<abstract xmlns="http://www.w3.org/1999/xhtml"><p> Hydrophobicity is a property of soils that reduces their affinity for water, which may help impeding the pressure build-up within aggregates, and reducing aggregate disruption. The purpose of this study was to examine the relation of soil hydrophobicity and drying temperature to water stability of aggregates while preventing the floating of dry aggregates using unhydrophobized and hydrophobized surface Andisol. Soil was hydrophobized using stearic acid into different hydrophobicities. Hydrophobicity was determined using sessile drop contact angle and water drop penetration time (WDPT). Water stability of aggregates (%WSA) was determined using artificially prepared model aggregates. The %WSA increased as the contact angle and WDPT increased. Contact angle and WDPT, which provided maximum %WSA showing less than 1 s of floating, was around 100° and 5 s, respectively. Although the %WSA gradually increased with increasing contact angle and WDPT above this level, high levels of hydrophobicity initiated aggregate floating, which would cause undesirable effects of water repellency. Heating at 50°C for 5 h d<sup>-1</sup> significantly affected %WSA and hydrophobicity in hydrophobized samples, but did not in unhydrophobized samples. The results indicate that the contact angle and wetting rate (WDPT) are closely related with the water stability of aggregates. The results further confirm that high levels of hydrophobicities induce aggregate floating, and the drying temperature has differential effects on hydrophobicity and aggregate stability depending on the hydrophobic materials present in the soil.</p></abstract>

Hydrophobicity is a property of soils that reduces their affinity for water, which may help impeding the pressure build-up within aggregates, and reducing aggregate disruption. The purpose of this study was to examine the relation of soil hydrophobicity and drying temperature to water stability of aggregates while preventing the floating of dry aggregates using unhydrophobized and hydrophobized surface Andisol. Soil was hydrophobized using stearic acid into different hydrophobicities. Hydrophobicity was determined using sessile drop contact angle and water drop penetration time (WDPT). Water stability of aggregates (%WSA) was determined using artificially prepared model aggregates. The %WSA increased as the contact angle and WDPT increased. Contact angle and WDPT, which provided maximum %WSA showing less than 1 s of floating, was around 100° and 5 s, respectively. Although the %WSA gradually increased with increasing contact angle and WDPT above this level, high levels of hydrophobicity initiated aggregate floating, which would cause undesirable effects of water repellency. Heating at 50°C for 5 h d-1 significantly affected %WSA and hydrophobicity in hydrophobized samples, but did not in unhydrophobized samples. The results indicate that the contact angle and wetting rate (WDPT) are closely related with the water stability of aggregates. The results further confirm that high levels of hydrophobicities induce aggregate floating, and the drying temperature has differential effects on hydrophobicity and aggregate stability depending on the hydrophobic materials present in the soil.

Water stable aggregates of Japanese Andisol as affected by hydrophobicity and drying temperature

Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya, Sri Lanka

Faculty of Agriculture, Ibaraki University, 3-21-1 Chuo, Ami-machi, Ibaraki-ken 300-0393, Japan

Journal of Hydrology and Hydromechanics

Hydrophobicity is a property of soils that reduces their affinity for water, which may help impeding the pressure build-up within aggregates, and reducing...

Water stable aggregates of Japanese Andisol as affected by hydrophobicity and drying temperature

Published Online: Apr 04, 2014

Page range: 97 - 100

DOI: https://doi.org/10.2478/johh-2014-0019

Keywords
Aggregate stability, Contact angle, Floating time, Japanese Andisol, Hydrophobicity, Wetting rate

This content is open access.

Water stable aggregates of Japanese Andisol as affected by hydrophobicity and drying temperature

Published Online: Apr 04, 2014

Page range: 97 - 100

DOI: https://doi.org/10.2478/johh-2014-0019

KeywordsAggregate stability, Contact angle, Floating time, Japanese Andisol, Hydrophobicity, Wetting rate

This content is open access.

Keywords
Aggregate stability, Contact angle, Floating time, Japanese Andisol, Hydrophobicity, Wetting rate