60 
BULLETIN 1026, U. S. DEPARTMENT OE AGRICULTURE. 
Table 16. 
ummary of records of the irrigation of crops in the Cache La 
Poudre Valley in 1916 and 1911. 
Crop. 
Num- 
ber of 
Total 
area of 
fields ! 
(acres). Aver- 
: age. 
Number of irrigations. 
Size of head used 
(second-feet). 
Ratio of hours attended 
to hours ran. 
Maxi- 
mum. 
Mini- 
mum. 
Aver- 
age. 
Maxi- 
mum. 
Mini- 
mum. 
Aver- 
age. 
Maxi- : Mini- 
mum, mum. 
Alfalfa 
74 
1,674 
3.02 
7 
i 
2.59 
7.78 
0.5S 
0.57 
1.00 l 
0.04 
Wheat 
26 
491 ' 
1.21 
2 
i 
2.23 
4.59 
1.16 
.56 
.88 
.22 
Oats 
15 
196 
1.64 
* 
i 
2.25 
5.20 
L21 
.62 
1.00 
.33 
Barlev 
31 
364 
1.27 
3 
i 
2.10 
5.22 
.99 
.62 
1.00 
.16 
Sugar beets. I 
61 
960 ; 
2.90 

i 
1.85 
4.47 
.52 
.71 
1.00 
.46 
Potatoes 
38 
442 i 
3.79 
6 1 
2 
1.99 
3.70 
.00 
.68 
1.00 
.40 
Beans 
18 
225 
2.69 
5 : 
2 
2.02 
3.17 
1.21 
.80 
1.00 I 
.55 
Crop. 
Number of acres irri- 
gated per day. 
Depth of water applied 
(feet). 
Aver- 
age. 
Maxi- 
mum. 
Mini- 
mum. 
Aver- 
age. 
Maxi- 
mum. 
Mini- 
mum. 
Average yield 
per acre. 
Alfalfa 6.02 19.52 1.55 2.57 13.59 
Wheat 5.13 17.54 2.22 1.04 2. SI 
Oats 5.43 12.02 1.61 I 1.35 3.07 
Barlev 4.45 31.04 1.39 1.19 3.96 
Sugar beets 5.70 24.72 1.75 1.86 6.59 
Potatoes 6.78 22.27 1.51 2.20 16.94 
Beans 15.63 54.80 6.72 1 .69 1.06 
0.52 
.17 
.60 
.14 
.32 
.74 
.34 
2. 75 tons. 
27. 75 bushels. 
4S. 06 bushels. 
40. 73 bushels. 
12. .56 tons. 
230.07 bushels 
22. 75 bushels. 
Table IT. — Average dates of irrigation. 
Crop. 
First. 
Second. 
Third. | Fourth. 
Fifth. 
Sixth. 
Alfalfa 
Mav 25 
June 16 
Julv 19 
Julv 30 
June 24 
July 8 
June 25 
Aug. 3 
July 9 
Aug. 17 
Aug. S 
Grain 
Sugar beets 
Potatoes 
Beans 
Aug. 14 
Aug. 15 
July 27 
Aug. 31 
Aug. IS 
July 24 
Sept. 5 | Sept. 2 
Aug. 21 1 Aug. 24 Sept. 8 
Aug. 14 I 
In figures 5 to 8 the distribution of the demand throughout the 
season is shown for the acreage in the principal crops on the farms 
selected for the investigation of farm irrigation. Figure 9 shows 
the combined demand of all the crops on these farms each year. 
It will be noticed by reference to figure 1 that 5 inches, or more 
than one-third of the average annual rainfall, occurs in April and 
May. For this reason it usually happens that the crops have a 
natural start and are growing vigorously before any irrigation is 
necessary. When it becomes necessary to irrigate to bring up the 
crops, poor returns are expected. 
The curves shown in figures 10, 11, 12, and 13 show for the four 
principal crops the relation between the depth of water applied 
and the yield obtained. The yield per acre for each field shown in 
Tables 17 and 18 was plotted against the corresponding depth of 
