IRRIGATION AT UNIVERSITY FARM, DAVIS, CAL. 9 
Group 1 (checks 22, 23. 24. and 25) received a total of 30 inches. 
applied in four 7^-inch irrigations, immediately following the first, 
second, third, and fourth cuttings. 
Group 2 ( checks 20. 21. 26, and 27 | received a total of 30 inches in 
eight of-inch irrigations, two irrigations being applied between cut- 
ting-, the first one week after cutting and the second two weeks later. 
Group 3 (checks IS. 19. 28, and 29 | received a total of 30 inches in 
four irrigations of 7J inches each, applied just after cutting the sec- 
ond, third, fourth, and fifth crops. 
The results obtained are shown in the following table : 
Results from irrigating alfalfa at different stages of growth. 
Total yield lor stason in 
tons per acre. 
Xuniber 
of group. 
Schedule, 
1910 
1 Four 7§-inch irrigations applied immediately after cutting 7. 53 
2 Eizht^-inch irrigation- apj lied in two irrigations between cuttings . . 8. 24 
3 Four 7§-ineh irrigations applied j itting 7.97 
9. 61 S. .57 
9.91 9.08 
S. 9o i 8. 46 
Each of these seasons -hows a small increase in yield to be pro- 
duced by two irrigations between cuttings. This averages 0.5 ton 
per acre for the two seasons, and if the extra labor, such as laying 
the pipe and preparing for the irrigation, is considered, the -mall 
additional profit is consumed in labor, and from a financial stand- 
point no advantage is gained. 
In heavy soils, subject to cracking after irrigation, frequent ap- 
plication of small amounts of water shows a decided advantage over 
the single irrigation between cuttings. It is true also, in light porous 
soils where the underground drainage is good and the moisture- 
holding capacity of the soil is small, that one heavy irrigation will 
not carry the crop through to a good yield and that a second ap- 
plication will produce good returns. 
The groups 3 and 1. irrigated before and after cutting, show op- 
posite results for the two seasons, irrigation before cutting showing 
the heaviest yield in 1910 and the lightest yield in 1911. but in each 
case the difference is so small that no conclusions can be drawn favor- 
ing either method. It was noticed, however, that toward the end 
of the season of 1911 the checks irrigated just before cutting had a 
very spotted appearance, the alfalfa standing at a very uneven height, 
and that after cutting, in spots the alfalfa was slow to start its new 
growth. A period of five days to a week always elapsed from the 
time of irrigation until the crop was cut. During this time the 
growing alfalfa was drawing heavily upon the moisture supply in 
6137°— Bull. 10—13 2 
