The Storage and Use of Soil Moisture 
11 
THE STORAGE AND USE OF SOIL MOISTURE. 
Studies relative to soil moisture have been carried on at the 
Substation since the spring of 1907. The purpose in starting the 
work was to determine the most efficient and economical methods 
of storing water in the soil, the amount of water required to 
produce crops, and to study the use or loss of water from the 
soil. 
GENERAL CONDITIONS. 
Part of the land used in making these studies is bench or 
second-bottom land, and part is table-land. The soil on the table- 
land is similar to that on the bench. On the bench land, sheet 
water is only twenty to forty feet below the surface. Subi nega- 
tion takes place on the bench land with deep-rooted plants like 
alfalfa, but has not been found to affect any other crops. On 
the table-land, sheet water is from 200 to 250 feet below the sur- 
face, and crops cannot get water by subirrigation. This absolute 
dependence of the crop on surface precipitation gives the best 
conditions for the study of soil moisture. 
TYPE OF SOIL. 
The soil on the farm is a fine sandy loam, commonly known 
as loess. The native vegetation is mainly buffalo and grama 
grasses. The soil is free from gravel and is easily tilled. The 
mechanical character of the soil is fairly uniform to a consider- 
able depth, the most noticeable change being less organic matter 
in the subsoil, indicated by a change in the color of the soil. This 
change in color begins in the third or fourth foot. Mechanical 
analyses have been made to a depth of three feet. 
The following table gives the results of eight analyses : 
