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Porosity of Surface Soil Aggregates at Various Moisture Contents
Author(s) -
Voorhees W. B.,
Allmaras R. R.,
Larson W. E.
Publication year - 1966
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1966.03615995003000020009x
Subject(s) - porosity , water content , saturation (graph theory) , moisture , chernozem , aggregate (composite) , soil water , volume (thermodynamics) , materials science , mineralogy , soil science , shrinkage , bulk density , composite material , chemistry , environmental science , geotechnical engineering , geology , mathematics , physics , combinatorics , quantum mechanics
Porosity of individual surface soil aggregates at moisture contents ranging from saturation to air‐dry was determined by glass bead displacement. Measurements were made on aggregates having a diameter range from 0.5 to 10 mm at air‐dry moisture content and 2.0 to 10 mm at suctions ≤ 15 bars. The coefficient of variation for a determination of aggregate density (g cm ‐3 ) ranged from 1 to 11% depending on diameter and moisture content. The major contributor to precision loss was heterogeneity of soil aggregates and not precision errors of the method. More than a 50% decrease in specific total pore volume (cm 3 g ‐1 of oven‐dry aggregate) upon desorption from saturation to air‐dry was found for three aggregate sizes each from a Chernozem and a Chestnut soil. In both soils, the percentage of pores having diameters > 29 µ increased as aggregate diameter increased. The volume fraction of air at a given moisture content increased as the diameter of aggregate increased. For all aggregate sizes, the volume fraction of air was ≥ 0.10 at 0.33 bar suction. The two soils exhibited different types of shrinkage curves.