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Soil organic matter transformations induced by Hieracium pilosella L. in tussock grassland of New Zealand (2000)

Knicker, H. ; Saggar, S. ; Bäumler, R. ; [et al.]

Springer

Biology and fertility of soils 32 (2000), S. 194-201

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ISSN: 1432-0789

Keywords: Key words Carbon-13 nuclear magnetic resonance ; Nitrogen-15 nuclear magnetic resonance ; Lignin ; Phenols ; Organic nitrogen

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract To study the effect of Hieracium pilosella L. invasion on the transformations of soil organic matter of New Zealand tussock grassland soils (Ustochrepts), plant material and soils underneath Hieracium, the surrounding halo, and the adjacent herbfield (depleted tussock grassland) were examined for their chemical composition. An attempt was made to reveal possible changes in chemical composition of the soil organic matter induced by H. pilosella invasion. Small differences were detected by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy in the composition of the plant and soil materials from these zones. Most of the differences in soil organic matter occurred due to differences in the amount and quality of plant-residue inputs. Comparable amounts of phenolic C were detected in the solid-state 13C NMR spectra of H. pilosella and herbfield vegetation, while alkaline CuO oxidation yielded considerable lower lignin oxidation products for H. pilosella. A slightly higher proportion of these compounds in H. pilosella soil revealed an accumulation and a low degradation rate of lignin compounds under H. pilosella. The HCl hydrolysis and solid-state 15N NMR spectroscopy showed similar chemical compositions of the N fractions of the three different soils. The absence of 15N NMR signal intensity assignable to aniline derivatives or aromatic heterocyclic N indicates that the condensation of phenolic compounds with N groups plays a minor role in N sequestration in these soils.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s003740000234

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2

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Changes in the chemical composition of soil organic matter after application of compost (2002)

Leifeld, J. ; Siebert, S. ; Kögel-Knabner, I.

Oxford, UK : Blackwell Science Ltd

European journal of soil science 53 (2002), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Is the composition of soil organic matter changed by adding compost? To find out we incubated biowaste composts with agricultural soils and a humus-free mineral substrate at 5°C and 14°C for 18 months and examined the products. Organic matter composition was characterized by CuO oxidation of lignin, hydrolysis of cellulosic and non-cellulosic polysaccharides (CPS and NCPS) and 13C cross-polarization magic angle spinning nuclear magnetic resonance (CPMAS 13C-NMR) spectroscopy. The lignin contents in the compost-amended soils increased because the composts contained more lignin, which altered little even after prolonged decomposition of the composts in soil. A pronounced decrease in lignin occurred in the soils amended with mature compost only. Polysaccharide C accounted for 14–20% of the organic carbon at the beginning of the experiment for both the compost-amended soils and the controls. During the incubation, the relative contents of total polysaccharides decreased for 9–20% (controls) and for 20–49% (compost-amended soils). They contributed preferentially to the decomposition as compared with the bulk soil organic matter, that decreased between 〈 2% and 20%. In the compost-amended agricultural soils, cellulosic polysaccharides were decomposed in preference to non-cellulosic ones. The NMR spectra of the compost-amended soils had more intense signals of O–alkyl and aromatic C than did those of the controls. Incubation for 18 months resulted mainly in a decline of O–alkyl C for all soils. The composition of the soil organic matter after compost amendment changed mainly by increases in the lignin and aromatic C of the composts, and compost-derived polysaccharides were mineralized preferentially. The results suggest that decomposition of the added composts in soil is as an ongoing humification process of the composts themselves. The different soil materials affected the changes in soil organic matter composition to only a minor degree.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1351-0754.2002.00453.x

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Speciation of sulphur in soils and soil particles by X-ray spectromicroscopy (2003)

Prietzel, J. ; Thieme, J. ; Neuhäusler, U. ; [et al.]

