Peak phosphorous: mankind's latest threat

21 Jan, 2010 07:41 AM
Image courtesy of Elsevier - The story of phosphorus: Global food security and food for thought. Dana Cordell, Jan-Olof Drangert, Stuart White.
Image courtesy of Elsevier - The story of phosphorus: Global food security and food for thought. Dana Cordell, Jan-Olof Drangert, Stuart White.

SOME believe that dwindling supplies of potable water is humanity's great resource challenge; others think it is the imminent prospect of "peak oil".

But an equally important milestone in modern history will be an inevitable tightening of global supplies of phosphorus.

Phosphorus has underpinned the leaps made in agricultural productivity since World War II, and the world's economies and population levels have become dependent on a continous supply of the element.

Unlike nitrogen, which can by synthesised from the air, or the use of renewable energy to substitute for fossil fuels, there is no substitute for phosphorus. All the world's phosphate fertilisers come from mined phosphate rock, making it a finite resource.

Various analyses suggest "peak phosphorus" - the point at which supply falls behind demand - will occur around 2040, with all currently known reserves potentially exhausted within 50 to 100 years.

However, University of Technology Sydney researchers Dana Cordell and Stuart White warn that for most countries, a phosphorus squeeze is likely to come much sooner.

Demand for phosphorus is growing in line with population growth, and is being pushed higher by greater consumption of meat in countries like China and India.

(Based on European practices, the Swedish Environmental Protection Agency estimates that a vegetable-based diet uses 0.6 kilograms of phosphorus per person per year, compared with 1.6 kg for a meat-based diet.)

Few nations have access to enough phosphorus to supply their own agricultural needs: in fact, most of the world's known phosphate reserves are controlled by China, the United States and Morocco.

China has the largest reported reserves, but in 2008, at the height of the food crisis, China's central government introduced a 135 per cent tariff on exports to protect domestic supply.

The US, historically the world's largest consumer, importer and exporter of phosphate fertilisers, is now thought to have only about 25 years of domestic phosphate reserves left. US fertiliser manufacturers are importing large quantities of phosphate from Morocco.

Morocco supplies more than a third of the world's phosphate, but it is an industry that stands on politically unstable ground. Much of Morocco's phosphate comes from the disputed territories of the Western Sahara, an activity that has been condemned by the United Nations.

Phosphorus may be in finite supply, and that supply politically uncertain, but Australia's agricultural and food systems remain highly inefficient users of the fertiliser.

Dana Cordell calculates that only two per cent of phosphate fertiliser applied in Australia is eaten in locally-consumed food.

Up to 75 per cent of P fertiliser is locked-up in agricultural soils. About 20 per cent of applied fertiliser is exported in farm produce, and a minor amount is leached into waterways, contributing to nutrient overload or carried out to sea.

One researcher has estimated that of the billion tonnes of phosphorus mined since 1950, about a quarter now lies in water bodies or landfills.

Each year, Ms Cordell says, humans eat about three million tonnes of phosphorus, and excrete close to 100 per cent of it.

In some countries, that has led to serious investigation of recycled urine as a source of agricultural phosphorus.

Urine is "essentially sterile", and contains nitrogen, phosphorus and potassium in the correct ratios for plant growth.

If all human urine was recycled, according to Jan-Olof Drangert of Linköping University in Sweden, where Dana Cordell also studies, it could supply half the phosphorus needs of the world's cereal crops.

Two Swedish municipalities have mandated that all new toilets must divert urine away from solid waste. The urine is collected in tanks either at the house, or in a communal collection point, and picked up once a year by farmers who use it as fertiliser.

However, in countries like Australia, with a large land area and a relatively small population, nutrient recycling can at best provide five per cent of the nation's phosphorus needs.

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Gerhard Grasser
21/01/2010 3:22:27 AM

All the more reason to be looking at making and using compost to keep nutrients cycling in our food production systems. Compost and compost teas made from organic materials such as food processing by-product (waste) and human by-product (waste) heralds the new era of biological farming where the pressure on the demands of the world's resources can be reduced and the already locked up nutrients in the soil released into the food chain. Scientifically based and practically proven biological farming ticks many boxes in environmental benefits, including carbon sequestration, soil health and productive capacity - but does no favours to suppliers of mined or manufactured inputs except reduce their demand.
Edward Metcalfe
22/01/2010 2:59:46 AM

Unlike oil, the phosphorus still exists after use, it's just dispersed. Considering that billions of lives are at stake it becomes obvious that we need to recycle our sewage, probably using earthworms, and cart out the castings back to the farms. This will also recycle a whole load of other minerals for farming as well.
22/01/2010 6:30:05 AM

Roll on the days of looking after the soil naturally.
22/01/2010 6:36:46 AM

Here we go...another fear campaign based on zero facts, prosecuted by those with a financial interest in the product of the fear created. Take just a moment to check with the FAO, and you will realise that this is yet another piece of crap...what happened to peak oil in 2008? Now they are saying at least 2040...wake up and use your heads.
Common Cents
22/01/2010 6:46:36 AM

Hey this reads like a history lesson. Did not our phosphorus problems peak during the '80s? A combination of rising avgas prices, fertiliser prices and drought plus ridiculous publicity saying phosphorus was evil in this desperately deprived country have resulted in a severe run down in our P soil banks and productive potential. I love your note about China's tariff. "China has the largest reported reserves, but in 2008, at the height of the food crisis, China's central government introduced a 135 per cent tariff on exports to protect domestic supply." Now seeing as we have some of the largest reserves of coal why don't we put a tarrif on coal so our farmer's can afford to import Phosphorus? Do we still believe in all that free trade crap?
22/01/2010 6:50:28 AM

The threat of Peak Oil exists because once you use a complex hydrocarbon it is gone. You cannot destroy phosphorous unless you are good at alchemy, you can only change its form and take it from dense deposits and spread it across the earth more thinly. The "potable water" threat is caused by things in the water and salts may be a problem, but those things often involve a lot of phosphate and nitrogen, and surprise surprise what do we need to make food: water, phosphrous and nitrogen. Pardon the pun but the SOLUTION is a piece of piss!
22/01/2010 7:05:27 AM

As the population increases and the available phosphate stocks dwindle, more use must be made of solid residuaes from sewage, which to a large extent in the western world goes to waste at present. This concept will be unpalatable (in a manner of speaking) to most, but processes must be developed to make it safe and acceptable, or else the world will run out of food.
Andrew Kennett
22/01/2010 9:09:42 AM

This has got to be one of the worse pieces of modelling ever seen - just look at the curve - a pretty little parabola has been fit but a hyperbolic rise would fit the data as well and a linear fit from 1950 would fit even better, if you want a parabola then a whole lot would fit as well with peaks at 2100, 2200 etc. The data suggests endless rising output not a peak - sure a peak will happen but we don't have the data to say when - no scare needed.
22/01/2010 9:56:59 AM

Recycled sewage will certainly help but what about all the heavy metals and salt?
22/01/2010 12:43:23 PM

Most phorphorus from human consumption is in urine which is a very good and pure fertiliser with no bacteria. It is easy to capture for men and can be done for women with purpose built toilets. Urine has about 1/6 of the nuturients of inorganic fertiliser by volume. What do we do with it now? We create pollution with it.
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