8 
Research Bulletin No. 5 
be kept down so far as possible both before and after seeding, to 
prevent their use of water. 
Crops which will withstand considerable drouth or escape 
drouth by maturing early are recommended. 
Live stock as a medium for marketing the crop, and to in- 
sure an income during unfavorable years, is essential to the 
success of a dry-farmer. 
This bulletin is concerned with problems relating to a greater 
use of the water that falls. Results of tests made relative to 
other phases of crop production in this section are given in 
Bulletin 135 of this Station. 
SUMMARY. 
1. The maximum amount of water that the soil on the North 
Platte, Nebr., Substation farm will hold under field conditions 
is from 16 to 18 per cent of its dry weight. 
2. The minimum point to which crops can use the water from 
the soil for growth is about 7 to 8 per cent based on the dry 
weight of the soil. In other words, water in the soil above 7 or 8 
per cent is available for plant use. 
3. Summer tillage is the most efficient means of storing water 
in the soil. 
4. The amount of water that can be stored in the soil in one 
year by summer tillage is influenced by a number of factors. On 
tbe same soil it is largely governed by the amount and distribu- 
tion of the rainfall, the effectiveness of the tillage, and the 
presence or absence of a growing crop. 
5. From 10 to 33 per cent of the seasonal rainfall has been 
stored annually by summer tillage at the Substation during the 
past six years. 
6. In favorable seasons the soil has been practically filled 
with water to a depth of six or seven feet by summer tilling. 
7. During the most unfavorable year the best summer tilled 
land accumulated water to a depth of only three feet. 
8. The distribution of the rainfall is almost as important from 
the viewpoint of storing water as the total amount of rain. 
9. Water is accumulated most rapidly when the rains are so 
frequent that the surface is still wet from one rain when another 
comes. 
10. An inch of rain falling on a very dry surface will seldom 
wet down more than six inches on this type of soil. 
