Ludwig, Bernard

[["dc.bibliographiccitation.firstpage","634"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Journal of Plant Nutrition and Soil Science"],["dc.bibliographiccitation.lastpage","643"],["dc.bibliographiccitation.volume","174"],["dc.contributor.author","Jacobs, Anna"],["dc.contributor.author","Helfrich, Mirjam"],["dc.contributor.author","Dyckmans, Jens"],["dc.contributor.author","Rauber, Rolf"],["dc.contributor.author","Ludwig, Bernard"],["dc.date.accessioned","2018-11-07T08:53:25Z"],["dc.date.available","2018-11-07T08:53:25Z"],["dc.date.issued","2011"],["dc.description.abstract","Differences in the mechanisms of storage and decomposition of organic matter (OM) between minimum tillage (MT) and conventional tillage (CT) are generally attributed to differences in the physical impact through tillage, but less is known about the effects of residue location. We conducted an incubation experiment at a water content of 60% of the maximum water-holding capacity and 15 degrees C with soils from CT (0-25 cm tillage depth) and MT fields (0-5 cm tillage depth) with N-15-labeled maize straw incorporated to different depths (CT simulations: 0-15 cm; MT simulations: 0-5 cm) for 28 d in order to determine the effects of the tillage simulation on (1) mineralization of recently added residues, (2) the dynamics of macroaggregate formation and physical protection of OM, and (3) the partitioning of maize-derived C and N within soil OM fractions. The MT simulations showed lower relative C losses, and the amount of maize-C mineralized after 28 d of incubation was slightly but significantly lower in the MT simulations with maize added (MTmaize) than in the respective CT (CTmaize) simulations. The formation of new water-stable macroaggregates occurred during the phase of the highest microbial activity, with a maximum peak 8 d after the start of incubation. The newly formed macroaggregates were an important location for the short-term stabilization of C and N with a higher importance for MTmaize than for CTmaize simulations. In conclusion, our results suggest that a higher amount of OM in MT surface soils compared with CT surface soils may not only result from decreased macroaggregate destruction under reduced tillage but also from a higher efficiency of C retention due to a more concentrated residue input."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft (DFG-Research Training Group) [1397]"],["dc.identifier.doi","10.1002/jpln.201000208"],["dc.identifier.isi","000294665300013"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/22404"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-v C H Verlag Gmbh"],["dc.relation.issn","1436-8730"],["dc.title","Effects of residue location on soil organic matter turnover: results from an incubation experiment with N-15-maize"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","315"],["dc.bibliographiccitation.issue","1-2"],["dc.bibliographiccitation.journal","Plant and Soil"],["dc.bibliographiccitation.lastpage","325"],["dc.bibliographiccitation.volume","278"],["dc.contributor.author","Ludwig, B."],["dc.contributor.author","Helfrich, Mirjam"],["dc.contributor.author","Flessa, Heiner"],["dc.date.accessioned","2018-11-07T10:54:01Z"],["dc.date.available","2018-11-07T10:54:01Z"],["dc.date.issued","2005"],["dc.description.abstract","Soil organic carbon (SOC) models have been widely used to predict SOC change with changing environmental and management conditions, but the accuracy of the prediction is often open to question. Objectives were (i) to quantify the amounts of C derived from maize in soil particle size fractions and at various depths in a long-term field experiment using C-13/C-12 analysis, (ii) to model changes in the organic C, and (iii) to compare measured and modelled pools of C. Maize was cultivated for 24 years on a silty Luvisol which resulted in a stock of 1.9 kg maize-derived C m(-2) (36% of the total organic C) in the Ap horizon. The storage of maize-derived C in particle size fractions of the Ap horizon decreased in the order clay (0.65 kg C m(-2)) > fine and medium silt (0.43) > coarse silt (0.33) > fine sand (0.13) > medium sand (0.12) > coarse sand (0.06) and the turnover times of C-3-derived C ranged from 26 (fine sand) to 77 years (clay). The turnover times increased