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  • 1
    Language: English
    In: Soil Science Society of America journal, 2011, Vol.75(5), pp.1626-1639
    Description: Soil organic matter (OM) of aggregate coatings and biopore walls can affect the transport of reactive solutes during preferential flow in structured soil. As a nondestructive method, diffuse reflection infrared Fourier transform (DRIFT) spectroscopy, has been proposed for mapping the millimeter-scale OM composition of intact flow path surfaces. The surfaces of such intact soil structures, e.g., aggregate and biopore surfaces, mostly have a distinctive microtopography, however, that affects the intensity of DRIFT signals. Thus DRIFT mapping data require geometric corrections for a quantitative interpretation. This study analyzed a digital terrain model (DTM)-based approach for describing microtopography effects on DRIFT reflectance. A gypsum block model was first used for developing the concept. The surface of the gypsum block had defined channels and pores and was partly coated with defined humic acid (HA). A millimeter-scale DTM of the DRIFT-mapped gypsum block surface was obtained with a laser scanner. The signal intensities at specific wavenumbers were corrected for microtopography effects using surface elevation, slope, and aspect data of the sample surfaces. The corrections were found to be dependent on both the wavelengths and the measured substance (gypsum or HA). The method was then applied to determine the OM composition at intact structural soil surfaces. The DTM-based approach reduced microtopography effects and was compared with an alternative approach in which spectral ratios between specific absorption bands were used for corrections. The results indicated differences in OM composition and local distribution between surfaces of worm burrows and crack walls. The results suggest that DTM correction of a DRIFT-mapped intact soil aggregate surface enhanced the interpretation of the millimeter-scale OM composition. ; p. 1626-1639.
    Keywords: Wavelengths ; Microrelief ; Solutes ; Humic Acids ; Preferential Flow ; Models ; Absorption ; Gypsum ; Burrows ; Coatings ; Reflectance ; Spectroscopy ; Soil
    ISSN: 0361-5995
    E-ISSN: 14350661
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  • 2
    Language: English
    In: Forest Ecology and Management, 15 October 2014, Vol.330, pp.283-293
    Description: Future climate projections for Central Europe indicate a decrease in summer precipitation which might range between 15% and 50%, and equally important, changes in the climate variability, resulting in consecutive years with drought periods. With respect to Central European forests, we asked to which degree realistic drought conditions are tolerated by the recruits of the dominant tree species L , and how the effects depend on biotic interactions. To test the combined effects of drought, competition and provenance of recruits we set up a rain shelter experiment at three sites in different regions of Germany. Transposable roof panels allowed a flexible precipitation reduction between 10% and 70% corresponding with a return period of 40 years. We planted saplings of three provenances, exposed them to drought and competition. We tested if understorey herbaceous competitors have a negative impact on saplings, and thus, exacerbate drought effects and that provenances from drier regions are adapted to drought conditions and cope better with drought conditions. Six months after the drought treatment started, we encountered significant drought effects, seen in a reduced leaf stomatal conductance, although there was not yet a response in growth rates. Overall, the site had the greatest impact on phytometer performance, while we found no indication of adaptation to drought of the different provenances. Furthermore, drought effects increased in interaction with site effects, being highest at the driest site. At the driest site, leaf stomatal conductance decreased in the presence of competition but increased in the control subplots, while the site of intermediate moisture conditions showed the opposite pattern and the wettest site displayed no differences. Our results highlight the fact that biotic interactions can mitigate or exacerbate drought effects, depending on regional site conditions.
