CROPS UNDER FALL IRRIGATION AT SCOTTSBLUFF. 3 
in these experiments were grown. The total precipitation from Octo- 
ber 1, 1910, to April 1, 1911, amounted to 1.19 inches. From Octo- 
ber 1, 1911, to April 1, 1912, the total precipitation was 3.59 inches, 
and from October 1, 1912, to April 1, 1913, it was 2.13 inches. The 
average total rainfall for this 6-months period during the three 
years was 2.3 inches, or a little less than 16 per cent of the average 
total annual rainfall during 1911, 1912, and 1913. 
The above facts substantiate the statement previously made in 
connection with the low precipitation of the fall and winter months. 
Since much of this precipitation comes as small showers or as light 
snowfalls, a large proportion of the moisture is lost by evaporation 
from the surface soil, so that during the months from October to 
March, inclusive, comparatively little moisture is added to the soil 
by precipitation. This being true, soil which has given up the 
greater part of its available moisture to a field crop remains compar- 
atively dry during the following winter. 
The precipitation which came during the growing season of 1911, 
1912, and 1913 could not be expected to influence greatly the results 
obtained with fall irrigation, since it fell on all the plats in the experi- 
ment and since irrigation water was applied uniformly to all the plats 
during the growing season. The chief point to be considered in con- 
nection with the rainfall as it affected the results of these experi- 
ments is that the fall and winter period was comparatively dry, the 
precipitation being insufficient to increase materially the quantity of 
moisture in the soil, particularly at depths of a foot or two below the 
surface. 
METHODS OF EXPERIMENT. 
Of the land used for these experiments one half was irrigated in 
the fall each year, and the other half was not so irrigated. In the 
fall irrigation, water was applied copiously to the soil, so as to sat- 
urate the latter to as great a depth as possible. This water was 
applied late in September or early in October each year, usually 
between September 15 and 30. In the fall of 1910 the land to be 
fall irrigated was plowed before irrigation, but it was found that 
this method necessitated considerable extra labor. In order to irri- 
gate after plowing, the land had to be leveled, and after irrigation 
it was necessary to harrow the land in order to check evaporation. 
If irrigation water were applied before plowing, the leveling could 
be dispensed with. For this reason, in the fall of 1911 and again in 
the fall of 1912 the land was irrigated before plowing. 
In the spring of each year crops were planted on the fall-irrigated 
land, and the same crops were planted on adjacent land not so irri- 
gated. The spring and summer treatment of the land and crops 
was identical in both cases. Each crop was planted on the same 
date on both the fall-irrigated land and the land not so irrigated, 