with increasing soil depth. We used the Rothamsted Carbon Model to model the C dynamics and tested two model approaches: model A did not have any adjustable parameters, but included the Falloon equation for the estimation of the amount of inert organic matter (IOM) and independent estimations of C inputs into the soil. The model predicted well the changes in C-3-derived C with time but overestimated the changes in maize-derived C 1.6-fold. In model B, the amounts of IOM and C inputs were optimized to match the measured C-3- and C-4-derived SOC stocks after 24 years of continuous maize. This model described the experimental data well, but the modelled annual maize C inputs (0.41 kg C m(-2) a(-1)) were less than the independently estimated total input of maize litter C (0.63 kg C m(-2) a(-1)) and even less than the annual straw C incorporated into the soil (0.46 kg C m(-2) a(-1)). These results indicated that the prediction of the Rothamsted Carbon Model with independent parameterization served only as an approximation for this site. The total amount of organic C associated with the fraction 0-63 mu m agreed well with the sum of the pools 'microbial biomass', 'humified-organic matter' and IOM of the model B. However, the amount of maize-derived C in this fraction (3.4 g kg(-1)) agreed only satisfactorily with the sum of maize-derived C in the pools 'microbial biomass' and 'humified organic matter' (2.6 g kg(-1))."],["dc.identifier.doi","10.1007/s11104-005-8808-2"],["dc.identifier.isi","000233643000026"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/49473"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.relation.issn","0032-079X"],["dc.title","Modelling the long-term stabilization of carbon from maize in a silty soil"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","168"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE-ZEITSCHRIFT FUR PFLANZENERNAHRUNG UND BODENKUNDE"],["dc.bibliographiccitation.lastpage","174"],["dc.bibliographiccitation.volume","169"],["dc.contributor.author","Terhoeven-Urselmans, T."],["dc.contributor.author","Michel, K."],["dc.contributor.author","Helfrich, Mirjam"],["dc.contributor.author","Flessa, H."],["dc.contributor.author","Ludwig, B."],["dc.date.accessioned","2018-11-07T10:02:52Z"],["dc.date.available","2018-11-07T10:02:52Z"],["dc.date.issued","2006"],["dc.description.abstract","The usefulness and limitations of near-infrared reflectance spectroscopy (NIRS) for the assessment of several soil characteristics are still not sufficiently explored. The objective of this study was to evaluate the ability of visible and near-infrared reflectance (VIS-NIR) spectroscopy to predict the composition of organic matter in soils and litter. Reflectance spectra of the VIS-NIR region (400-2500 nm) were recorded for 56 soil and litter samples from agricultural and forest sites. Spectra were used to predict general and biological characteristics of the samples as well as the C composition which was measured by C-13-CPMAS-NMR spectroscopy. A modified partial least-square method and cross-validation were used to develop equations for the different constituents over the whole spectrum (1st to 3rd derivation). Near-infrared spectroscopy predicted well the C : N ratios, the percentages of O-alkyl C and alkyl C, the ratio of alkyl C to O-alkyl C, and the sum of phenolic oxidation products: the ratios of standard deviation of the laboratory results to standard error of cross-validation (RSC) were greater than 2, the regression coefficients (a) of a linear regression (measured against predicted values) ranged from 0.9 to 1.1, and the correlation coefficients (r) were greater than 0.9. Satisfactorily (0.8 <= a <= 1.2, r >= 0.8, and 1.4 <= RSC <= 2.0) assessed were the contents of C, N, and production of DOC, the percentages of carbonyl C and aromatic C and the ratio of alkyl C to aromatic C. However, the N-mineralization rate and the microbial biomass were predicted unsatisfactorily (RSC < 1.4). The good and satisfactory predictions reported above indicate a marked usefulness of NIBS in the assessment of biological and chemical characteristics of soils and litter."],["dc.identifier.doi","10.1002/jpln.200521712"],["dc.identifier.isi","000236991000003"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/38323"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1436-8730"],["dc.title","Near-infrared