RICE CULTURE IX CALIFORNIA 
23 
Table 13. 
Yields of rice grown continuously on the same land for 11 years in 1, 
inclusive 
Acre 
Variety 
Year 
yields 
Crop 
No. 
Remarks 
(pounds) 
Wataribune . 
1913 
5,677 
1 
Grown on new land. 
Do..„ . 
1914 
3,692 
2 
Land fall plowed. 
Do 
1915 
3,914 
3 
Do. 
Do 
1916 
3,231 
4 
Do. 
Do 
1917 
3,704 

Do. 
Do 
1918 
2,628 
6 
Land spring plowed. 
Land fall plowed. 
Do 

1919 
1,596, 
7 
Do.. 
1920 
1,208 
8 
Yield from spring-threshed plats. 
No crop 
1921 
Fallow. 
1922 
1923 
3,092 
1,672 
9 
10 
Yield on fallow land. 
Do 
Land spring plowed. 
Do 
Average: 
1924 
1,094 
11 
Land winter plowed. 
11 years 
1913 
to 1924, 
with 
1921 
2,864 
omitted 
12 years, 
1913 to 1924, all inclusive. 

2,626 
Allowing to seasonal fluctuation its full importance in affecting 
yield, there is yet apparent a distinct decline in acre production be- 
tween the beginning of the experiment in 1913 and the present in 
1924. During the first six years of continuous cropping to rice each 
year the yields were profitable. In the second 6-year period the only 
profitable crop was that of 1922, and this was grown on fallow land. 
The yields in 1919 and in 1920 were not profitable. The threshed 
yield of 1920 was decreased by winter exposure; but if the yield ob- 
tained is increased by one-third it would still be only 1,600 pounds, 
which is below the limit of profit for that year. The data indicate 
that rice can not be profitably grown continuously on the same land 
by the old method of irrigation for more than six years in succession, 
even though weeds are kept under control. Data on methods of 
irrigation, which are given elsewhere in this bulletin, indicate that it 
may be possible to crop continuously for a longer period where irri- 
gation is by continuous submergence. These data cover a period of 
onlv three years, however, and are therefore not conclusive. 
The 11-year average yield from 1913 to 1924, with 1921 omitted, 
was 2,864 pounds, and for the 12-year period from 1913 to 1924, all 
inclusive, 2,626 pounds per acre. These are profitable average crops 
for the entire period, but the high average yield in each case is due 
to the high acre yields during the first six years of continuous cropping . 
VARIETAL EXPERIMENTS 
One of the principal lines of work at the station has been the 
testing of many varieties of rice from various sources in the hope of 
finding some that are superior in yield and milling quality to those 
now being grown commercially in California. 
CLASSES OF RICE 
The varieties of rice commercially grown in the United States are 
classed agronomically as long grain, medium grain, and short grain. 
By the Bureau of Agricultural Economics of the United States De- 
partment of Agriculture these rices are classed as long grain, short 
grain, and round grain, respectively. The short-grain rices have 
small stalks, narrow leaves, and short, round kernels. The medium- 
