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  • 1
    Online-Ressource
    Online-Ressource
    Discrete element modeling of aggregate shape and internal structure effects on Weibull distribution of tensile strength
    Elsevier BV ; 2022
    In:  Soil and Tillage Research Vol. 219 ( 2022-05), p. 105341-
    Details
    In: Soil and Tillage Research, Elsevier BV, Vol. 219 ( 2022-05), p. 105341-
    Materialart: Online-Ressource
    ISSN: 0167-1987
    URL: Article
    DOI: 10.1016/j.still.2022.105341
    Sprache: Englisch
    Verlag: Elsevier BV
    Publikationsdatum: 2022
    ZDB Id: 1498737-5
    SSG: 13
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  • 2
    Online-Ressource
    Online-Ressource
    Modelling of soil mechanical stability and hydraulic permeability of the interface between coated biopore and matrix pore regions
    Elsevier BV ; 2022
    In:  Geoderma Vol. 410 ( 2022-03), p. 115673-
    Details
    In: Geoderma, Elsevier BV, Vol. 410 ( 2022-03), p. 115673-
    Materialart: Online-Ressource
    ISSN: 0016-7061
    URL: Article
    DOI: 10.1016/j.geoderma.2021.115673
    RVK:
    RA 2235.4
    Sprache: Englisch
    Verlag: Elsevier BV
    Publikationsdatum: 2022
    ZDB Id: 281080-3
    ZDB Id: 2001729-7
    SSG: 13
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  • 3
    Online-Ressource
    Online-Ressource
    Infrared-based analysis of organic matter composition in liquid and solid runoff fractions collected during a single erosion event
    Elsevier BV ; 2024
    In:  Soil and Tillage Research Vol. 235 ( 2024-01), p. 105901-
    Details
    In: Soil and Tillage Research, Elsevier BV, Vol. 235 ( 2024-01), p. 105901-
    Materialart: Online-Ressource
    ISSN: 0167-1987
    URL: Article
    DOI: 10.1016/j.still.2023.105901
    Sprache: Englisch
    Verlag: Elsevier BV
    Publikationsdatum: 2024
    ZDB Id: 1498737-5
    SSG: 13
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  • 4
    Online-Ressource
    Online-Ressource
    In Situ DRIFT Characterization of Organic Matter Composition on Soil Structural Surfaces
    Wiley ; 2009
    In:  Soil Science Society of America Journal Vol. 73, No. 4 ( 2009-07), p. 1439-1439
    Details
    In: Soil Science Society of America Journal, Wiley, Vol. 73, No. 4 ( 2009-07), p. 1439-1439
    Materialart: Online-Ressource
    ISSN: 0361-5995 , 1435-0661
    URL: Article
    DOI: 10.2136/sssaj2008.0103er
    RVK:
    RA 4845
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2009
    ZDB Id: 241415-6
    ZDB Id: 2239747-4
    ZDB Id: 196788-5
    ZDB Id: 1481691-X
    SSG: 13
    SSG: 21
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  • 5
    Online-Ressource
    Online-Ressource
    FTIR spectral band shifts explained by OM–cation interactions
    Wiley ; 2021
    In:  Journal of Plant Nutrition and Soil Science Vol. 184, No. 3 ( 2021-06), p. 388-397
    Details
    In: Journal of Plant Nutrition and Soil Science, Wiley, Vol. 184, No. 3 ( 2021-06), p. 388-397
    Kurzfassung: Background : The organic matter (OM) in soils interacts with polyvalent cations such as Ca 2+ through hydroxyl (OH), carboxylic acid, ester, keto, aldehyde (summarized as C=O), and carboxylate (COO − ) functional groups. Such interactions affect the bonding strength of the double bond between the C and the O atom in the functional groups, which is assumed to shift the wavenumber (WN) region of O–H (hydroxyl), C=O, COO − , and OM cat ( i.e ., C=O interacting with cations plus O–H groups) absorption band maxima in the Fourier transform infrared (FTIR) spectra. Such band shifts limit the evaluation of spectral information on OM in soil samples. Aims : The objective of this study was to analyze the extent of band shifts and the changes in absorption band intensities for relations with cation concentrations, and to estimate effects of band shifts on OM properties such as potential wettability of OM evaluated from FTIR absorption band ratios. Methods : Polygalacturonic acid (PGA) solutions were mixed with a CaCl 2 solution at different relations. The freeze‐dried mixtures were analyzed with FTIR spectroscopy in the mid‐infrared spectral range by using KBr‐technique. The FTIR spectra were interpreted with respect to O–H, C=O, COO − , and OM cat bands, the latter reflecting the formation of PGA‐Ca 2+ complexes. Results : The FTIR spectra of the PGA–Ca mixtures compared to that of pure PGA indicate band shift effects by CaCl 2 addition on both, intensity and WN value of the OM cat , C=O and COO − absorption band maxima. The COO − /C–O–C ratio increased with Ca 2+ concentration while the C–H/C–O–C ratio decreased. Furthermore, the C=O and COO − absorption band maxima were shifted towards lower WN values, while the OM cat absorption band was shifted towards higher WN values. The shift of OM cat band maxima was two times higher than that of the C=O band maximum and increased with Ca 2+ concentration. Conclusion : Spectral band shifts depend on polyvalent cation concentration and limit automated interpretations of FTIR spectra without prior soil‐specific spectral corrections.
