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  • 1
    Electronic Resource
    Electronic Resource
    Assessing the organic phosphorus status of an Oxisol under tropical pastures following native savanna using 31P NMR spectroscopy (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 332-339 
    Details
    ISSN: 1432-0789
    Keywords: Soil phosphorus ; Organic P species ; 31P NMR spectroscopy ; Improved tropical pastures ; Acid savanna soils ; Earthworm casts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract 31P nuclear magnetic resonance (NMR) spectroscopy, P fractionation, and a P sorption experiment were used to follow the changes in P in the A horizons (0–10 cm) of acid savanna soils, Colombia, after little P fertilization and 15 years' continuous growth of a grass (Brachiaria decumbens) and a grass/legume (B. decumbens+Pueraria phaseoloides) pasture. Ready P supply as analyzed by Bray P was low under native savanna (1.3 mg kg-1 soil) and responded moderately on pasture establishment. Concurrently, the affinity of the soil for inorganic P declined slightly after pasture establishment. 31P NMR spectroscopy revealed that P associated with humic acids was dominated by monoester P followed by diester P. Smaller proportions were observed for phosphonates, teichoic acid P, orthophosphate, and pyrophosphate. P associated with fulvic acids had lower proportions of diester P and higher contents of orthophosphate. Under native savanna the reserves of labile organic P species (phosphonates and diester P including teichoic acid P) associated with humic and fulvic acids were 12.4 and 1.1 kg ha-1, respectively, and increased to 18.1 and 1.8 kg ha-1 under grass pasture, and to 19.5 and 2.3 kg ha-1 under grass/legume pasture. These data emphasize the importance of labile organic P species in the P supply for plants in improved tropical pastures, and further indicate that humic acid P in particular responds to land-use changes within a relatively short time-scale. Earthworm casts were highly abundant in the B. decumbens+P. phaseoloides plot and were enriched in labile organic P species. We conclude that earthworm activity improves the P supply in soil under tropical pastures by creating an easily available organic P pool.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335963
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  • 2
    Electronic Resource
    Electronic Resource
    Assessing the organic phosphorus status of an Oxisol under tropical pastures following native savanna using 31P NMR spectroscopy (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 332-339 
    Details
    ISSN: 1432-0789
    Keywords: Key words Soil phosphorus ; Organic P species ; 31P NMR spectroscopy ; Improved tropical pastures ; Acid savanna soils ; Earthworm casts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract 31P nuclear magnetic resonance (NMR) spectroscopy, P fractionation, and a P sorption experiment were used to follow the changes in P in the A horizons (0–10 cm) of acid savanna soils, Colombia, after little P fertilization and 15 years’ continuous growth of a grass (Brachiaria decumbens) and a grass/legume (B. decumbens+Pueraria phaseoloides) pasture. Ready P supply as analyzed by Bray P was low under native savanna (1.3 mg kg–1 soil) and responded moderately on pasture establishment. Concurrently, the affinity of the soil for inorganic P declined slightly after pasture establishment. 31P NMR spectroscopy revealed that P associated with humic acids was dominated by monoester P followed by diester P. Smaller proportions were observed for phosphonates, teichoic acid P, orthophosphate, and pyrophosphate. P associated with fulvic acids had lower proportions of diester P and higher contents of orthophosphate. Under native savanna the reserves of labile organic P species (phosphonates and diester P including teichoic acid P) associated with humic and fulvic acids were 12.4 and 1.1 kg ha–1, respectively, and increased to 18.1 and 1.8 kg ha–1 under grass pasture, and to 19.5 and 2.3 kg ha–1 under grass/legume pasture. These data emphasize the importance of labile organic P species in the P supply for plants in improved tropical pastures, and further indicate that humic acid P in particular responds to land-use changes within a relatively short time-scale. Earthworm casts were highly abundant in the B. decumbens+P. phaseoloides plot and were enriched in labile organic P species. We conclude that earthworm activity improves the P supply in soil under tropical pastures by creating an easily available organic P pool.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335963
