Half the nitrogen in our bodies most likely comes from an industrial process. The connection between nitrogen, energy, and food is way more than we expect. This science story traces that link, and there are also some fun facts waiting at the end.
Many of us have been hearing about natural gas shortages and how farmers are struggling with rising fertilizer prices and availability especially in low and middle income countries. And it got me thinking about something we don’t discuss enough – how feeding 8 billion people is closely tied to fossil fuels.
When we think about food, we picture plants. Plants use sunlight to produce glucose and oxygen but there is an important part of the story revolving around nitrogen. Nitrogen is present in every amino acid of proteins. Plants continuously build proteins including enzymes, structural components, and transport molecules, all of which require nitrogen. It is also a key component of chlorophyll, which captures sunlight, and of DNA and RNA, which store genetic information. Because of this, plants need a constant and reliable supply of nitrogen.
The Locked Nitrogen
Nitrogen in the soil is taken up by plants and then enters the food chain. It becomes part of the proteins we eat and even our own genetic material. When plants do not receive enough nitrogen, their growth is affected. This reduces crop yields and lowers the protein content of food, affecting both nutrition and overall food security. Therefore, the availability of usable nitrogen is central to food production.
Although the air around us is about 78 percent nitrogen, none of it is directly taken up by plants in its default form. Atmospheric nitrogen exists as N₂, where two nitrogen atoms are held together by a strong triple bond. This makes it one of the most stable small molecules in nature.
Nature’s Secret Workers
Only certain microorganisms can convert nitrogen into forms used by plants through a process called biological nitrogen fixation. Using their nitrogenase enzyme, they convert atmospheric nitrogen into ammonia. While we usually think of ammonia as a strong cleaning liquid, in the soil, it is the unlocked form of nitrogen that plants can use.
Some of these microorganisms live in close association with plants like Rhizobium in legumes (beans, peas, and lentils). These plants have a built-in supply of nitrogen. But our most important staple crops, like wheat, rice, and corn cannot do this. They rely on the nitrogen already present in the soil, which gets used up quickly.
Even in extreme places like deep-sea systems, some methanogenic archaea can fix nitrogen. These nitrogen fixers act as natural fertilizers to sustain ecosystems. Non-biological processes like lightning also contribute by breaking the N₂ bond but only in tiny amounts. By the late 19th century, these natural sources simply could not meet the demand of a growing world.
Nitrogen became a clear bottleneck in food production because we needed more than nature could provide.
The Chemistry Solution (and its cost)
In 1909, Fritz Haber demonstrated that we could use chemistry to do what biology does. He figured out how to crack that locked nitrogen box by combining atmospheric nitrogen with hydrogen under extreme temperature and pressure. Later, Carl Bosch scaled this into a industrial process. This Haber–Bosch process, in many ways has been a remarkable achievement in feeding a growing population and meeting global food demands. However, it has a massive cost that it is literally built from fossil fuels.
One estimate says that a large share of the nitrogen in our food today comes from industrial fertilizer made using fossil fuels that eventually becomes the building blocks of our muscles and DNA.
To produce ammonia, we need a massive amount of hydrogen. Most industrial hydrogen is made from natural gas, mainly through steam methane reforming. This forces the methane molecules to break apart to loose their hydrogen atoms, and the leftover carbon from the methane combines with oxygen to become carbon dioxide.
This is why ammonia production is so energy-heavy, accounting for roughly 2% of global energy use and 1-1.3% of global carbon dioxide emissions.
The Leakage Problem
It’s tempting to think more fertilizer always means better yields but that isn’t true. Once fertilizer enters soil, nitrogen can be lost in several ways before plants use it. It can escape into the air as ammonia gas (volatilization) or wash away into groundwater as nitrates (leaching).
When these nitrates reach our rivers and oceans, they act as a feast for algae. This causes algal blooms that soak up all the oxygen in the water, creating dead zones where fish and other marine life cannot survive. It turns out that over-fertilizing a field can accidentally suffocate an ecosystem even miles away.
What blew my mind is that some of this nitrogen also turns into nitrous oxide (N₂O). Many of us know it as laughing gas, but it is a potent greenhouse gas with a global warming potential nearly 300 times that of CO₂. So, our fertilizer use is directly associated with both water pollution and climate change.
