16 BULLETIX 133, U. S. DEPARTMENT OF AGEICTJLTDBE. 
land than on the land that was not fall irrigated. The difference was 
about 7 per cent on March 30 and May 15, about 3 per cent on Mar 28, 
more than 8 per cent on June 13, 4 per cent on June 27,1 per cent on 
July 10, and 4 per cent on September 28. That these differences in 
the average moisture content of the first 6 feet were due mainly to the 
relative dryness of the lower portion of the 6-foot zone of soil on the 
land not fall irrigated can be seen by an examination of figures 3, 4, 
and 5. 
Figure 3 shows the average moisture content of the first 3 feet on 
the two series. It is seen that the fall-irrigated land had more mois- 
ture in the upper 3 feet of soil than the land not fall irrigated, but the 
differences were decidedly less than those obtained where the upper 6 
feet were considered, except on March 30, when the difference was 
nearly as great as that shown in figure 2. 
As shown in figure 4, the moisture content of the upper foot of soil 
was very nearly the same on both series throughout the season, but 
the fail-irrigated land contained somewhat more moisture on all the 
sampling dates except July 10. 
Figure 5 shows the moisture content of the sixth foot of soil during 
the season of 1911. It is seen that the sixth foot of soil on the land 
not fall irrigated was comparatively dry throughout the season. It 
contained about 5 per cent of moisture on March 30, and this moisture 
content increased to about 9 per cent by September 28. The sixth 
foot of soil on the fall-irrigated land contained nearly 12 per cent of 
moisture on March 30, and about the same on September 28. 
A study of these four figures leads to the following conclusions: 
(1) The irrigation water applied in the fall supplied abundant moisture 
to the soil to a depth of at least 6 feet, while the land not fall irrigated 
remained relatively dry during the following winter. (2) The irriga- 
tion water applied during the season of 1911 percolated to the lower 
depths hi the moist soil of the fall irrigated land more rapidly than in 
the relatively dry soil of the land not fall-irrigated. (3) The more 
favorable soil-raoisture conditions on the fall irrigated land during 
the growing season were due chiefly to the fact that on that land the 
soil was well supplied with moisture at the beginning of the season. 
SUMMARY. 
(1) In many sections of the Great Plains area a comparatively 
small proportion of the annual precipitation comes during the period 
from October to March, inclusive, and the result is that the soil is fre- 
quently too dry at planting time in the spring to promote germina- 
tion and support an early growth of spring-planted crops. 
(2) Experiments were started in the fall of 1910 at the Scottsbluff 
Experiment Farm to determine whether fall irrigation of the land 
would improve the soil-moisture conditions and result in better yields 
of field crops. 