    Keywords: Global Change ; Fagus Sylvatica ; Drought ; Forest Understory ; Competition ; Provenances ; Forestry ; Biology
    ISSN: 0378-1127
    E-ISSN: 1872-7042
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  • 3
    Language: English
    In: Geoderma, 01 February 2016, Vol.263, pp.1-7
    Description: Mineral topsoils possess large organic carbon (OC) contents but there is only limited knowledge on the mechanisms controlling the preservation of organic matter (OM) against microbial decay. Samples were taken from the uppermost mineral topsoil horizon (0 to 5 cm) of seven sites under mature deciduous forest showing OC contents between 69 and 164 g kg and a wide range in mineral characteristics. At first, organic particles and the water-extractable OM were removed from the soil samples. Thereafter, Na-pyrophosphate extractable organic matter (OM(PY)), assumed to be indicative for OM bound via cation mediated interactions, and the OM remaining in the extraction residue (OM(ER)), supposed to be indicative for OM occluded in mechanically highly stable micro-aggregates, were sequentially separated and quantified. The composition of OM(PY) and OM(ER) was analyzed by FTIR and their stability by C measurements. The OC remaining in the extraction residues accounted for 38 to 59% of the bulk soil OC (SOC) suggesting a much larger relevance of OM(ER) for the OM dynamic in the analyzed soils as compared with OM(PY) that accounted for 1.6 to 7.5% of the SOC. The FTIR analyses revealed a lower relative proportion of C O groups in OM(ER) compared to OM(PY) indicating differences in the degree of microbial processing between these fractions. Correlation analyses suggest an increase in the stability of OM(PY) with the soil pH and contents of Na-pyrophosphate soluble Fe, Al, and Mg and an increase in the stability of OM(ER) with the soil pH and the contents of clay and oxalate-soluble Fe and Al. Despite the detected influence of soil mineral characteristics on the turnover of OM(PY) and OM(ER), the Δ C signatures indicated mean residence times less than 100 years. The presence of less stabilized OM in these fractions can be derived from methodological uncertainties and/or the fast cycling compartment of mineral-associated OM.
    Keywords: Forest Mineral Topsoil ; Organic Matter Stabilization ; Na-Pyrophosphate Soluble Organic Matter ; Micro-Aggregates ; Infrared Spectroscopy ; 14c Analyses ; Agriculture
    ISSN: 0016-7061
    E-ISSN: 1872-6259
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  • 4
    Language: English
    In: Journal of Plant Nutrition and Soil Science, October 2018, Vol.181(5), pp.721-736
    Description: Site conditions and soil management determine the content and the composition of soil organic matter (SOM). Organic matter (OM) is characterized by functional groups, which preferentially interact with polyvalent cations and soil minerals. These interactions could perhaps explain the site‐specific composition of bulk SOM and a pyrophosphate‐soluble OM fraction (OM‐PY) using basic soil properties. The objective of this study was to test a simplified model for the interactions between OM and polyvalent cations (., Ca, Mg, Al, Fe, and Mn) by using data from soils from long‐term field experiments. The model considered (1) OM–cation, (2) OM–cation‐mineral, and (3) OM–mineral associations and assumed that the availability of the cation's coordination sites for the interaction with OM depends on these three types of associations. The test was carried out using data (topsoil) from differently fertilized plots from three long‐term field experiments (Halle, Bad Lauchstädt, Rotthalmünster). The composition of SOM and OM‐PY was characterized by the relationship of the ratio of the C=O (., here indicating both carbonylic and carboxylic groups) C–O–C absorption band intensities obtained from the Fourier transform infrared (FTIR) spectra with the content of exchangeable, oxalate‐, and dithionite‐extractable polyvalent cations. The assumed associations between the OM and cations and the availability of the coordination sites explained most of the variations in the C=O/C–O–C ratios of the SOM, and fewer variations in the OM‐PY, when using the site‐specific exchangeable and oxalate‐extractable cation contents. The C=O/C–O–C ratios of the OM‐PY were site‐independent for samples from plots that regularly received farmyard manure. The results suggested that a simplified model that considers the polyvalent cation content weighted by the number of coordination sites per cation according to the type of association could be used to improve the explanation of site‐specific differences in the OM composition of arable soils.
