Experiment Station Record, Volume 39, July-December, 1918 Page: 19
xxix, 1002 p. ; 24 cm.View a full description of this book.
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1918.] SOILS-FERTILIZERS. 19
it increased from the coarse-textured or noncolloidal to the fine-textured or
colloidal classes of soil. In soils frozen and thawled several times and finally
supercooled to -4 and also cooled in -78 the amount of water which failed
to freeze varied from 0 cc. in quartz sand to about 2 cc. in some clays, or from
0 to 40 per cent of the amount of water added, or from 0 to 12.5 per cent on the
absolute dry basis. It also increased from the coarse-textured to the finetextured
classes of soil. "The results at these temperatures are the same as
those at the temperature of -1.5 with two important exceptions: First, the
amount of water which failed to freeze at the temperature of --4 and -78
is considerably smaller than that at the temperature of -1.5 . . . Second,
the relative amounts of water which refused to freeze at the two sets of temperatures
are not the same in the various soils." In artificial substances the
amount of water that failed to freeze varied from 0 per cent in quartz sand
to 2 per cent in lampblack, to 32 per cent in silica, and to 60 per cent in peat,
on the absolute dry basis.
"'When the amount of water which freezes and does not freeze at the various
temperatures is classified into free, capillary-adsorbed, and combined, by the
method described, it is found that the water in the soil does exist in these forms
and that the amount of these forms varies tremendously in the various soils."
In the sands and fine sandy loams the free water predominates, amounting in
some cases to about 95 per cent of the total water present, and the other 5 per
cent consisting as a rule of combined water, capillary-adsorbed water apparently
not being present in these classes of soil. In the loams and silt loams the free
and combined water predominates, capillary-adsorbed water being present in
small amounts. In some of the heavy loams all three forms were about equally
distributed. In clay loams, humus loams, and clay, combined water predominated,
followed by capillary-adsorbed and free. "Although the amount of free
water tends to decrease and the amount of the capillary-adsorbed and combined
water tends to increase correspondingly as the soils ascend from the simple
and noncolloidal to the complex and colloidal classes there are many exceptions
to this rule.
" The amount of water which fails to freeze is not influenced by the moisture
content present if the soils are frozen and thawed several times before the final
determination is made. If the determination is made at the first freezing then
the amount of water which fails to freeze is much greater at the low than at
the high moisture content. This is true, however, only in the fine-textured or
colloidal and not in the coarse-textured or noncolloidal types of soil. Repeated
freezing and thawing decreases the amount of water which fails to freeze in
the case of the fine-textured or colloidal soils. This is true, however, only at
a low and not at a high moisture content. The results of the coarse or noncolloidal
soils remain unaffected at both the high and low moisture content.
The degree of supercooling, up to a certain point, influences to a slight extent
the amount of water which refuses to freeze. This is particularly true in the
heavier classes of soil. Cooling the soil at the temperature of -78 causes
very little if any additional water to freeze above that which freezes at the
temperature of -4. The only substances in which the additional amount is
considerable are lampblack, animal charcoal, and silica.
" Small concentration of the soil solution affects the amount of water which
fails to freeze very little, if any. Great concentration, however, affects it
greatly. The concentration of the solution of normal soils is too small to affect
it to any measurable extent.
"There is no correlation between the factor of the amount of water which
fails to freeze and the moisture content of soils known as wilting coefficient
and moisture equivalent, in degree, but there is in order. The same is more or
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General Index to Experiment Station Record, Volumes 26-40, 1912-1919 (Book)
A topical, alphabetically arranged index to volumes 26-40 including experiment station records, publications reviewed, and foreign publications. In has a 'Consolidated Table of Contents' which lists all editorial notes and publications of the experiment stations and Department of Agriculture from the referenced volumes.
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United States. Office of Experiment Stations. Experiment Station Record, Volume 39, July-December, 1918, book, 1919; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc5015/m1/48/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.