The Haber-Bosch Process

By Steffen Schneider

Michael Pollan in his seminal book on the current food and agriculture system in the United States, The Omnivore’s Dilemma, paraphrases Vaclav Smil in describing the roles of nitrogen and carbon in the natural world. He states, “nitrogen is supplying life’s quality, while carbon provides the quantity” (Pollan, 2006).

When I read this for the first time, something in me sparked and I felt that here was an essential `nugget’ of truth and mystery. If this is so, what has happened in modern agriculture where nitrogen has become the main engine of increasing yields – quantity in other words? Are we encountering a paradox here, nitrogen being characterized as influencing quality and at the same time having a definite effect on quantity? Again my interest was sparked, because I have come to very much believe in the significance of paradoxes, rather than arguing a simple “either – or”, why not a more complex “both – and”? As the great physicist Niels Bohr said, “ wonderful that we have met with a paradox, now we have some hope of making progress” (Bohr, 1931).

Which leads me to the topic of this paper. Any consideration about the role of nitrogen in agriculture must sooner or later include the Haber-Bosch process and the dramatic impact it’s had in the world. I want to take a closer look at the historical context of Haber-Bosch and its influence on the evolution of agriculture. I will also touch upon alternative views regarding the use and role of nitrogen in agriculture going forward.
What is the Haber-Bosch process?

The Haber process, named after Fritz Haber, is a method of synthesizing ammonia (NH3, see diagrams below) from nitrogen (out of the air) and hydrogen (from natural gas) using iron as a catalyst in an environment of high temperature and pressure. Haber achieved this in 1909 at the University of Karlsruhe in Germany, initially using Osmium as a catalyst (Hager, 2006). In 1913 Carl Bosch succeeded in the industrial scaling of this invention at BASF in Ludwigshafen, Germany, therefore the `double’ name Haber-Bosch process. Both men were awarded the Nobel Prize in Chemistry for their work, Haber in 1918 and Bosch in 1931. This honor celebrated the importance of their achievement. An achievement long thought impossible because of the inert nature of nitrogen gas and its trivalent bond.

Today many scientists and historians consider Haber-Bosch the most important invention in modern history. With it came the ability to manufacture fertilizer by using the abundant nitrogen reserves in the atmosphere, which then resulted in large increases in crop yields to support the growing population on our planet (Smil, 2001). Currently, because of its many uses, ammonia is one of the most highly produced inorganic chemicals. There are numerous large-scale ammonia production plants worldwide, producing a total of 131 millions tons of nitrogen (equivalent to 159 million tons of ammonia) in 2010 (US Geological Survey). Nearly a third of this total production (32.1%) occurs in China, followed by India with 8.9%, Russia with 7.9%, and the United States with 6.3%. 80% or more of the ammonia produced is used for fertilizing agricultural crops. Ammonia is also used for the production of plastics, fibers, explosives, nitric acid and intermediates for dyes and pharmaceuticals. Here are two diagrams showing the chemical reactions at work in this process:
Google: Haber-Bosch process 960 x 397
Google: Haber-Bosch process 394 x 281

Two Nobel prizes and more than 100 years later what else can be said about this apparent miracle of “turning air into bread” (Hager, 2006)? While Haber- Bosch has been the major factor in increasing the food supply worldwide, it has also taken an unforeseen toll on the environment and the way we practice agriculture, as I will show later. I suggest we need to discover more about nitrogen and its role in the biosphere beyond the effects it exhibits in its form as synthetic fertilizer, harkening back to the above indication on its relationship to qualitative aspects. What’s at the root of this apparent mystery and paradox, quantity - quality? Haber-Bosch has long superseded the natural nitrogen cycle in volume and importance (Smil, 2001) and maybe covered up some other aspects of nitrogen.

