IRRIGATION At UNIVERSITY FARM, DAVIS, CAL. 
Summary of results of alfalfa irrigation investigations, 1910, 1911, and 1912. 
Depth of water 
applied. 
Yield in tons per 
acre. 
1910 1911 1912 
Incliti. 

3.85 
4.75 
6.02 
is" ............... 
7. 52 
24 
6.00 
7.53 
7.58 
8.45 
8.38 
30 
9.61 
36 
48 
9.33 
9.64 
60 
6.52 
6.51 
7.02 
S.32 
9.43 
10.04 
Value of hay per 
acre at S7 per ton. 
$26. 95 
33. 25 
§42. 14 
52.64 
42. 00 
58.66 
52.71 
67.27 
53. 00 
65.31 
59.15 
67.48 
45. 57 
49.14 
58.24 
66. 31 
65.66 
62.09 
70.20 
Cost of production. 
1910 1911 1912 
88. 65 
13.40 
IS. 90 
23.15 
24.15 
27.80 
$13. 50 
19.60 
24.20 
27.85 
28.05 
30.25 
812. 40 
17. 35 
. 19. 85 
24.10 
27.35 
28.10 
28.80 
33. 65 
Net profit per acre. 
1910 1911 1912 
81S. 30 
19. 85 
23.10 
29.56 
28.91 
31.35 
s2S. 64 
33.04 
34. 46 
39. 42 
37.26 
37. 23 
826. 24 
28.22 
29.29 
34.14 
38.96 
37.56 
33.29 
36. 63 
Note. — Labor of production figured at $2.25 per ton. Water figured at $1.70 per acre- 
foot. Labor for irrigation figured at 50 cents per acre per irrigation. While the value 
of the hay is figured at $7 per ton for each of the three years 1910, 1911, and 1912, the 
local value in 1912 was $11 per ton. 
The accompanying diagram (fig. 2) shows the average yields in 
tons per acre for the three years, with the corresponding depths of 
water applied, and figure 3 shows the average yield in tons per acre 
for each cutting from the unirrigated alfalfa and from the checks 
given 30 inches in four 7^-inch ap- 
plications. 
The first diagram shows a very 
uniform increase in yield up to 30 
inches of water applied, above 
which the increase is very small, 
and in the case of 36 inches ap- 
plied a slight decrease is shown, 
although the maximum average 
yield was produced by a total of 
48 inches applied in four 12-inch 
irrigations. 
The first half of the diagram 
shown in figure 3 illustrates the 
gradual decrease in yield in each 
succeeding crop where no water is 
applied, showing the need of irri- 
gation after the first crop has been 
removed. When this first half is 
compared with the other half of 
the diagram the result of irrigation is apparent. In each of the 
three seasons the maximum yield was produced in the third crop, 
probably because of more favorable growing conditions during June 
and the first part of July in which this crop was grown. 
9 
a 
$> 
it 
a 6 
t/> 
§5 
H 
?4 
a 
=53 
> 
2 
\ 

TOTAL DEPTH OF WATER IN INCHES 
o 
12 
18 i 24 30 ' 36 
4-8 
Fig. 2. — Average yield of alfalfa, 1910, 
1911, and 1912, using different quan- 
tities of water. 
