Soil microorganisms decrease barley biomass uniformly across contrasting nitrogen availability

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Aims: Microorganisms play a dichotomous role in the soil nitrogen cycle through mineralization and immobilization. We aimed to understand how nitrogen availability modifies the effect of microorganisms on plant growth. We hypothesized that soil microorganisms would increase plant biomass following amendment with a substrate rich in organic nitrogen (net mineralization), be neutral when adding inorganic nitrogen, and decrease biomass when adding organic nitrogen-limited substrate (nitrogen competition). Method: Barley (Hordeum vulgare L., cv. Evergreen) was exposed to either i) limited, organically bound nitrogen, ii) organically bound nitrogen or iii) inorganic nitrogen. In these amendments, we assessed the differences in plant biomass and physiology between plants with or without soil microbiome addition. Results: The soil microbiome reduced shoot biomass equally (12%) across all nitrogen amendments. However, nitrogen availability did modulate the effect of the soil microbiome on plant physiological parameters associated with nitrogen deficiency. Conclusions: The results indicate that the net negative effect of complex microbiomes on shoot biomass is independent of nitrogen availability. Thus, microbiome addition was deleterious to biomass even in a nutrient-stress-free environment. We suggest that strategies for improving plant growth through manipulation of microorganisms should not exclusively focus on beneficial and pathogenic microorganisms, but also include minimizing plant metabolic costs of microbiome interactions.

Original languageEnglish
Article number103311
JournalEuropean Journal of Soil Biology
Number of pages9
Publication statusPublished - 2021

Bibliographical note

Publisher Copyright:
© 2021 Elsevier Masson SAS

    Research areas

  • Bacteria, Nitrogen competition, Nitrogen mineralization, Plant growth, Plant-microbiome interaction, Protists

ID: 262846631