Peak Phosphorous: Crisis in the Making or Radical Opportunity?

Jay Bailey, of Fair Winds Farm, in Brattleboro, applying diluted human urine to his hayfield using horses.
Jay Bailey, of Fair Winds Farm, in Brattleboro, applying diluted human urine to his hayfield using horses.

Written By

Tatiana Schreiber

Written on

November 24 , 2013

For many years environmental activists have used the term “peak oil” to refer to the coming crisis in availability of fossil fuels, and as part of a rhetorical strategy to hasten our shift toward a post-oil economy. Recently, some activists and scientists have begun to talk about another “peak” crisis: that of phosphorous, an essential nutrient for plant growth and, as a component of DNA and cell membranes, critical to all life forms. In his 1959 essay “Life’s Bottleneck” author Isaac Asimov wrote, “Life can multiply until all the phosphorous is gone and then there is an inexorable halt which nothing can prevent.”

Some skeptics argue that “peak phosphorous” is a manufactured crisis, designed to undermine the corporate phosphorous industry. The primary modern-day use of phosphorous is for chemical fertilizers, but it is also found in animal feeds and pesticides, making it common in industrial agriculture. It is also present in detergents and weapons manufacturing; it is unusual in that it has both life-sustaining and destructive properties. Yet despite some skepticism over the timing of “peak phosphorous,” very credible research suggests that its availability really is in jeopardy. Demand is escalating, costs are rising, and global food security may be at stake.

Ironically, however, the means to avert this “crisis” is very close at hand. Here in Vermont some creative strategies are underway to conserve phosphorous.


Phosphorous is element 15 on the periodic table, and was first isolated from human urine (where it is still found in abundance, as we shall discuss shortly!) in 1669 by a German alchemist, Hennig Brandt, while he was trying to find the substance that would turn minerals into gold. Phosphorous is perhaps more valuable than gold: it is present in our teeth and bones and is known to gardeners and farmers as one of the three major nutrients needed by plants along with nitrogen and potassium.

Most of us think of phosphorous primarily in its role as a source of water pollution (i.e. as run-off from fertilizers used on farms and lawns, and from detergents; this phosphorous makes its way into waterways where it feeds algae, which die and decay, leading to depletion of oxygen in lakes and the death of many aquatic species). We’re led to think there’s too much phosphorous in the world, rather than to worry that there may be too little. Indeed, phosphorous is “the 11th most abundant element of the earth’s crust,” according to researchers Dana Cordell and Tina-Simone Neset, whose research on phosphorous is widely cited. Certain compounds containing phosphorous were formed over millions of years, starting as the remains of sea creatures. The buried material eventually found its way into soils through geological shifts that brought the sea floor to the surface; from there rocks eventually weathered down and were mineralized (the process by which soil organisms break down rock into its component parts), where the phosphorous became available to plants, dissolved in the fluid portion of the soil.


Clearly, however, as a substance that takes millions of years to form, phosphorous is a non-renewable resource, which, like fossil fuels, we are bound to run out of at some point. Demand for phosphorous fertilizers—for both food and biofuels—continues to increase, with world consumption expected to reach 45.3 million tons in 2016. Phosphorous is mined from deposits around the world, but in more and more challenging places to reach, such as deep within the sediment of the ocean floor. Currently, most of it comes from Morocco and Peru, but China and Saudi Arabia are poised to become big producers soon. Domestically, Florida and North Carolina are key producers, with new mining operations opening soon in Idaho as well. The U.S. Geological Survey reports that significant phosphate “reserves” (sources that could be mined some day) exist on the continental sea shelves of the Pacific and Atlantic oceans.

Estimates of when “peak phosphorous” might occur vary from 2030 to the end of the century—the difference depends largely on what new technology might be developed to exploit the more difficult-to-access and less-pure sources of the element. But even before “peak” phosphorous should occur, there are serious problems associated with phosphorous mining right now. Aside from the obvious energy costs, mining operations leave behind destroyed landscapes and tailing piles contaminated with heavy metals such as cadmium, chromium, arsenic, and lead. In addition, phosphate rock contains significant amounts of radioactive uranium and thorium. The EPA warns that waste products from fertilizer production, currently piled at production facilities, pose a significant radiological hazard.

