Aaron Hedge
9 min readMar 20, 2020


Bass Rock, covered in guano, off the east coast of Scotland. (photo attribution: “Bass Rock covered with guano” by John Lord is licensed under CC BY 2.0)

Thomas Malthus’s famous 1798 treatise on the dynamics of resource depletion and replenishment primarily concerned his home country of Great Britain, which constantly seemed mired in a population crisis. But he worried, too, about North America, which was lucky to lack many of the resource restrictions of an island. Of course, Malthus wrote in An Essay on the Principle of Population, the European-American population had doubled in a mere quarter-century — what was there in its way? And it would keep doing so: “The situation of new colonies, well governed, is a bloom of youth that no efforts can arrest,” Malthus wrote. Political methods were not up to the task of stopping population growth. But even the New World had its physical horizons, Malthus knew. These constraints would come to curtail the population when it surpassed the continent’s nurturing capacity. What he didn’t know was the breadth of that capacity.

In the nineteenth century, after Malthus’s death, American farmers faced an environmental crisis, as their profligate extraction of food from Midwest soil had sucked the nitrogen from it. Rotating certain crops whose roots, as Charles Mann wrote in Orion magazine “contain special bacteria that convert useless N2 into ‘bio-available’ nitrogen compounds,” was no longer enough. Seeding the land with animal body parts, desiccated seaweed, sawdust, shit, all the mainstream techniques had stopped working. Malthus’s prognostications were coming to bear. Americans needed a more exotic excrement to boost the health of the soil. They needed replenishable supplies of it. They found this elixir in the shit of bats and birds, known as guano. The best guano came from seafaring birds, whose diets were rich in plant nutrients, most importantly nitrogen. It was amazing stuff, guano. The nitrogen-, phosphate-, and potassium-rich substance offered a more robust method of restoring soil than any of those that were failing the American farmer.

But conditions in which good guano deposits could build up were quite specific and essentially nonexistent on the North American mainland. Too much rain leaches the nutrients from the fertilizer. Low-lying islands were prone to coastal flooding, which would wash the stuff away. But some rocky Pacific islands basked in constant ocean wind and an abundance of sunlight, which preserved the guano excreted by hundreds of thousands of migrating seabirds. These islands looked like ski resorts in the dead of winter, or frosted desserts (but they were not as lovely for obvious reasons). Incan agriculture in what is now Peru, located very close to several islands that ran with guano, depended on the stuff. It was so important that native governments suffered people to harm seabirds only on penalty of death.

The German naturalist Alexander von Humboldt, having observed the poop’s revitalizing qualities on a trip to Peru at the turn of the nineteenth century, sent samples back to Europe for farmers to experiment with. It was an instant sensation. Cara Giaimo wrote in Atlas Obscura: “It was boom time. A guano industry quickly sprung up, complete with new infrastructure, overnight millionaires, and widespread worker exploitation.” The population explosions that followed the industrial revolution were fed from crops raised in Pacific bird poop. It was such a big deal that countries considered it worth military conflict. Spain seized three Peruvian islands from the South American nation and was challenged in battle, losing the islands back. Bolivia and Peru fought a war over the guano islands.

The United States, its population swelling across the continent, was as keen on guano as any other nation. In the 1850s, President Millard Fillmore and his successor Franklin Pierce both sang bird shit paeans in addresses to Congress. Fillmore declared guano so important to the health of “the United States that it is the duty of the Government to employ all the means properly in its power for the purpose of causing that article to be imported into the country at a reasonable price.”

Pierce, Franklin’s successor, signed the Guano Islands Act of 1856 — which is still on the books — making it law that any island on which an American citizen discovered guano would then belong to the United States for the purpose of guano mining. Americans seized the Kingman Reef and Howland and Baker islands, along with dozens of other Pacific islands, atolls, keys, and reefs. American guano barons enlisted what amounted to slave labor from islanders and Chinese to mine it from these desolate and depressing South Pacific outposts. Daniel Immerwahr wrote in How to Hide an Empire: A History of the Greater United States: “It offered all the back-breaking labor and lung damage of coal mining, but to do the job, you had to be marooned on a hot, dry, pestilential, and foul-smelling island for months.” Disease and malnutrition were rampant among the laborers. “‘We were completely encased in a thick film of bird manure,’ one visitor remembered,” Immerwahr wrote.

The Guano Islands Act specified that the United States had no obligation to islands it annexed under the law. As Christina Duffy Burnett noted in American Quarterly in 2005, “the act would, it was hoped, supply Americans with affordable guano, nothing more.” The country cast off most of its guano islands after mining them shitless but kept several of the more attractive ones. In a positive irony, these remaining islands are now part of the largest collection of protected lands in the world, National Geographic reported in 2014. One of the final acts George W. Bush performed as president designated the Pacific Remote Islands Marine National Monument, which Barack Obama later expanded.

Guano collection on Jutten Island, off the coast of South Africa. (photo attribution: “Bags of guano in rain. Jutten Island. Saldanha Bay.” by Mary Gillham Archive Project is licensed under CC BY 2.0)

But had the United States and other industrializing countries continued extracting guano from Pacific islands at the pace of population growth, the resource would have fully collapsed. That’s not the way it happened. By the turn of the twentieth century, a chemist would seemingly overturn the Malthusian Theory of Population.

It’s estimated that the earth, of her own processes, is only capable of sustaining four billion people, less than two-thirds the current population of humans, especially with the consumption pattern the fortunate portion of the world follows. That amounts to about one-third of the projected 10 million people demographers say might call earth home by mid-century. Earth’s devices are exhaustible, as Malthus knew. She needs help keeping up with us.

