A new light on Peak Phosphorus

Fact, fact, fact,” said Thomas Gradgrind in Dickens’ Hard Times. “Never let the facts get in the way of a good story,” say others with a point to make. Both adages may be applied in the continuing debate on Peak Phosphorus. This is a debate that has become rather heated.

To begin with a definition, Peak Phosphorus is the point of time at which the maximum phosphorus production rate is reached. Phosphorus is a finite resource with no known substitute. Some researchers believe that the world’s phosphorus reserves will be
wholly depleted within the next 50-100 years and that the peak phosphorus production level will be reached between 2030 and 2035.

One positive effect from the debate to date has been the stronger spotlight that has been shone on the issue of recycling P, especially via the greater recycling of human and animal wastes. However, the accurate determination of peak phosphorus is dependent on knowing the world’s phosphate reserves and the future demand for phosphate rock. One primary source of information in this respect has been the US Geological Survey (USGS), which has estimated that there are currently 62 billion tonnes of phosphate rock worldwide, of which 15 billion tonnes are mineable. Although widely used for predicting future peak phosphorus, the USGS estimates have raised many doubts about their accuracy: the figures have been obtained from foreign governments and have not been independently verified by the USGS.

The recent report by the International Fertilizer Development Center (IFDC), summarised in Fertilizer International, suggested that there is no indication that phosphate production will peak in the next 20-25 years - or even within the next century. IFDC reached this conclusion on the basis of an entirely revised estimate of global phosphate reserves, of around 290 billion tonnes. This total included estimated product reserves of 60 billion tonnes. Assuming current rates of usage, world phosphate rock reserves and resources should be available for the foreseeable future, IFDC said. USGS subsequently revised its reserve estimates upwards.

IFDC’s intervention has by no means stifled the arguments pro and con, and it is clear that certain parties in the debate hold entrenched positions. Those who disagree with the Peak Phosphate theory centre their arguments on three prime points, as summarised in IFA’s position paper on the subject:

Phosphate rock reserves are a dynamic concept and are regularly revised upwards with discoveries of new deposits, technological advances and increases in commodity prices. Modelling of future phosphate rock demand has not been adequate to establish how quickly reserves could be exhausted. Nor have such models considered soil P dynamics or the need to build soil P levels up to a critical level that optimises P use efficiency by plants.

Predictions of Peak Phosphorus ignore the practicality of economic feasibility of P recycling and re-use. IFA endorses the IFDC contention that we are not facing a Peak Phosphate event. IFA also contends that attention should be focused away from a possible peak in P supply and more towards any potential peak in phosphorus demand. Since P accumulates in agricultural soils, P requirements do not increase linearly with agricultural production. “There is a need to increase P levels to a critical level that optimises P availability to plants while maintaining soil fertility,” IFA notes. “The steady improvement in soil P levels in Asian and Latin American countries, possibly leading to a peak in world phosphate fertilizer demand by 2050, is a scenario that has so far been overlooked.” IFA is following this line of enquiry further, having set up an industry-wide task force on phosphate fertilizer demand, looking at different consumption scenarios.

Meanwhile, Michael Mew, Director of Fertecon Research Centre has opened a fresh angle in the debate. Michael challenges the use of the Hubbert’s Peak Oil Theory to predict a peak phosphate event.

The phosphorus debate is undoubtedly to be welcomed, as it has caused many interested parties to stop and think. The fertilizer industry is keen to promote Best Management Practices, declaring its commitment to the sustainable use of all P resources and the encouragement of research and nutrient BMPs for better recycling of all safe phosphorus sources of organic and inorganic origin. Meanwhile, in February 2011, the Phoenix Phosphorus Declaration was issued, after scientists, engineers, farmers, policy-makers and others gathered to participate in the Sustainable Phosphorus Summit at Arizona State University. They reached a consensus on the essential but finite nature of P, its key role in global food security and called for its responsible use and recycling.

From these various standpoints, there should in due course arise a vastly enhanced knowledge base on the phosphorus resources we have available, how best we may exploit them and how best we may conserve them.