Oxford, UK : Blackwell Science Ltd

European journal of soil science 54 (2003), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Current wet chemical methods for the speciation of sulphur (S) in soils are inaccurate and do not allow one to assess the S speciation of individual soil particles and colloids. X-ray microscopy and Near Edge X-ray Absorption Fine structure Spectroscopy (NEXAFS) can be used to study individual species of S at the K-adsorption edge. We have used these techniques to identify and quantify S species in bulk soil, soil particles and colloids from Oh and Bh horizons of two forested Podzols. The partitioning of soil sulphur as determined on bulk samples of the Oh horizons by X-ray spectromicroscopy agreed fairly well with the results of a conventional S speciation for the soil at Schluchsee, and reasonably well for that at Rotherdbach. The NEXAFS analyses on individual soil particles revealed that they are richer in reduced organic sulphur than the bulk soil for the Schluchsee Oh and richer in sulphate for Rotherdbach Oh. The techniques can be used reliably to separate and quantify sulphur species with different oxidation states in the soil. The combination of X-ray transmission and sulphur fluorescence images with unfocused and focused NEXAFS spectra at the K-adsorption edge of sulphur at specific microsites allowed us to compare the distribution of S species in bulk soil with that of distinct soil particles and soil colloids. Moreover, we can use it to assess the spatial distribution of different S species on soil particles on a scale of a few hundred nanometres.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2389.2003.00543.x

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Chemical heterogeneity of humic substances: characterization of size fractions obtained by hollow-fibre ultrafiltration (2000)

Christl, I. ; Knicker, H. ; Kögel-Knabner, I. ; [et al.]

Oxford, UK : Blackwell Science Ltd

European journal of soil science 51 (2000), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: To investigate the chemical heterogeneity of humic substances in relation to molecular size, fulvic and humic acids were extracted and purified from the surface horizon of a Humic Gleysol in northern Switzerland. A fractionation scheme using hollow-fibre ultrafiltration cartridges was developed and used to obtain four size fractions of the humic acid with nominal molecular weight ranges 〉 300 kDa, 100–300 kDa, 30–100 kDa, and 10–30 kDa. The fulvic acid and all humic acid fractions were characterized by size exclusion chromatography, elemental analysis (C, H, N, S), as well as spectroscopic techniques including UV-VIS, CP-MAS 13C-NMR, FT-IR, and fluorescence spectroscopy.Clear chemical differences between the humic acid size fractions were observed. Smaller size fractions of the soil humic acid contained more chargeable functional groups and a larger percentage of aromatic carbon than the larger size fractions. Conversely, the percentage of aliphatic carbon increased with increasing apparent molecular weight. The chemical composition of the smallest humic acid fraction differed clearly from the fulvic acid fraction, despite similar apparent molecular size and carboxyl carbon content. Small humic acids contained much more aromatic carbon and less aliphatic carbon than the fulvic acid fraction. Apparently, humic size fractions differ in their chemical composition, which can have important implications for their environmental behaviour.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1365-2389.2000.00352.x

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5

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Organic matter in particle-size fractions from A and B horizons of a Haplic Alisol (2002)

Schmidt, M. W. I. ; Kögel- Knabner, I.

Oxford, UK : Blackwell Science Ltd

European journal of soil science 53 (2002), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: The organic matter in soils may be stabilized by its interactions with minerals. We have studied such interactions in a Haplic Alisol under forest in which clay and organic matter have migrated from an eluvial A horizon to accumulate in an illuvial B horizon. We have tried to trace the fate of organic matter in these horizons (Ah and Bvt) by determining clay mineralogy, carbon and nitrogen content, hydrolysable amino acids, lignin signature by alkaline CuO oxidation and carbon species by 13C CPMAS NMR of bulk soils and particle-size fractions. In both horizons, most of the organic matter was present in O–alkyl and methylene structures, each contributing one-third to the bulk organic matter. In the Ah horizon the ratios of carbon-to-nitrogen, and yields for lignin and hydrolysable amino acids decreased as the particle-size class decreased, but side-chain oxidation of lignin compounds increased with decreasing particle size. In contrast to previous observations, the proportions of O–alkyl carbon increased as particle size decreased, constituting a major proportion of the organic carbon in the clay-size fractions from both the Ah and Bvt horizons (≥ 38%), while proportions of methylene carbon decreased. Illite was the dominant mineral in the fraction ≤ 6 μm, whereas the mobile fine clay fraction (〈0.2 μm) was rich in smectites – minerals with large surface areas. Our results support the hypothesis that potentially labile organic matter, such as O–alkyl carbon typically present in polysaccharides, may be stabilized against further degradation in organomineral complexes.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2389.2002.00460.x