My Biographical Connection

The reason I am particularly interested in this event and discovery is twofold. For one I suggest that this discovery created a crossroad for the development around agriculture and food. And secondly I find myself linked into the story of nitrogen and its application in agriculture through my biography and work. Let me outline this second connection first. I was born and I lived the first part of my life (1957 to 1983) in the area of Germany where Fritz Haber and Carl Bosch’s work took place. This is the region in the Rhine river valley between the towns of Ludwigshafen and Karlsruhe. If you visit the main offices of BASF in Ludwigshafen today you will encounter the original steel synthesis vessel in front of the office tower, a monument to the significance of this process in the history of the company. Many members of my family have worked for BASF, my father, stepfather, uncle, grandfather and great- grandfather. In fact my great-grandfather Karl Holdermann, who served as director of the patent office at BASF, also was a colleague and friend of Carl Bosch and authored a biography of him. (“Im Banne der Chemie”, Econ Verlag 1953)
As I reflect on my biographical connection to this historically significant event I can’t but wonder if it not only created a “fork” in the road of the evolution of agriculture but also in my own life’s path, which has taken me into practical farming but in the direction of organic/biodynamic agriculture. In fact it’s fair to say that I chose this path (which includes a Masters degree in agriculture from the Justus von Liebig University in Giessen, Germany) as a reaction to what I perceived happening in modern conventional farming and its heavy reliance on synthetic nitrogen fertilizers and everything that went along with that practice, decreasing ecological diversity, increasing monocultures, increasing use of pesticides, a more toxic environment. I continue to have plenty of opportunities to think about nitrogen and its role in nature and specifically in agriculture in my ongoing farming work.

The History of the Haber-Bosch Process

Before examining and describing in more detail the consequences of Haber- Bosch in the development of agriculture I want to look at the historical context and some of the individuals involved in science, chemistry and agriculture at that time. I do this because I think this story offers interesting perspectives on science and scientific discoveries in general. The role of serendipity in the history of scientific inventions is well documented. (See the discovery of penicillin and Viagra for example) The Haber-Bosch discovery differs from these inventions that occur almost accidentally, in that it was the result of a multi-year, focused, competitive effort responding to the widespread fear of food scarcity. It also reveals the `human’ side of science; the intertwining stories of individuals dealing with pride, greed, jealousy, competing for money and reputation (Hager, 2008).

Here now a listing, in chronological order, of individuals that are more or less linked to this discovery:

  • Daniel Rutherford, 1749 to 1819
  • Johann Wolfgang von Goethe, 1749 to 1832 Justus von Liebig, 1803 to 1873
  • John Bennet Lawes, 1814 to 1900
  • Sir William Crooke, 1832 to 1919
  • Rudolf Steiner, 1861 to 1925
  • Fritz Haber, 1868 to 1934
  • Carl Bosch, 1874 to 1940
  • (Karl Holdermann, 1882 to 1968)

Even a cursory look at the history of soil chemistry reveals many fundamental advances in the late eighteenth and early nineteenth century (Montgomery, 2007). An increasing analytic approach narrowed the more holistic view of alchemy into chemistry, as we know it today. Rutherford discovered nitrogen as a distinct component of air in 1772. Liebig established the basis for modern agro-chemistry by demonstrating the importance of mineral nutrients for plant growth. Liebig’s work created the basis that allowed a fundamental shift to occur in agriculture. No longer did it seem necessary to maintain and build soil fertility by recognizing the importance of organic matter and soil life; soils could be viewed as simple reservoirs of replaceable nutrients (Smil, 2001). Ironically Liebig himself continued to recommend the building of organic matter through manures and legumes, while at the same time predicting the chemical manufacture of plant nutrients. Lawes then took this idea and proved through trials at Rothamstead (the longest running agricultural research station in the world) that the application of mineral fertilizer increased yields even beyond those of well-manured fields (Smil, 2001).

These scientific advances occurred in the socio-economic context of their time. With his influential speech in 1898 Sir William Crooke paints a vivid picture of this and points the way towards Haber’s invention:
“England and all civilized nations stand in deadly peril of not having enough to eat. As mouths multiply, food resources dwindle. Land is a limited quantity, and the land that will grow wheat is absolutely dependent on difficult and capricious natural phenomena... I hope to point a way out of the colossal dilemma. It is the chemist who must come to the rescue of the threatened communities. It is through the laboratory that starvation may ultimately be turned into plenty... The fixation of atmospheric nitrogen is one of the great discoveries, awaiting the genius of chemists.”
Presidential Address to the British Association for the Advancement of Science 1898. Published in Chemical News, 1898, 78, 125.

Also part of this historical context and worth noting is the fact that there were contrasting views voiced as well. Goethe rejected the emerging analytical science and introduced a much more holistic and phenomenological approach working with plants and also light and color in particular (Bortoft, 1996). Steiner then picks up this method, elaborates it further and in the process establishes practical life applications, as for example biodynamic agriculture.

