RICE EXPERIMENTS IN CALIFORNIA. 
9 
mergence period (June to September) reduces evaporation 25 per 
cent, there is a loss by evaporation of 30 inches, or half of the irriga- 
tion water applied to the rice crop. 
CULTURAL EXPERIMENTS. 
The cultural experiments which have been conducted include 
studies of different depths, dates, and rates of seeding and different 
methods of preparing the seed bed for rice. The experiments in 
1913 and 1914 were conducted on land which had not previously 
been cropped to rice. In 1915 and 1916 they were on land on which 
one crop of rice had been grown previously, but which was fallowed 
during the year immediately preceding. The experiments in 1917 
and 1918 were on fallowed land that had grown two crops of rice, 
in 1919 and 1920 on fallowed land that had grown three crops of 
rice, and in 1921 on fallowed land that had grown four rice crops. 
The usual method of preparation was to plow the land in June for 
fallow, following an irrigation late in May. The fallow is left rough 
and is given no further treatment until the following spring, when 
it is disked or shallow plowed. If the land is dry enough in late 
February or early March it may be double-disked at that time and 
again just before seeding. One of the principal objects of the thor- 
ough disking is to kill weeds, which usually make a heavy growth on 
the land in late winter and early spring. If the stand of weeds and 
weedy grasses is thick, it is often better to plow the land shallow than 
to attempt to destroy them by disking. In these experiments the plats 
have usually been spring plowed. After plowing or disking, a good 
seed bed is prepared by harrowing and dragging. 
In the various experiments, all plats have been prepared alike each 
year except for the particular factor under investigation. Thus, in 
the date-of-seeding experiment, the preparation of the land, method 
of seeding, rate of seeding, and all other factors have been uniform 
except that the different plats have been sown on varying dates. 
DEPTH OF SEEDING. 
The yields obtained in depth-of-seeding experiments during the 9- 
year period from 1913 to 1921, inclusive, are shown in Table 7. These 
yields are the average yields of two tenth-acre plats each year for each 
depth of seeding. The 1920 yields are omitted because of damage to 
the crop by rains before it could be threshed. The preparation of 
the land and the rate, time, and manner of seeding were the same for 
all plats, but the depth of seeding on the various plats was 1.2. and 3 
inches, respectively. 
Table 7. — Annual and average yields of Wataribune rice obtained in the depth-of-seeding 
experiments at the Biggs Rice Field Station, Biggs, Calif, during the 9- /■ 
from 1913 to 1921, inclusive. 
Depth of seeding. 
Yield per acre (pounds). 1 
1913 
1914 
1915 
1916 
1917 1918 
1919 
1921 
1 inch 
6,305 
6,360 
6,050 
5,170 
5,588 
5,240 
5 290 
1 RfK 
A 07* •> 7on 
2,755 
3,125 
3 l id 
2 inches 
5,440 3,695 4.S90 2.915 
4 180 a r >" 4 JM l "~> 
3, $75 4 423 
3 inches 
3 205 •» f»Q 

' 1 ' 1 
1 The 1920 yields are omitted because of damage to the crop by rains, floods, birds, and field mice before 
it could be threshed in the spring of 1921. 
32862— 23— Bull. 1155 2 
