Angelika Kölbl

Nationalparkverwaltung Bayerischer Wald · Sachgebiet III: Naturschutz und Forschung

When acid sulfate soils dry, oxidation of pyrite can cause acidification and formation of iron (Fe) oxyhydroxy sulfate phases such as jarosite. Remediation via re-establishment of reducing conditions requires submergence and addition of biodegradable organic carbon (OC) to stimulate activity of reducing bacteria. Addition of fresh plant litter has...

Acid sulfate soils contain hypersulfidic material, e.g. pyrite (FeS2). Under oxidizing conditions, it transforms to sulfuric material (pH < 4), which is accompanied with the formation of jarosite [KFe3(SO4)2(OH)6] along root channels (designated as jarositic phyto tubules). The encapsulation of root residues with jarosite can lead to reduced spatia...

Aeration of wetland soils containing iron (Fe) sulfides can cause strong acidification due to the generation of large amounts of sulfuric acid and formation of Fe oxyhydroxy sulfate phases such as jarosite. Remediation by re-establishment of anoxic conditions promotes jarosite transformation to Fe oxyhydroxides and/or Fe sulfides, but the driving c...

Aggregation includes the formation of organo-mineral-associations, which become arranged in a heterogenic pattern and stabilized thereafter. Up to now, little is known about the role of different organic matter qualities in this process. We developed a new approach to disentangle the role of organic carbon (OC) derived from particulate organic mat...

Saturated acid sulfate soils with hypersulfidic material are productive wetland soils, but when they dry, they generate large amounts of sulfuric acid due to oxidation of pyrite to form sulfuric material (pH <4) and consequently sulfuric soils. After re-saturation of sulfuric soils and thus the re-establishment of reduced conditions, activity of su...

The awareness about floodplain soils being an important reservoir of deep soil organic carbon (SOC) is growing and there is an increasing number of research dedicated on SOC in these ecosystems. Due to its inherent OC stocks, floodplains are highly productive sites. Most of them are regulated, drained and agriculturally used in Central Europe, but...

Floodplain soils are important reservoirs of organic carbon (OC) in the terrestrial carbon cycle. Few rivers and floodplains in the world and particularly in central Europe are in a natural state. They are regulated, stabilised from erosion behind artificial levees, drained and used for agriculture. Fluvisols store high amounts of OC from the topso...

Submerged rice cultivation is characterized by redox fluctuations and results in the formation of paddy soils, often accompanied by soil organic carbon (SOC) accumulation. The impact of redox fluctuations and the underlying soil type on the fate of organic carbon (OC) in paddy soils are unknown. Hence, we mimicked paddy soil development in the labo...

When acid sulfate soils with hypersulfidic material dry, oxidation of pyrite can cause strong acidification due to formation of sulfuric (pH < 4) material. Re-saturation of acid sulfate soils containing sulfuric material can lead to reformation of pyrite and pH increase through activity of sulfate reducing bacteria, which require available organic...

Acid sulfate soils with hypersulfidic material (pH > 4) are formed under reducing conditions and contain iron sulfides (mostly pyrite). When these hypersulfidic soils dry pyrite can be oxided, which leads to the formation of sulfuric acid and the formation of sulfuric soils (pH <4). Remediation is possible by re-submerging sulfuric soils and adding...

Rationale: Al-substituted goethite is ubiquitous in soils and sediments. The extent of Al substitution affects the physicochemical properties of the mineral and influences its macroscale properties. Bulk analysis only provides total Al/Fe ratios without providing information with respect to the Al-substitution of single minerals. Here, we demonstr...

Long-term paddy management promotes nitrogen (N) sequestration, but it is unknown to what extent the properties of the parent soil modify the management-induced N sequestration in peptide-bound amino acids (AA-N). We hypothesized that paddy management effects on the storage of AA-N relate to the mineral assembly. Hence, we determined contents and c...

