JOOMAL OFACRIIMIRALESEMH 
Vol. XIV Washington, D. C., September 9, 1918 No. 11 
VARIATIONS IN THE MOISTURE CONTENT OF THE 
SURFACE FOOT OF A LOESS SOIL AS RELATED TO 
THE HYGROSCOPIC COEFFICIENT 1 
By Frederick J. Alway, Chief of Division of Soils, and Guy R. McDole, Assistant in 
Soils, Minnesota Agricultural Experiment Station 
INTRODUCTION 
In this paper we report a study of the variations in moistness of the 
various inch sections of the surface foot of soil in some fields near Lincoln, 
Nebr., during seasons which were exceptionally favorable to the develop¬ 
ment of both the driest and the moistest conditions ordinarily encountered 
there. 
The moisture content of the soil may be reported as either the total 
amount present, the free water—the difference between the total water 
and the hygroscopic coefficient, the growth water—the difference be¬ 
tween the total water and the wilting coefficient, the latter value being 
computed from the moisture equivalent, the hygroscopic coefficient, or 
some other physical constant (6, p. 72)*— or, as in the present paper, in a 
form which makes evident the relative moistness of the soil, as well as 
all the above-mentioned values, by stating both the hygroscopic coef¬ 
ficient and the relation of the moisture content to this. 3 Thus, the 
expression 10 X 1.7 would indicate a total moisture content of 17.0 #- 
per cent, a wilting coefficient of 15.0, 4 7.0 per cent of free water, and 2.0 
per cent of growth water. 
Variations in the moisture content of the surface soil might be expected 
to increase in importance with increasing humidity of climate, but even 
in arid regions on lands with the water table far below the surface any 
important changes in the moistness of the subsoil, other than reductions 
effected by plant roots or by percolation, appear to be almost entirely 
dependent upon preceding changes in the moisture content of the sur¬ 
face stratum of soil (2), which for the purposes of the present discussion 
we may consider to extend to a depth of 12 inches. 
1 The work reported in this paper was carried out in 1910 and 1912 at the Nebraska Agricultural Ex¬ 
periment Station, where the authors were, respectively, Chemist and Research Assistant in Chemistry. 
2 References made by number (italic) to “ Literature cited,” p. 480. 
* Alway, F. J., McDole, G. R., and Trumbull, R. S. relation op the minimum moisture content 
OP THE subsoil OP prairies To THE hygroscopic coeppicient, To be published in Botanical Gazette. 
4 14.7, to be exact. 
Vol. XIV, No. 11 
Sept. 9, 1918 
Key No. Nebr.-a 
Journal of Agricultural Research, 
Washington, D. C. 
pe 
(453) 
