Peak Phosphorus: The Biggest Problem You’ve Never Heard Of

By Andrew Schell
Published: October 1, 2014 | Last updated: April 19, 2022 09:40:43
Key Takeaways

In this day of dwindling resources and overpopulation, the term “peak oil” is often seen in headlines, but have you ever heard of “peak phosphorus”?

Source: Dusan Kostic/

Our society is dependent on mined phosphorus as fertilizer, and global food demands are diminishing our reserves of this suddenly precious element.


If phosphorus reserves vanished suddenly from the Earth’s crust, scientists estimate that two-thirds of the world would starve. Many scientists believe we are approaching the peak of phosphorus production, if we haven’t already passed it.

The Global Phosphorus Research Initiative estimates we have 50-100 years left of known phosphorus reserves. The global markets have already started to be affected by the depletion.


Phosphorus: Essential for Life

Every living being on Earth requires phosphorus. It is a fundamental component of DNA, RNA and ATP. ATP (adenosine triphosphate) is the energy “currency” of living cells and is necessary in large amounts for chemical reactions such as photosynthesis and cellular respiration. ATP powers the production of essential biomolecules like fats, proteins and carbohydrates. Phosphorus also makes up phospholipids that assemble into cell membranes, the semi-permeable boundaries of cells that allow the exchange of ions. Flower, fruit and root development require phosphorus uptake.

All the human and animal manure which the world wastes, restored to the land instead of being cast into the water, would suffice to nourish the world.” – Victor Hugo in Les Misérables

The Guano Wars: The War on Poop

Before human civilization, plants obtained phosphorus from the flooding and weathering of soils, as well as the natural composting of organic matter. After the dawn of agriculture, humans eventually figured out that adding manure and compost to their crops would increase their harvests. This was furthered by the addition of the inedible remains of animals including bones and fish.


After the famines of the 18th century, a surge in farm production was necessary to revamp the withered populations of Western Europe. Then, in 1802, explorer Alexander von Humboldt (yes, the namesake of Humboldt County) documented the agricultural techniques used by the indigenous people of Peru, who used seabird guano as a fertilizer. The local inhabitants understood the value of the phosphorus-rich guano, as harm to the seabirds was punishable by death.

Islands off South America containing large seabird guano reserves as deep as 300 ft. were soon coveted by the Western world. The guano reserves peaked and declined, and political and military battles broke out over control of the resource. This culminated in the Guano Wars of the mid-1860s between Spain and an alliance between Chile and Peru (yes, it was a war over piles of bird poop). The guano reserves were mostly depleted and unattractive to market demands by 1900, and the world found a new source of phosphorus: mined rock phosphate.


Addiction and Diminishing Phosphorus Supply

Almost all of the phosphorus used in farming today is mined rock phosphate. Millions of tons are used each year, and 90% of the world’s known rock phosphate deposits are controlled by five countries: US, Morocco, China, Jordan and South Africa. India and Western Europe have no reserves and import everything they need.

The market shows that demand is starting to outstrip supply, which is partly what lead to an 800% price increase on phosphorus in 2008. In recent years, China has placed large tariffs on exports of phosphorus, which hints at the country wanting to keep its current reserves for domestic use. The quality of phosphate is declining each year as well, and the cost of technology is rising.

While scientists debate the exact dates of peak phosphorus, it is believed extraction methods and other affiliated technologies will improve as well as the refining processes of lower-grade resources.

Also, there are probably large deposits that are still undiscovered. Regardless, the supply of rock phosphate cannot keep up with geopolitical policies and the current rates of consumption and population growth. While peak theories have their flaws, I believe alternative sources of available phosphorus must be developed and our entire system of global food production must be re-evaluated.

Read also:

The Phosphorus Cycle: From Mine to Fork

The current system of getting phosphorus to a plant and then to humans is extremely inefficient. For example, 80% of the rock phosphate mined for agriculture gets wasted somewhere along the line and ends up in a landfill or a waterway. On top of that, the usable phosphorus in the form of human waste is flushed down the drain.

The extra phosphorus from fertilizer runoff and human sewage gives rise to algal blooms in our lakes, rivers and streams in a process called eutrophication. The algae then dies and is broken down by micro-organisms. This depletes the oxygen levels in the water, harming fish and other aquatic animals.

Proposed Solutions

  • Composting – Returning phosphorus from food waste back to the soil
  • Recycling human and animal waste – Sweden and other countries have mandated urine diverting toilets for use on farms since human urine is sterile and packed with phosphorus and nitrogen. One person’s urine supplies enough phosphorus to fill half the phosphorus requirement for that one person
  • Biotechnology and selective breeding – Plants can be bred or engineered to use less phosphorus and adapt to low-phosphorus soils
  • Diets with less meat and dairy and more vegetables
  • Local food movement – Produce food where it is needed. Animals and crops should be raised together
  • Financial incentives
  • Regulation – Caps and taxes
  • More knowledge – Hands-on organic gardens and compost piles in schools and at home
  • Have less children!


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Written by Andrew Schell

Profile Picture of Andrew Schell

Andrew Schell has 15 years of technical gardening experience, from warehouse operations in Los Angeles to the full-sun fields of Humboldt County. With a biochemistry degree from Humboldt State University and a plethora of lab experience, Andrew lends his perception of plant processes and nutrients from the molecular level. He is the International Sales Manager for House and Garden Nutrients.

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