Bay Journal

Ability to ‘fix’ nitrogen led to explosive growth of fertilizer use

Continued from the November 2002 ‘Past is Prologue.’

A coincidence occurred about the turn of the 20th century. First, a paper was presented before a British agricultural association resurfacing the near-forgotten 1798 work of Parson Thomas Robert Malthus. In his “Essay on the Principle of Population,” which in fairness was expanded and republished in 1807, Malthus proposed that population, left unchecked, would increase faster that the means of sustenance. The optimism of other philosophers, Malthus suggested, was baseless and, absent population control, famine would surely follow.

Luminaries like Thomas Jefferson and Charles Darwin had been influenced by Malthus but were did not have the scientific means to combat his predictions through the expansion of agricultural production. Farming technology near the end of the 19th century showed symptoms of coming up against exactly what Malthus had predicted.

In 1913, about the same time that Malthus’ ideas were resurfacing, German chemist Fritz Haber perfected a technique to artificially “fix” nitrogen from the atmosphere. Scientists, aware of the abundance of atmospheric nitrogen, had been trying to develop this process for about 100 years, when Haber solved the riddle by combining nitrogen with hydrogen and “capturing” it as the compound ammonia (NH-3). In this form, nitrogen became soluble in water and was made available for uptake by plant roots or for direct industrial applications.

The discovery revolutionized farming; in 1920, another German, Carl Bosch and his company, BASF, commercialized the process and nurtured the emergence of a worldwide fertilizer industry.

Fertilizers — fish tissue or animal manure from Pacific and Caribbean bird guano islands, as well as from mineral deposits in Eastern North America — had been used for a substantial period of time, but how they were used was more rote application or an art than science.

This lack of efficiency was not immediately recognized because it was not known how to test the effects of differing combinations of nitrogen and phosphorus, the timing of their application during the agricultural year, and their results on widely different crops. The tools of “biometry,” a discipline prominent today, had yet to be developed.

While the concept of using measurements in biology to understand living things had been proposed earlier by London zoologist W.F.R. Weldon, it remained for another Briton, mathematician Ronald Aylmer Fisher, to lay the foundations of modern statistics early in the 20th century.

Disenchanted by his original training in mathematics and astronomy, Fisher went to work at Britain’s Rothamstead Agricultural Experiment Station.

Around 1925, he developed new arithmetic analytical methods, especially the analysis of variance and the use of randomization, for making unbiased, quantitative studies of plant nutrient requirements, as well as the effects of varying nutrient additions — fertilization — on different natural soils.

While Fisher’s methods were challenging computations in the decades before computers, they were extraordinarily elegant and powerful tools. The analyses he developed and applied to wheat crops helped agronomists to sort out the roles of different factors separating the contributions of phosphorus, nitrogen and differing proportions thereof from the effects of variable soils and growing conditions.

When I studied statistics in 1967, performing a modest analysis of variance was a challenging exercise using big and noisy Marchant calculators that frequently broke down. Watching one churn out the square root of a large number was a blur of shaking machinery and spinning dials. Manually copy the 10– or 12-digit number resulting from a computation incorrectly, and the whole analysis was flawed, the critical “f” ratio at the end nonsense.

By 1971, a few “large” computer programs could take piles of manually punched computer cards and grind out selected analyses, but one usually had to wait in line for technicians to process the information. The computer filled an entire building on campus. Outside, a two-story continuous waterfall ran down one wall, where fans drew in oceans of air to be used by the massive air conditioners cooling the building.

Fisher was knighted for his work and continued to make important contributions until his death in 1962.

His tools and their progeny are still universally used in all the life sciences, although today they are applied with the speed and ease offered by even our tiniest computers.

In the 1930s and ’40s, Fisher and his associates quickly learned how fertilizers could augment poor soils, how different application rates benefited specific crops and how “side dressing” in addition to fertilizing in the early growth stages of a plant could accelerate its life cycle and greatly multiply yields.

