95-3 Hydrophobic Soils: Exploring the Mechanism for Reversible Hydrophobicity.

Poster Number 905

See more from this Division: S01 Soil Physics
See more from this Session: Soil Change: Characterization and Modeling Across Scales: II
Monday, November 1, 2010
Long Beach Convention Center, Exhibit Hall BC, Lower Level
Share |

Priscilla Woolverton, Maria Ines Dragila and Markus Kleber, Oregon State University, Corvallis, OR
Arable soils can develop seasonal hydrophobic properties. Current models, for hydrophobic organic matter (OM) on soil particles, do not explain soil wetting behavior reversibility. We present a new conceptual model for OM structure which describes moisture dependant hydrophobicity. Dynamic contact angles (CA) of soil samples were correlated with water content (WC) and grower-observed lower crop productivity. Data fell into two distinct groups: (1) higher WC, lower CA, less degraded; (2) lower WC, higher CA, more degraded. High CA soils had more total organic carbon (TOC). The zonal model for OM identifies mineral surface OM that consists of amphiphilic molecules which screen non-polar functional groups from the soil solution. Amphiphilic compounds change their orientation exposing the hydrophobic layer as soil dries. This mechanical hydrophobicity is reversible with addition of soil moisture. This model is supported by successful demonstration that the CA is determined by two parameters: soil WC; soil OM.
See more from this Division: S01 Soil Physics
See more from this Session: Soil Change: Characterization and Modeling Across Scales: II