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  • 3
    Electronic Resource
    Electronic Resource
    Formation and mobilization pathways of dissolved organic matter: evidence from chemical structural studies of organic matter fractions in acid forest floor solutions
    Amsterdam : Elsevier
    Organic Geochemistry 21 (1994), S. 51-66 
    Details
    ISSN: 0146-6380
    Keywords: DOM fractionation ; DOM mobilization ; chemical characterization ; dissolved organic matter ; forest floor ; microbial organic matter degradation ; pyrolysis-field ionization mass spectrometry
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0146-6380(94)90087-6
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  • 4
    Electronic Resource
    Electronic Resource
    Mineral surfaces and soil organic matter (2003)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 54 (2003), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The organic carbon content of soil is positively related to the specific surface area (SSA), but large amounts of organic matter in soil result in reduced SSA as determined by applying the Brunauer–Emmett–Teller (BET) equation to the adsorption of N2. To elucidate some of the controlling mechanisms of this relation, we determined the SSA and the enthalpy of N2 adsorption of separates with a density 〉 1.6 g cm−3 from 196 mineral horizons of forest soils before and after removal of organic matter with NaOCl. Likewise, we investigated these characteristics before and after sorption of increasing amounts of organic matter to four mineral soil samples, oxides (amorphous Al(OH)3, gibbsite, ferrihydrite, goethite, haematite), and phyllosilicates (kaolinite, illite).Sorption of organic matter reduced the SSA, depending on the amount sorbed and the type of mineral. The reduction in SSA decreased at larger organic matter loadings. The SSA of the mineral soils was positively related to the content of Fe oxyhydroxides and negatively related to the content of organic C. The strong reduction in SSA at small loadings was due primarily to the decrease in the micropores to which N2 was accessible. This suggests preferential sorption of organic matter at reactive sites in or at the mouths of micropores during the initial sorption and attachment to less reactive sites at increasing loadings. The exponential decrease of the heat of gas adsorption with the surface loading points also to a filling or clogging of micropores at early stages of organic matter accumulation. Desorption induced a small recovery of the total SSA but not of the micropore surface area.Destruction of organic matter increased the SSA of all soil samples. The SSA of the uncovered mineral matrix related strongly to the amounts of Fe oxyhydroxides and the clay. Normalized to C removed, the increase in SSA was small in topsoils and illuvial horizons of Podzols rich in C and large for the subsoils containing little C. This suggests that micropores preferentially associate with organic matter, especially at small loadings. The coverage of the surface of the soil mineral matrix as calculated from the SSA before and after destruction of organic matter was correlated only with depth, and the relation appeared to be linear.We conclude that mineralogy is the primary control of the relation between surface area and sorption of organic matter within same soil compartments (i.e. horizons). But at the scale of complete profiles, the surface accumulation and stabilization of organic matter is additionally determined by its input.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.2003.00544.x
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  • 5
    Electronic Resource
    Electronic Resource
    Dissolved organic matter sorption on sub soils and minerals studied by 13C-NMR and DRIFT spectroscopy (1997)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of soil science 48 (1997), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Sorption on the mineral matrix is an important process restricting the movement of dissolved organic matter (DOM) in soils. In this study, we aimed to identify the chemical structures responsible for the retention of DOM by sorption experiments with total DOM and acidic humic substances (AHS), containing humic and fulvic acids, on soil samples and minerals (goethite, ferrihydrite, and amorphous Al(OH)3). The AHS remaining in solution after sorption were studied by 13C nuclear magnetic resonance (NMR) analysis, and total DOM and AHS for bed on the surfaces of minerals by diffuse reflectance Fourier-transform infrared (DRIFT) spectroscopy. The soil samples