Journal ArticleDOI
Stabilization mechanisms of soil organic matter: Implications for C-saturation of soils
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The relationship between soil structure and the ability of soil to stabilize soil organic matter (SOM) is a key element in soil C dynamics that has either been overlooked or treated in a cursory fashion when developing SOM models as discussed by the authors.Abstract:
The relationship between soil structure and the ability of soil to stabilize soil organic matter (SOM) is a key element in soil C dynamics that has either been overlooked or treated in a cursory fashion when developing SOM models. The purpose of this paper is to review current knowledge of SOM dynamics within the framework of a newly proposed soil C saturation concept. Initially, we distinguish SOM that is protected against decomposition by various mechanisms from that which is not protected from decomposition. Methods of quantification and characteristics of three SOM pools defined as protected are discussed. Soil organic matter can be: (1) physically stabilized, or protected from decomposition, through microaggregation, or (2) intimate association with silt and clay particles, and (3) can be biochemically stabilized through the formation of recalcitrant SOM compounds. In addition to behavior of each SOM pool, we discuss implications of changes in land management on processes by which SOM compounds undergo protection and release. The characteristics and responses to changes in land use or land management are described for the light fraction (LF) and particulate organic matter (POM). We defined the LF and POM not occluded within microaggregates (53–250 μm sized aggregates as unprotected. Our conclusions are illustrated in a new conceptual SOM model that differs from most SOM models in that the model state variables are measurable SOM pools. We suggest that physicochemical characteristics inherent to soils define the maximum protective capacity of these pools, which limits increases in SOM (i.e. C sequestration) with increased organic residue inputs.read more
Citations
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Journal ArticleDOI
A history of research on the link between (micro)aggregates, soil biota, and soil organic matter dynamics
TL;DR: In this article, Tisdall and Oades [J. Soil Sci. 62 (1982) 141] coined the aggregate hierarchy concept describing a spatial scale dependence of mechanisms involved in micro- and macroaggregate formation.
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Stabilization of organic matter in temperate soils: mechanisms and their relevance under different soil conditions – a review
Margit von Lützow,Ingrid Kögel-Knabner,Klemens Ekschmitt,Egbert Matzner,Georg Guggenberger,Bernd Marschner,Heinz Flessa +6 more
TL;DR: In this article, a review of the mechanisms that are currently, but often contradictorily or inconsistently, considered to contribute to organic matter (OM) protection against decomposition in temperate soils is presented.
Journal ArticleDOI
Is soil carbon mostly root carbon? Mechanisms for a specific stabilisation
TL;DR: In this article, the authors discuss the main SOM stabilisation mechanisms with respect to their ability to specifically protect root-derived organic matter (SOM) and show that rootC has a longer residence time in soil than shootC.
Journal ArticleDOI
Soil organic matter turnover is governed by accessibility not recalcitrance
TL;DR: In this article, the authors explore how advances in quantitative analytical techniques have redefined the new understanding of SOM dynamics and how this is affecting the development and application of new modelling approaches to soil C.
Journal ArticleDOI
Temperature and soil organic matter decomposition rates – synthesis of current knowledge and a way forward
Richard T. Conant,Richard T. Conant,Michael G. Ryan,Göran I. Ågren,Hannah E. Birge,Eric A. Davidson,Peter E. Eliasson,Sarah E. Evans,Serita D. Frey,Christian P. Giardina,Francesca M. Hopkins,Riitta Hyvönen,Miko U. F. Kirschbaum,Jocelyn M. Lavallee,Jens Leifeld,William J. Parton,J. M. Steinweg,Matthew D. Wallenstein,J. Å. Martin Wetterstedt,Mark A. Bradford +19 more
TL;DR: In this paper, a new conceptual model that explicitly identifies the processes controlling soil organic matter availability for decomposition and allows a more explicit description of the factors regulating OM decomposition under different circumstances is presented.
References
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HUmus Chemistry Genesis, Composition, Reactions
TL;DR: In this paper, the authors present an analysis of organic matter in soil using NMR Spectroscopy and analytical pyrolysis, showing that organic matter is composed of nitrogen and ammonium.
Journal ArticleDOI
Organic matter and water-stable aggregates in soils
Judith. Tisdall,J.M. Oades +1 more
TL;DR: In this article, the effectiveness of various binding agents at different stages in the structural organization of aggregates is described and forms the basis of a model which illustrates the architecture of an aggregate.
Journal ArticleDOI
Analysis of factors controlling soil organic matter levels in Great Plains grasslands
TL;DR: In this article, a model of soil organic matter (SOM) quantity and composition was used to simulate steady-state organic matter levels for 24 grassland locations in the U.S. Great Plains.
Journal ArticleDOI
Soil macroaggregate turnover and microaggregate formation: a mechanism for C sequestration under no-tillage agriculture
TL;DR: In this paper, a conceptual model which links the turnover of aggregates to soil organic matter dynamics in no-till (NT) and conventional tillage (CT) cropping systems was proposed.
Journal ArticleDOI
Particulate soil organic-matter changes across a grassland cultivation sequence
C. A. Cambardella,E.T. Elliott +1 more
TL;DR: The POM fraction was isolated by dispersing the soil in 5 g L-1 hexametaphosphate and passing the dispersed soil samples through a 53-micrometer sieve as mentioned in this paper.