Universität zu Köln

Clayton, Jessica ORCID: 0000-0003-3644-6891, Lemanski, Kathleen and Bonkowski, Michael ORCID: 0000-0003-2656-1183 (2021). Shifts in soil microbial stoichiometry and metabolic quotient provide evidence for a critical tipping point at 1% soil organic carbon in an agricultural post-mining chronosequence. Biol. Fertil. Soils, 57 (3). S. 435 - 447. NEW YORK: SPRINGER. ISSN 1432-0789

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Abstract

Soil microbial C:N:P stoichiometry and microbial maintenance respiration (i.e. metabolic quotient, qCO(2)) were monitored along a nutrient gradient in soils from a 52-year space-for-time chronosequence of reclaimed agricultural land after brown-coal mining. Land reclamation produced loess soils of initially low (0.2%) SOC. Consecutive agricultural land management led to a gradual recovery of SOC contents. Our data revealed sudden shifts in microbial stoichiometry and metabolic quotient with increasing SOC at a critical value of 1% SOC. As SOC increased, accrual rate of C into microbial biomass decreased, whereas microbial N increased. Simultaneously, metabolic quotient strongly decreased with increasing SOC until the same critical value of 1% SOC and remained at a constant low thereafter. The microbial fractions of the soil in samples containing < 1% SOC were out of stoichiometric equilibrium and were inefficient at immobilising C due to high maintenance respiration. Increasing SOC above the threshold value shifted the soil microbes towards a new equilibrium where N became growth limiting, leading to a more efficient acquisition of C. The shift in microbial N accrual was preluded by high variation in microbial biomass N in soils containing 0.5-0.9% SOC indicative of a regime shift between microbial stoichiometric equilibria. Our data may help in establishing a quantitative framework for SOC targets that, along with agricultural intensification, may better support feedback mechanisms for a sustainable accrual of C in soils.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Clayton, Jessica UNSPECIFIED orcid.org/0000-0003-3644-6891 UNSPECIFIED Lemanski, Kathleen UNSPECIFIED UNSPECIFIED UNSPECIFIED Bonkowski, Michael UNSPECIFIED orcid.org/0000-0003-2656-1183 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-562694
DOI:	10.1007/s00374-020-01532-2
Journal or Publication Title:	Biol. Fertil. Soils
Volume:	57
Number:	3
Page Range:	S. 435 - 447
Date:	2021
Publisher:	SPRINGER
Place of Publication:	NEW YORK
ISSN:	1432-0789
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language Soil Science Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/56269