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Phosphate essentials


Phosphates are becoming a global strategic resource, essential for modern agriculture.  But finding out how much we have is a difficult job, reports Ted Nield.

Geoscientist 21.07 August 2011

Living things need phosphate – the subject of this month’s main feature. Nucleic acids and cell metabolism depend upon it. Obtaining adequate phosphate supplies is therefore a key need for farmers all over the world, especially in areas where phosphate is the main growth-limiting factor. Sadly, indiscriminate over-use of phosphates is now as much of a headache in some countries as under-supply is in others.

Worse still, the world may be running out of phosphate. In 2009 the USGS suggested that reserves might begin to run out in as little as a quarter of a century. A more reassuring picture was recently painted (2010) by the Alabama-based International Fertilizer Development Center (IFDC), which suggested 300-400 years was a more likely figure. But it is notoriously hard to get reliable information on phosphate reserves out of either industry or governments.

Figures available to international bodies like the IFDC consist of unverifiable and often highly dubious government statistics. The absence of any international agency charged with collating and verifying world data on phosphate reserves continues to pose a major obstacle to assessing the size of the problem. Nevertheless, with demand set to grow by up to 3% per year, even optimistic commentators are now warning that the time is fast approaching when the world will begin to see phosphates in a “strategic” light.

Most reserves are to be found in sedimentary deposits, and are heavily concentrated in China and Morocco/Western Sahara, who together with USA and Russia (see this month's feature) control over 70% of world reserves. This concentration raises issues of food security - and of potential market manipulation in future. The Paris-based International Fertilizer Industry Association, which represents producers, points out that markets will function to bring more reserves online as the prices rise. However this may be scant comfort to less well-off countries, and ignores the fact that many deposits are uncommercial because of intractable difficulties with toxic elements, such as cadmium.

One thing is certain – phosphate has no substitutes. The best hope for the future now lies in reducing waste by more sophisticated application of fertilizers, and by recovering phosphates from such potent waste sources as dairy and pig manure, or at waste-water treatment plants, where pipes are often blocked by buildups of ‘struvite’ (a deposit of phosphate, magnesium and ammonium). Processes to make these recovery processes industrially viable are under development, but may be decades away.