scispace - formally typeset
Search or ask a question
Author

Georg Guggenberger

Bio: Georg Guggenberger is an academic researcher from Leibniz University of Hanover. The author has contributed to research in topics: Organic matter & Soil organic matter. The author has an hindex of 74, co-authored 268 publications receiving 25644 citations. Previous affiliations of Georg Guggenberger include Martin Luther University of Halle-Wittenberg & Chinese Academy of Sciences.


Papers
More filters
Journal ArticleDOI
06 Oct 2011-Nature
TL;DR: In this article, a new generation of experiments and soil carbon models were proposed to predict the SOM response to global warming, and they showed that molecular structure alone alone does not control SOM stability.
Abstract: Globally, soil organic matter (SOM) contains more than three times as much carbon as either the atmosphere or terrestrial vegetation. Yet it remains largely unknown why some SOM persists for millennia whereas other SOM decomposes readily—and this limits our ability to predict how soils will respond to climate change. Recent analytical and experimental advances have demonstrated that molecular structure alone does not control SOM stability: in fact, environmental and biological controls predominate. Here we propose ways to include this understanding in a new generation of experiments and soil carbon models, thereby improving predictions of the SOM response to global warming.

4,219 citations

Journal ArticleDOI
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.
Abstract: Summary Mechanisms for C stabilization in soils have received much interest recently due to their relevance in the global C cycle. Here we review the mechanisms that are currently, but often contradictorily or inconsistently, considered to contribute to organic matter (OM) protection against decomposition in temperate soils: (i) selective preservation due to recalcitrance of OM, including plant litter, rhizodeposits, microbial products, humic polymers, and charred OM; (ii) spatial inaccessibility of OM against decomposer organisms due to occlusion, intercalation, hydrophobicity and encapsulation; and (iii) stabilization by interaction with mineral surfaces (Fe-, Al-, Mn-oxides, phyllosilicates) and metal ions. Our goal is to assess the relevance of these mechanisms to the formation of soil OM during different stages of decomposition and under different soil conditions. The view that OM stabilization is dominated by the selective preservation of recalcitrant organic components that accumulate in proportion to their chemical properties can no longer be accepted. In contrast, our analysis of mechanisms shows that: (i) the soil biotic community is able to disintegrate any OM of natural origin; (ii) molecular recalcitrance of OM is relative, rather than absolute; (iii) recalcitrance is only important during early decomposition and in active surface soils; while (iv) during late decomposition and in the subsoil, the relevance of spatial inaccessibility and organo-mineral interactions for SOM stabilization increases. We conclude that major difficulties in the understanding and prediction of SOM dynamics originate from the simultaneous operation of several mechanisms. We discuss knowledge gaps and promising directions of future research.

2,332 citations

Journal ArticleDOI
TL;DR: In this article, the SOM fractions obtained with such operational fractionation procedures are described in terms of their pool sizes, chemical properties, and turnover rates, and the main objective is to evaluate these operationally defined fractions with respect to their suitability to describe functional SOM pools that could be used to parameterize SOM turnover models.
Abstract: Soil organic matter (SOM) consists of various functional pools that are stabilized by specific mechanisms and have certain turnover rates. For the development of mechanistic models that predict changes in SOM storage, these pools have to be quantified and characterized. In the past, numerous fractionation schemes have been developed to separate and analyse such SOM fractions. In this review, the SOM fractions obtained with such operational fractionation procedures are described in terms of their pool sizes, chemical properties, and turnover rates. The main objective of this review is to evaluate these operationally defined fractions with respect to their suitability to describe functional SOM pools that could be used to parameterize SOM turnover models. Fractionation procedures include (1) physical separation of SOM into aggregate, particle size, and density fractions and fractions according to their magnetic susceptibility, and (2) various wet chemical procedures that fractionate SOM according to solubility, hydrolysability, and resistance to oxidation or by destruction of the mineral phase. Furthermore, combinations of fractionation methods are evaluated. The active SOM pool with turnover rates

1,172 citations

Journal ArticleDOI
TL;DR: It is concluded that black carbon can act as a significant carbon sink and is a key factor for sustainable and fertile soils, especially in the humid tropics.
Abstract: Many soils of the lowland humid tropics are thought to be too infertile to support sustainable agriculture. However, there is strong evidence that permanent or semi-permanent agriculture can itself create sustainably fertile soils known as 'Terra Preta' soils. These soils not only contain higher concentrations of nutrients such as nitrogen, phosphorus, potassium and calcium, but also greater amounts of stable soil organic matter. Frequent findings of charcoal and highly aromatic humic substances suggest that residues of incomplete combustion of organic material (black carbon) are a key factor in the persistence of soil organic matter in these soils. Our investigations showed that 'Terra Preta' soils contained up to 70 times more black carbon than the surrounding soils. Due to its polycyclic aromatic structure, black carbon is chemically and microbially stable and persists in the environment over centuries. Oxidation during this time produces carboxylic groups on the edges of the aromatic backbone, which increases its nutrient-holding capacity. We conclude that black carbon can act as a significant carbon sink and is a key factor for sustainable and fertile soils, especially in the humid tropics.