But for millennia, farmers worldwide recycled phosphorous efficiently. Remember how phosphorous is essential to all life? It is therefore present in all life forms, and in all organic waste. Animal manures, bones and feathers, plant debris, leaves, grass, and human waste all contain enough phosphorous to meet our agricultural needs, but only if we radically re-organize our priorities for its use. As Fred Magdoff, professor emeritus of soil science at UVM points out, because so many humans now live in cities, and because of the industrialization of agriculture, “we’ve become separated from the land that grows our food, and that’s compounded with farm animals… literally millions of animals are raised in small areas, fed [phosphorous–rich] feed shipped in from far away” and that phosphorous is lost when the animal waste and our own waste is sent to landfills and is leached out to contaminate waterways. “From an ecological point of view,” Fred believes, “it makes sense to try to reunite animals with the land that produces their feed.” He includes us in his definition of “animals.”  “If peak phosphorous is going to hit us, and it will hit sometime, this is the answer: You have to recycle nutrients back from people to the land.”


In Brattleboro, the Rich Earth Institute (REI) is experimenting with ways to do just that. The Institute has been collecting urine from 170 individuals in the area, pasteurizing it (probably not necessary, since urine is nearly sterile, but required by the state), and applying it in various concentrations on a hayfield at Fair Winds Farm in Brattleboro. (Urine contains not just phosphorous, but also nitrogen and potassium and many of the minor plant nutrients as well, making it an ideal fertilizer.) This year the experiment focused on trialing different levels of dilution and improving the efficiency of the application. Abe Noe-Hays, cofounder of REI, along with Kim Nace, reports that the treated fields were more than twice as productive as the controls, and there was no appreciable difference between the urine treated fields and those treated with chemical fertilizers. The treated fields stood out as “bright green strips. It was quite graphic,” said farmer Jay Bailey. Undiluted urine did not damage the crop, but a 50/50 mix may make the most efficient use of the nutrients.

The urine from the REI experiment may be more significant as a source of nitrogen than as a source of phosphorous because Fair Winds Farm soils were not deficient in phosphorous at the start. Nonetheless, the experiment offers important data for the potential of recycling human waste for fertilizer worldwide. According to Abe, REI is the first U.S. project to collect urine for agricultural application on a community scale. He says a day’s worth of human urine produces roughly 1 gram of phosphorous and 14 grams of nitrogen per person and can fertilize one square yard of a food crop, on average. Soil scientist Fred Magdoff argues that “we as a civilization need to do this, and we need to find out how to do this in a safe way…. I am convinced that human waste can be used safely, it has been, and still is being done, but you need to be careful.” Jay Bailey concurs, “It’s important that we as a society get ourselves to stop throwing this stuff away and then paying through the nose to replace it. We have to find a way to do it well and we know we can.”

Magdoff notes that most of the phosphorous in the food we consume gets excreted as waste and currently undergoes energy-intensive treatment at sewage-treatment plants. It seems the least we can do for the planet is to take that phosphorous out of the treatment plants and put it back on the land where it came from. The major concern of course is the contaminants that currently get into sewage sludge, including the pharmaceuticals we consume and dispose of. The REI will shortly begin an investigation of the level of pharmaceutical contaminants in collected urine, at the plant root zone, and in harvested crops. “Our project is a natural bridge,” says Abe.” It is a solution that turns human waste from a pollutant of our waterways to a fertilizer for sustainable farms.”


There are many other ways that we as farmers and gardeners can conserve phosphorous and do our part to avert “peak phosphorous.” Farming practices such as reduced tillage and use of composts and cover crops enhance the organic matter and favor a healthy microbiota in the soil. These microorganisms are critical to making phosphorous available to plants, preventing its runoff into waterways. The vegetable and berry specialist for UVM Extension, Vern Grubinger, adds that many New England soils are already rich in phosphorous, sometimes excessively so, from years of compost and manure use. So, before thinking of using rock phosphate or any other phosphate fertilizer, get your soil tested! You may not need to add phosphorous at all. You can also learn which composts have higher or lower amounts of phosphorous and use those that are most appropriate to your soil’s specific needs.

Peak phosphorous may not be a near-term crisis for us in New England, but as fertilizer use for industrial agriculture and biofuels continues to escalate globally, perhaps the idea that we are running out of a substance that is expensive to produce, is a huge consumer of energy, and is a major source of pollution can be turned into an opportunity to bank on the currency of phosphorous by returning what we’ve taken from the land. It’s one small step we can take in the process of learning to sustain ourselves and our habitat.

For more information on the Rich Earth Institute, go to richearthinstitute.org. For more on phosphorous, go to Global Phosphorous Research Initiative, phosphorousfutures.net. For work on recycling human waste, see EcoSan Research of the Stockholm Environment Institute, ecosanres.org.


About the Author

Tatiana Schreiber

Tatiana Schreiber

Tatiana Schreiber is a research associate at Rich Earth Institute in Brattleboro, and also consults on complementary plants for growing with solar arrays. She teaches ecological agriculture at local colleges and grows heirloom and unusual garden seedlings including medicinal plants at Sowing Peace Farm in Westminster West.

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