[Note: The following is a significant expansion of the soil nutrients discussion of Sample 44.]
All life depends, directly or indirectly, on essentials like sunlight, water, oxygen, carbon dioxide, nitrogen, phosphorus, potassium, soil, and so on. In healthy wild ecosystems, these essentials are not depleted. The magic of evolution nurtures their ability to adapt to changing conditions in the circle dance of life.
Agriculture operates in a far less elegant manner. It’s a powerful, rowdy, perfectly unnatural, manmade monstrosity. Its unpredictable mood swings can range from feast to famine, prosperity to oblivion. In Mary Shelley’s classic horror story, the foolishly clever Dr. Frankenstein got cold shivers when his ghoulish monster turned to him and spoke these words, “You are my creator, but I am your master.”
Wild vegetation excels at recycling essential nutrients. On the other hand, field crops excel at extracting and exporting nutrients, a slippery clumsy dance of destruction. For example, phosphorus is transferred from the soil to the corn, from the corn to the hog, from the hog to the human, and finally flushed down the toilet, bye-bye! Little if any is returned to the field to replenish what was removed from the soil.
Poop is precious. Remember that. In 1588, Anzelm Gostomski, a Polish gentleman, once proclaimed an eternal truth: “Manure is worth more than a man with a doctorate.” In the modern world, every shipment of food that moves from the local countryside to faraway consumers is carrying away essential soil nutrients on a one-way ride, never to return.
To keep a farm operation on life support for as long as possible, efforts must be made to replace the deported nutrients. Over the centuries, farmers have kept soil fertility on life support by applying stuff like sewage, manure, ashes, lime, bone meal, seaweed, compost, peat moss, guano, synthetic fertilizer, and so on. In China, human wastes have been used as fertilizers for 5,000 years. Traditionally, manure has been a popular fertilizer. Gathering and spreading manure was far more fun than depleting the soil and starving.
Even modest sized cities could religiously indulge in rituals that recycled holy shit. In 1909, Franklin Hiram King visited Kyoto, Japan. While traveling down a road one lovely morning, he observed a long caravan of men pulling cartloads of precious night soil from town. They were in the process of returning this sacred life giving treasure to the fields where their food was grown.
Each cart carried six 10-gallon (38 l) covered containers of delightfully fragrant plant food. King noted that he passed 52 of these carts. Then, on the return trip, he passed another 61 carts. Other caravans moved down other roads. He estimated that 90 tons of sewage was hauled out of town on that morning. I wonder if this was a daily routine.
With the growth of population and urbanization, returning more and more human poop to fields that were farther and farther away, became impractical. Eventually, imported fertilizers were able to save the day (temporarily). Guano, phosphates, and synthetic ammonia were powerful, but nonrenewable. Unfortunately, they accelerated population growth, forcing the jumbo sized mob to zoom faster down a one-way road to a less than utopian future.
Writing in 2001, when the population was a mere six billion, Vaclav Smil estimated that 40 percent of the people alive in 2000 existed only because of the intensive use of synthetic ammonia fertilizer. It had succeeded in shattering the population ceiling (temporarily).
In order to survive in good health, all living plant and animal organisms must acquire the mix of nutrients that are essential for them. Different species prefer different mixes. David Montgomery explained that there are three absolutely must-have macronutrients for all plant and animal life (including you), for which there are no substitutes — nitrogen (N), phosphorus (P), and potassium (K). General purpose “NPK” fertilizers contain portions of all three. Humans acquire these essential nutrients by eating plant and/or animal foods.
Vaclav Smil noted that all living organisms require carbon, hydrogen, oxygen, and nitrogen. In the world, there are huge quantities of all four, but nitrogen is the oddball. The air we breathe is about 78 percent nitrogen, but it’s not in a form that most living things can actually use.
In the air, it’s a gas that consists of tightly bonded pairs of nitrogen atoms (N2) that are too stable to readily intermingle with other atoms. Before it can be utilized by living organisms, it must be transformed via a process called nitrogen fixation. In the soil are nitrogen-fixing bacteria that can combine nitrogen and hydrogen to produce ammonia (NH3), a compound that can nourish natural processes. Ammonia is 82 percent nitrogen.
