The Miraculous Nitrogen Cycle – How fertilizers Warm the Earth

My first science film 🙂

I am very excited to share with you the first video on this blog today! During a science filmmaking event, the Exposure Science Film Hackathon Lausanne 2018, I had the opportunity to make a very cool science film with a team of scientists, filmmakers, and science communicators. As the topic, we chose the miraculous nitrogen cycle, the research field of my PhD thesis. So please follow this link and enjoy the video!

the mosers happy growth
Science film ‘Happy Growth’

I hope you were entertained by this film, learned something, and also got inspired to learn more! If so, I would like to give you some background information.

The history of nitrogen fertilizers

Nitrogen-based fertilizers are essential in agriculture and quite an amazing thing. Plants need nitrogen because it is an essential element. In the air, there are huge amounts of nitrogen in the form of dinitrogen gas (N2) but this unreactive compound cannot be used by plants, just by some specialized microorganisms. Until around 1920, a limitation of nutrients in the soils, which gets worse over time in agriculture, didn’t allow higher yields of crops. Therefore, the two German scientists Fritz Haber and Carl Bosch developed a process that transforms Nfrom the air into reactive nitrogen in the form of ammonia (NH3), which can be used by plants. It is amazing that we need very high temperatures and pressure, hence a lot of energy, to make this reaction happen, while microorganisms manage to do it under normal conditions. The invention of the Haber-Bosch process enabled the growth of the human population from 2 billion to the current size. On a side note, the two chemists had quite an exciting life showing the close connection between science and society. They both got the Nobel prize in chemistry for inventing their nitrogen-fixation process. Fritz Haber also developed a powerful chemical weapon for world war I, whereupon his wife committed suicide, probably as a protest. Interestingly, he died and was buried in Basel. 

Blessing and curse

Once the new synthetic fertilizers were established, everyone got excited about the big increase in yields. But in the beginning, people didn’t really think about the potential bad consequences of the (excessive) use of nitrogen fertilizers or they just didn’t know them yet. There are actually quite a few, like the deterioration of soil properties, the contamination of groundwater, and the increase of nutrients in fresh waters and coastal zones when the fertilizers are transformed and transported from the soils into aquatic systems. This process is called eutrophication and causes more growth of algae, hence toxin production, and the consumption of oxygen leading to dying fish. These are the more or less direct consequences that were not predicted. But particularly the indirect effect that these fertilizers are transformed into greenhouse gases and warm the Earth was not considered until much later. Under various environmental conditions, microorganisms in soils, fresh waters, and oceans produce naturally nitrous oxide (N2O), also known as laughing gas, by converting other nitrogen compounds. The application of nitrogen fertilizers enhances these processes enormously, basically by feeding not only the plants but also the microbes. Due to the production and the application of synthetic nitrogen fertilizers, the entire global nitrogen cycle went out of whack because now there are just much more nutrients on Earth – a huge problem.

The importance of laughing gas

Nitrogen fertilizers are the main contributor to the increase in atmospheric nitrous oxide levels by ~18% since the invention of the Haber-Bosch process. Another important nitrous oxide source is manure, consisting mostly of feces and urine from cows and pigs, which is also rich in nitrogen and a paradise for microbes. Other industrial processes contribute to a lesser percentage. Nitrous oxide is now the 3rd most impactful human-made greenhouse gas after carbon dioxide and methane and contributes with ~8% to the human-made greenhouse gas effect. It is a gas with a long average lifetime of ~120 years and a substance that depletes the ozone layer – one more reason to reduce its emissions. In the media, we hear mostly about carbon dioxide. Yes, it is the most important greenhouse emitted by humans and emissions need to be reduced. But let us not forget other greenhouse gases and take a look at agriculture and see what we can do there! Meanwhile, we know the nitrogen cycle very well and know what consequences fertilizers have. Several things could improve the balance in the global nitrogen cycle and minimize nitrous oxide emissions:

How can we reduce nitrous oxide emissions?

Reduce the use of fertilizers to a needed minimum

Back then, the attitude was pretty much ‘the more the merrier’ and still, often more fertilizers than necessary are used. On the other side, in some region as in Africa, the soils remain poor in nutrients because the farmers can’t afford to buy fertilizers. In Europe, for instance, the amount of nitrogen fertilizers used every year is more or less stable nowadays but globally, with the biggest contribution of Asia, the use of nitrogen fertilizers is still increasing. In general, they should just be applied as much as they are needed in a very controlled way, which is mostly a matter of legal regulations, agriculture, and also fertilizer producers.

Support organic farming

The goal of organic farming is to make food production as healthy as possible both for us and for nature. This includes the least use of pesticides and fertilizers that is possible. Hence, consumers and politics should support that.

Reduce the overproduction and waste of food

When you look in the supermarkets in the developed world: They are full. It represents the overproduction of food, while in some developing countries people are still starving. When there is an overproduction, automatically, there is food waste. Some regulations, for instance, the industry norms that don’t allow imperfect looking food, contribute to the waste. When the disposed food is rotting, not only carbon dioxide but also the strong greenhouse gas methane is produced. Therefore, the reduction of the overproduction and the waste of food is important, although it is difficult to implement. Measures as contract farming, where the sales of the harvest are guaranteed by contracts between farmers and consumers, would contribute to minimizing the problems that fertilizers cause as well.

Reduce the production of meat and other animal products – a lot!

The production of meat and dairy is really bad for the climate, not only because of the manure, which is releasing greenhouse gases. Animal-based food needs much more resources than plant-based food. A lot of the plants we grow, we feed to the animals. So without them, we would need to grow less crops and use less fertilizers. Not talking about the methane, which is massively emitted by cows. Of course, we don’t need to renounce all animal products now but it is necessary to reduce the amount of livestock to help our climate.

Stabilize the size of the human population

There are more than 7.5 billion humans on Earth and the number is increasing continuously. The more humans there are, the more resources are needed to feed them. That means we need to grow more crops for which we need more freshwater and land – and more fertilizers. It is logical that the Earth cannot host an infinite number of humans. It will not be in the next decades, but at some point, there won’t be resources available anymore for more humans. But when that point is reached, the Earth will not be as habitable any more as it is still now. Therefore, it is very important to stabilize the size of the human population rather sooner than later. Of course, it is challenging for various political and cultural reasons but with measures that let people keep a free choice regarding offsprings like providing free access to contraception options and improving education – especially for girls – much could be achieved.

Time for change!

The Earth and humans are in great danger. Climate change is already affecting life on Earth and it will even more in the future. How bad it will get, is up to us. It is not the time to just change a little bit and wait. We need to take drastic measures to stop global warming. One power we have on the fertilizer topic, among others, is to choose more climate-friendly food. Change needs to come from higher instances as well, for instance, politics need to be much stricter in their regulations and mustn’t bend towards lobbies at the expense of nature. 

There are many more aspects to this topic in terms of science, politics, industries, and society. For now, I hope I got you interested in the miraculous nitrogen cycle and its human-made unbalance!

In case you were wondering: Laughing gas only has a narcotic or euphorigenic effect on humans in high concentrations. The atmospheric levels are way too low for this 😉

In the end, some making-off impressions from the filmmaking!

One thought on “The Miraculous Nitrogen Cycle – How fertilizers Warm the Earth

  1. Pingback: Environmental Topics at the Carnival of Basel 2019 | Colors of science

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