RICE CULTURE IN CALIFORNIA 
EFFECT OF IRRIGATING DRILLED CHECK PLAT5 IN THE ORDINARY WAY 
The check plats were drilled and then when necessary were irri- 
gated and drained at intervals until 30 days after the rice emerged. 
The plats were then submerged 6 inches. Some water grass and 
sprangletop were present on these plats in 1922. The plats were 
foul in 1923 and extremely foul in 1924. The growth of water grass 
on the check plats was so great in 1923 and 1924 that the yields of 
rice were materially reduced. 
YIELD DATA 
Table 6 presents the annual and average acre yields obtained from 
rice seed sown broadcast on different dates and immediately sub- 
merged to different depths during the three years 1922, 1923. and 1924. 
The average data are shown graphically in Figure 3. 
The yields given are 
the average of two 
tenth-acre plats in 
each case, except for 
the drilled plats sown 
and submerged on 
April 25, which are 
averages of two fif- 
teenth-acre plats, and 
for the check plats, 
which are averages of 
four tenth-acre plats. 
In 1922 on fallow 
land the acre yields 
were comparatively 
high for all dates and 
depths of submer- 
gence. In 1923 and 
1924 the plats sown 
broadcast and imme- 
diately submerged on 
April 25 and May 5 
produced consider- 
ably higher acre yields than were obtained from plats sown broad- 
cast and immediately submerged on May 15 and May 25. 
The average acre yields for the plats sown broadcast and immedi- 
ately submerged 4 inches for all dates of seeding in 1922, 1923, and 
1924 were3,27S, 2,132, and 1,735 pounds, respectively. The plats 
sown broadcast and immediately submerged 6 inches yielded 3,461, 
2,425, and 1,947 pounds, respectively; and the plats sown broadcast 
and immediately submerged 8 inches yielded 3,274, 2,030, and 1,601 
pounds, respectively. The average acre yield for 1922, 1923, and 1924 
for plats sown broadcast and immediately submerged 4 inches for all 
dates of seeding was 2,3S2 pounds; for plats sown broadcast and 
immediately submerged 6 inches, 2,611 pounds; and for plats sown 
broadcast and immediately submerged 8 inches. 2,302 pounds. The 
acre yields of the plats sown broadcast and immediately submerged 
6 inches have been higher each year than for the plats submerged 4 
and 8 inches; but the difference is not marked and in the light of 
seasonal variations from the average may not be significant. 
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Fig. 3. — Average yields of rice sown on three dates and immediately 
submerged at four different depths at the Biggs Rice Field Station 
in 1922, 1923, and 1924 
