18 
BULLETIN 1387, U. S. DEPARTMENT OF AGRICULTURE 
and 190 pounds per acre, whereas the drilled plats in series 2 and 3 
gave the highest yields from the 130 and 150 pound rates. On the 
other hand, each rate of seeding in series 1 produced a higher aver- 
age acre yield than the corresponding rate in series 2, and likewise 
each rate of seeding in series 2 outyielded the corresponding rates in 
series 3. This emphasizes the fact that the method of irrigation, 
because of its effect on grass control and consequent rice yields, is the 
most important factor for consideration. 
EXPERIMENTS ON SEED-BED PREPARATION 
The land on which seed-bed experiments were conducted had grown 
six rice crops in nine years and was very foul. It produced a crop 
in 1921 by continuous submergence. The land was spring plowed, 
double disked, and dragged in the spring in 1922 and 1923, except 
two plats which received no seed-bed preparation in 1922. In 1924 
the experiments and yields here reported were obtained on the first 
eight plats of series 300, 400, 500, and 600. 
The yields for the plats submerged 4 inches in 1922 and 1923 were 
obtained from single half-acre plats; those for the plats sown broad- 
cast and submerged 6 inches were from duplicate half-acre plats; 
those for plats sown broadcast in 6 inches of water were from single 
third-acre plats; those for plats sown broadcast and submerged 8 
inches were from duplicate and triplicate half-acre plats, respectively; 
those plats sown broadcast at the rate of 200 pounds per acre were 
from triplicate third-acre plats; and those for plats sown on unpre- 
pared land were from single fourth-acre plats. The yields reported 
for 1924 were obtained on tenth-acre plats, and the circled figures 
given with the data in Table 11 indicate the number of plats aver- 
aged where more than one was grown. The rice was either sown 
broadcast and immediately submerged to the required depths, or the 
land was submerged and the rice then sown broadcast in the water. 
Table 11. — Yields of Caloro rice obtained by broadcast seeding on well-prepared, 
poorly prepared, and unprepared seed beds Iwith different depths of submergence 
at the Biggs Rice Field Station in 1922, 1923, and 1924 
[The circled figures indicate the number of plats averaged where more than one was grown] 
Seed-bed 
Date 
Seeding 
Method 
Date of 
submer- 
gence 
Depth 
of sub- 
mer- 
gence 
(inch- 
es) 
Acre yields (pounds) 
preparation 
1922 
1923 
1924 
Aver- 
age 
Good 
May 9 
...do 
May 15i 
May 9 2 
...do.*... 
..do 
May 11 
...do 
...do.... 
...do..__ 
do. 
4 
6 
6 
8 
6 
4 
6 
8 
3,492 
3, 553 
3,144 
3,589 
2, 590 
"_\768~ 
2,148 
1.959 
1,941 
© 2,583 
© 2,440 
1. 625 
2,741 
k_ Do 
£~f Do 
Broadcast in water- 
Broadcast 
_do 
2.651 
2,237 
Do 
2,661 !(a) 1.973 
2,741 
Do ... 
2, 030 
' 
2,310 
...do 
..do..- 
(2) 1.425 
do... 
...do - 
do... 
(§ 1^257 
G) 645 
2,012 
.do... 
.do 
-do_. 
'Submerged on May 14, 1923. 
2 Sown at the rate of 200 pounds per acre. 