These bacteria grow on the roots of leguminous plants, like beans, soybeans, peas, chickpeas, peanuts, lentils, carob, alfalfa, and clover. So, when you eat beans, your body is able to absorb the usable nitrogen. After a legume crop is harvested, the leftover plant material decomposes, releasing fixed nitrogen into the soil, fertilizer for future crops. This “green manure” is plowed back into the field.
When livestock graze, they absorb usable nitrogen from their food, and then produce “brown manure” that generously boosts soil fertility. You and I commonly get our nitrogen when we digest the amino acids in high protein foods, including beans, leafy greens, nuts, seeds, eggs, milk, and lean meat. At the rear end of the process, we expel a potent brown fertilizer called poop.
Old fashioned low tech farming could produce modest harvests when assisted by good luck and determined efforts. Unlike modern industrial agriculture, old fashioned farm soil only provided modest amounts of usable nitrogen. Low nitrogen content results in low yields, while high content boosts them. So, nitrogen is a limiting nutrient, something like the gas pedal in a car. So is phosphorus.
Ordinary soil generally contains modest amounts of N, P, and K. Applying additional potassium (K) to the soil does little or nothing to boost crop yields. But synthetic fertilizers can boost the content of nitrogen and phosphorus beyond normal levels, and this actually promotes bigger harvests. Of course, bigger harvests can feed larger mobs of hungry humans.
In the short version of nitrogen history, there were two huge leaps in fertilizer technology — guano and synthetic ammonia.
¶ Guano is an organic fertilizer created by dense accumulations of bird shit or bat shit. Seabirds often nest on islands, where they are less vulnerable to pesky predators. For the same reason, bats prefer to shit in the comfort and privacy of caves.
Each day, seabirds gobble up lots of yummy anchovies, return to their nesting ground, and happily unload magic excrement. Century after century, more and more piles of crap grew higher and higher. Mounds of guano could have nitrogen content ranging from 8 to 21 percent by mass! Holy shit!
In arid regions, like the Pacific coast of South America, the nesting islands were deeply covered with nutrient rich guano. Islands off the shore of Peru used to be guano heaven — some deposits were over 200 feet (61 m) deep. In wetter regions, birds also colonize offshore islands, and shit all over them, but rainy weather and humidity leaches out vital nutrients.
According to Wikipedia, “The rulers of the Inca Empire greatly valued guano, restricted access to it, and punished any disturbance of the birds with death.” Guano was used for centuries by indigenous folks.
By the 1840s or so, in Europe and North America, a persistent brutally abusive relationship between farmers and their precious dirt was taking a serious toll on soil fertility. Meanwhile the mobs of hungry white folks continued snowballing. How in the <bleep> are we going to feed them? Trouble ahead!
White folks first learned about magic guano in 1802, via the writings of Alexander von Humboldt, which were translated into several languages. Eventually, some ambitious lads experienced a breathtaking revelation. Holy shit! We could become filthy rich guano tycoons!
As we all know, money is a devilish hallucinogen that can turn kind and decent people into batshit crazy idiots. Consequently, humankind began a dramatic transition from traditional food production that utilized local manure, into a fast lane powered by imported bird shit. In some locations, the guano had an exceptionally high content of nitrogen, phosphate, and potassium. It greatly excited the productivity of field crops.
And so, in the nineteenth century, guano was the world’s super fertilizer, and a source of great wealth. A guano gold rush was born. Nations vigorously competed to claim ownership of guano islands. Disputes triggered the War of the Pacific (1879-1884).
Traditions got tossed on the compost pile. Farmers no longer had to devote lots of time to nutrient recycling. They didn’t need to plant cover crops of nitrogen fixing legumes, or do crop rotations. They could simply buy what they needed, magic bird shit, harvest far greater yields, and get rich quick.
Industrial scale guano mining was extremely disruptive to the seabirds that squirted out the valuable shit. On Peru’s guano islands, bird populations plummeted from the 53 million in the late 1800s to just 4.2 million in 2011.
Of course, guano was a finite resource created over the passage of countless millennia, and it was being extracted as fast as humanly possible. Production peaked around 1870. Insatiable greed heads then directed their attention to the saltpeter deposits in the deserts of Chile. Saltpeter is sodium nitrate, a compound that contained usable nitrogen.