In 1924 Steiner speaks about the importance of nitrogen:
“One of the most important questions that can be asked with regard to agricultural production is: What is the significance of nitrogen? But it is just this question as to the essence of nitrogen’s activity that has become extremely confused. We see, as it were, wherever nitrogen is active, only the last remnants of its influence, only its most superficial manifestations, and are unable to see the natural relationships in which it works. In fact, we cannot possibly see these relationships if we restrict ourselves to a specialized area of nature, but only if we look at nature in a broader sense and consider nitrogen’s activity in the whole universe. As we will come to see, nitrogen as such may not even play the leading role in the life of plants. However, knowing what role it does play, is one of the first things we need to know in order to understand the life of plants.”
Lecture 3, Steiner, “Agriculture”, BDGFA 1993

Crooke’s speech has historic significance, as he points to the threat of food scarcity and looks to chemists for solutions. I consider Goethe and Steiner as voices speaking out of a much more holistic context of the world and our place in it. Such a view, as I will try to show later, can help guide development and possibly help avoid long term unintended and harmful consequences. Lastly I want to point out that the theme of `needing to feed the world’, or a fear of food scarcity, as one main motivator and rationale behind agricultural developments and practices is still in effect today; not being able `to feed the world’ is the main argument against any alternative views of agriculture, i.e. agro-ecology, permaculture, organic and biodynamic farming.

The Significance of Haber-Bosch in the World

The Haber-Bosch process has dramatically changed the face of agriculture and with it the face of our planet. Let me begin by describing its effects on agriculture. The introduction of nitrogenous fertilizers and their increasing application had a dramatic impact on grain yields. Together with new high yielding, short-stalked varieties and chemical protection, yields of wheat and rice worldwide eventually tripled and quadrupled during the 20th century (Smil 2011). The availability of these fertilizers also opened the door for farms to move away from the proven and millennia-old system of cycling and re-cycling nutrients and organic matter in each farm. Diversified farms growing crops for humans, soil-building crops for livestock where the manure was applied back onto the land had been the norm. Now it suddenly became possible to look at a farm in a much more linear way, importing plant nutrients and exporting crops. Industrial monocultures began to take over. Farms moved away from being diversified and multi-dimensional and the `modern’ corn-soybean crop farm took over. Also the disconnecting of animal husbandry from the land and from crop growing set the stage for the so- called CAFO’s (Concentrated Animal Feeding Operations). What used to be the perfect “marriage” between cropping and livestock turned into two serious problems, the need to import expensive fertilizer into farms and the necessity to dispose of animal manure. A much-valued resource, `black gold’ has suddenly become a waste disposal problem (Pollan 2006, Montgomery 2007, Hager 2008). Haber-Bosch also made possible the `Green Revolution’, which transformed agriculture during the mid 1900’s in many so-called developing countries. This massive technology transfer of a more industrial style agriculture rested on the availability and application of nitrogen fertilizer. In 1970 Norman Borlaug, considered the `Father of the Green Revolution’, was awarded the Nobel Peace Prize. The increased yields worldwide supported the rapidly expanding global population, which grew by 5 billion between 1900 and 2000. The number of humans supported per hectare of arable land has increased from 1.9 to 4.3 persons from 1908 to 2008 (Zmaczynski 2012). Today our world food supply has become very dependent on anthropogenic nitrogen. Synthetic nitrogen fertilizers supply just over half of the need of our world’s crops (Smil 2011).

Without this industrial nitrogen our soils today simply could not grow enough food to provide for our current dietary needs. While this fact might be a reason to celebrate, it does come at a higher and higher price. The increasing application of soluble nitrogen fertilizer and pesticides into soils and environment brings with it serious ecological challenges in form of emissions of nitrous oxide, a powerful greenhouse gas, as well as ground water contamination and surface water eutrophication (Smil 2001, Smil 2011, Charles 2013). The well-documented `dead zones’ in the Gulf of Mexico and the Baltic Sea have gained infamous notoriety among countless other examples. Additionally, industrial agriculture and the `Green Revolution’ have had other dramatic negative, unforeseen and unintended consequences. Socio-economically, with the advent of industrial agriculture came the disruption and weakening of traditional farming systems and the communities and local economies they were embedded in (Berry 1986, Shiva 1991). The significance of Haber-Bosch in our current world can hardly be overstated. But a century or so later we need to ask a serious and difficult question. How will we take care of the many hungry mouths on our planet without literally destroying it in the process?

Where Do We Go From Here?

Fritz Haber himself acknowledged in his Nobel acceptance speech that his invention might not be the endpoint in our working with nitrogen:
“It may be that this solution is not the final one. Nitrogen bacteria teach us that Nature, with her sophisticated forms of chemistry of living matter, still understands and utilizes methods which we do not yet know how to imitate.” Haber quoted in Smil, 2001

I strongly suggest that Haber was correct in this assessment and in order to learn more about the “sophisticated forms of chemistry of living matter” we need to create a new context for today’s predominant scientific inquiry. In focusing on the world mostly through analytical science we’ve gained tremendous knowledge, but we’ve also lost sight of many essential attributes, foremost an understanding and appreciation of the interrelatedness of the whole living world, us included.