    Keywords: Cation Exchange Capacity ; Ftir ; Oxides ; Soluble Fraction
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 5
    Language: English
    In: Applied Soil Ecology, 2014, Vol.80, p.15(11)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.apsoil.2014.03.010 Byline: Rudiger Reichel, Diana Patzelt, Christoph Barleben, Ingrid Rosendahl, Ruth H. Ellerbrock, Soren Thiele-Bruhn Abstract: acents Influences of microhabitat on microbial status controls responses to antibiotics (SDZ). acents SDZ accumulates in earthworm burrows and at soil macroaggregates surfaces. acents Analogies of SDZ fate and effects were indicated among laboratory and field experiments. Author Affiliation: (a) Soil Science, Faculty of Regional and Environmental Sciences, University of Trier, Behringstra[sz]e 21, D-54286 Trier, Germany (b) Institute of Crop Science and Resource Conservation (INRES), Soil Science and Soil Ecology, University of Bonn, Nussallee 13, D-53115 Bonn, Germany (c) Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalder Stra[sz]e 84, D-15374 Muncheberg, Germany Article History: Received 17 June 2013; Revised 19 March 2014; Accepted 19 March 2014
    Keywords: Soil Ecology ; Sulfadiazine ; Soil Microbiology
    ISSN: 0929-1393
    Source: Cengage Learning, Inc.
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  • 6
    Language: English
    In: Soil & Tillage Research
    Description: In hummocky landscapes, soil erosion is forming truncated profiles at steep slope positions and colluvial soils in topographic depressions thereby affecting soil organic carbon (SOC) storage. However, the knowledge on the spatial distribution and composition of differently stable organic matter (OM) fractions in arable landscapes is still limited. Here, amount and composition of OM from top- and subsoil horizons at eroded, colluvic, and non-eroded slope positions were compared. The horizons were from a Luvisol at plateau (LV), an eroded Luvisol (eLV) at mid slope (6% slope gradient), a calcaric Regosol (caRG) at steep slope (13%), and a colluvic Regosol (coRG) at hollow position. Water soluble (OM-W) and pyrophosphate soluble (OM-PY) fractions were extracted sequentially. Soil samples, OM fractions, and extraction residues were analyzed with transmission Fourier transform infrared (FTIR) spectroscopy. The soluble fractions were 3% of SOC for OM-W and 15% of SOC for OM-PY. For topsoil samples, extraction rates were independent of slope position. The highest intensities of both, C H (alkyl groups) and C O (carboxyl groups) absorption band, were found in FTIR spectra of OM-PY from top and subsoil horizons at the steep slope position (caRG). The C H/C O ratio in OM-PY decreased with increasing contents of oxalate soluble Fe and Al oxides from steep slope (0.25 for caRG-Ap) towards plateau, and hollow position (0.09 for coRG-Ap) except for the Bt-horizons. This relation is reflecting that the downslope-deposited Ap material, which is higher in poorly crystalline Fe and Al oxides, consists of relatively stable OM. This OM is enriched in C O groups that are known for their interaction with soil minerals. These OM-mineral interactions may help explaining C storage in arable soil landscapes.
    Keywords: Pyrophosphate Soluble Organic Matter Fraction ; Fourier Transform Infrared Spectroscopy ; Soil Landscape ; Colluvial Soil ; Truncated Profile ; Oxalate Soluble Iron ; Agriculture
    ISSN: 0167-1987
    E-ISSN: 1879-3444
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  • 7
    Language: English
    In: Journal of Plant Nutrition and Soil Science, February 2016, Vol.179(1), pp.29-38
    Description: 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 (, glacial till 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 (, wavenumbers 2000 to 1700 cm). 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 (, cation exchange capacity) of hot spots in structured soils.
