IRRIGATION REQUIREMENTS OF THE GREAT BASIN 
19 
and 6 medium quantities, while the soil in tanks 7 and 8 was main- 
tained at a fairly constant moisture condition. Similar experiments 
were made by growing oats in tanks. 
The mean quantity of water utilized in each set of tanks in grow- 
ing wheat and oats and the corresponding seasonal yield are shown 
in Figure 10. 
TIME OF IRRIGATION 
The purpose of this discussion is to indicate as definitely as the 
varied conditions will permit, the quantity of water needed by 
typical crops during their successive stages of growth, in order to 
So <o 
WATER APPLIED 
Inches in Depth on Land 
40 35 30 25 20 15 10 5 
IRRIGATION Hi 
RAINFALL I 1 
CROP 
ALFALFA 
On acre plots and 
smaller sub-plots at 
Gooding, Idaho. 
Soil, medium clay loam 
with clay subsoil. 
All surface waste water 
excluded. 
YIELD 
Tons per Acre 
2 3 4 5 6 
Bushels pen Acre 
10 20 30 40 50 60 70 
SPRING WHEAT 
On i acre plots 
of Gooding, Idaho. 
Ml 
to ->»^> 
OATS 
On plots af 
Goo ding, Idaho. 
«1 
5 IS 
150 200 250 
POTATOES 
On plots af 
Gooding, Idaho. 
7& 
Fig. 9. — Relationship between amount of water applied and crop yield for alfalfa, 
wheat, oats, and potatoes, as determined by plot experiments at Gooding, Idaho, 
from 1909 to 191G. While Gooding is outside Great Basin the results are appli- 
cable 
guide to 
deciding when water should 
be 
serve as a £ 
applied 
If it were practical to maintain in each type of soil the quantity 
of soil moisture best adapted to the kind of crop grown, it would go 
far toward settling the question of proper time of water application. 
Of the many ways of applying water to soils and crops, the sprinkl- 
ing method 6 may be considered the only one by which small quanti- 
ties of water can be spread uniformly over the soil at frequent inter- 
vals in order to maintain a reasonably constant soil moisture content. 
U. S. Department of Agriculture Bulletin Nc. 495, Spray Irrigation. 