spectroscopy can predict the composition of organic matter in soil and litter"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1316"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","European Journal of Soil Science"],["dc.bibliographiccitation.lastpage","1329"],["dc.bibliographiccitation.volume","58"],["dc.contributor.author","Helfrich, Mirjam"],["dc.contributor.author","Flessa, H."],["dc.contributor.author","Mikutta, R."],["dc.contributor.author","Dreves, Alexander"],["dc.contributor.author","Ludwig, B."],["dc.date.accessioned","2018-11-07T10:47:36Z"],["dc.date.available","2018-11-07T10:47:36Z"],["dc.date.issued","2007"],["dc.description.abstract","Stable soil organic matter (SOM) is important for long-term sequestration of soil organic carbon (SOC), but the usefulness of different fractionation methods to isolate stable SOM is open to question. We assessed the suitability of five chemical fractionation methods (stepwise hydrolysis, treatment with H2O2, Na2S2O8, NaOCl, and demineralization of the NaOCl-resistant fraction (NaOCl + HF)) to isolate stable SOM from soil samples of a loamy sand and a silty loam under different land use regimes (grassland, forest and arable crops). The apparent C turnover time and mean age of SOC before and after fractionation was determined by C-13 and C-14 analysis. Particulate organic matter was removed by density fractionation before soils were exposed to chemical fractionation. All chemical treatments induced large SOC losses of 62-95% of the mineral-associated SOC fraction. The amounts of H2O2- and Na2S2O8-resistant SOC were independent from land use, while those of NaOCl- (NaOCl + HF)- and hydrolysis-resistant SOC were not. All chemical treatments caused a preferential removal of young, maize-derived SOC, with Na2S2O8 and H2O2 being most efficient. The mean C-14 age of SOC was 1000-10000 years greater after chemical fractionation than that of the initial, mineral-associated SOC and mean C-14 ages increased in the order: NaOCl < NaOCl + HF <= stepwise hydrolysis << H2O2 approximate to Na2S2O8. None of the methods appeared generally suitable for the determination of the inert organic matter pool of the Rothamsted Carbon Model. Nonetheless, our results indicate that all methods are able to isolate an older, more stable SOC fraction, but treatments with H2O2 and Na2S2O8 were the most efficient ones in isolating stable SOM."],["dc.identifier.doi","10.1111/j.1365-2389.2007.00926.x"],["dc.identifier.isi","000251026300010"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/48001"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Blackwell Publishing"],["dc.relation.issn","1351-0754"],["dc.title","Comparison of chemical fractionation methods for isolating stable soil organic carbon pools"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","331"],["dc.bibliographiccitation.issue","1-2"],["dc.bibliographiccitation.journal","Geoderma"],["dc.bibliographiccitation.lastpage","341"],["dc.bibliographiccitation.volume","136"],["dc.contributor.author","Helfrich, Mirjam"],["dc.contributor.author","Ludwig, B."],["dc.contributor.author","Buurman, P."],["dc.contributor.author","Flessa, H."],["dc.date.accessioned","2018-11-07T08:53:46Z"],["dc.date.available","2018-11-07T08:53:46Z"],["dc.date.issued","2006"],["dc.description.abstract","Changes in soil organic carbon (SOC) contents with soil cultivation have been investigated extensively, but information on the influence of land use changes on the chemistry of soil organic matter (SOM) and SOM fractions is scarce. To make a contribution in this context, we sampled silty soils under different land use (spruce forest (A(h) horizon, 0-7 cm), continuous maize cropping (A(p) horizon. 