MOVEMENT OF SOIL MOISTURE FROM SMALL CAPIL¬ 
LARIES TO THE LARGE CAPILLARIES OF THE SOIL 
UPON FREEZING* 
By Gsorgb John Bouyoucos 
Research Professor in Soils, Michigan Agricultural Expefiment Station 
INTRODUCTION 
In conducting various studies upon the temperature^ and freezing- 
point lowering* of soils, many evidences have obtained whidi in<S- 
cate that the moisture of the soil upon freezing moves from the small 
capillaries, and probably also from around the particles as thick films, 
into the larger capillaries of the soil. This accumulation of the soil 
moisture in ^e large capillaries takes place especially when the moisture 
content of the soil is low. When the moisture content is high and under 
proper conditions the water accumulates as ice capillary columns at the 
top of the soil surfaces. These results are of considerable interest and 
importance as they bear on many soil-water relationships, such as the 
unfree water, available water, freezing-point lowering, vapor-pressure 
lowering, rate of evaporation, capillary movement, osmotic pressure, aud 
perhaps others. 
EXPERIMENTAL EVIDENCES 
In measuring the freezing-point lowering of soils at low moisture con¬ 
tent, it was found that upon repeated freezing and thawing the lowering 
of the freezing point diminished greatly. But upon stirring the soil, 
even gently, the freezing-point lowering would go back to the original 
magmtude. If the soil was again subjected to alternate freezing and 
thawing, the freezing-point lowering would again diminish, and if it was 
stirred the lowering of the freezing point would become as before. This 
process could be continued almost indefinitely with practically the same 
results. Allowing the soil to stand after it was frozen and thawed several 
times tended to have somewhat the same effect as stirring, that is, it 
tended to restore the freezing-point depression to the original magnitude. 
In Table I the results in the case of two soils which will serve as t3rpical 
examples of the phenomena in question are presented. 
1 Accepted for publication Aug. 15, 1922. 
* Bouyoucos, George J. son. temperature. Mich. Agr. Exp. Sta. Tech. Bui. 26,133 p. 1916. 
* Bouyoucos, George J. and McCool, M. M. further studies on the freezing point lowering 
OF SOILS. Mich. Agr. Exp. Sta. Tech. Bui. 31, 51 p., x fig. 1916. Bibliographical footnotes. 
Vol. XXIV. No. s 
May 5,1923 
Key No. Mich.-i3 
Journal <rf Agricultural Research, 
Washington, D. C. 
^idt 
(427) 
