Abstract
Background and aims: The amount of nitrogen (N) derived from symbiotic N2 fixation by legumes in grasslands might be affected by anthropogenic N and phosphorus (P) inputs, but the underlying mechanisms are not known. Methods: We evaluated symbiotic N2 fixation in 17 natural and semi-natural grasslands on four continents that are subjected to the same full-factorial N and P addition experiment, using the 15N natural abundance method. Results: N as well as combined N and P (NP) addition reduced aboveground legume biomass by 65% and 45%, respectively, compared to the control, whereas P addition had no significant impact. Addition of N and/or P had no significant effect on the symbiotic N2 fixation per unit legume biomass. In consequence, the amount of N fixed annually per grassland area was less than half in the N addition treatments compared to control and P addition, irrespective of whether the dominant legumes were annuals or perennials. Conclusion: Our results reveal that N addition mainly impacts symbiotic N2 fixation via reduced biomass of legumes rather than changes in N2 fixation per unit legume biomass. The results show that soil N enrichment by anthropogenic activities significantly reduces N2 fixation in grasslands, and these effects cannot be reversed by additional P amendment.
Original language | English |
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Pages (from-to) | 689-707 |
Number of pages | 19 |
Journal | Plant and Soil |
Volume | 478 |
Issue number | 1-2 |
DOIs | |
State | Published - Sep 2022 |
Bibliographical note
Publisher Copyright:© 2022, The Author(s).
Keywords
- Grasslands
- Legumes
- N natural abundance method
- Nitrogen addition
- Nutrient Network (NutNet)
- Phosphorus addition
ASJC Scopus subject areas
- Soil Science
- Plant Science