﻿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, 2G, and 27) received a total of 30 inches in 

 eight 32-inch irrigations, two irrigations being applied between cut- 

 tings, the first one week after cutting and the second two weeks later. 



Group 3 (checks 18, 19, 28, and 29) received a total of 30 inches in 

 four irrigations of 7^ 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. 



Number 



Schedule. 



Total yield for season in 

 tons per acre. 



of group. 



1910 



1911 



Aver- 

 age 



1 





7.53 

 8.24 

 7.97 



9.61 

 9.91 

 8.95 



8.57 



2 



Eight 3 J- inch irrigations applied in two irrigations between cuttings. . 



9.08 



3 



8.46 









. 



Each of these seasons shows 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 small 

 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 



