Phosphorus (P) is an essential nutrient to all life, and thus our food system. Humans cannot manufacture P for fertilizer and must rely on the geological processes that have concentrated phosphate deposit, mine it, and invest large amount of energy to process it. Instead of being cyclical, the movement of P is now increasingly linear on human time scales. P is mostly utilized in food production (in rural settings), while consumption is now mostly in urban areas. Our current extraction and use of P as a fossil resource threatens our ability to continue mining. This has resulted is a unique set of environmental, political, and economic considerations and the idea of peak phosphorus, the depletion of easily extractable phosphate rock, in the next 50 to 100 years. My PhD work examines how current urban and peri-urban agriculture in the Phoenix Metropolitan Area (Arizona, USA) and Accra (Ghana) area influence local P cycling, and how these types of agriculture do or have the potential to increase the sustainability of the global P cycle and increase the adaptive capacity of the city in terms of food security. On a larger theoretical scale, these case studies will contribute to the identification of features of urban agriculture that may be appropriate to generalize and incorporate in the theory of a sustainable food system, and the aspects of urban agriculture that must be specific to each city.
Economically viable mineral deposits are concentrated in three regions: China, Morocco, and the US, thus the 3 miners in the dance. Most of the phosphorus is processed as fertilizer that goes to the farmers who are planting seeds in the dance. Plants then grow (incorporating P) and produce food and fiber. As cities become more alluring (the city invites everyone in) and urban populations grow (dancers become part of the city), the movement of P (I am a P atom, as indicated by the periodic table information on my shirt) from the earth’s crust, to farms, to table becomes more linear (P dances from one step to the next, doing the dance of the miner than transitioning to the farmer dance, and than to the plant where P is incorporated in growth and than cut and exported to the city). The city consumes food and dilutes P through waste (thus P becomes smaller and than fades in the waste stream). Because P is not recoverable, one by one the actors in the food chain collapse.
But STOP (as illustrated by movement). There are some alternatives. If all members of food production and consumption work together in this new urban environment things may change (everyone dancing all the parts). There is an opportunity to make a P cycle (a circle in the dance) instead of a linear process. This can make the city more adaptive to peak P (where the wave top represents the peak, but the circle keeps P in the city). P will interact with the outside but multiple mechanisms can ensure its sustainable use (P stretches the circle). To end we all vibrate like atoms and call it a day!