Germans Fritz Haber, a chemist, and Carl Bosch, an engineer, entered the stage of the problem in 1909. Haber developed a method to bind the nitrogen compound N2, which is the most abundant chemical found in the earth’s air, with the hydrogen compound H3. This creates ammonia, the chemical that dead bodies and feces release when they decompose. It’s the substance that introduces nitrogen back into the soil, providing the correct chemical makeup to grow healthy crops. Bosch scaled up this process to an industrial level. Cited in most histories of how the world came to be the way it is, Haber and Bosch nullified the need for any other fertilizer, which is gotten only by the sweat of extractive labor, as in guano mining. Today, hundreds of billions of pounds of ammonia are made through what’s come to be known as the Haber-Bosch Process (or, simply, the Haber Process). The fixing of nitrogen, once performed slowly by bacteria, is now performed quickly by factories.

“The Malthusian logic was repealed,” Immerwahr wrote. “Soil exhaustion ceased to be an existential threat. You could just add more chemicals.” Natural famine was eliminated; only political food shortages remain. Fritz won the Nobel Prize in Chemistry in 1918 for this work. But as Immerwahr wrote, Haber’s reputation as a pioneer of liberal advancements became complicated as fascists used his innovations for destructive political ends. He went on to be the father of chemical weapons of mass destruction, much to the depression of his Jewish wife Clara (Immerwahr’s mother) who committed suicide after Haber had become fantastically successful and well-known in Western countries for his Frankenstein monster. Haber developed the very chemicals used to kill Jews during the Holocaust, including the family members of his late wife.

Perhaps the dark elements of Fritz’s career foreshadowed a ghost in the machine that manufactures industrial fertilizer. Though human ingenuity had proven Malthus’s pessimistic assumptions about the constraints to population growth false, another scary thing is happening to the world because of the use of artificial ammonia in agriculture. Mann wrote in Orion that the Haber-Bosch Process “has literally changed the chemical composition of the earth, a feat previously reserved for microorganisms.” It has transformed the earth’s soil into an entity capable of feeding the billions of people currently alive, along with the billions more that are predicted to come.

This sounds positive, but there are frightening drawbacks. Hugh S. Gorman, writing in the journal GAiA: Ecological Perspectives for Science and Society, compared artificial fertilizer to steroid use in sports: “In both cases, one is manipulating a chemical that regulates production, and the end goal — whether it be larger muscles or muscular harvests — comes at the expense of greater stress being placed on other parts of the system.”

Gorman, a social scientist at Michigan Technological University, listed some examples: Farmers producing vastly increased amounts of a crop need vastly increased amounts of water and must compete in politically contentious ways with other parts of society that increasingly need more water, too; more food means more people, meaning more resource consumption, meaning more need for food; wholesome family farming operations have morphed “into capital-intensive chemical factories serving urban populations;” leftover nitrogen “cascades through ecosystems,” piling up in unintended places like rivers and drinking supplies, causing algal blooms and spoiling the water; and, finally, when these excess nitrates are broken down by denitrifying bacteria, they can release heat-trapping gasses that contribute to climate change.

Societies have taken some measures to limit the ill effects of ammonia nitrates on human health. The American Safe Drinking Water Act of 1974 established limits on nitrates in drinking water, as the World Health Organization did in 1958, Gorman wrote. Scientists have been concerned for decades about the 15,000 square-mile hypoxic dead zone in the Gulf of Mexico caused by nitrogen that spills in from the Mississippi River. Authorities have made modest progress in reducing the size of the dead zone by establishing wetlands that act as denitrifying filters, Gorman wrote. Food activists and local communities have tried to move away from this industry-intensive model of food production. They advocate in part for natural fertilizers and more sustainable methods of growing crops than forcing the earth to perform a function she doesn’t do without human intervention. Larger concerns are also trying to revert to natural fertilizers; in the aughts, Peru went back to its islands to restart its guano trade. This time, The Independent reported in 2010, it’s much more modest and intended mostly for domestic use (though Walmart sells Peruvian guano on its website).

But these movements offer only cold comfort for those who yearn for sustainable human behavior; there remains a dearth of political solutions to how humans are changing the earth’s chemistry. The Food and Agriculture Organization of the United Nations reported in 2017 that world demand for nitrogen as a fertilizer would be more than 37 billion tons, up from less than 34 billion in 2015. It only makes sense in a faster and more populous world in which people want to eat more protein-heavy diets.

There are only two ways in a commons to get around resource collapse, ecologist Garrett Hardin wrote in the 1960s: render it inaccessible by privatizing it, or regulate it by imposing use limits via the legal system. The United States does both in several ways, but I’ll focus on regulation of public lands. Historically, the government has designated restricted use zones in the form of national parks and monuments, where it’s most often illegal to hunt, collect relics, use marijuana, smoke cigarettes, take video footage for commercial use, fly drones, feed wildlife.

Other designations are more liberal, imposing lighter restrictions, like BLM, where individuals can camp, hike, hunt, fish, run ATVs — pretty much whatever she wants, as long as she gets permission. These activities impact the land in palpable ways — visible scarring, pollution. The impact is amplified when businesses, which have the resources and intent to do far more damage, can graze cattle for a below-market-value fee, harvest and transport oil and trees.

Public lands are not treated as essential and sacred places that need protection from the incursions of well-meaning tourists. All that’s prohibited in many American commons is the worst people can do, a parameter defined by the Executive Branch of government and implemented by its bureaucrats and deputies. The incredible progress secured for American commons during the Theodore Roosevelt and Nixon administrations proved ephemeral when Donald Trump stepped into the White House.

Note: This is part of my master’s thesis, which I am slowly dissecting and publishing here.



Aaron Hedge

I like to write about human-wildlife relationships, mostly.