0-30 cm), and grassland (A(h) horizon, 0-10 cm)) as well as the organic layer (L, O-f, and O-h) of the forest floor and collected plant materials from the three sites. Separation of SOM density fractions (free particulate organic matter, occluded particulate organic matter, and mineral-associated organic matter) and water-stable aggregate size fractions of the surface soils was performed in order to follow changes in the chemical composition of SOM in physical soil fractions using CPMAS C-13 NMR spectroscopy and to determine land use effects on the chemistry of SOM fractions. The CPMAS C-13 NMR spectra showed that maize litter had the highest content of O-alkyl-C and the lowest content of alkyl-C, aryl-C and carbonyl-C compared with the plant material from the spruce stand and the grassland. The forest litter had the largest content of aromatic and alkyl-C. Decomposition of spruce litter in the humus layer resulted in a decreasing O-alkyl-C content and an increasing alkyl-C content. The SOM of the acid forest soil consisted mainly of particulate organic matter (POM) with a high content of spruce litter-derived alkyl-C. The SOC stocks in the grassland and maize soil were dominated by mineral-associated SOM which contained relatively larger proportions of aryl and carbonyl-C. The decrease of the SOC concentration induced by cultivation resulted in a relative accumulation of aromatic C structures in the mineral-bound SOM. In all soils, the free POM had a smaller proportion of alkyl-C and a larger proportion of O-alkyl-C than the POM occluded in aggregates. The mean age of the SOM in the density fractions of the maize soil increased with increasing aromaticity in the order free POM < occluded POM < mineral-associated organic matter. (c) 2006 Elsevier B.V. All rights reserved."],["dc.identifier.doi","10.1016/j.geoderma.2006.03.048"],["dc.identifier.isi","000242837500029"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/22502"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Bv"],["dc.relation.issn","0016-7061"],["dc.title","Effect of land use on the composition of soil organic matter in density and aggregate fractions as revealed by solid-state C-13 NMR spectroscopy"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1823"],["dc.bibliographiccitation.issue","7"],["dc.bibliographiccitation.journal","Soil Biology and Biochemistry"],["dc.bibliographiccitation.lastpage","1835"],["dc.bibliographiccitation.volume","40"],["dc.contributor.author","Helfrich, Mirjam"],["dc.contributor.author","Ludwig, Bernard"],["dc.contributor.author","Potthoff, Martin"],["dc.contributor.author","Flessa, Heiner"],["dc.date.accessioned","2018-11-07T11:13:50Z"],["dc.date.available","2018-11-07T11:13:50Z"],["dc.date.issued","2008"],["dc.description.abstract","We investigated the effect of plant residue decomposability and fungal biomass on the dynamics of macroaggregate (250-2000 mu m) formation in a three months' incubation experiment and determined the distribution of residue-derived C and N in the microbial biomass and in aggregate size fractions (250-2000 mu m, 53-250 mu m and <53 mu m) using (13)C and (15)N data. A silty loam soil (sieved <250 mu m) was incubated with and without addition of (15)N labelled maize leaves (C/N = 27.4) and roots (C/N = 86.4). Each treatment was carried out with and without fungicide application. The addition of maize residues enhanced soil respiration and microbial biomass C and N and resulted in increased macroaggregate formation with a higher and more rapid maximum macroaggregation in the soil amended with maize leaves than in that with addition of roots. Fungicide application led to a significant decline of microbial biomass C and mineralization of the added residues compared to untreated soils, which demonstrates a successful suppression of part of the active microbial biomass by the fungicide. However, this was not confirmed by a generally lower ergosterol concentration. Consequently, ergosterol was no reliable fungal biomarker in periods of rapid decline of the fungal biomass. A single addition of fungicide was insufficient for continued inhibition of the fungal biomass. Yet, a significant delay (28-42 days) in macroaggregation in fungicide treated compared to untreated samples highlighted the importance of the fungal biomass in macroaggregate formation. Macroaggregates were enriched in maize-derived (13)C and (15)N compared to microaggregates or the fraction <53 mu m. They turned over rapidly with decreasing substrate availability, which entailed a transfer of maize-derived C and N stored within macroaggregates during the first weeks of incubation to microaggregates with proceeding incubation time. Our results indicate that this transfer happened within macroaggregates, because no considerable amount of free