One Earth (2026). DOI: 10.1016/j.oneear.2026.101621"> Global fixation of reactive nitrogen in oxidized and reduced form until 2010. Credit: One Earth (2026). DOI: 10.1016/j.oneear.2026.101621

Ammonia has been feeding the world for decades as a fertilizer and is now rapidly emerging as a carbon-free fuel for shipping and industry. But if we focus only on CO₂ emissions, we risk creating new nitrogen problems, warns nitrogen expert Jan Willem Erisman in an article published in the journal One Earth .

Ammonia is one of the most important inventions of the last century. Thanks to the Haber-Bosch process , nitrogen from the air can be converted into ammonia. This made large-scale plastic production possible and contributed to a huge increase in global food production.

But the invention also has a downside. Large-scale use has disrupted the natural nitrogen cycle —the balance of nitrogen in soil, water and air.…