The physical, chemical, and biological processes forming the backbone of important soil functions (e.g. carbon sequestration, nutrient and contaminant storage, and water transport) take place at reactive interfaces of soil particles and pores. The accessibility of these interfaces is determined by the spatial arrangement of the solid mineral and or...

Rice (Oryza sativa) is usually grown under flooded conditions, leading to anoxic periods in the soil. Rice plants transport oxygen via aerenchyma from the atmosphere to the roots. Driven by O2 release into the rhizosphere, radial gradients of ferric Fe and co-precipitated organic substances are formed. Our study aimed at elucidating the composition...

When acid sulfate soils containing hypersulfidic material (pH > 4) dry, oxidation of pyrite causes strong acidification with the formation of sulfuric material (pH < 4), which may release high concentrations of metals and metalloids. Re-submerging of sulfuric material can lead to re-formation of pyrite and pH increase to re-form hypersulfidic and h...

Paddy soil management is generally thought to promote the accumulation of soil organic matter (SOM) and specifically lignin. Lignin is considered particularly susceptible to accumulation under these circumstances because of the recalcitrance of its aromatic structure to biodegradation under anaerobic conditions (i.e., during inundation of paddy fie...

Crop-residue burning and frequent paddy-soil flooding can lead to a substantial accumulation of black carbon (BC), thus contributing to long-term C sequestration. There is evidence that the turnover of BC in soils also depends on the soil mineral assembly.We studied the effects of paddy and non-paddy soil management and different major reference so...

Despite of its ecological and economic importance, only limited information is available on spatial variability of soil organic C (OC) in paddy fields during soil development. To obtain deeper insights into the accumulation and spatial distribution of OC with ongoing paddy management, the present study investigates spatial heterogeneities in puddle...

Inundation of paddy soils for submerged rice production strongly impacts soil formation. Here we used chronosequences with up to 2000 years of cultivation history to compare soil formation in non-inundated (non-paddy) cropping systems with the formation of soils used for paddy rice production. This approach allowed us to identify the influence of a...

We studied organic carbon (OC) accumulation in organo-mineral associations during soil development on calcareous parent material. Two chronosequences in the Zhejiang Province, PR China, were investigated; one under paddy cultivation with a maximum soil age of 2000 years, and the other under upland crops where the oldest soil was 700 years old. Bulk...

To better understand how carbon and nitrogen mineralization are linked in soils, we conducted a long-term incubation experiment and compared carbon and nitrogen dynamics in the bulk soil and in soil fractions. Topsoil of a Rendzic Leptosol from a beech forest site near Tuttlingen, Germany, was separated into three particle size classes: sand (2000–...

Dolomite (CaMg(CO3)2) constitutes half of the global carbonates. Thus, many calcareous soils have been developing rather from dolomitic rocks than from calcite (CaCO3)-dominated limestone. We developed a physical fractionation procedure based on three fractionation steps, using sonication with subsequent density fractionation to separate soil organ...

More than 50% of the world's population feeds on rice. Soils used for rice production are mostly managed under submerged conditions (paddy soils). This management, which favors carbon sequestration, potentially decouples surface from subsurface carbon cycling. The objective of this study was to elucidate the long-term rates of carbon accrual in sur...

Iron (Fe) oxides strongly interact with organic matter in soil and play an important role in the stabilization of organic matter. These processes are often influenced by soil cultivation, including tillage, crop rotation and irrigation. We assessed the effect of Fe oxides on organic carbon (OC) accumulation during the development of soils used for...

The assessment of grassland degradation due to overgrazing is a global challenge in semiarid environments. In particular, investigations of beginning steppe degradation after a change or intensification of the land use are needed in order to detect and adjust detrimental land-use management rapidly and thus prevent severe damages in these sensitive...