particulate organic matter (POM) was released upon macroaggregate breakdown. We conclude that substrate decomposability and fungal activity are key factors determining extent and dynamics of macroaggregation during decomposition processes. Macroaggregate formation implied rapid incorporation and thereby short-term protection of maize-derived C and N. Moreover, macroaggregates allowed a transfer of maize-derived organic matter into microaggregates within macroaggregates, which prevented the release of significant amounts of free POM upon macroaggregate breakdown. Consequently, macroaggregates constitute to the transfer of recently added C into more stable soil organic matter fractions. (C) 2008 Elsevier Ltd. All rights reserved."],["dc.identifier.doi","10.1016/j.soilbio.2008.03.006"],["dc.identifier.isi","000257616100032"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/53989"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Pergamon-elsevier Science Ltd"],["dc.relation.issn","0038-0717"],["dc.title","Effect of litter quality and soil fungi on macroaggregate dynamics and associated partitioning of litter carbon and nitrogen"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","3222"],["dc.bibliographiccitation.issue","11"],["dc.bibliographiccitation.journal","Soil Biology and Biochemistry"],["dc.bibliographiccitation.lastpage","3234"],["dc.bibliographiccitation.volume","38"],["dc.contributor.author","Yamashita, Tanion"],["dc.contributor.author","Flessa, Heiner"],["dc.contributor.author","John, Bettina"],["dc.contributor.author","Helfrich, Mirjam"],["dc.contributor.author","Ludwig, Bernard"],["dc.date.accessioned","2018-11-07T09:04:40Z"],["dc.date.available","2018-11-07T09:04:40Z"],["dc.date.issued","2006"],["dc.description.abstract","The location of soil organic matter (SOM) within the soil matrix is considered a major factor determining its turnover, but quantitative information about the effects of land cover and land use on the distribution of SOM at the soil aggregate level is rare. We analyzed the effect of land cover/land use (spruce forest, grassland, wheat and maize) on the distribution of free particulate organic matter (POM) with a density < 1.6 g cm(-3) (free POM < 1.6), Occluded particulate organic matter with densities < 1.6 g cm(-3) (occluded POM < 1.6) and 1.6-2.0 g cm(-3) (occluded POM1.6-2.0) and mineral-associated SOM (> 2.0 g cm(-3)) in size classes of slaking-resistant aggregates (53-250, 250-1000, 1000-2000, > 2000 mu m) and in the sieve fraction < 53 mu m from silty soils by applying a combined aggregate size and density fractionation procedure. We also determined the turnover time of soil organic carbon (SOC) fractions at the aggregate level in the soil of the maize site using the C-13/C-12 isotope ratio. SOM contents were higher in the grassland soil aggregates than in those of the arable soils mainly because of greater contents of mineral-associated SOM. The contribution of occluded POM to total SOC in the A horizon aggregates was greater in the spruce soil (23-44%) than in the grassland (11%) and arable soils (19%). The mass and carbon content of both the free and occluded POM fractions were greater in the forest soil than in the grassland and arable soils. In all soils, the C/N ratios of soil fractions within each aggregate size class decreased in the following order: free POMI < 1.6 > occluded POM < 1.6-2.0 > mineral-associated SOM. The mean age of SOC associated with the < 53 mu m mineral fraction of water-stable aggregates in the Ap horizon of the maize site varied between 63 and 69 yr in aggregates > 250 mu m, 76 yr in the 53-250 mu m aggregate class, and 102 yr in the sieve fraction < 53 mu m. The mean age of SOC in the occluded POM increased with decreasing aggregate size from 20 to 30 yr in aggregates > 1000 mu m to 66 yr in aggregates < 5 3 mu m. Free POM had the most rapid rates of C-turnover, with residence times ranging from 10 yr in the fraction > 2000 mu m to 42 yr in the fraction 53-250 mu m. Results indicated that SOM in slaking-resistant aggregates was not a homogeneous pool, but consisted of size/density fractions exhibiting different composition and stability. The properties of these fractions were influenced by the aggregate size. Land cover/land use were important factors controlling