J. R. McNeill noted that by 1900, German farmers were highly dependent on imported guano. Without it, they could no longer feed the growing mob of hungry Germans. Gosh! Wouldn’t it be wonderful if we could produce fixed nitrogen on an industrial scale? Could it be possible? Yes! Unfortunately, two Germans figured out how.
¶ Synthetic Ammonia. I’d now like to introduce you to Fritz Haber and Carl Bosch. In 1909, chemist Fritz Haber invented a process that could extract nitrogen from the air (N2), mix it with natural gas (CH4), and embed it in ammonia (NH3), via an energy-guzzling process of high heat and pressure. Synthetic ammonia created a sharp turn in human history. (Years later, Haber invented Zyklon B, the poison used in Nazi gas chambers.)
Carl Bosch figured out how to perform this catalytic process on an industrial scale. Haber and Bosch opened the first ammonia plant in Germany in 1911.
Ammonia was also a feedstock for explosives, which were in high demand for countless bloody military adventures. So, many new ammonia plants were built. At the end of World War II, large quantities of ammonia became available for other uses, and the production of synthetic ammonia fertilizer soared.
In the second half of the twentieth century, the production of synthetic NPK fertilizers skyrocketed: 4 million tons in 1940, 40 million tons in 1965, and 150 million tons in 1990. Far more food was produced, and the human population grew at an explosive rate.
Today, the intended benefits of these fertilizers are maxing out — applying more of it to a field no longer increases the size of the harvest. But the potent fertilizer runoff is able to continue increasing the contamination of groundwater, rivers, coastal dead zones, and oceans.
Richard Manning noted that when farmers apply synthetic fertilizer on a field, less than half of it is absorbed by crop plants. Fertilizer can acidify the soil. Some of it dissolves and contaminates the groundwater that folks drink, and lots of it runs off into waterways. Much of the U.S. Corn Belt drains into the Mississippi River, which is an ecological catastrophe.
Fertilizer runoff stimulates the growth of algal blooms. As the blooms die, they consume oxygen and emit CO2. As the oxygen content of the water is depleted (anoxia), this can cause everything to die (eutrophication). The Mississippi flows into the Gulf of Mexico, where it has created a dead zone the size of New Jersey. The Baltic Sea is home to seven of the of the world's ten largest marine dead zones. About half of U.S. lakes have low oxygen content, and the number of dead zones in the world continues growing (415 in 2022).
The National Science Foundation reported that fertilizer runoff is increasing the nitrogen content in rivers and streams, where microbes convert it into nitrous oxide (N2O), “a potent greenhouse gas, with a warming potential of approximately 300 times that of carbon dioxide.” Nitrous oxide persists in the atmosphere a long time, and promotes global warming and acid rain (it’s also a pain reliever, laughing gas). Cow shit is another source of nitrous oxide emissions, and their belches are a significant source of methane.
In the twentieth century, global population skyrocketed at a rate similar to the rapid increase in fertilizer use. Nitrogen and phosphorus are limiting nutrients, and synthetic fertilizers exceled at sweeping away longstanding limits to crop productivity. Julian Cribb wrote that the wellbeing of most of humankind is now heavily reliant on the use of these potent fertilizers to assure adequate food harvests.
Today, about 80 percent of synthetic ammonia is made using a natural gas feedstock — a finite nonrenewable fossil energy resource. As natural gas prices rise, so will the cost of nitrogen fertilizer, which will increase the cost of food. Political instability in the world is increasing. A few nations have abundant reserves of gas, while all nations are dependent on reliable access to food. This presents many opportunities for heavy handed dog-eat-dog mischief.
Like nitrogen, phosphorus is also a limiting nutrient. It is always found in mixed compounds, never in pure form. Much of the P in soil is in a form that plants cannot use. This puts a firm ceiling on crop productivity. In NPK fertilizers, usable P is provided by phosphate (P2O5), a mineral compound.
When phosphate is applied to a field, crop yields are boosted. When it runs off cropland into bodies of water, it can trigger eutrophication. Phosphorus enters your body at the mouth, and departs via urine and excrement. It’s possible to recover it from sewage and manure, but not cheap. When mixed 50/50 with water, your urine is an excellent liquid fertilizer that contains both nitrogen and phosphorus — and it’s free. Waste not!
