater recycling for peri-urban agriculture.
With his engineering background he is passionate about using numbers, both to quantify big-picture sustainability problems at the global scale and also to design (and assess the effectiveness of) sustainable and regenerative solutions at the local scale. James is a member of the Wellbeing Economy Alliance (WE-All).
Faculty bio: https://people.unisa.edu.au/James.Ward
(Header image and tiles courtesy of Pixabay.com)