The Storage and Use of Soil Moisture 
31 
We have used a summer tilled field because summer tillage is 
more effective than any other farm practice in storing moisture. 
In the lower portion of the table are given the rainfall during 
the intervals, the number of inches of water held in the upper 6 
feet of the soil, and the per cent of the total rainfall held in the 
upper 6 feet. In some cases, which is true in 1909, water 
was accumulated below 6 feet, but we have not tried to show 
this in the per cent since below 6 feet the soil is not as uniformly 
dry at the first sampling as it is above 6 feet. This is shown in 
two fields used in 1910 and 1911. Tt is evident that in either of 
these years no water was accumulated below 6 feet, and yet there 
is no agreement between the first and second samplings on these 
fields. This is probably due to the sampling in different places 
in the field and in one case finding more water left by the pre- 
ceding crop than in the other. 
It will be noted that for the year 1907 the first sampling was 
to only 3 feet. This is the depth we were sampling in the 
spring. At the close of the season, the soil was practically filled 
to a depth of 6 feet. In 1908 the spring sampling was to 6 feet, 
but during the season a longer tube was obtained and samplings 
in the fall were taken to 10 feet. During this interval 13.9 inches 
of water fell, 33 per cent of which has held. 
In 1909 water was accumulated to a depth of 7 feet. In 1910 
and 1911 water was accumulated to a depth of only 3 or 4 feet, 
and in neither case was the soil filled to normal carrying capac- 
ity. The rainfall of 1910 was too low, and in 1911 the distribu- 
tion of the rainfall was unfavorable for accumulating water. In 
1912 water was accumulated to 5 feet. 
It will be noted that during these six years we have held from 
10 to 33 per cent of the rainfall in the upper 6 feet of the soil. 
Reference to the distribution of the rainfall in the tables given 
under climatic data will probably explain this. 
These data are taken from 5- and 10-acre fields, one of 
which is summer tilled each year at the Station and receives uni- 
formly good summer tillage. It shows, however, that we cannot 
store moisture unless it falls in sufficient amount and with a 
proper distribution to get it into the soil. 
EFFECT OF CONDITION OF SOIL AT SURFACE AND CHARACTER 
OF RAIN ON WATER RETENTION. 
The condition of the surface soil has an important influence 
on the amount of water that will be retained from a certain rain. 
Water runs off much more freely from a smooth, dry surface 
