Campus Units

Ecology, Evolution and Organismal Biology

Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

4-2021

Journal or Book Title

Soil Biology and Biochemistry

Volume

155

First Page

108168

DOI

10.1016/j.soilbio.2021.108168

Abstract

Human activities have increased nitrogen (N) and phosphorus (P) inputs in terrestrial ecosystems and altered carbon (C) availability, shifting the stoichiometry of microbial substrates in soils, such as the C:N:P ratios of the dissolved organic matter pool. These stoichiometric deviations between microbial biomass and its substrate may control microbial processes of N cycling. We studied the effects of this stoichiometric mismatch using a full factorial N and P addition experiment replicated in six grassland ecosystems in South Africa, the USA, and the UK. We found that N and P addition changed the dissolved organic matter C:N ratio, but not the C:N ratio of the soil microbial biomass. Compared to P addition, N addition decreased microbial N acquisition via non-symbiotic N2 fixation by -55% and increased microbial N release via net N mineralization by +134%. A possible explanation is that the dissolved elements, e.g., dissolved organic C (DOC) and dissolved total N (DN), serve as the main microbial substrate and its C:N ratio defines whether N is scarce or abundant with respect to microbial demands. If N is available in excess relative to microbial demands, net N mineralization increases. In contrast, when N is scarce, immobilization outweighs release decreasing net N mineralization. However, the activity of leucine aminopeptidases, which decompose peptides, was not affected by nutrient additions. Further, C rather than P availability may control the rates of non-symbiotic N2 fixation in the six studied grassland sites. In conclusion, globally increasing nutrient inputs change processes of microbial N acquisition and release in grassland ecosystems and these changes are largely driven by shifts in substrate stoichiometry.

Comments

This is a manuscript of an article published as Schleuss, P. M., M. Widdig, L. A. Biederman, E. T. Borer, M. J. Crawley, K. P. Kirkman, E. W. Seabloom, P. D. Wragg, and M. Spohn. "Microbial substrate stoichiometry governs nutrient effects on nitrogen cycling in grassland soils." Soil Biology and Biochemistry (2021): 108168. doi:10.1016/j.soilbio.2021.108168.

Copyright Owner

Elsevier Ltd.

Language

en

File Format

application/pdf

Available for download on Saturday, April 01, 2023

Published Version

Share

COinS