52 
BULLETIN 1155, U. S. DEPARTMENT OF AGRICULTURE. 
Table 28. — Yields and agronomic notes on the water-grass control experiments with 
Caloro rice sown at the rate of 150 pounds per acre at the Biggs Rice Field Station, 
Biggs, Calif., in 1921. 
Date. 
Stand 
(per 
cent). 
Plat. 
Sown. 
First 
irriga- 
tion. 
Emerged. 
Headed. 
Ripe. 
Har- 
vested. 
Height 
(inches). 
Yield 
(pounds). 
No. 1 
May 9 
May 12 
May 30 
Sept. 2 
Oct. 8 
Oct. 11 
75 
30 
i 1,658- 
No. 2 
...do.... 
...do.... 
...do.... 
...do.... 
...do.... 
100 
30 
2,284 
No.3 
...do.... 
...do.... 
...do.... 
...do.... 
...do.... 
...do.... 
95 
32 
3,028 
No.4 
May 16 
May 21 
June 6 
Sept. 14 
Oct. 11 
...do.... 
90 
36 
3,272 
No. 5 
...do.... 
...do.... 
...do.... 
...do.... 
...do.... 
...do.... 
85 
36 
3,168 
No.6 
...do.... 
...do.... 
...do.... 
...do.... 
...do.... 
...do.... 
90 
33 
3, 150 
No.7 
Mav 25 
.. .do 
June 10 
Sept. 5 
...do.... 
...do.... 
100 
32 
3,230 
: Wire-grass reduced the yield. 
The yields obtained ranged from 1.658 pounds on plat 1 to 3,272 
pounds per acre on plat 4. Plats 1, 2, and 3 were practically free 
from red barnyard grass, but there were some late water grasses 
present. Considerable barnyard grass grew on plats 4 and 5. Plats 
6 and 7 were practically free of red barnyard grass, but there were 
some late water grasses on these plats. Spike rush {Eleocharis palus- 
tris) , locally known as wire-grass, was largely responsible for the low 
yield on plat 1. 
All plats were drained from September 21 to 25. The rice obtained 
was of good quality, and only a very small quantity of grass seed was 
present in the threshed grain. 
The water-grass control experiments in 1921 appear to justify the 
following conclusions, which may be somewhat revised on the basis 
of further experiments: (1) On land irrigated and drained in the 
usual way until the rice and water grass emerge, then submerged 6 
inches deep and the water held continuously, the rice emerges through 
the water but the early barnyard grass is unable to emerge and is 
killed. (2) Rice sown broadcast and submerged 6 inches deep con- 
tinuously from the first irrigation germinates and emerges to the sur- 
face of the water, but the early barnyard grass does not emerge. (3) 
Sowing rice in 6 inches of water resulted in a good stand of rice, but 
early barnyard grass was unable to emerge through the water. (4) 
In order to prevent early red barnyard grass from emerging it must be 
kept under 4 to 6 inches of water continuously. (5) It is easier to 
get a good stand of rice by drilling or broadcasting and irrigating in 
the usual way until the rice has emerged than by broadcasting and 
submerging the land immediately. (6) Better stands are obtained by 
seeding in the water than by seeding and then holding the water 
continuously, but seeding in the water is not practicable on a large 
scale. (7) Broadcasting in 6 inches of water, or broadcasting and 
immediately submerging in 6 inches of water and then holding this 
depth continuously, appear to be about equally effective in controlling 
water grass and more effective than drilling or broadcasting and irri- 
gating ths rice up before submerging 6 inches desp. 
Rice will germinate under water, but it does not germinate well 
under water and soil. Therefore, if water is to be held continuously 
the seed bed should be compact and level so that the seed when 
broadcasted will remain on the surface. If rice is to be submerged 