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6

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Fate of anthracene in contaminated soil: transport and biochemical transformation under unsaturated flow conditions (2002)

Weigand, H. ; Totsche, K. U. ; Kögel-Knabner, I. ; [et al.]

Oxford, UK : Blackwell Science Ltd

European journal of soil science 53 (2002), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: To obtain reliable estimates for the loss of polycyclic aromatic hydrocarbons (PAHs) from contaminated soils, one has to distinguish between (i) losses due to release and solute transport and (ii) losses resulting from degradation. We studied the interplay of these processes in a column experiment representing a typical soil contamination scenario: in the upper part of the column was a contaminated layer, spiked with 9-13C-labelled anthracene, and beneath it uncontaminated pristine soil. The experimental course comprised a steady-state flow phase (constant irrigation for 4 months) followed by several periods during which flow was halted. The effects of varied residence time on anthracene biodegradation and on anthracene mass transfer were investigated. We monitored labelled anthracene and its transformation products, dissolved organic carbon, electric conductivity (EC), pH, and inorganic carbonate content in the column effluent, and the CO2 evolved.Under steady-state flow, pH, dissolved organic C, and EC approached steady states after 350 pore volumes. Concentrations of anthracene in the effluent, however, increased continuously and levelled off after 800 pore volumes. This marked retardation reflects the great affinity of anthracene to soil organic matter. The response to interruptions in the flow revealed that mass is transferred without equilibrium between solid and liquid phase for both anthracene and dissolved organic C. Thus, residence time is one factor controlling the concentration of anthracene in the effluent and therefore the export of contaminant to the aquifer. In the course of the experiment several labelled anthracene degradation products appeared in the effluent. At least three of them were identified as transformation products showing a dramatic increase in mobility relative to the parent compound. A third of the overall anthracene loss from the column was due to solute transport, and biodegradation was responsible for the remaining two thirds. The incomplete degradation of anthracene leads to the formation of highly mobile transformation products and thus promotes the export of carbon, derived from the contaminant.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2389.2002.00427.x

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Microaggregates in agricultural soils and their size distribution determined by X-ray attenuation (2003)

Leifeld, J. ; Kögel-Knabner, I.

Oxford, UK : Blackwell Science Ltd

European journal of soil science 54 (2003), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Understanding mechanisms of microaggregate formation in soils requires knowledge of their exact size distribution. With this in mind, we have used X-ray attenuation to determine the size distributions of microaggregates and primary particles in the range 0.2–63 μm, with a resolution of 100 size increments. Ten arable and grassland soils with organic C contents ranging from 14.7 to 37.7 g kg−1 were analysed. They were subjected to ultrasound at 52 J ml−1 which destroyed most aggregates 〉 63 μm to give microaggregates in the size range 1–63 μm. The size distribution of microaggregates differed significantly from that of primary particles and was largely independent of their organic C content. Microaggregates were most abundant in 19 of the 100 size increments, contributing to 92% of the major peaks of the size distribution. These preferred increments differed from those of primary particles, but the order for the two was similar. Further analysis of the size distribution revealed a larger mean weight diameter of microaggregates, depending on the size distribution of primary particles. The results suggest a major effect of the size distribution of primary particles on microaggregation, whereas land use seems to have a negligible effect. The proportion of mechanically dispersible clay decreased with increasing C content and indicates structural stability at the microscale.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2389.2003.t01-1-00511.x

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