Irrigation and Drainage 135 
five-inch irrigations to these various stages both singly 
and in various combinations. The results are shown in 
Fig. 15, which gives the average yield of roots and tops 
for the various treatments. The lowest yield was ob- 
tained when the land was irrigated after the seed was 
planted and before it came up. The yield with this treat- 
ment was decidedly less than it was when no water was 
given. 
Comparing the various periods in which but one five- 
inch irrigation was given, it will be seen that the third 
period, when the beets averaged two inches in diameter, 
was the most favorable; the last period, when the beets 
were nearly ripe, was the least favorable. The second 
period was decidedly more favorable than the first. It 
will be noted further that the yield of tops was greatest 
with the very late irrigation. This means that the farmer 
by looking at his beet field will doubtless be deceived into 
thinking that the very late irrigation is increasing his 
yield much more than it really is. 
Upon examining the plants receiving two, three, and 
four irrigations, the greater value of irrigation water 
during the third stage is clearly evident. The highest 
yield was received where a total of fifteen inches was ap- 
plied. It will be remembered that in the weekly irri- 
gations a higher yield was obtained for 12.8 inches than 
for 32 inches. It seems, therefore, that the total require- 
ment of sugar-beets for irrigation water is not large, but 
that the period of application is important. 
The old ideas, that it is necessary to withhold water 
until the beets suffer before giving the first irrigation and 
that irrigation should be discontinued five or six weeks 
