Pedosphere 34(2): 399--410, 2024
ISSN 1002-0160/CN 32-1315/P
©2024 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Mycorrhizal fungi mitigate nitrogen losses of an experimental grassland by facilitating plant uptake and soil microbial immobilization |
Yangyang JIA1,2, Marcel G.A. VAN DER HEIJDEN2,4, Alain Y. VALZANO-HELD2, Markus JOCHER3, Florian WALDER2,5 |
1 Postdoctoral Mobile Station of Ecology, College of Ecology and Environment, Xinjiang University, Ürümqi 830046 (China);
2 Research Group Plant-Soil Interactions, Agroscope, Zürich 8046 (Switzerland);
3 Research Group Climate and Agriculture, Agroscope, Zürich 8046 (Switzerland);
4 Department of Plant and Microbial Biology, University of Zürich, Zürich 8008 (Switzerland);
5 Research Group Soil Quality and Soil Use, Agroscope, Zürich 8046 (Switzerland) |
| ABSTRACT |
| Nitrogen (N) is one of the most limited nutrients of terrestrial ecosystems, whose losses are prevented in tightly coupled cycles in finely tuned systems. Global change-induced N enrichment through atmospheric deposition and application of vast amounts of fertilizer are now challenging the terrestrial N cycle. Arbuscular mycorrhizal fungi (AMF) are known drivers of plant-soil nutrient fluxes, but a comprehensive assessment of AMF involvement in N cycling under global change is still lacking. Here, we simulated N enrichment by fertilization (low/high) in experimental grassland microcosms under greenhouse conditions in the presence or absence of AMF and continuously monitored different N pathways over nine months. We found that high N enrichment by fertilization decreased the relative abundance of legumes and the plant species dominating the plant community changed from grasses to forbs in the presence of AMF, based on aboveground biomass. The presence of AMF always maintained plant N:phosphorus (P) ratios between 14 and 16, no matter how the soil N availability changed. Shifts in plant N:P ratios due to the increased plant N and P uptake might thus be a primary pathway of AMF altering plant community composition. Furthermore, we constructed a comprehensive picture of AMF’s role in N cycling, highlighting that AMF reduced N losses primarily by mitigating N leaching, while N2O emissions played a marginal role. Arbuscular mycorrhizal fungi reduced N2O emissions directly through the promotion of N2O-consuming denitrifiers. The underlying mechanism for reducing N leaching is mainly the AMF-mediated improved nutrient uptake and AMF-associated microbial immobilization. Our results indicate that synergies between AMF and other soil microorganisms cannot be ignored in N cycling and that the integral role of AMF in N cycling terrestrial ecosystems can buffer the upcoming global changes. |
| Key Words: N cycling,N enrichment,N uptake,N:P ratio,plant community structure,symbiotic soil fungi |
| Citation: Jia Y Y, van der Heijden M G A, Valzano-Held A Y, Jocher M, Walder F. 2024. Mycorrhizal fungi mitigate nitrogen losses of an experimental grassland by facilitating plant uptake and soil microbial immobilization. Pedosphere. 34(2): 399-410. |
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