Soil microbial CNP and respiration responses to organic matter and nutrient additions: evidence from a tropical soil incubation
Soong, Jennifer L. (Universiteit Antwerpen. Departement Biologie)
Marañón Jiménez, Sara (Universidad de Granada. Departamento de Física Aplicada)
Cotrufo, M. Francesca (Colorado State University. Natural Resource Ecology Laboratory)
Boeckx, Pascal (University of Ghent. Isotope Biosciencie Laboratory)
Bode, Samuel (University of Ghent. Isotope Biosciencie Laboratory)
Guenet, Bertand (Laboratoire des Sciences du Climat et de l'Environnement)
Peñuelas, Josep (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Richter, Andreas (Universität Wien. Institut für Mikrobiologie und Ecosystem Wissenschaft)
Stahl, Clément (Institut National de la Recherche Agronomique (França))
Verbruggen, Erik (Universiteit Antwerpen. Departement Biologie)
Janssens, Ivan (Universiteit Antwerpen. Departement Biologie)

Date:	2018
Abstract:	Soil nutrient availability has a strong influence on the fate of soil carbon (C) during microbial decomposition, contributing to Earth's C balance. While nutrient availability itself can impact microbial physiology and C partitioning between biomass and respiration during soil organic matter decomposition, the availability of labile C inputs may mediate the response of microorganisms to nutrient additions. As soil organic matter is decomposed, microorganisms retain or release C, nitrogen (N) or phosphorus (P) to maintain a stoichiometric balance. Although the concept of a microbial stoichiometric homeostasis has previously been proposed, microbial biomass CNP ratios are not static, and this may have very relevant implications for microbial physiological activities. Here, we tested the hypothesis that N, P and potassium (K) nutrient additions impact C cycling in a tropical soil due to microbial stoichiometric constraints to growth and respiration, and that the availability of energy-rich labile organic matter in the soil (i. e. leaf litter) mediates the response to nutrient addition. We incubated tropical soil from French Guiana with a ¹³C labeled leaf litter addition and with mineral nutrient additions of +K, +N, +NK, +PK and +NPK for 30 days. We found that litter additions led to a ten-fold increase in microbial respiration and a doubling of microbial biomass C, along with greater microbial N and P content. We found some evidence that P additions increased soil CO² fluxes. Additionally, we found microbial biomass CP and NP ratios varied more widely than CN in response to nutrient and organic matter additions, with important implications for the role of microorganisms in C cycling. The addition of litter did not prime soil organic matter decomposition, except in combination with +NK fertilization, indicating possible P-mining of soil organic matter in this P-poor tropical soil. Together, these results point toward an ultimate labile organic substrate limitation of soil microorganisms in this tropical soil, but also indicate a complex interaction between C, N, P and K availability. This highlights the difference between microbial C cycling responses to N, P, or K additions in the tropics and explains why coupled C, N and P cycling modeling efforts cannot rely on strict microbial stoichiometric homeostasis as an underlying assumption.
Grants:	European Commission 610028
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Subject:	13C ; CNP ; Microbial stoichiometry ; Priming ; Soil respiration ; Tropics
Published in:	Soil biology and biochemistry, Vol. 122 (July 2018) , p. 141-149, ISSN 0038-0717

DOI: 10.1016/j.soilbio.2018.04.011

Postprint 24 p, 1.8 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > CREAF (Centre de Recerca Ecològica i d'Aplicacions Forestals) > Imbalance-P
Articles > Research articles
Articles > Published articles