RICE EXPERIMENTS IN CALIFORNIA. 49 
CULTIVATION 
Barnyard grass can be materially reduced on foul land by thorough 
cultivation. The best method of control consists of fallowing the 
land. In the spring the foul fields should be irrigated t« insure 
germination of the weed seed. Then, before the land gets too dry 
and before any of the grass matures seed, the land should be plowed 
shallow. In July another irrigation should be given, and if a second 
growth of grass appears the land should be plowed shallow again. 
This treatment wall kill most of the young grass plants, but this 
method is considered too expensive for general use. In the fall 
the land can be sown to some grain crop, such as wheat or barley. 
After harvesting a grain crop, the land can be sown to rice the fol- 
lowing spring, and good yields should be obtained. 
IRRIGATION. 
Many attempts have been made to control or eradicate barnyard 
grass by changing the usual method of irrigation. The writer has 
observed several fields submerged at various times and at various 
depths during the past three years. 9 The following effects have been 
noted: Early applications of water and continuous submergence 
prevent to a large extent the growth of early red barnyard grass. 
When the land is submerged 6 inches deep early in the season, poor 
stands of rice are sometimes obtained. Deep continuous submergence 
after the rice and weeds have emerged will suffocate most of the red 
barnyard grass, but the rice will stretch through the water and con- 
tinue to grow. Deep continuous submergence if started too late in 
the spring may result in poor stands, due apparently to the scalding 
of the young rice sprouts and the formation of a scum on the water 
which prevents the emergence of the rice. 
If the land is to be submerged continuously after seeding, the rice 
should be sown broadcast on the surface at the rate of 150 pounds per 
acre, but if submergence is to be delayed until the rice and barnyard 
grass have emerged, then the seed can be drilled or sown broadcast 
in the usual way. Some growers submerge the fields, let the water 
get warm, and then broadcast the rice in the water. Good stands 
are usually obtained in this way, and less seed is required because no 
rice is covered with too much soil, but the method has some draw- 
backs for use on large acreages. Rice germinates in the water and 
makes a slender growth until it reaches the water surface. It then 
lies prostrate on the surface of the water for several days. At this 
time strong winds often damage the young rice plants by breaking 
them off and uprooting them. In about 10 days or 2 weeks the 
rice stands erect and looks normal in all respects. Rice seems to 
stool as well when grown in this way as it does when irrigated in the 
usual manner. A scum sometimes forms on the water and bakes on 
top before the rice emerges, preventing the growth of the rice and 
causing thin stands. 
The successful control of barnyard grass by continuous deep sub- 
mergence depends to a large extent upon the time of seeding, rate oi 
seeding, and effective control of the depth of water. Fluctuation in 
9 Extensive experiments in the control of water grass by irrigation were conducted at Biggs in 1922 and 
also by the California Agricultural Experiment Station at Cortena, Colusa County, but the results of these 
were not available when this bulletin was written. 
