Opponents of this view harken back to doomsday forecasts framed decades ago by prominent analyses like The Limits to Growth or The Population Bomb. Economic and environmental disasters that should already have overwhelmed us by now have instead been postponed indefinitely, thanks to changes in our behavior, economic policy or technological capabilities. Discussion of those disasters undoubtedly prompted at least some of the necessary changes, and could do so again in the case of phosphorus.
This optimistic perspective benefited from a 2010 revision of estimates of the world’s phosphate reserves. New figures from the International Fertilizer Development Center raise the estimate from 16 billion metric tons to more than 60 billion metric tons. The author of that report, geologist Steven Van Kauwenbergh, insists that this finding should put an end to any immediate concerns about peak phosphorus.
“Based on this estimate,” he says, “at current rates of production, phosphate rock reserves to produce fertilizer will be available for 300 to 400 years.”
At the same time, Van Kauwenbergh cautions that the sources of information used for this estimate tend to be limited, provided primarily by industrial interests. “A collaborative effort by phosphate rock producers, government agencies, international organizations and academia will be required to make a more definitive estimate of world phosphate rock reserves and resources,” he concludes.
Brave New Sources
Even if phosphate is more abundant than previously thought, the distribution of reserves poses a big challenge.
According to the U.S. Geological Survey’s latest figures, published in January 2013, Morocco and Western Sahara appear to contain no fewer than 50 billion of the estimated 67 billion metric tons of phosphates, some 74 percent of the total. The rest is found in various places in much smaller amounts, with 5.5 percent in China, 3.3 percent in Algeria and 2.7 per cent in Syria. The remainder is spread among the rest of the world’s nations, with major agricultural countries such as South Africa, Russia, and the United States each holding less than 2.5 percent.
One promising technology is a chemical reactor that can be installed in municipal wastewater streams, where human urine provides a rich supply of raw material. In addition to political considerations, poor transportation links limit the volume of fertilizer reaching farmers in some countries, where a correspondingly high price makes this input all the less accessible. Even without the dire threat of peak phosphorus, as growing population boosts demand for food, intensifying competition along narrow international supply lines could place fertilizers beyond the reach of many more farmers.
Faced with this challenge, sources like that tapped in Brave New World could take on a fresh appeal. In fact, though it does not yet extend to crematoria, phosphorus recovery is not consigned to science fiction.
One promising technology is a chemical reactor that can be installed in municipal wastewater streams, where human urine provides a rich supply of raw material. Urine forms the basis of ammonium magnesium phosphate, a white crystal known as struvite. Struvite cakes on the walls of sluiceways and sewers, hardening into a concrete-like consistency that is onerous to remove.
Struvite, if it can be extracted in a pure form, offers the basis for an effective fertilizer. For example, an extraction technology produced by Vancouver-based Ostara Nutrient Recovery Technologies Inc. has been installed in cities in Canada, the U.S. and the U.K. The system, like others, aspires to provide a cost-effective means of capturing struvite for agricultural use.
The Other Half
The other half of the phosphorus predicament, ironically, is a problem of localized overabundance. Soils in many parts of North America have naturally high levels of phosphorus. Add too much more in an attempt to boost crop yields, and nutrients drain off the land to fertilize lakes and rivers. What often follows is the proliferation of algae in these waters, which then become oxygen-poor and inhospitable to plant or animal life. This process, known as eutrophication, can compromise aquatic ecosystems.
“We have understood the causes of eutrophication for more than 40 years, while the drivers have gotten worse,” says Stephen Carpenter, a professor at the University of Wisconsin’s Center for Limnology in Madison. “Increased planting of corn, increased livestock numbers and increasingly variable precipitation due to climate change are principal drivers of increased eutrophication. We decreased the discharge from sewage treatment plants, but at the same time the runoff of manure and overfertilized soil became much worse.”