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Updated: May 11, 2026

Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
Biological nitrogen fixation: rates, patterns and ecological controls in terrestrial ecosystems
Peter M Vitousek1, Duncan N L Menge, Sasha C Reed
1Department of Biology, Stanford University, Stanford, CA 94305, USA. vitousek@stanford.edu
Pre-industrial biological nitrogen fixation (BNF) was lower than previously estimated. This suggests human activities have significantly altered the global nitrogen cycle more than thought.
Area of Science:
- Ecology
- Biogeochemistry
- Environmental Science
Background:
- Biological nitrogen fixation (BNF) is vital for ecosystem health and the global nitrogen cycle.
- While new techniques reveal diverse nitrogen-fixing organisms, ecosystem-level BNF rates remain poorly understood.
- Understanding BNF is critical for assessing anthropogenic impacts on the nitrogen cycle and global environmental change.
Purpose of the Study:
- To estimate pre-industrial terrestrial biological nitrogen fixation (BNF) rates.
- To provide a baseline for quantifying human alteration of the nitrogen cycle.
Main Methods:
- Combined data on nitrogen (N) fluxes with (15)N relative abundance in terrestrial ecosystems.
- Estimated pre-industrial BNF rates.
Main Results:
- Pre-industrial terrestrial BNF was estimated at 58 Tg N yr(-1) (range 40-100 Tg N yr(-1)).
- Including geological nitrogen sources, the best estimate decreased to 44 Tg N yr(-1).
- These estimates are substantially lower than most recent calculations.
Conclusions:
- The magnitude of human alteration to the nitrogen cycle is likely greater than previously assumed.
- Accurate BNF rate estimations are crucial for understanding global biogeochemical cycles and environmental change.
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