There are no substitutes for phosphorus in agriculture. That's the hard truth that appears in the 2009 issue of the United States Geological Service annual commodity survey for phosphorus. It's printed in every issue in the same place in that dry official document, but now it seems to take on a special significance - in the last few years some analysts have claimed production of phosphorus has already peaked, and demand is rising continuously.

Suddenly however, it seems the limits are almost upon us.

In 2007, physicist Patrick Déry applied to phosphate rock the same statistical method that has been used consistently to predict when oilfields will peak.

He found that phosphate production has already peaked.

In the last 100 years, world agriculture has developed an increasing dependence on mineral phosphate fertilisers – a suite of compounds produced exclusively from phosphate rock.

Extracted from phosphate rock mined from Morocco to Florida, phosphorus has been spread on farmers' fields to the tune of 1 billion tonnes of pure phosphorus since 1950.

Until now, the main concerns about phosphorus production were how to manage the toxic and radioactive byproducts of phosphate mining and reducing what ecologists call eutrophication – the toxic growth of algae when excess phosphorus spreads from the land into watercourses. The non-renewable stocks of phosphate rock were treated as if they were limitless. Life-giver Obtaining sufficient phosphorus is crucial for the survival of all forms of life – it forms an irreplaceable part of cell membranes, energy transfer molecules and DNA – it is truly part of every living thing. Compared to how important phosphorus is to life's flourishing, it is often the hardest nutrient for organisms to obtain in the natural world, making it a 'limiting factor' of many ecosystems, or as science-fiction writer Isaac Asimov wrote in , 'life's bottleneck'. As in the wild, so on our fields - phosphorus, alongside nitrogen and potassium, is one of the three major nutrients needed for plant growth. Increasing the availability of phosphorus is a key technique used by farmers of all persuasions in order to improve their yields.