For some years now I’ve mistakenly believed that all it takes is 50 sq.m of land to produce the amount of nutrients sufficient to sustain one adult human. I don’t know where that misbelief came from because the figure I now see is a hundred times that at 5,000 sq.m or just a little over one acre. It’s roughly equivalent to four Olympic swimming pools or about 11 basketball courts.
The rural resettlement settlements I mentioned in the Retirement Plan post were all designed for populations of around 4,200. Multiplying this by 5,000 sq.m per person means that, if each village is to be self sustaining in food alone, it needs a hinterland of 4,200 x 5,000 sq.m = 21 mil. sq.m in addition to say 210,000 sq.m for shelter – let’s say a square with 4.6 km sides. This density of just less than 1,000 persons per square kilometer is break-even for full-on, non-stop, self-sufficient agriculture at 100% productivity.
Such a village could conceivably also be socially sustaining in terms of personal and interpersonal relationships, as is often the case in rural areas. However, even if it could, it won’t exist in isolation as far as food and shelter are concerned. The villagers won’t have built their own houses using materials they gathered and processed themselves, and they won’t be making their own clothes or furniture. They may not get meals and coffee delivered but they will still be participating in the retail economy and its attendant service economy. And although they might be capable of amusing and entertaining themselves, they’ll most likely be online and have alternative streaming entertainments on offer. Despite all this, being self-sufficient in food alone is a big one even if there’s no surplus for us city folk.
There’s a few things nations do to make up for the shortfall.
- They can import food from places that have a surplus of foods they either want or need.
- They can make foodstuffs that have calories but little or no nutritional value. (This is not good, but it happens.)
- They can amalgamate farms and industrialize the production of food.
- They can use fertilizers to improve the productivity of farmland, insecticides to deter pests, and genetically modified seeds to improve crop yields.
- They can stack farmland into 1-metre layers and use artificial light and soil to grow value-added crops in those growhouses we’ve come to call vertical farms.
All these techniques mean we never have to ask ourselves if maybe 50 sq.m of agricultural land is too little or 5,000 sq.m too much per person, or if 2,000 nutritional calories per person per day is an over or underestimate. Arable land is defined as land with temporary crops, temporary meadows for mowing or for pasture, land under market or kitchen gardens, and land that is temporarily fallow. On a rankinghere of area of arable land per capita, Australia is 1st with 2.42 hectares per person. This is almost five times the minimum area per capita but Australians shouldn’t be too complacent since over-dependance on artesian water is causing subterranean salt to rise and turn former wheat fields into non-arable land. Some 70% of land affected by dryland salinity is Western Australia where the rural dependence on artesian water is highest.
This a problem, and not just for Australia. The Federation of Russia has the world’s 5th highest proportion of arable land per capita at 0.85 hectare per person. This is 1.7 times the self-sustainable minimum. The US is 9th at 0.59 hectare per person and a mere 1.18 times the minimum per capita (all 2005 figures). For reference, China is 142nd with 0.08 hectare per person and which, at 800 sqm per person, is less than 20% of the minimum. Kuwait at 191st place has 0.006 ha (60 sq.m) per person and Singapore at 193rd place has only 0.001 hectare (10 sq.m) per person. Any country with less than 0.5 ha of arable land per person can’t be self-sufficient in agriculture and this is where that 5,000 sq.m figure comes from.
The good thing about this figure for the amount of arable land per person is that it hasn’t been calculated from the land required to grow sufficient food to satisfy the minimal nutritional requirements of one adult and, on the back of that, to design a supposedly self-sustaining housing community. Rather than erring on the small side, this area of 5,000 sq.m per capita takes into account children as well as all those not directly involved with food production. It factors in mechanized farming, and it represents the amount of land left over for the production of food after subtracting the area of land taken up by non-arable landscape, transportation infrastructure (such as roads and airports) and land used by human settlement. It’s a better way of doing it. Even so, this 5,000 sq.m per person figure doesn’t take into account failed harvests, blight or climate events.