    Materialart: Online-Ressource
    ISSN: 1436-8730 , 1522-2624
    URL: Issue
    URL: Article
    DOI: 10.1002/jpln.v184.3
    DOI: 10.1002/jpln.202100056
    RVK:
    RA 5430
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2021
    ZDB Id: 1481142-X
    ZDB Id: 1470765-2
    ZDB Id: 200063-5
    SSG: 12
    SSG: 13
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  • 6
    Online-Ressource
    Online-Ressource
    Interpretation of infrared spectra for OM characterization of soil structural surfaces of Bt‐horizons
    Wiley ; 2016
    In:  Journal of Plant Nutrition and Soil Science Vol. 179, No. 1 ( 2016-02), p. 29-38
    Details
    In: Journal of Plant Nutrition and Soil Science, Wiley, Vol. 179, No. 1 ( 2016-02), p. 29-38
    Kurzfassung: The surfaces of macropores or aggregates can act as hot spots for biogeochemical processes and solute transport during preferential flow. For the characterization of organic matter (OM) at macropore surfaces non‐destructive methods have been applied such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). However, effects of organic components on DRIFT signal intensities are often difficult to distinguish from those of mineral components. Here, DRIFT spectra from intact earthworm burrow walls and coated cracks were re‐evaluated to improve the interpretation of C–H and C=O bands. We compared DRIFT and transmission Fourier transform infrared (FTIR) spectra of entire samples that were from the same pedogenetic soil horizon (Bt) but different in mineral composition and texture ( i.e. , glacial till vs. loess). Spectra of incinerated samples were subtracted from the original spectra. Transmission FTIR and DRIFT spectra were almost identical for entire soil samples. However, the DRIFT spectra were affected by the bulk mode bands ( i.e. , wavenumbers 2000 to 1700 cm −1 ). These bands affected spectral resolution and reproducibility. The ratios between C–H and C=O band intensities as indicator for OM quality obtained with DRIFT were smaller than those obtained from transmission FTIR. The results demonstrated that DRIFT and transmission FTIR data required separate interpretations. DRIFT spectroscopy as a non‐destructive method for analyzing OM composition at intact surfaces in structured soils could be calibrated with information obtained with the more detailed transmission FTIR and complementary methods. Spectral subtraction procedure was found useful to reduce effects of mineral absorption bands. The improved DRIFT data may be related to other soil properties ( e.g. , cation exchange capacity) of hot spots in structured soils.