Fred Pearce noted that every living cell needs P, and there is no substitute. It’s as essential to plant life as water is. We are great at misusing it, suck at recycling it, and it’s vital for feeding humans and other critters. Each year, the world mines 170 million tons of phosphate.
The world’s primary source of phosphate rock is an open-cast mine in the Western Sahara, a region currently controlled by Morocco — an unpleasant situation that irritates the native Saharans. Political instability in the region could disrupt the production and distribution of phosphate, and generate a food crisis in many nations.
So, demand is rising, most of the world’s best phosphate reserves are gone, and those that remain are in just a handful of countries. Most of these reserves are in hard rock form, which requires vastly more fossil energy to mine and process. There are also large deposits of phosphates in deep sea locations, but mining them would be deeply expensive.
When will phosphate production peak? That’s a highly contentious question, because accurately estimating the remaining reserves requires lots of guesswork. Today, of the three essential NPK nutrients, P is the most worrisome to experts.
Just as I was about to send this info to the world, my faithful muse gave me a dope slap and directed me to an important research paper. It’s written in super-cryptic science jargon, and ordinary readers (like me) may suffer some permanent brain damage, but it’s a fascinating horror story.
Christine Alewell and team put a spotlight on the latest news. If global heating doesn’t blindside industrial civilization, phosphorus depletion will. Big Mama Nature brilliantly guided the evolution of wild ecosystems that did a wonderful job of protecting precious topsoil and perpetually recycling essential nutrients. Sadly, cleverness has pulled the rug out from under this delicate balancing act. The tilling of agricultural soils eliminates the protective covering of wild vegetation, and exposes the delicate treasure below.
When P is not locked within solid rock, its water soluble. When rain splatters directly on pulverized farm soil, gravity carries the P runoff elsewhere, like wetlands and streams. Erosion causes about half of the P depletion in farm soil. As P content decreases, so does the productivity of the field. Harvests shrink.
Alewell noted, “The world’s soils are currently being depleted in P in spite of high chemical fertilizer input.” In poor countries, where folks can’t afford potent fertilizer, the rate of P depletion is even higher. In the long run, agriculture is not sustainable. “Soil phosphorus (P) loss from agricultural systems will limit food and feed production in the future.”
To continue producing chemical fertilizer requires continued mining of nonrenewable geological deposits of P, an increasingly limited resource. The P moves in a one-way flow from the mines, to the agricultural land, into freshwaters, and finally into oceans.
The “organic management” of P is also unsustainable. A cornfield extracts P from the soil. Then, the harvested grain is sent somewhere else, along with its P content. Added manure and compost won’t replace all of the P exported. Similarly, livestock grazing extracts the P from the greenery consumed. Some of it is returned to the land via manure and urine, but some of it is sent away to the meat processor, never to return.
In plants, potassium is important for the synthesis of protein. The potassium component of NPK fertilizer is provided by a variety of minerals rich in potash (K2O) that are found in the salt beds of ancient seas and lakes. The K added to NPK fertilizer comes from nonrenewable mined sources. David Montgomery noted that “potassium occurs in rocks almost everywhere in forms readily used as natural fertilizer.” We don’t have to worry about near term potassium shortages. Lots of other future crises are closer to the front of the line.
Abby Rockefeller wrote a fascinating essay that thoroughly explored the long and exciting history of human pooping and peeing. In modern cities, sewage treatment plants regularly generate sludge, which has to be removed and put somewhere. Somewhere is often cropland.
Besides the holy shit that happily splashes in your toilet, sludge also contains lots of weird stuff produced by industrial civilization. For example, volatiles, organic solids, disease-causing pathogenic organisms, heavy metals, and toxic organic chemicals from industrial wastes, household chemicals, and pesticides. Crops grown in fields treated with toxic sludge produce foods that may be less than wholesome.
BOTTOM LINE: Bill McGuire reported that intensive industrial agriculture is depleting the quality of cropland soils. In many parts of the world, including in the U.K., E.U., and the U.S., these soils are becoming “effectively sterile in the absence of regular fixes of artificial fertilizer.” No free lunch. No sustainable agriculture. But eight billion get to pee and poop every day (for a while). Hooray!