A new report from the Soil Association reveals that supplies of phosphate rock are running out faster than previously thought and that declining supplies and higher prices of phosphate are a new threat to global food security. ‘A rock and a hard place: Peak phosphorus and the threat to our food security’ [pdf 1.1mb] highlights the urgent need for farming to become less reliant on phosphate rock-based fertiliser. [1]

Intensive agriculture is totally dependent on phosphate for the fertility needed to grow crops and grass. Worldwide 158 million tonnes of phosphate rock is mined every year, but the supply is finite. Recent analysis suggests that we may hit ‘peak’ phosphate as early as 2033, after which supplies will become increasingly scarce and more expensive. [2]

This critical issue is missing from the global policy agenda – we are completely unprepared to deal with the shortages in phosphorus inputs, the drop in production and the hike in food prices that will follow. Without fertilisation from phosphorus it has been estimated that wheat yields could more then halve in coming decades, falling from nine tonnes a hectare to four tonnes a hectare. The current price of phosphate rock is approximately twice that of 2006. When demand for phosphate fertiliser outstripped supply in 2007/08, the price of rock phosphate rose 800%.

In Europe we are dependent on imports of rock phosphate, having no deposits of our own, but the geographical concentration of reserves adds further uncertainty to the future security of our sources. In 2009, 158 million metric tonnes of phosphate
rock was mined worldwide. 67% of this resource was mined in just three countries – China (35%), the USA (17%) and Morocco and Western Sahara (15%). China has now restricted, and the USA has stopped, exports of phosphate. [3]

Author of the report, Dr. Isobel Tomlinson, said:
“A radical rethink of how we farm, what we eat and how we deal with human excreta, so that adequate phosphorus levels can be maintained without reliance on mined phosphate, is crucial for ensuring our future food supplies.”

‘A rock and a hard place’ sets out the actions needed to close the loop on the phosphorus cycle. These include:

Changing how we farm
Different farming systems vary enormously in their reliance on mined phosphate. Organic farms are more resilient to the coming phosphorus rock ‘shock’, as it can only be used as a supplement to nutrient recycling (including crop rotations, green manures, and composting), and not as a replacement. Organic crops generally have a lower fertiliser requirement than non-organic crops, with a greater capacity to scavenge for nutrients through denser and deeper root systems.

Changing what we eat

Eating less meat can reduce the demand for mined phosphate. This is because vegetable-based production is more efficient in its use of phosphorus then livestock production. Although different types of meat have different levels of mined phosphate demand depending on the farming system used to produce them. Meat from livestock grazed on grassland that has not been fertilised with artificial fertilisers, will perform much better than meat from livestock grazed on fields that have been, or livestock fed on grain grown using artificial fertilisers.

Changing how we deal with human exreta
The report recommends a radical change in the way we treat human exreta and the need to abandon our current ‘flush-and-forget’ toilet systems in favour of Ecological Sanitation. The report also calls for a change to EU organic regulations to allow the use of human sewage – rich in ‘natural’ phosphate – on agricultural land to ensure phosphate levels are maintained. Globally only 10% of human waste is returned to agricultural soils. Urine alone contains more than 50% of the phosphorus excreted by humans.

Notes:

[1] ‘A rock and a hard place: Peak phosphorus and the threat to our food security’
Download the report here: http://www.soilassociation.org/peakphosphate.aspx [pdf 1.1mb]

[2] Cordell D, Drangert J, and White S (2009), ‘The story of phosphorus: global food security and food for thought’, Global Environmental Change, 19, p292–305.

[3] The geopolitical realities of the sources of phosphate rock, which are highly geographically concentrated, add a further level of uncertainty in securing future
phosphate supplies. The uneven distribution of reserves led to an article in Scientific American to declare, phosphorus “a geostrategic ticking time bomb”.