RICE EXPERIMENTS IN CALIFORNIA. 
17 
TIME OF SUBMERGENCE. 
Table 12 shows the yields obtained from the time-of-submergence 
irrigation experiments during the 8-year period from 1914 to 1921, 
inclusive. In six of the eight years the highest yield was obtained by 
submerging the land 30 days after the rice emerged. In five of the 
eight years higher yields were obtained by submerging the land 45 
days after emergence than by submerging 15 or 60 days after the rice 
had emerged. 
/s 
60 fc 
^ Z V 
^ ,< 93 
r7£L£> /°f/? ^9C/^^ f/^OV/SPS-J 
33<26 
^ 3 
eo\ 
3,37&\&\i 
\3^^S 
Fig. 7. — Average acre yields of Wataribune rice obtained in experiments at the Biggs Rice Field Station, 
in which the crop was submerged to a depth of 6 inches at varying periods after emergence, during the 
vyear period from 1914 to 1921, inclusive. 
The highest average yield. 3,699 pounds per acre, was obtained by 
submerging the land 30 days after the rice emerged: submerging the 
land 60 days after the rice had emerged ranked second, with an 
average yield of 3.425 pounds per acre; submerging the land 45 days 
after the rice had emerged ranked third in yield, with 3.379 pounds 
per acre: and submerging the land 15 days after the rice had emerged 
produced the lowest average yield. 3.326 pounds per acre. The 
average yields in the date-of-submergence experiments with rice at 
the Biggs Rice Field Station from 1914 to 1921. inclusive, are shown 
graphically in Figure 7. 
Table 12. — -Annual and average yields obtained in the date-of-submergence experiments 
with Wataribune rice at the Biggs Rice Field Station, Biggs, Calif., from 1914 to 
1921, inclusive. 
Submergence. 
Yield per acre when 
submerged 6 inches (pounds). 1 
1914 
1915 
1916 
1917 
1918 
1919 1920 
1921 
Average. 
15 days after emergence. . . 
30 days after emergence. . . 
45 days after emergence. . . 
60 days after emergence 
. 4,510 
. 5.610 
. 5.410 
. 5,240 
3.860 
4. 270 
4,100 
3.910 
3. 750 
4.020 
3, 890 
3,610 
4,220 
4.500 
4,310 
4.040 
3. 420 
4,185 
3. 240 
4,115 
1,700 2,205 
2,230 2,450 
2, 050 2. 045 
1,980 2,665 
2.940 
2.330 
1,990 
3.326 
3,699 
! 
1 Yields computed from vields of single fifth-acre plats in 1914, 1915, 1916, 1918, and 1920 and from yields of 
single tenth-acre plats in 19*17, 1919, and 1921. 
2 Plat grassy. 
DEPTH OF SUBMERGENCE. 
Table 13 shows the yields obtained from the depth-of-submer- 
gence irrigation experiment during the 8-year period from 1914 to 
1921, inclusive. Each year, 30 days after the rice had emerged, 
plats were submerged to depths of 2, 4. 6. and 8 inches, respectively. 
In 1914, 1915, 1917, 1919, and 1921 the highest yield was obtained 
by submerging the land 6 inches deep during the submergence period. 
In 1916 and 1920 the highest yield was obtained by submerging the 
land 8 inches deep during the submergence period. In 1918 the 
32862— 23— Bull. 1155 3 
