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United States Department of Agriculture

Agricultural Research Service

Title: Probe Microphone Instrumentation for Determining Soil Physical Properties

Authors
item Sabatier, Jim - UNIV OF MISSISSIPPI
item Sokol, D - UNIV OF MISSISSIPPI
item Frederickson, C - UNIV OF MISSISSIPPI
item Romkens, Mathias
item Grissinger, Earl - COLLABORATOR - ARS
item Shipps, J - NOISE CANC. TECHN. INC.

Submitted to: Soil Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 16, 1995
Publication Date: N/A

Interpretive Summary: Sound wave absorption by porous media such as soil is a functino of soil characteristics such as porosity, pore size distribution, pore tortuosity and of sound wave characteristics such as frequency. The degree of sound absorption may serve as an indicator of the magnitude of these physical properties. In this paper, a probe and a procedure are described, which allows the accurate determination of sound waves in the upper part (0-10 cm) of the soil profile. The procedure, which is complemented with a theoretical discussion of sound wave propagation into porous media, allows the determination of important of flow resistivity. This property is related to permeability, which in turn determines infiltration and other transport processes into the soil profile.

Technical Abstract: An acoustic technique for evaluating soil physical properties is described. A probe microphone is used to measure the acoustic signal attenuation and phase speed. Emphasis is on the probe construction, insertion in soils and reduction of acoustic data to predict tortuosity and an effective air-flow resistivity of the soil. Well-known capillary-tube models of porus materials which incorporate these two porus material properties are used to invert the acoustic data. The probe microphone, associated hardware, data acquisition and analyses are implemented on a personal computer. The system can provide real time prediction of the soil properties in the field. Measurements in three materials: glass beads, washed sand and loess soil are analyzed and discussed

Last Modified: 7/28/2014
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