Degradation of semi-arid grasslands is a global environmental problem, particularly in Inner Mongolia, Northern China, where up to 70% of the total area is classified as degraded steppe. The main cause of grassland degradation in Northern China is overgrazing as a result of increasing stocking rates and a static grazing management during the last 5...

Spatial inaccessibility of soil organic carbon (SOC) for microbial decay within soil aggregates is an important stabilization mechanism. However, little is known about the stability of aggregates in semiarid grasslands and their sensitivity to intensive grazing. In this study, a combined approach using soil chemical and physical analytical methods...

The specific features of the nano-scale secondary ion mass spectrometry (NanoSIMS) technology with the simultaneous analysis of up to seven ion species with high mass and lateral resolution enables us to perform multi-element and stable isotope measurements at the submicron scale. To elucidate the power of this technique, we performed an incubation...

Considerable amounts of soil organic matter (SOM) are stabilized in paddy soils, and thus a large proportion of the terrestrial carbon is conserved in wetland rice soils. Nonetheless, the mechanisms for stabilization of organic carbon (OC) in paddy soils are largely unknown. Based on a chronosequence derived from marine sediments, the objectives of...

Grazed steppe ecosystems are discussed as one of the big global carbon sinks that may have the potential to sequester large amounts of atmospheric CO2 and mitigate the effects of global change if grazing is abandoned or management improved. But until today, little is known about sequestration potentials and stabilisation mechanisms in complete soil...

Semiarid steppe ecosystems account for large terrestrial areas and are considered as large carbon (C) sinks. However, fundamental information on topsoil sensitivity to grazing is lacking across different spatial scales including the effects of topography. Our interdisciplinary approach considering soil chemical, physical, and vegetation properties...

The long-term impact of lowland rice growing on C stocks in soils was evaluated in the coastal region of subtropical China. During the past 2000 years new farmland was created through consecutive land reclamation by protective dikes, providing a unique chronosequence of soil formation under agricultural use. Parts of the land were used for paddy ri...

Soils in semi-arid grasslands are discussed to store significant amounts of soil organic carbon (SOC) and to be of global importance for carbon sequestration. However, land use changes, in particular overgrazing, caused a large release of SOC in the last decades. The aim of this study was to investigate the sequestration potential of degraded grass...

Paddy soils make up the largest anthropogenic wetlands on earth. They may originate from any type of soil in pedological terms, but are highly modified by anthropogenic activities. The formation of these Anthrosols is induced by tilling the wet soil (puddling), and the flooding and drainage regime associated with the development of a plough pan and...

To understand plant–microbe relationships, a simple method is required for identification of the nature of soil polysaccharides. Acid hydrolysis, reduction of sugar monomers to the corresponding alcohols and subsequent derivatisation with acetic anhydride prior to gas chromatography has often been used for identification and quantification of hydro...

Paddy soils are described as important accumulator for OM (Zhang and He, 2004). In southeast China, paddy soils have the second highest OM stocks (Zhao et al, 1997) and thus a large proportion of the terrestrial carbon is conserved in wetland rice soils. The paddy soil management is believed to be favorable for accumulation of organic matter, as it...

Overgrazing has led to severe degradation and desertification of semi-arid grasslands in Northern China over the last decades. Despite the fact that vegetation is often heterogeneously distributed in semi-arid steppes, little attention has been drawn to the effect of grazing on the spatial distribution of soil properties. We determined the spatial...

Land-use change affects not only the amount of soil organic matter (SOM) but also its composition. We performed cross-polarization magic angle spinning (CPMAS) C-13 and N-15 nuclear magnetic resonance (NMR) spectroscopy to investigate the chemical composition of bulk SOM in topsoils (0-15 cm) under different land use, namely native forest (NF), 27-...

In the Zhejiang province (Yangtze River Delta, China), during the past 2000 years new farmland was created through consecutive land reclamation by protective dikes. The construction of the dikes is historically well-dated and provides a unique chronosequence of soil formation under agricultural use. Parts of the land were used for paddy rice, other...

