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The Adequacy of Pressure Plate Apparatus for Determining Soil Water Retention.

Authors :
Cresswell, H. P.
Green, T. W.
McKenzie, N. J.
Source :
Soil Science Society of America Journal. Jan/Feb2008, Vol. 72 Issue 1, p41-49. 9p. 1 Diagram, 4 Charts.
Publication Year :
2008

Abstract

This study evaluated the accuracy of pressure plate apparatus for measuring soil water retention at -0.5 and -1.5 MPa matric potential. Samples from 35 contrasting Australian soils were wetted with distilled water and drained on pressure plate apparatus at -0.5 and -1.5 MPa. The soil matric potential of each sample was then determined using a thermocouple psychrometer, and water content was measured. Water content at exactly -0.5 and -1.5 MPa matric potential was determined independently by interpolating between replicates of matric potential-water content data measured using a thermocouple psychrometer. Water content of the soil samples at apparent equilibrium on pressure plates was compared with these "target" water contents. The 35 samples on pressure plates at -1.5 MPa equilibrated, on average, to 0.3% (w/w) wetter than the target water content, with mean matric potential of-i .10 MPa. Fifteen samples were significantly wetter than the target values. Soil samples on pressure plates at -0.5 MPa equilibrated, on average, to 0.2% (w/w) wetter than the target water content, attaining a mean matric potential of -0.48 MPa. Mean error in water content at -1.5 MPa on pressure plates was reduced from >0.5 to <0.1% (w/w) in a subset of 10 samples prone to dispersion by wetting with 0.01 mol L-1 CaCI2. Water contents of samples equilibrated on pressure plates at -1.5 MPa were good estimates of "true" -1.5 MPa water content for the nonswelling soils tested, provided CaCI2 was used to minimize dispersion. Vapor equilibrium measurement methods are recommended for swelling soils. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
03615995
Volume :
72
Issue :
1
Database :
Academic Search Index
Journal :
Soil Science Society of America Journal
Publication Type :
Academic Journal
Accession number :
32149772
Full Text :
https://doi.org/10.2136/sssaj2006.0182