Mining For The Phosphorus Locked In Ancient Poop

Scientists once looked to fossilized feces to help fertilize new agriculture fields. But do the costs outweigh the benefits in the longterm?

The following is an excerpt from from The Devil’s Element: Phosphorous and a World Out of Balance by Dan Egan.

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The Devil’s Element: Phosphorous and a World Out of Balance


The idea of fossilized feces went mainstream in the late 1820s after pioneering Oxford University geologist William Buckland, who had worked on excavations with Anning and praised her “skill and industry,” presented to the Geological Society of London his argument (bolstered by Mary’s discoveries) that the pinecone-​shaped stones regularly found amid the remains of ichthyosaurs and other ancient sea life were indeed fossilized stools. He named the rocky droppings “coprolites,” derived from the Greek words for feces: kopros and stone: lithos, and he reported that they weren’t confined to the stomachs of petrified sea creatures; in some coastal areas of England they could be found on their own, tons of them, littering the landscape “like potatoes scattered on the ground.”

Buckland described the earthy clumps as resembling, well, run-​of-​the-​mill poop.

“They, for the most part, vary from two to four inches in length, and from one to two inches in diameter. Some few are much larger, and bear a due proportion to the gigantic calibre of the largest ichthyosauri… some are flat and amorphous, as if the substance had been voided in a semifluid state,” Buckland wrote. “Their usual colour is ash-​grey, sometimes interspersed with black, and sometimes wholly black. Their substance is of a compact earthy texture, resembling indurated clay.”

This was all more than a scatological curiosity. That ichthyosaurs feasted on other sea life—​and even their own young—​upended the Christian belief of the time that God’s creatures lived in harmony before the Fall. It even inspired an 1830 painting that brought to life many of the fossilized species Mary had unearthed in a fashion that graphically illustrated the kill-​or-​be-​killed reality for prehistoric life on Earth. The painting depicted all manner of savage creatures, including ichthyosaurs, long-​necked plesiosaurs, and belemnites (our Baltic Sea beachcomber Gerd Simanski’s favorite find) chasing and preying upon each other.

The animals rendered in watercolor are either attacking with their mouths agape or desperately flitting away. Above the waterline, a fat turtle plunges from the shore to attack a squid-​like creature, and a nearby alligator, standing along the shoreline with its mouth open like a barking dog, is attacked from the water by a long-​necked plesiosaur. Palm trees bend in the wind as winged pterosaurs engage in a paleo dogfight in the sky above.

The Garden of Eden, the fossilized poop proved, was no picnic.

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Balancing The Good And Bad Of Phosphorus

“Coprolites form records of warfare, waged by successive generations of inhabitants of our planet on one another,” Buckland observed.

The painting was so popular the artist had reproductions made, and he donated proceeds of their sales to Mary to allow her to keep digging, which she did until breast cancer killed her at age forty-​seven.

In the early 1840s, just as John Lawes was beginning to test his chemically enhanced fertilizers on crops at Rothamsted, Buckland scoured the British coast examining coprolites with two renowned chemists, Lyon Playfair and Justus von Liebig. Buckland’s companions didn’t only look at the sausage-​shaped clumps as mere paleontological wonders but also as a potential source of fertilizer in a world that had finite caches of dried bird poop and was fast running out of bones.

“The interesting question arose as to whether these excretions of extinct animals contained the mineral ingredients of so much value in animal manure,” chemist Playfair recalled some years later. “We took specimens, in order to confirm by chemical analysis, the views of the geologist.”

Liebig himself conducted the analysis and was stunned it revealed the coastline was littered with coprolites and other rocky materials that were, in aggregate, loaded with phosphorus. Liebig proclaimed these rocks as, potentially, even more impor­tant to nineteenth-​century England than the chunks of coal that fueled the steam engines powering the Industrial Revolution. Just as burnable coal was known at the time to be the remnant of ancient plant life, Liebig believed these fossils could be similarly harnessed for an equally important fuel—​fertilizer to make food.

“What a curious and interesting subject for contemplation!” Liebig exclaimed after his coprolite analysis yielded phosphorus. “In the remains of an extinct animal world, England is to find the means of increasing her wealth in agricultural produce, as she has already found the great support of her manufacturing industry in fossil fuel—​the preserved matter of primeval forests—​the remains of a vegetable world.”

Not everyone was as enthusiastic.

“I well recollect the storm of ridicule raised by these expressions of (Liebig),” Playfair wrote several years after the discovery, “and yet truth has triumphed over scepticism, and thousands of tons of similar animal remains are now used in promoting the fertility of our fields. The geological observer, in his search after evidence of ancient life, aided by the chemist, excavated the extinct remains which produced new life to future generations.”

Certain types of rocks had been mined for fertilizer on a relatively small scale prior to Liebig publishing the theory of mineral plant nutrition in 1840, but perhaps more important than the phosphorus contained in the coprolites (most of which actually turned out to be phosphorus-​rich sedimentary rocks) is that the discovery of coprolites seems to have helped focus agriculturists in their hunt for greater deposits of rock-​based phosphorus.

They ultimately realized, through chemical analysis, that they could find significant concentrations of phosphorus in certain sedimentary rock formations created by all manner of dead sea life raining upon the ocean floor year after year, eon after eon. Under the right conditions, the phosphorus in all that petrified detritus got concentrated as ocean currents stripped away other elements of the rock. Over the course of millions of years, geologic spasms then heaved the phosphorus-​laden rock onto land, where it could be mined.

Many of the early deposits of what came to be known as “phosphate nodules” were found scattered across England, where mining of it peaked in the 1870s. The deposits were quickly depleted, and harvests had plummeted by the early 1890s, right about the time the Peruvian guano reserves were also running out.

All this was happening just as Earth’s population was on its way to doubling to two billion in little more than a century. Fortunately for all those additional mouths, similarly mineable phosphorus-​rich sedimentary rock deposits were found in the southeastern United States, first in South Carolina in the 1860s and then, on a far grander scale, in central Florida in the early 1880s. By the mid-​1890s, scores of Florida companies and thousands of miners were harvesting more than one million tons of phosphorus rock annually.

The Florida “Bone Valley” deposits consisted largely of sedimentary rocks in the shape and size of pebbles you find underneath playground swing sets. And, as on the coast of England, they were commonly found among the fossilized remains of all manner of long-​gone creatures—​sabretooth tigers, humungous sharks, monstrous manatees, and super-​sized bears. But the scientific significance of this bizarre menagerie was overshadowed by all the prospectors flooding into Florida with a Wild West mentality that had prospectors willing to kill over the gravel used to construct Bone Valley roads. As the Jacksonville Florida Times Union reported on February 13, 1890:

“Pete Downing pulled out his gun and said he owned more of the phosphate that had been thrown in the street than any two men and he meant to protect his share… And they kept pulling out their guns and knives until there were 30 or 40 ready for business, each one swearing he owned most of the rock and meant to have it or the red gore would run deep.”

Florida phosphorus mines were flooding the world with chemical fertilizer by the turn of twentieth century. But humans’ hunger for the element only grew more acute as the often-​violent hunt for it spread across the globe.

Soon the casualties weren’t just individuals, but entire cultures.

Excerpted from The Devil’s Element: Phosphorous and a World Out of Balance by Dan Egan. Copyright © 2023 by Dan Egan. Used with permission of the publisher, W. W. Norton & Company, Inc. All rights reserved.

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About Dan Egan

Dan Egan is the author of The Devil’s Element, and Journalist in Residence in the School of Freshwater Sciences at the University of Wisconsin-Milwaukee in Milwaukee, Wisconsin.

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