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

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...

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Main Authors: Fér Miroslav, Leue Martin, Kodešová Radka, Gerke Horst H., Ellerbrock Ruth H.
Format: Article
Language:English
Published: Sciendo 2016-06-01
Series:Journal of Hydrology and Hydromechanics
Subjects:
Online Access:https://doi.org/10.1515/johh-2016-0021
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spelling doaj-8a85a44571f94e4da40f2a6a3925676c2021-09-06T19:40:47ZengSciendoJournal of Hydrology and Hydromechanics0042-790X2016-06-0164211112010.1515/johh-2016-0021johh-2016-0021Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiorsFér Miroslav0Leue Martin1Kodešová Radka2Gerke Horst H.3Ellerbrock Ruth H.4 Czech University of Life Sciences Prague, Faculty of Agrobiology, Food and Natural Resources, Dept. of Soil Science and Soil Protection, Kamýcká 129, CZ-16521 Prague 6, Czech Republic. Leibniz-Centre for Agricultural Landscape Research (ZALF), Institute of Soil Landscape Research, Eberswalder Straße 84, Müncheberg, 15374, Germany. Czech University of Life Sciences Prague, Faculty of Agrobiology, Food and Natural Resources, Dept. of Soil Science and Soil Protection, Kamýcká 129, CZ-16521 Prague 6, Czech Republic. Leibniz-Centre for Agricultural Landscape Research (ZALF), Institute of Soil Landscape Research, Eberswalder Straße 84, Müncheberg, 15374, Germany. Leibniz-Centre for Agricultural Landscape Research (ZALF), Institute of Soil Landscape Research, Eberswalder Straße 84, Müncheberg, 15374, Germany.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 (R2 = 0.75). The a parameter was significantly related to the WDPT (R2 = 0.84) and to the PWI (R2 = 0.64). The relations between the b parameter and the WDPT (R2 = 0.61) and the PWI (R2 = 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 (R2 = 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.https://doi.org/10.1515/johh-2016-0021aggregatesclay and organic matter coatingswdptcontact angledrift spectroscopy
collection DOAJ
language English
format Article
sources DOAJ
author Fér Miroslav
Leue Martin
Kodešová Radka
Gerke Horst H.
Ellerbrock Ruth H.
spellingShingle Fér Miroslav
Leue Martin
Kodešová Radka
Gerke Horst H.
Ellerbrock Ruth H.
Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors
Journal of Hydrology and Hydromechanics
aggregates
clay and organic matter coatings
wdpt
contact angle
drift spectroscopy
author_facet Fér Miroslav
Leue Martin
Kodešová Radka
Gerke Horst H.
Ellerbrock Ruth H.
author_sort Fér Miroslav
title Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors
title_short Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors
title_full Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors
title_fullStr Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors
title_full_unstemmed Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors
title_sort droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors
publisher Sciendo
series Journal of Hydrology and Hydromechanics
issn 0042-790X
publishDate 2016-06-01
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 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 (R2 = 0.75). The a parameter was significantly related to the WDPT (R2 = 0.84) and to the PWI (R2 = 0.64). The relations between the b parameter and the WDPT (R2 = 0.61) and the PWI (R2 = 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 (R2 = 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.
topic aggregates
clay and organic matter coatings
wdpt
contact angle
drift spectroscopy
url https://doi.org/10.1515/johh-2016-0021
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