But it remains an open – and sometimes boisterous – debate how long reserves of the non-renewable nutrient will last, with projections ranging from a few decades to hundreds of years.
“Phosphorus is a major problem for Europe because it is only found in six or seven countries,” Gilberto Garuti of Neorurale, a rural development organisation in Milan, said at a recent European Parliament conference on farming. Garuti estimated that global demand will exceed supply by 2035, a figure that is in line with other assessments.
The EU is dependent on imports for nearly all its phosphorus and the European Commission’s environment directorate has cited supply security of phosphorus and the need to consider more efficient use of the resource.
European officials have raised concerns about the concentrations of supply in a handful of countries and food production pressures in developing countries that could crimp supplies in advanced nations.
Phosphorus is one of the most abundant earth elements and is mined from phosphate rock. Consumption grew fourfold between 1960 and 2008, a period of rapid world food production, according to the International Fund for Agricultural Development.
Experts have called for expanding research and technology to recover phosphorus from non-mining sources like sewage sludge, or regulatory measures like taxing consumption to reduce waste.
Past estimates by the US Geological Survey put total global reserves at least 16 billion tonnes – one-third of it in Morocco. China, South Africa, Jordan, United States, Brazil, Russia, Israel and Syria also have significant reserves. Current production is more than 160 million tonnes per year.
Supply concerns overstated
Yet there is an enormous gulf in forecasts for how long stable supplies will last with the planet expected to feed 2 billion more mouths, up from 7 billion today, by mid-century.
Researchers in the water and environmental studies research programme at Sweden’s Linköping University say phosphorous stocks will run out within 50 to 100 years. Earlier studies suggested supplies peaked more than 20 years ago, but new discoveries and rapid growth in phosphorus output in China dampened concerns about looming shortages.
Other researchers say the projections are way off and point to new discoveries in countries including Iraq.
“There is no indication there is going to be a ‘peak phosphorus’ event within the next 20-25 years,” says a study by the International Fertilizer Development Center (IFDC) in the United States, adding that “phosphate rock reserves to produce fertiliser will be available for 300-400 years.”
Steven Van Kauwenbergh, a geologist who wrote the IFDC report, told EurActiv he estimates world reserves at 60 billion tonnes, a figure he contends is “very conservative” and doesn’t factor in known supplies that are more difficult to access.
“In the Western United States there is another Morocco in terms of resources, it’s just imbedded and folded in contorted mountains,” he said by telephone from the IFDC headquarters in Muscle Shoals, Alabama.
“If the price of rock gets up high enough, people will go back under ground for it.”
Rising demand – and need
What is certain is that prices for agricultural phosphorus and other crop fertilisers have risen and are likely to continue to do so – driven in part by production and shipping costs, but also growing food demand.
Phosphate rock prices hit their highest mark this century in 2008, more than $400 per tonne, before plummeting to less than $100 in 2009. Prices topped $200 a year ago and stood at $185 per tonne last month, the InfoMine news service reported.
Researchers at the Sydney University of Technology have also raised concerns about geopolitical consequences of supplies being concentrated in the hands of China, which has imposed steep tariffs on phosphorous exports, and in Morocco and the disputed Western Sahara region.
“In 2008 China imposed a 135% export tariff to secure domestic supply for food production; a move which essentially halted exports from the region overnight," says a study by the university’s Institute for Sustainable Futures.
“Morocco currently occupies Western Sahara and controls that region’s extensive reserves in defiance of UN resolutions,” it added, highlighting potential security concerns that could disrupt trade.
Agreement on recovery
Despite the differing takes on future supplies, there is broad agreement that recycling and more judicious application are important to supply security and reducing environmental hazards.
The United Nations Environmental Programme contends that “major gains can be made through improving plant nutrient management and recycling phosphorus from waste streams,” including sewage sludge.
The more efficient use of phosphorous fertilisers opens the door to better environmental stewardship, the UNEP also says.
While nitrates and other minerals used for plant nutrition work their way through plants quickly, phosphorus dissipates very slowly and excess use can lead to long-term contamination of soils. Scientists say Soviet agricultural planners’ over application of phosphorus and other fertilisers to turn arid Central Asian land into cotton and wheat fields contributed to one of the world’s worst environmental disasters – the near-death of the Aral Sea.
But European-led efforts to mine phosphorus from sewage sludge and farm waste also could have human health consequences. “There’s a lot of ins and outs to that,” Van Kauwenbergh said, noting that sewerage treatment systems in Europe often do not separate metals that could prove harmful if applied to crops.