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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10/07/2010 7:57:05 AM

It seems that we are about "peak" everything at a time of the planet's peak in population numbers. Just how is population growth for Australia, or anywhere, "sustainable"?
23/01/2010 3:36:00 AM

@ Andrew Kennett. Well, wrong. Perhaps not even wrong! The curve that was used, was done so because there are estimates of the available extractable deposits. You sound like a stupid economist, prepared to fit straight lines and exponentials for no underlying reason apart from the maths. Well this thing called REALITY intervenes to discredit that approach. The USGS is not infallible, but at least there is more than mere assertion behind these stats. /pubs/commodity/phosphate_rock/ph ospmcs06.pdf Page 2 of this. Reserves Reserves Base(Ultimate?) 18,000,000 50,000,000 There are no substitutes for phosphorus in agriculture. So I suspect that armed with knowledge, something you should acquire, they had sound reasons for fitting the model they did. If you really want to wade in, try this. ile/of02-156/OF02-156A.PDF Unlike nitrogen, which started to become limiting at around 1900, we cannot, REPEAT not, manufacture PO4. LUCKILY we could fix atmospheric N2 with some clever chemistry and using natural gas to form NH3. Of course as gas prices increase so to will NH3 prices.
22/01/2010 3:52:01 PM

Even if by some miraculous event we don't reach peak phosphorous in the next 50 or so years it is a certainty that the cost of P-based ferts will rise dramatically given projections of world population growth in the near term. The fact is that we are consuming resources (mostly finite) at a rate that suggests there is no end to everything. I guess the free market will take care of the variables.
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.
22/01/2010 9:56:59 AM

Recycled sewage will certainly help but what about all the heavy metals and salt?
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 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.
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!
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 6:36:46 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.
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