32 BULLETIN 339, U. S. DEPARTMENT OF AGRICULTURE. 
53.) As these were comparatively old, well-developed projects, and 
normal in every way, there is good reason to believe that the acreages 
of the different crops on other projects will bear practically the same 
relationship to one another in the future. If this is the case, and 
the normal project of the West is ultimately devoted to approximately 
equal acreages of (1) sprig and winter grains, root crops, and 
orchards, and (2) alfalfa, clover, pastures, and crops requiring simi- 
lar quantities of water, the requirements of the projects as a whole 
will be found by averaging the requirements of the two classes of 
crops. This has been done in Table XVII, each line of the table repre- 
senting the requirement of one class during a single year of the investi- 
gation. The average given in the table therefore shows the combined 
requirements during each month of the irrigation season for the two 
classes of crops during the four years of the investigation, the process 
of averaging having neutralized and offset the eccentricities of irri- 
gators and the individual differences of the seasons, stand of crop, 
soils, and plots included in the investigation. 
TABLE X VII.— Average depths of water applied to 171 selected fields of grain and alfalfa 
on medium clay and sandy loam soils. 
[Altitudes ranging from 2,400 to 5,000 feet. ] 
Depth of water applied. = 
Num- l Total 
Crop. Season.| ber of April— September—| for 
Dlots. # season. 
lene === ay une. July. | Aue SSS SSS 
| 1-15 | 16-30 1-15 | 16-30 
| | | 
| 
| Foot.| Foot. | Foot.| Foot.| Foot.| Foot.| Foot.| Feet. | Feet 
AN fal iar ae oe ees eet 1910 15 | 0.06 | 0.02 | 0.55 | 0.74 | 0.65 | 0.6L |-0:07 |---== Peed| 
(Cir TOY 4k. <a ee ee | 1910 SL. 2.23 areas 32 . 60 55 08) |23. 222 bee See 1.55 
(Alialinwans Gays ss 3 cee ae 1911 | 1 ee ee ee .04 49 .29 Stain PAT ee ees 2.68 
Grainne et fe eee 1911 ee eae lao -03 | .65 AS. | 501 56s ees TEs 
PAU Ea teens eee see 1912 Pe See ae ect - 49 -50 62 61 O04“ ses 2.26 
TAIN epi es eee 1912 D5 lacs So paeonce eee .94 66 05) | 52. SS Ee 1.65 
BA Iara ese eee cinta 1913 16M esehecliseiccioee -86 a20 74 39 O27 esate 2.24 
Grane seen ee ns 1913 BB besese -04 avait 54 59 <23" | eons oe See eee 1.61 
ASS CRE eae el ae a eae -O1} .01| .37| .56] .65| -34) -04}-..-22- 1.98 
Per Cento totale pe sere eee Suv lhe eon isa? 2 |Pekas ee 8 ee 2:0. |e eae 
Table XVII is a general average of the results which have been 
secured on the average soil of southern Idaho during the entire four 
years’ investigation, after eliminating the results secured from all 
tracts whose yield was reduced by excessive or insufficient applica- 
tion, and is considered by far the most important table included 
in this report. The facts given in the table are shown graph- 
ically in figure 9. It is in reality the meat, or final result, of the 
entire four years’ study of water investigation, and as the soil in 
question is an average of that- which is, or will be, included in at 
least 75 per cent of Idaho’s irrigation projects, and probably of as 
large a per cent of the projects in many other States, it is believed 