    Materialart: Online-Ressource
    ISSN: 1436-8730 , 1522-2624
    URL: Issue
    URL: Article
    DOI: 10.1002/jpln.v179.1
    DOI: 10.1002/jpln.201400619
    RVK:
    RA 5430
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2016
    ZDB Id: 1481142-X
    ZDB Id: 1470765-2
    ZDB Id: 200063-5
    SSG: 12
    SSG: 13
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  • 7
    Online-Ressource
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    Spectroscopic characterization of mucilage (Chia seed) and polygalacturonic acid
    Wiley ; 2019
    In:  Journal of Plant Nutrition and Soil Science Vol. 182, No. 6 ( 2019-12), p. 888-895
    Details
    In: Journal of Plant Nutrition and Soil Science, Wiley, Vol. 182, No. 6 ( 2019-12), p. 888-895
    Kurzfassung: Polygalacturonic acid (PGA) has frequently been suggested and used as a model substance for studying mucilage properties and effects in soil. While PGA has a defined chemical structure, the composition of mucilage as natural product can vary in space and time depending on the plant and soil conditions. However, it is still unclear if PGA can be used as surrogate for original mucilage when considering soil–mucilage interactions in the rhizosphere. Here the organic matter (OM) composition of PGA was compared with that of Chia seed mucilage and small‐scale spatial distribution of OM composition in mucilage droplets was analysed using Fourier transform mid infrared spectroscopy in KBr‐transmission technique (FTIR). Selected regions of dried Chia seed mucilage droplets were analysed using micro‐ Fourier transform mid infrared spectroscopy in transflection technique (micro‐FTIR). For PGA, the FTIR spectra revealed lower C–H/C=O and higher C=O/C–O–C ratios as compared to Chia seed mucilage, indicating a relatively lower potential hydrophobicity and higher sorption capacity of the OM in PGA than OM in mucilage. The micro‐FTIR spectra revealed that the potential hydrophobicity of a single freeze‐dried mucilage droplet was higher at the tip as compared to regions located above the tip. The results suggest that the use of PGA as model substance for mucilage is limited especially when trying to imitate the sorption and wettability properties of the Chia seed mucilage OM. The spatial heterogeneity in OM composition as well as shifts in maxima of C=O and O–H bands in micro FTIR spectra of the cross sectioned mucilage droplet suggest that the composition of mucilage is changing with time. These findings may help initiating future studies on the dynamics and variability of OM composition of mucilage.
    Materialart: Online-Ressource
    ISSN: 1436-8730 , 1522-2624
    URL: Issue
    URL: Article
    DOI: 10.1002/jpln.v182.6
    DOI: 10.1002/jpln.201800554
    RVK:
    RA 5430
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2019
    ZDB Id: 1481142-X
    ZDB Id: 1470765-2
    ZDB Id: 200063-5
    SSG: 12
    SSG: 13
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  • 8
    Online-Ressource
    Online-Ressource
    Correcting Microtopography Effects on DRIFT Mapping Signals of Organic Matter at Intact Soil Aggregate Surfaces
    Wiley ; 2011
    In:  Soil Science Society of America Journal Vol. 75, No. 5 ( 2011-09), p. 1626-1639
    Details
    In: Soil Science Society of America Journal, Wiley, Vol. 75, No. 5 ( 2011-09), p. 1626-1639
    Materialart: Online-Ressource
    ISSN: 0361-5995
    URL: Article
    DOI: 10.2136/sssaj2010.0462
    RVK:
    RA 4845
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2011
    ZDB Id: 241415-6
    ZDB Id: 2239747-4
    ZDB Id: 196788-5
    ZDB Id: 1481691-X
    SSG: 13
    SSG: 21
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  • 9
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    Online-Ressource
    Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors
    Walter de Gruyter GmbH ; 2016
    In:  Journal of Hydrology and Hydromechanics Vol. 64, No. 2 ( 2016-6-1), p. 111-120
    Details
    In: Journal of Hydrology and Hydromechanics, Walter de Gruyter GmbH, Vol. 64, No. 2 ( 2016-6-1), p. 111-120
    Kurzfassung: The organo-mineral coatings of soil aggregates, cracks, and biopores control sorption and macropore-matrix exchange during preferential flow, in particular in the clay-illuvial Bt-horizon of Luvisols. The soil organic matter (SOM) composition has been hypothesized to explain temporal changes in the hydraulic properties of aggregate surfaces. The objective of this research was to find relations between the temporal change in wettability, in terms of droplet infiltration dynamics, and the SOM composition of coated and uncoated aggregate surfaces. We used 20 to 40 mm sized soil aggregates from the Bt2 horizon of a Haplic Luvisol from loess that were (i) coated, (ii) not coated (both intact), and (iii) aggregates from which coatings were removed (cut). The SOM composition of the