    Keywords: Drift ; Transmission Ftir ; Coatings ; Intact Surfaces ; Ash Correction ; Spectral Subtraction
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 8
    Language: English
    In: Advances in agronomy, 2013, Vol.121, pp.117-177
    Description: Surfaces of macropores in structured soils can made of clay-organic coatings on soil aggregates or linings on worm burrow or root channel walls. The outermost layer of such surfaces is mostly covered by organic matter (OM), which finally controls sorption properties that are relevant for preferential flow and transport. However, the OM properties and local distributions along flow path surfaces are largely unknown, and methods for analyzing intact surfaces are limited. This chapter reviews the principles and applications of Fourier Transform infrared (FTIR) spectroscopy in comparison with complementary nuclear magnetic resonance technique; it describes FTIR techniques for analyzing the composition of bulk soil OM and of OM fractions and of the millimeter-scale spatial distribution at intact surfaces in structured soils for comparing OM composition with cation exchange capacity of OM and soil wettability. Maps of the millimeter-scale heterogeneous spatial distribution of OM composition at aggregate and burrow surfaces could be obtained with diffuse reflectance FTIR (DRIFT) mapping technique. The distribution of OM composition suggests that sorption properties of the OM and wettability of macropore surfaces are also spatially variable at this local scale. DRIFT mapping technique requires relatively smooth and fine-textured intact sample surfaces; further developments need to account for effects of microtopography on the scattering of infrared light. The results indicate yet unknown implications for preferential flow and transport in structured soil, especially for reactive solutes. ; p. 117-177.
    Keywords: Sorption ; Cation Exchange Capacity ; Microrelief ; Solutes ; Organic Matter ; Soil Aggregates ; Preferential Flow ; Root Channels ; Burrows ; Wettability ; Coatings ; Macropores ; Reflectance ; Nuclear Magnetic Resonance Spectroscopy ; Fourier Transform Infrared Spectroscopy
    ISSN: 0065-2113
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 9
    Language: English
    In: Journal of Hydrology and Hydromechanics, 01 June 2016, Vol.64(2), pp.111-120
    Description: 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...
    Keywords: Aggregates ; Clay and Organic Matter Coatings ; Wdpt ; Contact Angle ; Drift Spectroscopy ; Geography
    E-ISSN: 0042-790X
    E-ISSN: 13384333
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  • 10
    Language: English
    In: International agrophysics, 2015, Vol.29(2), pp.247-255
    Description: Anaerobic digestates are used as organic fertilizers; however, they are suspected to interfere negatively with soils. To investigate the relevance of the anaerobic digestates composition on potential wettability and contact angle of the soil, we mixed in a laboratory experiment 30 m³ ha⁻¹ of anaerobic digestates derived from mechanically pre-treated substrates from maize and sugar beet with a homogenized Cambic Luvisol. Fourier transform infrared-spectra and diffuse reflectance infrared Fourier transform-spectra of particle intact and finely ground soilanaerobic digestates-mixtures were analyzed to determine the quantities of hydrophobic functional groups in the soil-anaerobic digestates-mixtures that are used here as an indicator for the potential hydrophobicity. The anaerobic digestates application increased the amount of hydrophobic functional groups of the mixtures and reduced the wettability of the soil. However, for intact particle samples an up to threefold higher amount of hydrophobic groups was found as compared to the finely ground ones, indicating a dilution effect of mechanical grinding on the effectivity of the organic matter that is presumably located as a coating on mineral soil particles. For the particle intact samples, the intensity of hydrophobic functional groups bands denoting hydrophobic brickstones in organic matter is indicative for the actual wettability of the soil-anaerobic digestates-mixtures. ; p. 247-255.
    Keywords: Anaerobic Digestates ; Luvisols ; Organic Fertilizers ; Mineral Soils ; Organic Matter ; Grinding ; Contact Angle ; Corn ; Water Repellent Soils ; Soil Water ; Sugar Beet ; Wettability ; Organic Matter Composition ; Coatings ; Hydrophobicity ; Reflectance ; Diffuse Reflectance Infrared Fourier Transform Spectroscopy ; Fourier Transform Infrared Spectroscopy
    ISSN: 2300-8725
    ISSN: 02368722
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