I recently read this brief history of the use of nitrogen fertilizer, and it was so interesting to learn more about this crucial agricultural input! In my agricultural economics classes, we often use nitrogen as an input for our examples, so it was good to beef up my knowledge about it. Maybe you will discover a couple of new-to-you facts as well?
(All facts, unless otherwise linked, are from this article here).
- What we should actually talk about when we talk about fertilizer is nitrate – plant-available nitrogen – as opposed to atmospheric nitrogen (N2), which is joined together so tightly that it can’t be used as a nutrient by plants.
- Transforming nitrogen into nitrate has been a challenge for farmers for centuries and been accomplished through the use of manure and composting crop waste. As you can see in the above image, the organic fixation of atmospheric nitrogen and the number of steps involved until you reach nitrate (over decomposition, ammonification, nitrification, and assimilation) is highly complex. Thus, nitrate has actually been a rather scarce resource for most of agricultural history.
- That is, until 1909, when the German chemist Fritz Haber discovered a process that could directly transform atmospheric nitrogen into plant-available nitrate using a high-temperature, energy-intensive process. This is today known as the industrial fixation of nitrogen, or the Haber-Bosch process.
- It is estimated that half of the protein within human beings is made of nitrogen that was originally fixed by this process, whereas the other half comes from the organic cycle of nitrogen-fixing bacteria and archaea. (Side-note: isn’t that a crazy fact?)
- This development, which was able to produce ammonia from air, proved to be the starting point of synthetic nitrogen fertilizers and was a huge shift in the trajectory of food production. But not only that – it was also of high interest for the militaries involved in World War I, since it gave Germans the possibility to produce nitric acid, a precursor to munitions. These chemical processes were also widely used – and thereby perfected – in the European and US munition industry during World War II.
- By the end of World War II, the US had built 10 large-scale nitrate factories in order to make bombs, but no more bombs were needed. Yet, with European and Japanese factories in ruins, the US had a quasi-monopoly on nitrogen production. The former-munition industry thus quickly moved into the production of nitrogen fertilizer and the US became a country whose agriculture relies very heavily on synthetic nitrogen fertilizer, especially because the new hybrid strands of corn that emerged were particularly dependent on high fertilizer application.
- However, applying massive amounts of fertilizer that cannot all be taken in by plants can cause great environmental damage. This process is known as leaching. It can cause huge “dead zones” in river deltas where algae take up all the ecosystem space and prevent other marine life from existing (I am preparing a separate post on that topic). Also, if nitrate leaches into the groundwater, it can be a severe human health hazard: elevated levels of nitrate in drinking water can cause nitrate poisoning (or “blue baby syndrome”) in infants, where the baby’s blood loses its oxygen-carrying capacity.
- One of the reasons environmental protection agencies such as the EPA are so concerned about the levels of nitrate-nitrogen in drinking water and enforce it is because once a water source is contaminated, it is very costly to remove the nutrient from the water – conventional drinking water processing is unable to remove nitrate and thus expensive specialized treatment facilities are needed.
- Despite it being a topic of huge debate in the US, I was surprised to see that the US agricultural industry is actually not the greatest global consumer of nitrogen fertilizer products – according to this presentation, 31% of global nitrogen consumption takes place in China, 16% in India, 11% in the US, 3% in Brazil and the final 39% is distributed among the rest of the world. According to the same presentation, the world nitrogen consumption is forecast to continue its steady increase to 110 million metric tons (!) in 2012/2013.
- However, there are alternatives – as you can see again in the nitrogen-cycle picture above, the use of leguminous plants has been used for centuries in rotation cropping to increase the nitrate level of soils naturally. In fact, this is because leguminous plants live in symbiotic relationships with bacteria that are able to fix nitrogen as organic nitrogen and furnish it to other bacteria that transform it as seen above. This process has been shown to be more environmentally sustainable and equally profitable as the industrial agricultural process.
Bonus: I haven’t had time to listen to it, but this BBC documentary about “Fixing the Nitrogen Fix” sounds really interesting if you have a spare half hour of free time.