DRIFT Mapping of Organic Matter Composition at Intact Soil Aggregate Surfaces

Leue, Martin; Ellerbrock, Ruth H.; Gerke, Horst H.

doi:10.2136/vzj2009.0101

Cited by 69 publications

(88 citation statements)

References 66 publications

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“…Droplet infiltration tests were performed at the intact aggregates according to Leue (2010) using a CA device coupled with a 1 mL syringe and a high-speed camera (OCA 20, DataPhysics, Filderstadt, Germany; Hamilton, Reno, Nevada). Penetration of the water drop of 6.3 µL volume was recorded at a rate of 500 frames per second (i.e., 500 Hz).…”

Section: Water Drop Penetration Time and Contact Angle Measurementmentioning

confidence: 99%

“…DRIFT spectroscopy was carried out on selected circular spots of about 1.5 mm 2 in size at the aggregate surfaces as described previously (e.g., Ellerbrock et al, 2009;Leue et al, 2010). Briefly, the DRIFT spectra were recorded by 16 coadded scans between wave numbers (WN) 4000 and 400 cm −1 at a resolution of 4 cm −1 using a gold target as the background (99% Infragold©, Labsphere, North Sutton, NH, USA).…”

Section: Drift Spectroscopymentioning

confidence: 99%

“…The blocks were transported within 1 day to the laboratory and stored in a refrigerator until analyzed. Individual aggregates were manually separated by carefully breaking the blocks according to the criteria that the samples should have at least two relatively plane intact sides with coated or uncoated surfaces (c.f., Leue et al, 2010Leue et al, , 2015. Some of the aggregates, and their selected side coatings, were cut by a scalpel to study the characteristics of the aggregate interior (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors

Fér

Leue

Kodešová

et al. 2016

Journal of Hydrology and Hydromechanics

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Abstract: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.

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Section: Water Drop Penetration Time and Contact Angle Measurementmentioning

confidence: 99%

Section: Drift Spectroscopymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors

Fér

Leue

Kodešová

et al. 2016

Journal of Hydrology and Hydromechanics

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“…The majority of SOM utilized by soil microbes, the former both as large individual particles and more finely disseminated material associated with minerals, occurs both on the surfaces of, and within, soil aggregates (Leue et al, 2010). In controlled laboratory experiments, the magnitude of SHR has been shown to vary considerably between soil aggregates .…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional soil organic matter distribution, accessibility and microbial respiration in macroaggregates using osmium staining and synchrotron X-ray computed tomography

Rawlins

Wragg

Reinhard

et al. 2016

SOIL

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Abstract. The spatial distribution and accessibility of organic matter (OM) to soil microbes in aggregatesdetermined by the fine-scale, 3-D distribution of OM, pores and mineral phases -may be an important control on the magnitude of soil heterotrophic respiration (SHR). Attempts to model SHR on fine scales requires data on the transition probabilities between adjacent pore space and soil OM, a measure of microbial accessibility to the latter. We used a combination of osmium staining and synchrotron X-ray computed tomography (CT) to determine the 3-D (voxel) distribution of these three phases (scale 6.6 µm) throughout nine aggregates taken from a single soil core (range of organic carbon (OC) concentrations: 4.2-7.7 %). Prior to the synchrotron analyses we had measured the magnitude of SHR for each aggregate over 24 h under controlled conditions (moisture content and temperature). We test the hypothesis that larger magnitudes of SHR will be observed in aggregates with (i) shorter length scales of OM variation (more aerobic microsites) and (ii) larger transition probabilities between OM and pore voxels.After scaling to their OC concentrations, there was a 6-fold variation in the magnitude of SHR for the nine aggregates. The distribution of pore diameters and tortuosity index values for pore branches was similar for each of the nine aggregates. The Pearson correlation between aggregate surface area (normalized by aggregate volume) and normalized headspace C gas concentration was both positive and reasonably large (r = 0.44), suggesting that the former may be a factor that influences SHR. The overall transition probabilities between OM and pore voxels were between 0.07 and 0.17, smaller than those used in previous simulation studies. We computed the length scales over which OM, pore and mineral phases vary within each aggregate using 3-D indicator variograms. The median range of models fitted to variograms of OM varied between 38 and 175 µm and was generally larger than the other two phases within each aggregate, but in general variogram models had ranges < 250 µm. There was no evidence to support the hypotheses concerning scales of variation in OM and magnitude of SHR; the linear correlation was 0.01. There was weak evidence to suggest a statistical relationship between voxel-based OM-pore transition probabilities and the magnitudes of aggregate SHR (r = 0.12). We discuss how our analyses could be extended and suggest improvements to the approach we used.

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“…Soil organic matter (OM) consists of amphiphilic components; therefore, Negre et al (2002) linked the ability of water to spread on a soil surface to the macromolecular composition of OM. In consequence, the wetting behaviour of soils may change with the content and composition of OM coatings on mineral particle surfaces (Leue et al, 2010) as well as the spatial arrangement of OM compounds at the molecular scale (Morrison and Boyd, 1983). Spectroscopic techniques like Fourier transmission infrared (FTIR) and diffuse reflection infrared Fourier transform (DRIFT) spectroscopy have been widely used to characterize the composition of functional groups in soil organic matter (SOM) (Capriel et al, 1995;Gerzabek et al, 1997;Tatzber et al, 2007) and at intact aggregate surfaces (Leue et al, 2010) in order to determine the potential wettability of OM.…”

Section: Introductionmentioning

confidence: 99%

Quantity of Hydrophobic Functional CH-Groups – Decisive for Soil Water Repellency Caused by Digestate Amendment

Voelkner¹,

Holthusen²,

Ellerbrock³

et al. 2015

International Agrophysics

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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.

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DRIFT Mapping of Organic Matter Composition at Intact Soil Aggregate Surfaces

Cited by 69 publications

References 66 publications

Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors

Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors

Three-dimensional soil organic matter distribution, accessibility and microbial respiration in macroaggregates using osmium staining and synchrotron X-ray computed tomography

Quantity of Hydrophobic Functional CH-Groups – Decisive for Soil Water Repellency Caused by Digestate Amendment

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