Apr. 9,1917 
Water-Retaining Capacity of Soil 
55 
The coarse sand exerts a retarding influence upon the movement of 
moisture through its own mass as well as upon that from overlying layers 
of finer texture. 
The similarity in conduct of the soils with hygroscopic coefficients 
between 3.3 and 13.3 and the entirely different behavior of the sand with 
one of 0.6 make the conduct of the soils with values between 0.6 and 3.3 
of great interest. As we included no representatives of these in the 
laboratory experiments, our conclusions in regard to them are based only 
upon field studies (p. 64). 
RATIOS FOUND IN FIELD STUDIES 
The published data on the total moisture content of soils of almost 
every degree of coarseness or fineness of texture, and determined under 
all kinds of weather, crop, and tillage conditions, are almost innumerable; 
but, as almost none of these are accompanied by statements of the hygro¬ 
scopic coefficients of the samples or of any physical constants which 
would permit the calculation of these (8, p. 56; 6, p. 842; 4, p. 351), 
the data do not admit of testing the generalizations drawn from the 
above-described laboratory experiments. Occasionally an author has 
made such determinations on a few of the samples and then assumed 
that the subsoils were so uniform that these would apply to all. This 
assumption is correct in only exceptional places, and even then it should 
be first experimentally justified instead of the question being merely 
glossed over by the statement that the soils are characterized by great 
uniformity. For this reason we have to confine ourselves to our own 
field studies, carried out between 1907 and 1913 and as yet unpublished. 
All of these, we hope, will soon appear in another paper. As the deter¬ 
minations of the water content of each of the field samples was followed 
by one of the hygroscopic coefficient, the ratios are available in each case. 
In most instances the subsoil moisture had been more or less exhausted 
by plant roots and showed a ratio of between 1.0 and 1.5; such data are 
not of interest in the present study. 
Our data on soils with hygroscopic coefficients lying between 3.0 and 
14.0 are very numerous; those on the sands with a coefficient below 1.0 
limited; and those on fine sands with coefficients between 3.0 and 1.1 
very scanty. Of the first group we select only some worked out in the 
most detail. 
It is scarcely permissible to compare the ratios of the final water con¬ 
tent to the moisture equivalent, unless the latter value has been directly 
determined in the case of the samples in question, because the relation 
of this constant to the hygroscopic coefficient is quite variable (6, p. 845). 
A.— Coarse sands. —Our data from field studies of the moisture in 
coarse sands are not numerous, but what we have are in accord with the 
results of the cylinder experiments. Table XX shows the conditions in 
the Nebraska sand hills in 1911 and 1912. Alternating hilltops and 
