Nitrogen Pollution and Management

January 22, 2025

Recent reports highlight the increase in reactive nitrogen added to the Earth’s surface, primarily due to human activities. This rise has doubled compared to pre-industrial levels, with projections suggesting a further increase due to climate change. The Food and Agriculture Organization has emphasised the urgent need for improved nitrogen use efficiency (NUE) to mitigate environmental impacts.

Current Nitrogen Contributions

Humans add approximately 150 teragrammes (Tg) of reactive nitrogen annually.
This is primarily from agriculture and industry.
Livestock alone contributes about one-third of total nitrogen emissions.
Other sources include synthetic fertilisers and manure emissions.

Planetary Boundaries

Global nitrogen flows have exceeded safe environmental limits. This exceedance has intensified since 2015. It marks the need for tailored policies that consider regional differences in nitrogen management.

Nitrogen Use Efficiency (NUE)

NUE measures the ratio of nitrogen recovered in outputs compared to inputs.
It has fluctuated over the decades, with a notable increase from 40% in the 1980s to 56% in 2022.
Variations exist between regions and crops, with soybeans achieving high NUEs and fruits and vegetables showing low efficiency.

Regional Nitrogen Pollution

Nitrogen pollution is most severe in North America, Western Europe, and parts of Asia.
Countries in these regions have extensively used fertilisers, leading to environmental damage.

Recommendations for Improvement

The report advises the fertiliser industry to reduce greenhouse gas emissions.
It also suggests promoting biological nitrogen fixation through leguminous crops.
National governments should implement best practices for manure management and encourage the use of organic nitrogen fertilisers.

Policy and Sustainable Practices

Agrifood system policies should focus on sustainable nitrogen management.
This includes spatial planning to redistribute livestock and promoting circular bioeconomy approaches.
National commitments to reduce nitrogen pollution are essential for meeting global biodiversity and climate goals.

Future Projections

Without intervention, nitrogen contributions could rise to 600 Tg per year by 2100. This potential increase poses further risks to air, water, and soil quality, necessitating immediate actions to enhance NUE and mitigate environmental impacts.

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