aggregate surfaces was characterized by infrared spectroscopy in the diffuse reflection mode (DRIFT). A potential wettability index (PWI) was calculated from the ratio of hydrophobic and hydrophilic functional groups in SOM. The water drop penetration times (WDPT) and contact angles (CA) during droplet infiltration experiments were determined on dry and moist aggregate samples of the three types. The decrease in the CA with time was described using the power function (CA( t ) = at −b ). For dry aggregates, the WDPT values were larger for coated as compared to uncoated regions on the aggregate surfaces, and increased with increasing PWI value ( R 2 = 0.75). The a parameter was significantly related to the WDPT ( R 2 = 0.84) and to the PWI ( R 2 = 0.64). The relations between the b parameter and the WDPT ( R 2 = 0.61) and the PWI ( R 2 = 0.53) were also significant. The WDPT values of wet soil aggregates were higher than those of dry aggregates due to high water contents, which limited the droplet infiltration potential. At the wet aggregate surfaces, the WDPT values increased with the PWI of the SOM ( R 2 = 0.64). In contrast to dry samples, no significant relationships were found between parameters a or b of CA( t ) and WDPT or PWI for wet aggregate surfaces. The results suggest that the effect of the SOM composition of coatings on surface wettability decreases with increasing soil moisture. In addition to the dominant impact of SOM, the wettability of aggregate surfaces could be affected by different mineralogical compositions of clay in coatings and interiors of aggregates. Particularly, wettability of coatings could be decreased by illite which was the dominant clay type in coatings. However, the influence of different clay mineral fractions on surface wettability was not due to small number of measurements (2 and 1 samples from coatings and interiors, respectively) quantified.
    Materialart: Online-Ressource
    ISSN: 0042-790X
    URL: Article
    DOI: 10.1515/johh-2016-0021
    Sprache: Englisch
    Verlag: Walter de Gruyter GmbH
    Publikationsdatum: 2016
    ZDB Id: 2503779-1
    SSG: 14
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  • 10
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    Analyzing organic matter composition at intact biopore and crack surfaces by combining DRIFT spectroscopy and Pyrolysis‐Field Ionization Mass Spectrometry #
    Wiley ; 2016
    In:  Journal of Plant Nutrition and Soil Science Vol. 179, No. 1 ( 2016-02), p. 5-17
    Details
    In: Journal of Plant Nutrition and Soil Science, Wiley, Vol. 179, No. 1 ( 2016-02), p. 5-17
    Kurzfassung: In the clay‐illuvial horizons (Bt) of Luvisols, surfaces of biopores and aggregates can be enriched in clay and organic matter (OM), relative to the bulk of the soil matrix. The OM composition of these coatings determines their bio‐physico‐chemical properties and is relevant for transport and transformation processes but is largely unknown at the molecular scale. The objective of this study was to improve the interpretation of spectra from Fourier transform infrared spectroscopy in diffuse reflectance mode (DRIFT) by using thermograms and released ion intensities obtained with pyrolysis‐field ionization mass spectrometry (Py‐FIMS) for a more detailed analysis of the mm‐scale spatial distribution of OM components at intact structural surfaces. Samples were separated from earthworm burrow walls, crack coatings, uncoated cracks, root channels, and pinhole fillings of the Bt‐horizons of Luvisols. The information from Py‐FI mass spectra enabled the assignment of OM functional groups also from spectral regions of overlapping DRIFT signal intensities to specific OM compound classes. In particular, bands from C=O and C=C bonds in the infrared range of wave numbers between 1,641 and 1,605 cm −1 were related to heterocyclic N‐compounds, benzonitrile, and naphthalene. The OM at earthworm burrow walls was composed of chemically labile aliphatic C‐rich and rather stable lignin and alkylaromatic compounds whereas the OM of thick crack coatings and pinholes was dominated by heterocyclic N and nitriles and high‐molecular compounds, likely originating from combustion residues. In combination with Py‐FIMS, DRIFT applications to intact samples seem promising for generating a more detailed mm‐scale spatial distribution of OM‐related sorption and wettability properties of crack and biopore surfaces that may serve as preferential flow paths in structured soils.
    Materialart: Online-Ressource
    ISSN: 1436-8730 , 1522-2624
    URL: Issue
    URL: Article
    DOI: 10.1002/jpln.v179.1
    DOI: 10.1002/jpln.201400620
    RVK:
    RA 5430
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2016
    ZDB Id: 1481142-X
    ZDB Id: 1470765-2
    ZDB Id: 200063-5
    SSG: 12
    SSG: 13
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