The Storage and Use of Soil Moisture 
13 
From Table 1 we note that the soil has a low per cent of all 
material coarser than very line sand. This, with the low per 
cent of organic matter, would indicate that the soil would bake 
or crust badly. However, the soil is easily tilled, this being due 
probably to the correspondingly low per cent of clay and the 
comparatively large per cent of very fine sand. Little trouble 
has been experienced with the soil baking or crusting badly ex- 
cept in the spring of 1912. After the melting of the heavy snow 
late in the spring of 1912, the soil crusted badly and cracked to 
a depth of several inches. 
In considering the work given in this bulletin, it is important 
that one should not lose sight of the character of the soil on 
which the work was done. It is not probable that the same re- 
sults will be obtained upon soils of widely different character. 
DEPTH OF SAMPLING. 
When the work was started, samples were taken to a depth 
of only three feet. As the work progressed, longer tubes for 
sampling were procured, until samples were taken to a depth of 
fifteen feet. The reason for the deeper sampling was to find a 
point where the moisture content remains constant, where it 
would not be affected by the tillage or by growing crops. It was 
necessary to do this deeper sampling in order to determine how 
far the moisture from the surface would move downward, and 
whether water left in the soil below the reach of the crops for 
one season might not move upward into the feeding zone of the 
following crop. We have found from a large number of samp- 
lings that frequent deep sampling is not necessary on this "hard" 
land, under continuous cropping, except during seasons of 
abnormally frequent and heavy rains. The available water is 
confined to a few feet of soil at the surface. Our aim is to sample 
deeply enough to include the whole zone in which the movement 
of water affects crop growth. 
WATER IN THE SOIL. 
In order better to understand the work presented in this bul- 
letin, a brief discussion is given of the water found in the soil. 
Water is found in the upper strata of the soil in three condi- 
tions : 
1. That which is absorbed by the soil particles from the water 
vapor of the air — called hygroscopic water. 
2. That which is held by surface tension, as more or less 