This work — coupled with an increased understanding of plant genetics, selective breeding and hybridization — fueled the Green Revolution and virtually negated Malthus’ postulates for about a century.

Scientist Vaclav Smil indicates that the fixation of nitrogen allowed the world’s population to expand from about 1.6 billion people in 1900 to its present 6 billion. He considers this to be more significant than the airplane or space flight, nuclear energy or television.

He has a point. Using corn as an example, the result of fertilizer use — together with breeding and mechanization — took the U.S. annual yield from 337,531,537 bushels in 1839 to 3,451,202,000 bushels by the mid-1950s. A single kernel planted and properly grown can produce a stalk with several 800-kernel ears of corn — certainly a remarkable achievement of genetic manipulation and invested energy.

Meanwhile, the seeds of a tempering mechanism were already present through Haber’s discovery of the chemical fixation of nitrogen. Modern warfare was made possible when nitrogen compounds were made available in immense quantities for the manufacture of explosives and other munitions.

Haber’s work fixing atmospheric nitrogen earned him a Nobel prize in 1918, the year that World War I ended. The award was met with considerable controversy, not because of its link to explosives, but because his work had led to the development of poison gas. His wife was so appalled at his open involvement with this consummate evil that she took her own life.

Even though he was a Jew, Haber was a loyal German, and continued his work. Paradoxically, he was forced into exile by the Nazis in 1933, and must have reflected in later life upon how his countrymen used poison gas in their attempt to exterminate the entire body of his faith.

At the conclusion of hostilities in the mid-1940s, those involved in the nitrogen-fixing industry faced a dilemma: either shut down their plants and discharge workers, or put this capacity to work synthesizing other products useful to society. Fertilizer production and consumption skyrocketed.

In the primeval Chesapeake, nutrients, especially nitrogen, were likely at a premium. Vast areas, perhaps 95 percent of the watershed, were probably forested. And even when disturbances from storms occurred, or where Native Americans burned areas to either drive game or open agricultural fields, forests were growing, taking nitrogen and phosphorus from the soil, not spilling it into nearby streams.

Dr. Greg Garman at Virginia Commonwealth University once said that he believed the massive migration of anadromous fishes, which return to their natal rivers in the Bay to spawn, may have been an important part of the nitrogen budget.

Garman’s case received a fascinating boost when scientists working on the West Coast used the signature of a nitrogen isotope found in ocean-grown fish to trace the path of actual nitrogen molecules into the terrestrial landscape. Fish arriving rich with spawn are captured and eaten by many species: from raccoons or bobcats, to birds or bears, whose wastes are deposited in the adjacent landscape. About 70 percent of some anadromous species are so spent after spawning that they die. Their carcasses are food for scores of scavenger species or may simply be deposited on the floodplain during times of high flows.

In an interesting footnote to this story, scientists have found the signature of that nitrogen isotope in 400-year-old tree rings. Native Americans on the Eastern Seaboard, thus followed good instincts when they planted a shad, herring or alewife in every corn hillock.

According to historian Arthur Pierce Middleton, even George Washington used part of his large Potomac River herring catch as fertilizer.

Given the astounding abundance of migratory species reported by early colonial observers, and the distances they traveled — river herring spawned in the tiniest tributary tidewater streams and even reached Lake Otsego at the source of the Susquehanna — the potential for vast nitrogen contributions to nutrient-poor streams was certainly present. This potential was seriously interrupted as thousands of dams and diversion structures impeded upstream swimmers, not to mention the immense harvests of fish biomass that occurred until the resource was literally exhausted.

Meanwhile, agriculture was expanding across the basin, eventually removing as much as 80 percent of the watershed’s forest cover, according to paleobotanist Grace Brush of Johns Hopkins University.

Immense quantities of timber in Pennsylvania, Virginia and West Virginia were cut and shipped, removing hundreds of years of accumulated forest biomass.