Grazing is one of the most important factors that may reduce soil organic carbon (SOC) stocks and subsequently aggregate stability in grassland soils. The central aim of this study was to analyse the quality and quantity of SOC fractions and their contribution to aggregate formation, stability and carbon sequestration, as affected by increased inpu...

Grazing is one of the most important factors that may reduce soil organic matter (SOM) stocks and subsequently deteriorate aggregate stability in grassland topsoils. Land use management and grazing reduction are assumed to increase the input of OM, improve the soil aggregation and change species composition of vegetation (changes depth of OM input)...

It is not clear from the literature how the spatial distribution of topsoil and vegetation properties is affected by grazing cessation. Thus, the objective of this study was to elucidate if long-term grazing exclosure increases spatial heterogeneity of topsoil and vegetation properties in a steppe ecosystem in NE China. Variograms and crossvariogra...

Historic and recent fires affect a broad range of terrestrial ecosystems and are reflected in the composition of soil organic matter (SOM). Although the assignments of different sources and pools of black carbon (BC) are still under debate, the importance of BC for carbon (C) storage, nutrient supply and contaminant sorption is well recognized. Nev...

Grazing is one of the most important factors that may reduce soil organic carbon (SOC) stocks and subsequently aggregate stability in grassland topsoils. Improvements of land use management and grazing reduction are assumed to increase the carbon sequestration of steppe ecosystems which may act as one of the big global carbon sinks. The central aim...

Intensive grazing in the grasslands of Inner Mongolia resulted in degradation of steppe vegetation and soil structure followed by a decline of soil organic carbon (SOC), associated with a change of the naturally heterogeneous distribution of vegetation and topsoil properties in semiarid environments to a more homogeneous pattern in the overgrazed s...

It is not clear from the literature whether heavy grazing leads to a deterioration of physical and chemical parameters of topsoils in steppe ecosystems. We sampled five sites in northern China with different grazing intensities, ranging from ungrazed since 1979 to heavily grazed, at 540 sampling points to a depth of 0–4 cm. Each sample was analysed...

The application of ¹³C-labeled litter enables to study decomposition processes as well as the allocation of litter-derived carbon to different soil C pools. ¹³Carbon-labeled mustard litter was used in order to compare decomposition processes in an agricultural cropland with high-yield (HY) and low-yield (LY) areas, the latter being characterized by...

High-yield (HY) areas of an agricultural cropland were characterized by different positions on a slope and lower silt and clay contents, compared to low-yield (LY) areas, and this was associated with differences in water regime and C and N turnover. To understand differences in N flows of HY and LY areas, a combination of 15N tracer techniques and...

Various methods exist for the isolation of particulate organic matter (POM), one of the soil-organic-matter (SOM) fractions reacting most sensitive on land-use or soil-management changes. A combination of density separation and ultrasonic treatment allows to isolate two types of POM: (1) free POM and (2) POM occluded in soil aggregates. POM fractio...

The composition of functional light soil organic matter pools of arable Cambisols with a gradient in clay content was investigated. Soil texture differences originate from increasing loess admixture to the parent material (coarse-grained tertiary sediments). Using density fractionation in combination with ultrasonic dispersion, two types of particu...

The rate at which water percolates in soils may have a considerable effect on the kinetics of transport processes. Undisturbed samples of a Luvisol subsoil that differed in their hydraulic conductivities (k1: 4 to 6 cm d(-1); k2: 20 to 21 cm d(-1); k3: 42 to 59 cm d(-1)) were leached under saturated conditions with 4, 20, 102, and 205 mM BaCl2 at a...

Cation exchange is often studied with disturbed and dried soils, but the applicability of the results to undisturbed soils is not straightforward. We investigated the value of exchange coefficients obtained from standard procedures for predicting cation exchange in soil. Columns of undisturbed and disturbed subsoil of a Luvisol (SBt horizon) were l...