were taken from strongly sorbing Bw horizons of two Inceptisols rich in pedogenetic Fe (29 and 35 g kg −1) and containing little C (7 and 22 g kg−1). The 13C-NMR spectra showed that sorption causes a preferential removal of aromatic and carboxyl C from the solution, whereas alkyl-C accumulates in the solution. No change was observed for O-alkyl C. The DRIFT spectra of sorbed total DOM and AHS showed a relative increase of the band intensity of carboxyl groups compared to DOM in the initial solution, confirming the importance of those groups for the sorption to mineral surfaces. The spectra also indicated reactions of carboxyl groups with metals at the mineral surfaces. The extent to which the carboxyl groups are bound depended on the surface coverage with DOM and the type of mineral.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2389.1997.tb00550.x
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  • 6
    Electronic Resource
    Electronic Resource
    Isotopic fractionation of dissolved organic carbon in shallow forest soils as affected by sorption (2001)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 52 (2001), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Isotopic fractionation of dissolved organic carbon percolating through the soil is often interpreted as due to microbial transformation. We investigated the potential effects of sorption on the δ13C of dissolved organic C in field and laboratory experiments. We sampled the organic C in soil water at two forested sites and measured sorption with intact mineral soil and individual minerals (dolomite, ferrihydrite, goethite, and quartz). The dissolved organic C was separated into hydrophilic and hydrophobic fractions using a resin approach. The δ13C values of bulk soils, alkaline-extractable organic C, and dissolved organic C and its fractions were measured. Hydrophilic and hydrophobic fractions in forest floor seepage water were characterized by 13C-NMR spectroscopy.At both sites, δ13C of dissolved organic C increased with increasing depth, suggesting that decomposition contributes to the loss of the dissolved organic C. However, there was an enrichment of hydrophilic organic C in the soil solution as the water moved down the soil. The δ13C values of hydrophilic fractions were less negative than those of hydrophobic fractions. The smaller δ13C in the hydrophobic fraction was due to the large contribution of compounds derived from lignin that are depleted in 13C. As the isotope composition of both fractions of dissolved organic C did not change throughout the profile, changes in δ13C of total organic C reflected changes in the relative proportions of its hydrophilic and hydrophobic fractions. The sorption experiments with minerals and soil cores gave similar results. When dissolved organic C came into contact with mineral material, the δ13C of that remaining in solution increased due to preferential sorption of the 13C-depleted hydrophobic fractions. Moreover, the soils released hydrophilic organic C with large δ13C values, increasing the δ13C of organic C in effluents from soil compared with that in the inflow. Thus, selective sorption of organic C fractions changes δ13C in a way that mimics metabolic transformation and decomposition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.2001.00407.x
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  • 7
    Electronic Resource
    Electronic Resource
    Sources and composition of soil organic matter fractions between and within soil aggregates (2001)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 52 (2001), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: It is generally accepted that particulate organic matter derives from plants. In contrast, the enriched labile fraction is thought by many to derive from microbes, especially fungi. However, no detailed chemical characterization of these fractions has been done. In this study, we wanted to assess the sources (plants or microbes; fungi or bacteria) and degree of microbial alteration of (i) three particulate organic matter fractions – namely the free light fraction (1.85 g cm−3), the coarse (250–2000 μm) and the fine (53–250 μm) intra-aggregate particulate organic matter fractions – and of (ii) three density fractions of fine-silt associated carbon – namely 〈 2.0, 2.0–2.2 (i.e. enriched labile fraction) and 〉 2.2 g cm−3– by analysing the amino sugars, by CuO oxidation analyses, and by 13C-, 1H- and 31P-NMR analyses. Macroaggregates (250–2000 μm) were separated by wet-sieving from a former grassland soil now under a no-tillage arable regime. The three particulate organic