Research Spotlight
Unlike carbon, which plants pull directly from the air as carbon dioxide, nitrogen is primarily taken from the soil. This creates a problem at harvest: when we take crops off the field to eat them, we are physically removing the nitrogen they contain. Because most nitrogen doesn’t just cycle back into the soil from the air on its own, fertility declines unless we manually add it back.
Scientists are exploring how to introduce nitrogen-fixing machinery directly into plants. But it comes with this huge challenge that the key enzyme nitrogenase is inactivated by oxygen, yet plant cells need oxygen to live. It is a biological conflict we are trying to solve.
In the near-term, we are looking at green ammonia using renewable electricity to get hydrogen from water instead of natural gas. This has a potential to decouple our food from fossil fuels. We are also using precision farming, which uses technology to apply fertilizer at the right time and place, in the right amount to make their uptake process more efficient.
The Bottom Line – Fertilizers to Food Security
We often think of food security in terms of farming practices, land availability or poverty but the chemistry and energy systems underneath food production are just as important and far less visible. The chain from a natural gas to a fertilizer to a harvest is not something most of us think about when we buy food. The system that feeds the world is more fragile and more fossil fuel dependent than most of us realize.
When natural gas prices surge or supplies are disrupted, fertilizer costs rise sharply with consequences that reach beyond the farm: food becomes scarcer, nutritional quality can decline, and grocery prices spike globally.
Understanding how all of this connects, we can focus more on building a food system that’s more resilient, supports the ecosystem, and doesn’t depend so heavily on the finite resources we’ve relied on for so long.
I enjoyed putting together about the Nitrogen based Fertilizer Edition – It’s definitely fun to read!
- Fritz Haber won the 1918 Nobel Prize in Chemistry for synthesizing ammonia, which is one of the most impactful discovery in human history.
- Lightning was one of nature’s primary ways to fix nitrogen.
- Nitrogen fixation is so expensive that a microbe must spend 16 molecules of ATP just to break one nitrogen.
- In the mid‑1800s, guano islands were called white gold because the seabird‑dropping deposits were extremely rich in nitrogen and other plant nutrients.
- Most ammonia is made from natural gas while a smaller share comes from coal gasification and a tiny but growing share comes from green ammonia.
- Legumes use leghemoglobin in their root nodules to keep oxygen low enough for nitrogen fixation. It gives the nodules a pink color, and a related soy-derived heme made through fermentation helps give some plant-based burgers a meat-like taste and color.
- One group of researchers found that changing two amino acids in a plant receptor could alter how the plant responds to symbiotic bacteria, which is an early step toward engineering nitrogen-fixing crops.
I love all of them and my favorite is the 4th and 8th ones. What’s yours?
Want to read more?
Galloway, J. N., Bleeker, A., & Erisman, J. W. (2021). The human creation and use of reactive nitrogen: A global and regional perspective. Annual Review of Environment and Resources, 46, 255–288. https://doi.org/10.1146/annurev-environ-012420-045120
Erisman, J. W., Sutton, M. A., Galloway, J. N., Klimont, Z., & Winiwarter, W. (2008). How a century of ammonia synthesis changed the world. Nature Geoscience, 1(10), 636–639. https://doi.org/10.1038/ngeo325
Rosa, L., & Gabrielli, P. (2023). Energy and food security implications of transitioning synthetic nitrogen fertilizers to net-zero emissions. Environmental Research Letters, 18(1), 014008. https://doi.org/10.1088/1748-9326/aca815
Tufail, M. A., Ayyub, M., Tariq, L., Iltaf, J., Asbat, A., Bashir, I., & Umar, W. (2024). Nitrogen fertilizers and the future of sustainable agriculture: A deep dive into production, pollution, and mitigation measures. Soil Science and Plant Nutrition, 70(5–6), 457–477. https://doi.org/10.1080/00380768.2024.2361068
Mingolla, S., & Rosa, L. (2025). Low-carbon ammonia production is essential for resilient and sustainable agriculture. Nature Food, 6, 610–621. https://doi.org/10.1038/s43016-025-01125-y
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