Trains left the region with huge single logs, one to a railroad car, many to be reduced to charcoal to fuel the industrial furnaces producing iron and steel. Afterward, millions of smaller trees in regenerating forests were cut for prop timbers in coal mine tunnels, when that resource replaced the once-abundant charcoal.

This merciless activity unleashed a great bleeding of the landscape, a flow of phosphorus-rich sediment — lost topsoils — that choked many Chesapeake rivers and harbors, and remained on the estuary floor to regenerate and repeatedly fuel algal blooms throughout the Bay.

Logging was not the only activity responsible for soil losses. Some of the farmland in the eastern part of Pennsylvania lost all of its topsoil in the first quarter century after settlement.

Farmland fertility diminished for a variety of reasons, but the abandonment of long fallow periods once characteristic of colonial agriculture, and its replacement with intensive tillage and cropping, made fertilizing a necessity, not an option.

Photos of many Chesapeake tidewater farms during the first few decades of the 20th century show some pretty sere landscapes, with sunbaked houses sitting on bare hillocks and lean people trying to make a go of it.

The availability of cheap fertilizers after World War II made a vast difference. To be sure, the mechanization of agriculture, the careful breeding of productive varieties and the introduction of chemical pest management also had impressive impacts. But the engine of plant growth ran on fertilization.

Norbert Jaworski, a former scientist for and past director of the EPA’s Narragansett, RI, Laboratory has a long history in the Chesapeake. He was one of the stalwarts who pressed for nutrient removal at the Potomac River wastewater plants as early as 1969, a very unpopular political position at that time.

But Jaworski was never one to quietly go with the flow and has always retained a sense for the great changes in nutrient loads to East Coast estuaries, particularly the Chesapeake.

During his later years at the EPA, in the late 1990s, he circulated an interesting series of data records on the last half century of nutrient history. They cover the period subsequent to World War II and the burgeoning U.S. East Coast agriculture. His data cover a variety of animal and plant crops and both nitrogen and phosphorus consumed on a per-area basis, or “application rate.”

His nitrogen data, which reflect both application rate and changes in agricultural acreage, suggest that in addition to world increases in production, more fertilizer per acre was also applied. The rates he documented cover most Northeast states, with the largest figures belonging to states in the Chesapeake watershed.

Scientist L.E. Lanyon states in the Journal of Product Agriculture that nationally, nitrogen fertilizer consumption in 1940 was 500,000 tons annually. By 1980, it was more than 11 million tons. It also discussed the tremendous consumption of fossil fuel used to produce and transport fertilizer, as well as an inefficient method of broadcasting it so that a large proportion does not reach plant roots but eventually makes its way into runoff.

North American water quality records are relatively recent. There are only brief fragments of nitrogen data for Chesapeake Bay from the 1950s to the mid-1980s, when the Chesapeake Bay Program began to coordinate monitoring.

French scientist Gilles Billen has published a data set for the River Seine above Paris, where the city’s water supply intake at Ivry was sampled beginning in the 1880s. So far as I know, this directly sampled data set for nitrate concentration (NO-3) is unique in the world. It shows early values from 20–40 micromoles per liter catapulting to 250 mmol/l 100 years later. The sharpest upswing appeared after a lag in World War II and paralleled the exponential increase in nitrogen fertilizer application in France.

For a global perspective, Vaclav Smil has published data from 1880 to 1985 for the mining of phosphate rock, (zero to 150 million tons annually) and from 1920 to 1985 for the synthesis of nitrogen fertilizers (zero to about 78 million tons annually). Both follow almost exponential curves of increase after World War II.

Chesapeake Bay scientist Scott Nixon also presents data that between 1975 and 1989, the United State’s two major fertilizers (diammonium phosphate and urea) actually became cheaper, falling from more than $300 a ton to less than $150.

Jaworski’s records date from 1945 and cover the consumption of nitrogen and phosphorus fertilizers. Nitrogen exhibits a strong overall and continuing increase, while phosphorus does not.