matter fractions and the three density fractions were isolated from the macroaggregates by a combination of density flotation, sonication and sieving techniques. Proton NMR spectroscopy on alkaline extracts showed that the enriched labile fraction is not of microbial origin but is strongly degraded plant material that is enriched in aliphatic moieties partly bound to aromatics. In addition, the enriched labile fraction had a glucosamine content less than the whole soil, indicating that it is not enriched in carbon derived from fungi. Decreasing yields of phenolic CuO oxidation products and increasing side-chain oxidation in the order coarse intra-aggregate particulate organic matter 〈 fine inter-aggregate particulate organic matter 〈 fine-silt fractions indicate progressive alteration of lignin as particle size decreases. The light fraction was more decomposed than the coarse inter-aggregate particulate organic matter, as indicated by (i) its larger ratio of acid-to-aldehyde of the vanillyl units released by CuO oxidation, (ii) the smaller contribution of H in carbohydrates to total extractable H as estimated by 1H-NMR spectroscopy, and (iii) a larger contribution of monoester P to total extractable P in the 31P-NMR spectra. In conclusion, the four fractions are derived predominantly from plants, but microbial alteration increased as follows: coarse inter-aggregate particulate organic matter 〈 light fraction ≈ fine inter-aggregate particulate organic matter 〈 enriched labile fraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.2001.00406.x
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  • 8
    Electronic Resource
    Electronic Resource
    Land-use effects on the composition of organic matter in particle-size separates of soils: II. CPMAS and solution 13C NMR analysis (1995)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of soil science 46 (1995), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Soils from A horizons of Eutrochrepts under spruce forest (Sf), mixed deciduous forest (Df), permanent grassland (Gp), and arable rotation (Ar) were fractionated into clay- (〈2 μm), silt-(2–20 μm) and sand- (20–2000 μm) sized separates. 13C NMR spectroscopy was used to compare SOM composition across size separates and between land-use regimes.CPMAS 13C NMR spectroscopy showed that the intensity of signals assigned to carbohydrates (representing most O-alkyl C) and lignin (phenolic and methoxyl C) declined with decreasing particle size. Concurrently, alkyl C and C-substitution of aromatic C increased in the order sand, silt, clay. The amount of alkyl C correlated well with microbial resynthesis of carbohydrates. Solution 13C NMR spectra suggested that humic acids (HA) extracted from the size separates were richer in carboxyl C and aromatic C than the bulk size separates. Also HA reflected increasing percentage of alkyl C with decreasing particle size. O-alkyl C were lower in silt HA than in clay HA whereas aromatic C tended to peak in silt HA. These results suggested that sand-sized separates were enriched in plant residues (primary resources) whereas clay-sized separates were dominated by products of microbial resynthesis (secondary resources). Silt was rich in selectively preserved and microbially transformed primary resources. 13C NMR spectroscopy showed only small differences in SOM composition between land-use regimes, except that silt and silt HA from Ar were richer in aromatic C than those from the other plots. But enrichment factors (E= content in fraction/content in whole soil) revealed differences in the distribution of C species across the size separates. Relatively high Earomatic (0.9) and Eo-alkyl (1.0) for sand from Gp indicated high amounts of plant residues, probably due to intense rhizodeposition and to occlusion of plant debris within aggregates. Low Earomatic (0.3) and Eo-alkyl (0.3) for sand from Ar suggested depletion of primary resources, which could be attributed to disintegration of soil aggregates upon cultivation. A pronounced enrichment of alkyl C in Ar clay-sized separates (Ealkyl= 3.1) suggested large amounts of microbial carbon. Microbial products attached to clay surfaces by a variety of physico-chemical bondings appeared more stable against mineralization induced by cultivation than plant residues sequestered in aggregates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2389.1995.tb01821.x
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  • 9
    Electronic Resource
    Electronic Resource