1,029 citations

Journal ArticleDOI
TL;DR: In this article, the authors summarize progress with respect to different approaches to isolate, extract, and quantify organomineral compounds from soils, types of mineral surfaces and associated interactions, the distribution and function of soil biota at organo-mineral surfaces, and factors controlling the turnover of organic matter (OM) in organic matter associations from temperate soils.
Abstract: We summarize progress with respect to (1) different approaches to isolate, extract, and quantify organo-mineral compounds from soils, (2) types of mineral surfaces and associated interactions, (3) the distribution and function of soil biota at organo-mineral surfaces, (4) the distribution and content of organo-mineral associations, and (5) the factors controlling the turnover of organic matter (OM) in organo-mineral associations from temperate soils. Physical fractionation achieves a rough separation between plant residues and mineral-associated OM, which makes density or particle-size fractionation a useful pretreatment for further differentiation of functional fractions. A part of the OM in organo-mineral associations resists different chemical treatments, but the data obtained cannot readily be compared among each other, and more research is necessary on the processes underlying resistance to treatments for certain OM components. Studies using physical-fractionation procedures followed by soil-microbiological analyses revealed that organo-mineral associations spatially isolate C sources from soil biota, making quantity and quality of OM in microhabitats an important factor controlling community composition. The distribution and activity of soil microorganisms at organo-mineral surfaces can additionally be modified by faunal activities. Composition of OM in organo-mineral associations is highly variable, with loamy soils having generally a higher contribution of polysaccharides, whereas mineral-associated OM in sandy soils is often more aliphatic. Though highly reactive towards Fe oxide surfaces, lignin and phenolic components are usually depleted in organo-mineral associations. Charred OM associated with the mineral surface contributes to a higher aromaticity in heavy fractions. The relative proportion of OC bound in organo-mineral fractions increases with soil depth. Likewise does the strength of the bonding. Organic molecules sorbed to the mineral surfaces or precipitated by Al are effectively stabilized, indicated by reduced susceptibility towards oxidative attack, higher thermal stability, and lower bioavailability. At higher surface loading, organic C is much better bioavailable, also indicated by little 14C age. In the subsurface horizons of the soils investigated in this study, Fe oxides seem to be the most important sorbents, whereas phyllosilicate surfaces may be comparatively more important in topsoils. Specific surface area of soil minerals is not always a good predictor for C-stabilization potentials because surface coverage is discontinuous. Recalcitrance and accessibility/aggregation seem to determine the turnover dynamics in fast and intermediate cycling OM pools, but for long-term OC preservation the interactions with mineral surfaces, and especially with Fe oxide surfaces, are a major control in all soils investigated here.

928 citations


Cited by
More filters
01 May 1993
TL;DR: Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems.
Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

29,323 citations

Journal ArticleDOI
06 Oct 2011-Nature
TL;DR: In this article, a new generation of experiments and soil carbon models were proposed to predict the SOM response to global warming, and they showed that molecular structure alone alone does not control SOM stability.
Abstract: Globally, soil organic matter (SOM) contains more than three times as much carbon as either the atmosphere or terrestrial vegetation. Yet it remains largely unknown why some SOM persists for millennia whereas other SOM decomposes readily—and this limits our ability to predict how soils will respond to climate change. Recent analytical and experimental advances have demonstrated that molecular structure alone does not control SOM stability: in fact, environmental and biological controls predominate. Here we propose ways to include this understanding in a new generation of experiments and soil carbon models, thereby improving predictions of the SOM response to global warming.

4,219 citations

Journal Article
TL;DR: In this paper, a documento: "Cambiamenti climatici 2007: impatti, adattamento e vulnerabilita" voteato ad aprile 2007 dal secondo gruppo di lavoro del Comitato Intergovernativo sui Cambiamentsi Climatici (Intergovernmental Panel on Climate Change).
Abstract: Impatti, adattamento e vulnerabilita Le cause e le responsabilita dei cambiamenti climatici sono state trattate sul numero di ottobre della rivista Cda. Approfondiamo l’argomento presentando il documento: “Cambiamenti climatici 2007: impatti, adattamento e vulnerabilita” votato ad aprile 2007 dal secondo gruppo di lavoro del Comitato Intergovernativo sui Cambiamenti Climatici (Intergovernmental Panel on Climate Change). Si tratta del secondo di tre documenti che compongono il quarto rapporto sui cambiamenti climatici.

3,979 citations

Journal ArticleDOI
TL;DR: 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.

3,301 citations

Journal ArticleDOI
01 Jan 2005-Geoderma
TL;DR: In this paper, soil organic carbon (SOC), biota, ionic bridging, clay and carbonates are associated with aggregation by rearrangement, flocculation and cementation.

3,241 citations