The information was there all along, but dazzled by a growing economy, self-satisfied with the cornucopia of agricultural production and seduced by the wellspring of consumer goods, we paid no attention and forged on while the Bay accepted our insults for a century.

In the late 1950s and early 1960s, Dr. James Durand a scientist at Rutgers University in Camden, NJ, worked in the relatively pristine Mullica River Estuary of South Jersey. He clearly demonstrated that in summer, phytoplankton growth in this estuary repeatedly ran out of steam. All one had to do to stimulate growth though, was to add nitrogen.

The late Hal Haskin, my professor of oceanography at Rutgers, invited Durand to present a guest lecture for his graduate students. Haskin told us to pay close attention to what Dr. Durand had discovered because it was a very important principle. We did, but outside that venue, no one else seemed to have figured it out.

It amazes me that society long resisted the reality that nitrogen was an environmental linchpin of such significance. In 1978-79, while I worked at the Chesapeake Biological Laboratory, Chris D’Elia and Jim Sanders did definitive experiments to show that nitrogen was the limiting nutrient in the Patuxent estuary. They did these in the face of EPA protests that phosphorus control was sufficient to manage algal blooms in natural waters.

In 1980, I interviewed for an environmental scientist position with the District of Columbia. In the days before the District became a Chesapeake Bay Program principal, The Department of Environmental Services had serious conflicts of interest with the Blue Plains Wastewater Treatment Plant. The District and the EPA were jointly facing an administrative hearing over the mandating of new nutrient controls for Blue Plains’ effluent. Millions of dollars were at stake.

During the job interview, I was asked: “If you had to testify about which nutrient should be removed to benefit the Potomac River, which would it be, phosphorus or nitrogen?” I answered, “Why both of course, phosphorus for the freshwater portion and nitrogen for the estu…”

“Thank you,” the interviewer cut me off and turning aside to those assembled for my review, said, “We won’t be asking him to testify at the hearings.”

I still got the job, and with my colleagues, share credit for later bringing the District forward as a full partner in the Chesapeake Bay Program’s Implementation Phase.

Using funding from the EPA, the states adjacent to the District, the Metropolitan Washington Council of Governments and its contractors, we began implementing an early model to study the effects of nutrient reductions proposed at Blue Plains. The model stated that algal growth could be pretty well controlled in the freshwater portion of the Potomac, but as long as nitrogen was present in the water column, this load, when it reached the saline portion of the estuary, would be available to stimulate algal growth and consume oxygen, the two upriver problems targeted by nutrient reductions.

While our understanding of nitrogen and its agricultural, industrial, atmospheric and population has greatly improved, we waver when it comes to making the really hard choices to meet our ambitious goals and reverse the swelling tide of inputs.

The Blue Plains Wastewater Treatment plant, the largest in the basin, still leads the pack when it comes to its capability for nitrogen removal in its final effluent.

Keep in perspective, though, that while many plants have a total effluent nitrogen of 15 mg/l, even 5 milligrams of nitrogen in effluent — an impressive 67 percent reduction of which Blue Plains is capable — is more than threefold the level in most natural waters.

We should soberly reflect on the technological outgrowth of Haber’s fixation of nitrogen: cheap explosives, poison gas and fertilizers — regardless of any short-term benefits — will ultimately do more damage to humanity.

Dr. Alan Taylor, who had a half-century career as a USDA scientist, speculated in 1998 that while the human population is no longer “source” limited — we can grow enough food if we can distribute it — we are "sink" limited; that is, we are unable to handle or assimilate the wastes created.

We must meet that challenge here in the Chesapeake Basin as our society’s nitrogen leakage continues to grow without apparent bounds.

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About Kent Mountford

Dr. Kent Mountford is senior scientist for the Chesapeake Bay Program in Annapolis.

Read more articles by Kent Mountford