    Land-use effects on the composition of organic matter in particle-size separates of soil: I. Lignin and carbohydrate signature (1994)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of soil science 45 (1994), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Soil from Eutrochrept A horizons under long-term spruce forest (Sf), mixed deciduous forest (Df), permanent grassland (Gp) and arable rotation (Ar) was fractionated according to particle size and analysed for contents of C, N, lignin-derived phenols and carbohydrates.Whole soil from Sf, Df, Gp and Ar contained 84, 59, 73 and 25 g C kg−1 soil, respectively. For all sites, the C content declined and C/N ratio increased in the order: clay (〈2 μm), silt (2–20 μm), sand (20–2000 μm). Clay and silt were significantly lower in C in Ar than in Sf, Df and Gp, C associated with sand being substantially lower under arable rotation.The yield of lignin-derived phenols decreased and carboxyl functionality and methoxyl demethylation of lignin derivatives increased with decreasing particle size, indicating a progressive lignin alteration. Whole soil from Sf and Gp was substantially higher in vanillyl (V), syringyl (S) and cinnamyl (C) units (VSC) than soil from Df and Ar. Compared to whole soil, clay was depleted and sand enriched in VSC. Only sand appeared to be affected significantly by land use. Sand from Ar and Df was more enriched in VSC than sand from Gp and Sf.Whole soil carbohydrates decreased in the order: Gp〉Ar〉Df〉Sf. Sand- and clay-sized separates were enriched in carbohydrates compared to silt. Carbohydrates in sand were mainly of plant origin whereas microbially-derived sugars accounted for a larger proportion in the clay. Compared to Sf, Df and Gp, clay from Ar was enriched and sand depleted in microbial sugars.Lignin and carbohydrate distribution patterns indicate that organic matter was in a more advanced stage of decomposition in the sand separates from forest than from agricultural A horizons. The forest soils also show a higher degree of oxidative changes in lignin associated with clay. In contrast, differences between silt from the four A horizons were small.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2389.1994.tb00530.x
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  • 10
    Electronic Resource
    Electronic Resource
    Land-use and fertilization effects on P forms in two European soils: resin extraction and 31P-NMR analysis (1996)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of soil science 47 (1996), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Macroporous anion-exchange resin extraction and 31P-NMR spectroscopy of dialysed NaOH extracts were used to investigate the effects of land use (Taubenberg, Bavaria: spruce forest, deciduous forest, permanent grass, arable) and fertilization (Askov, Denmark: unmanured, mineral fertilizer, animal manure) on forms of phosphorus in soil with emphasis on the potentially labile organic (Po) and inorganic (Pi pools. Carbon content ranged from 12.5–118.1 g kg−1 and total P (Pi) content from 511 to 2063 mg kg−1. For all soils, the C:Po ratios of SOM decreased in the order: whole soil, 150: 1–44:1; alkali extract, 57:1–41: 1; resin extract, 20:1–9:1; suggesting an increasing P functionality of the OM with increasing Po lability. Analysis of functional relation showed a close relation between resin Po and 31P-NMR estimates for diester-P including teichoic acid-P, indicating that these species contributed significantly to the labile Po pool as determined by the resin method. The most marked effects of land-use were an increase in Pi under grass and arable, a concurrent sequestration of Po and SOM under grass, and a depletion of Po under arable. The amount of resin Pj appeared to be a function primarily of fertilization, and amounted to around 100 mg kg−1 in the fertilized soils irrespective of the SOM content and P source. The forest soil and the unfertilized agricultural soil had much smaller resin Pj values. The soil under grass had the largest amounts in resin Po and diester-P including teichoic acid-P, indicating a rapid turnover of Po with build-up of a large potentially labile, microbially derived Po pool. 31P NMR also showed large proportions of labile Po species in soils where microbial activity is restrained by acidity (Taubenberg spruce forest, phosphonates) or where highly microbially altered OM is relatively enriched (Taubenberg arable, diester-P including teichoic acid-P).We conclude that the resin used in this study isolates a structurally and functionally reasonably uniform pool of potentially labile soil Po.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2389.1996.tb01859.x
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