Universität zu Köln

Herre, Michael, Heitkoetter, Julian, Heinze, Stefanie, Rethemeyer, Janet, Preusser, Sebastian ORCID: 0000-0001-6599-9933, Kandeler, Ellen and Marschner, Bernd (2022). Differences in organic matter properties and microbial activity between bulk and rhizosphere soil from the top- and subsoils of three forest stands. Geoderma, 409. AMSTERDAM: ELSEVIER. ISSN 1872-6259

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Abstract

The distribution of soil organic carbon (SOC) in subsoil is much more heterogeneous than in topsoils. This is largely caused by more localized inputs of fresh substrates and nutrients that mainly derive from rhizodeposition creating hotspots of microbial activity. To elucidate the role of rhizosphere soil as an important input path for substrates into deeper soil layers, we investigated differences of organic matter distribution and microbial degradation in the rhizosphere soil and the surrounding bulk topsoil as well as in the subsoil. In addition, we considered the effect of different parent materials on SOC dynamics by analyzing soils developed in pleistocene sand, triassic sandstone and loess all covered with similarly aged beech forest within the same climatic region. Besides basic soil parameters, basal respiration, microbial biomass (C-mic) and C-14 content were determined. Further, extracellular enzymes involved in C-, N-and P-cycling were analyzed. Differences in the microbial community were investigated using a taxonspecific real time qPCR approach. The results revealed significant differences of the microbial community composition between bulk and rhizosphere in top-and subsoil at the investigated sample sites. The mean SOC contents were 322% and 475% higher in the rhizosphere soil in both the top-and subsoil, respectively. The microbial biomass (C-mic) in the rhizosphere was up to 80% higher in the topsoil and on average 200% higher in the subsoil (SOC normalized), compared to the respective bulk soil. The qPCR results for all samples showed a higher diversity and abundance in the rhizosphere compared to the respective bulk samples and a shift in community composition with increasing soil depth. Total activity of the analyzed extracellular enzymes involved in different nutrient cycles differed significantly between bulk and rhizosphere soil and revealed that the microbial community in the rhizosphere subsoil can effectively utilize substrates even under scarce availability. The SOC normalized basal respiration at the Pleistocene sand and Loess sites and K2SO4-extractable C were higher in the subsoil compared to the topsoil showing more labile C in deeper soil layers with younger C-14 in the rhizosphere. These results show that the rhizosphere at the investigated forest sites is a hotspot for microbial activity, which is more pronounced in the subsoil where the relevance of these hotspots is important for C turnover.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Herre, Michael UNSPECIFIED UNSPECIFIED UNSPECIFIED Heitkoetter, Julian UNSPECIFIED UNSPECIFIED UNSPECIFIED Heinze, Stefanie UNSPECIFIED UNSPECIFIED UNSPECIFIED Rethemeyer, Janet UNSPECIFIED UNSPECIFIED UNSPECIFIED Preusser, Sebastian UNSPECIFIED orcid.org/0000-0001-6599-9933 UNSPECIFIED Kandeler, Ellen UNSPECIFIED UNSPECIFIED UNSPECIFIED Marschner, Bernd UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-674406
DOI:	10.1016/j.geoderma.2021.115589
Journal or Publication Title:	Geoderma
Volume:	409
Date:	2022
Publisher:	ELSEVIER
Place of Publication:	AMSTERDAM
ISSN:	1872-6259
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language SUBSTRATE AVAILABILITY; CHEMICAL-COMPOSITION; SPATIAL-DISTRIBUTION; FUMIGATION-EXTRACTION; VERTICAL-DISTRIBUTION; PHOSPHATASE-ACTIVITY; FUNGAL COMMUNITIES; EUROPEAN BEECH; FINE ROOTS; CARBON Multiple languages Soil Science Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/67440