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Research article - Peer-reviewed, 2022

Nitrogen but not phosphorus addition affects symbiotic N-2 fixation by legumes in natural and semi-natural grasslands located on four continents

Vazquez, Eduardo; Schleuss, Per-Marten; Borer, Elizabeth T.; Bugalho, Miguel N.; Caldeira, Maria C.; Eisenhauer, Nico; Eskelinen, Anu; Fay, Philip A.; Haider, Sylvia; Jentsch, Anke; Kirkman, Kevin P.; McCulley, Rebecca L.; Peri, Pablo L.; Price, Jodi; Richards, Anna E.; Risch, Anita C.; Roscher, Christiane; Schutz, Martin; Seabloom, Eric W.; Standish, Rachel J.;
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Background and aims: The amount of nitrogen (N) derived from symbiotic N-2 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 N-2 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 N-15 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 N-2 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 N-2 fixation via reduced biomass of legumes rather than changes in N-2 fixation per unit legume biomass. The results show that soil N enrichment by anthropogenic activities significantly reduces N-2 fixation in grasslands, and these effects cannot be reversed by additional P amendment.


Grasslands; Legumes; Nitrogen addition; Nutrient Network (NutNet); Phosphorus addition; N-15 natural abundance method

Published in

Plant and Soil
2022, volume: 478, number: 1, pages: 689-707
Publisher: SPRINGER

Authors' information

Vazquez, Eduardo (Vázquez Garcia, Eduardo)
University of Bayreuth
Swedish University of Agricultural Sciences, Department of Soil and Environment
Schleuss, Per-Marten
University of Bayreuth
Borer, Elizabeth T.
University of Minnesota Twin Cities
Bugalho, Miguel N.
Universidade de Lisboa
Caldeira, Maria C.
Universidade de Lisboa
Eisenhauer, Nico
German Ctr Integrat Biodivers Res iDiv
Eskelinen, Anu
Helmholtz Association
Fay, Philip A.
United States Department of Agriculture (USDA)
Haider, Sylvia
Martin Luther University Halle Wittenberg
Jentsch, Anke
University of Bayreuth
Kirkman, Kevin P.
University of Kwazulu Natal
McCulley, Rebecca L.
University of Kentucky
Peri, Pablo L.
Instituto Nacional de Tecnologia Agropecuaria (INTA)
Price, Jodi
Charles Sturt University
Richards, Anna E.
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
Risch, Anita C.
Swiss Federal Institute for Forest, Snow and Landscape Research
Roscher, Christiane
Helmholtz Association
Schutz, Martin
Swiss Federal Institute for Forest, Snow and Landscape Research
Seabloom, Eric W.
University of Minnesota Twin Cities
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UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use
Soil Science

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