the amount and composition of SOM fractions at the aggregate level. (c) 2006 Elsevier Ltd. All rights reserved."],["dc.identifier.doi","10.1016/j.soilbio.2006.04.013"],["dc.identifier.isi","000241484700005"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/25158"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Pergamon-elsevier Science Ltd"],["dc.publisher.place","Oxford"],["dc.relation.conference","Annual Meeting of the American-Geophysical-Union"],["dc.relation.eventlocation","San Francisco, CA"],["dc.relation.issn","0038-0717"],["dc.title","Organic matter in density fractions of water-stable aggregates in silty soils: Effect of land use"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","37"],["dc.bibliographiccitation.journal","Geoderma"],["dc.bibliographiccitation.lastpage","44"],["dc.bibliographiccitation.volume","311"],["dc.contributor.author","Heinze, Stefanie"],["dc.contributor.author","Ludwig, Bernard"],["dc.contributor.author","Piepho, Hans-Peter"],["dc.contributor.author","Mikutta, Robert"],["dc.contributor.author","Don, Axel"],["dc.contributor.author","Wordell-Dietrich, Patrick"],["dc.contributor.author","Helfrich, Mirjam"],["dc.contributor.author","Hertel, Dietrich"],["dc.contributor.author","Leuschner, Christoph"],["dc.contributor.author","Kirfel, Kristina"],["dc.contributor.author","Kandeler, Ellen"],["dc.contributor.author","Preusser, Sebastian"],["dc.contributor.author","Guggenberger, Georg"],["dc.contributor.author","Leinemann, Timo"],["dc.contributor.author","Marschner, Bernd"],["dc.date.accessioned","2018-02-26T10:15:31Z"],["dc.date.available","2018-02-26T10:15:31Z"],["dc.date.issued","2018"],["dc.description.abstract","Organic carbon in subsoils amounts to 40–60% of the global soil carbon pool and is generally characterized by apparent turnover times of hundreds to thousands of years and an increasing spatial variability with depth. The objective of this study was to analyze the amounts and distribution of SOC and to elucidate the turnover and storage mechanisms throughout deep soil profiles of a sandy Dystric Cambisol on Pleistocene glacial deposits under beech forest in northern Germany. The soil was sampled within a grid design at three replicated profiles, each at 8 sampling depths (10, 35, 60, 85, 110, 135, 160, 185 cm) and 8 horizontal sampling points. 192 samples were analyzed for bulk density, texture, pH, SOC, total N, 13C-SOC, oxalate- and dithionite-extractable Fe and Al, root bio- and necromass, and microbial biomass C. For each sampling depth, a multi-effect model analysis was performed to identify the parameters explaining SOC variability. While SOC in the topsoil is only related to pH and dithionite-extractable Al, SOC in the subsoil is always related to root bio- and necromass and to Fe oxides and/or silt content. The comparison of SOC within rooted and root-free subsoil samples showed an up to 10 times higher SOC content in the rooted soil samples in comparison to the root-free samples. While the SOC content in the root-free soil declined with increasing depth the rooted soil samples showed no stratification with depth but were characterized by a higher spatial variability of SOC. At the same time, SOC in rooted soil samples has the same δ13C values as in root-free samples, indicating a similar degree of microbial processing. Microbial biomass C (Cmic) was not different between rooted and root-free samples, resulting in much higher Cmic:SOC ratios in the root-free soil. Since rooted soil samples are characterized by significantly higher silt and oxalate-extractable Fe (Feo) contents, it appears that roots preferentially grow into these chemically and physically slightly more favorable zones. At the same time, these higher inputs were apparently better stabilized through sorption to silt and metal oxyhydroxides, thus leading to the longer-term SOC sequestration in these hot-spots enhancing the spatial variability of SOC in subsoils."],["dc.identifier.doi","10.1016/j.geoderma.2017.09.028"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/12581"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.title","Factors controlling the variability of organic matter in the top- and subsoil of a sandy Dystric Cambisol under beech forest"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]