Between a rock and a hard place: the threat of peak phosphorus

There is one critical issue in securing our future food security that is missing from the global policy agenda: we are facing the end of cheap and readily-available phosphate fertilizer on which intensive agriculture is totally dependent. The supply of phosphorus from mined phosphate rock could ‘peak’ as soon as 2033, after which this non-renewable resource will become increasingly scarce and expensive.

Without fertilisation from phosphorus it has been estimated that wheat yields could more than halve in the coming decades – 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.

That’s why here at the Soil Association we’ve just published a new report on the issue – ‘A rock and a hard place: Peak phosphorus and the threat to our food security’.  We reveal 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. We believe there’s an urgent need for farming to become less reliant on phosphate rock-based fertiliser.

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.

We all – the public, farmers and politicians – need to take this issue seriously and start preparing now. Necessary actions include:

• Changing how we farm: Organic farms are more resilient to the coming phosphorus rock ‘shock’, with a greater capacity to scavenge for nutrients through denser and deeper root systems.
• Changing how we deal with human excreta: Globally only 10% of human waste is returned to agricultural soils. Urine alone contains more than 50% of the phosphorus excreted by humans.
• Changing what we eat: Eating less meat can reduce the demand for mined phosphate, because vegetable-based production is more efficient in its use of phosphorus then livestock production.

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.

Dr Isobel Tomlinson is Policy and Campaigns Officer for the Soil Association.

What do you think? Have you noticed changes in fertilizer price? Do you think we need to make use of human excreta as a fertilizer?
•  Read the Soil Association’s report here
•  Read another of our blogs on phosphorous here
•  Read a great article on the peak phosphorous issue here