Direct observation of soil water movement through soil macropores using soft X-rays. (5888)
Authors:
K. Iwama* - Univ. of Shiga Prefecture K. Yabe - Univ. of Shiga Prefecture
T. Maruyama - Ishikawa Agricultural College
Abstract:
Although non-equilibrium or preferential flow in soils is important for soil science, it is difficult to analyze because of the complexity of the macropores, which we cannot directly observed. In this study, flow in soil was observed directly and recorded on videotape using soft X-ray technology with a liquid contrast agent (CH2I2) after saturating the soil samples with water and keeping the water head to drive the agent. Quantitative analyses about the movement of soil water occurred in undisturbed clayey paddy soils and sandy soils were carried out. The following results are obtained: (1) many tubular macropores which connected each other were monitored in the paddy soil samples and the constant agent in them moved
irregularly, (2) the courses of agent in sandy soil samples became irregular shapes and moved randomly, (3) various permeabilities of soil were calculated using the diameters of the dominant macropores and actual velocities from X-ray movies.
The permeability was compared with the permeability tested independently by the constant head method. The differences were significant.
Speaker Information: Kenji Iwama, Univ. of Shiga Prefecture, 2500 Hassaka, Hikone, Sh 522-8533; Phone: +81-749-28-8324; E-mail: [email protected]
Session Information: Wednesday, November 3, 2004, 4:00 PM-6:00 PM Presentation Start: 4:00 PM (Poster Board Number: 2801)
Keywords: soil water movement; pore network; soft X-ray; hydraulic conductivity