Most countries don’t have that 5,000 sq.m per person and this explains the large amount of food moving around the world. However, not only is the lack of slack in the system worrying, this simple statistic ignores the fact that food and shelter compete for the same land. There’s a lot of talk about urban farms and growing one’s own vegetables but we don’t need Object Oriented Ontology or Heidegger to tell us that plants have their own spatial requirements. For millennia, anyone who has grown anything has known this.
It’s all very well growing your own tomatoes or chillies for fun but it stops being funny when you have to produce your full nutritional intake yourself on what land you can farm. Maybe you can grow a few beans or tomatoes or your own cilantro/coriander/香菜/ผักชี but if you want to have some rice to go with your vegetables then you suddenly have no land left. There’s a reason nobody grows their own rice or wheat and let’s not even talk about the spatial requirements of meat.
Stacking people in high-rises makes sense if the loss in area of arable land for each unstacked person is too large a price to pay.
On the other hand, the stacking of agricultural land makes sense if we are unwilling to reduce human spatial requirements (or increase the density of human occupation).
Vertical farming assumes that crops so grown will be nutritionally substantial but we never hear about growing the rice or wheat that comprises a large portion of the calorific intake of much of the world. Vertical farming is suited to compact and quick-growing leafy plants that respond well to artificial light and that people will pay a premium for. We never see grains, legumes, root vegetables, cruciferous vegetables, fruit or nuts. This all suggests a technology designed for harvesting profits, not sustenance. Architects were quick to oblige.
Another inherent problem with vertical farming is that it relies upon artificial systems for lighting, watering and nutrient delivery, not to mention a structure for vertically stacking the growing platforms in the first place. All this creates additional problems of resource and energy use and, further back down the line, energy production. Plants are plants and their lighting requirements are different from ours. Plants are also well adapted to growing with minimal input on horizontal surfaces exposed to the sun and rain but humans live in buildings to avoid being exposed to the sun and rain and are largely content to get their daylighting through vertical windows even if they are all facing in one direction as is often the case. If agriculture and people are to be co-located, then this is already suggesting a building configured in section in the shape of a letter “L”, with the plants on the horizontal arable surface and the people housed in the vertical non-arable surface. It’s a bit like recreating the Chinese terraced landscape above, but with vertical layers of habitation instead of walls. The Asma Bahçeler Residences in Izmir in Turkey, by Marti D Mimarlik, are the closest I can find to what I’m thinking of.
The only question is how high the vertical bit needs to be and how long the corresponding horizontal bit. Taking the above development as an example, and assuming all two-bedroom 12.5m wide apartments housing three persons (on average), then each apartment would need an area of land 12.5m x 200m in front of it (four Olympic swimming pools, remember), and each apartment stacked above would require that much area again. Conclusion: The terraced apartments on terraced fields isn’t a viable idea for the viable colocation of housing and realistic agriculture. Even if such a configuration avoids housing and agriculture competing for the same land, the land requirements of agriculture are so great compared to those of housing, that it makes no sense to force the two together.
Nevertheless, L-shaped configurations such as the Asma Bahçeler Residences do leave the maximum amount of arable land for domestic food production even if the amount of that production will never be sufficient. Even a degree of self-sufficiency is better than none and some people enjoy growing some of their own food. In some countries such as China, the link between people and the land is still strong and, if there is land, people will grow their own vegetables and make their own pickles because that is what they do. Guerilla farming on unused arable land is not uncommon.
The idea of the self-sufficient co-location of agriculture and housing was probably flawed from the start. There’s a reason why we don’t see any examples of a rural-urban hybrid. Farmland is best at being farmland and cities are best at being cities. We haven’t (yet?) regressed to a situation where every person needs to be attached to their own piece of land for subsistence farming for survival. And if we ever were to, then architecture would be the least of our worries. In the meantime, it’s a good idea to keep cities compact and dense and not waste arable land.