In his own words Goethe outlines the principles of such a new scientific inquiry:
“In living nature nothing happens that does not stand in a relationship to the whole, and if experiences appear to us only in isolation, if we are to look upon experiences solely as isolated facts, that is not to say that they are isolated; the question is, how are we to find the relationship of these phenomena, of these givens?” With this in mind we need to move from an “aboutness- understanding” to a withness-understanding.”
Goethe (quoted in Sepper, 1988, p.69). This “delicate empiricism”, as Goethe called it, can create the foundation of a new epistemology in our exploration of the living world. Moving us from spectators of disconnected facts about the world to active participants in its living relationships and connections might help us discover more about the true nature of nitrogen and maybe help understand the paradox mentioned in the beginning. In fact there might be no better `research subject’ than this element, since we are in such an intimate relationship with it. Not only do we all breathe it in and out every few seconds, but it is also an essential part of our food and nourishment.

Conclusion and Outlook

What does the emerging future ask of us? I propose in order to orient oneself in the very difficult and complex terrain of the current global food system, where both food scarcity and food excess and waste are present (Bittman 2013) a new science of the living world is needed. A science that will hopefully further ground international studies and reports highlighting the importance of reintegrating agricultural practices of cropping and livestock husbandry using agro-ecological methods as well as focusing on the growth of locally based food economies, rather than the global market place (UN 2010, IAASTD 2008). I also suspect solving the puzzle and paradox of nitrogen will be an essential aspect in this pursuit. In the dynamic interplay of carbon, which is the dominant constituent of all living matter (life’s quantity, see above) and nitrogen (life’s quality, see above) much of life on Earth unfolds, carbon as the main building block of plants and nitrogen as the main building block of proteins (Hager 2008, Smil 2011). In simply looking at the `yield effect’ of nitrogen we might be overlooking the subtle dynamic in all plants between vegetative growth and maturing/ripening /fruit formation. Well-known dangers of over fertilizing with nitrogen are lodging in grains (Virginia Cooperative Extension 2009) and excessive leaf and tree growth at the cost of fruit formation in orchards (Colorado State Extension 2015). Both these phenomena can be seen as imbalances between growth and ripening. Already in 1840 Liebig interestingly identified one principle purpose of agriculture as the production of nitrogen (i.e. proteins) in contrast to forestry, which is characterized by the production of carbon (Smil 2001). Highly nutritious crops are the result of a healthy balance between growth and ripening. In what amount and form would we need to apply nitrogen to achieve this goal? A more holistic approach to science will focus not only on nitrogen but learn about it in the complex web of “the chemistry of living matter”. I am suspecting Steiner’s indications on the role of nitrogen might also become clearer during the course of such inquiry.


Berry, W. (1977) The Unsettling of America. San Francisco: Sierra Club Books
Bittman, M. (2013) How to Feed the World. New York Times 10/14/13
Bohr, N. (1987) The Philosophical Writings, Vol.1. Ox Brow Press
Bortoft, H. (1996) The Wholeness of Nature: Goethe’s way toward a science of conscious participation in nature. New York: Lindisfarne Press.
Charles, D. (2013) Fertilized World. Colorado State Extension (2015) Publication 07612
Hager, T. (2008) The Alchemy of Air. Three Rivers Press
IAASTD (2008) International Assessment of Agricultural Knowledge, Science, and Technology for Development. Washington: Island Press
Montgomery, D (2007) Dirt – The Erosion of Civilizations. University of California Press
Pollan, M (2006) The Omnivore’s Dilemma. New York: Penguin Books Sepper, D.L. (1988) Goethe contra Newton: Polemics and the project for a new
science of color. New York: Cambridge University Press.
Shiva V. (1991) The Violence of the Green Revolution. New York: Zed Books
Smil, V. (2001) Enriching the Earth, Cambridge: MIT press
Smil, V. (2011). Nitrogen cycle and world food production. World Agriculture 2:9-1
Steiner, R. (1993) Agriculture, Biodynamic Farming and Gardening Association
United Nations – General Assembly A/HRC/16/49. 2010 Report submitted by the Special rapporteur on the right to food Olivier de Schutter
Virginia Cooperative Extension (2009) Publication 424 - 026 Zmaczynski, R. (2012) The Effect of the Haber process on Fertilizers.