EICE EXPERIMENTS IN CALIFORNIA, 
15 
safely later and will produce rice of good quality. Late seeding of 
either early or late varieties, however, is not good practice, as the 
possibilities of loss in the fall from heavy rains are too great to be 
ignored. The evidence available indicates that rice should be sown 
as early as the land and weather permit, provided water for flooding 
is available. 
PREPARATION OF THE SEED BED. 
Table 11 shows the yields obtained from duplicate tenth-acre plats 
in experiments in which a smooth seed bed was compared with plats 
disked but left rough during the 9-year period from 1913 to 1921, 
inclusive. Since 1915 the experiment has been conducted on land 
fallowed the previous year, and there has not been a wide difference 
between the two plats. Fallow land pulverizes readily the following 
spring, and even when not replowed the desired roughness has not 
always been present. However, the smooth plats have been in better 
condition than the rough plats at seeding time. The average yields 
for the 9-year period show a slight increase for the smooth over the 
rough seed bed. 
Table 11. — Annual and average yields in the seed-bed preparation experiments with 
Wataribune rice at the Biggs Rice Field Station, Biggs, Calif., for the 9-year period 
from 1913 to 1921, inclusive. 
Treatment. 
Yield per acre (pounds). 1 
1913 
1914 1915 
1916 
1917 1918 1919 
1920 
1921 
Average. 
Disked, surface 
6,160 
6,255 
5,765 
6,135 
4,660 
5,020 
3 760 
4 680 
3,395 2,570 
3,590 2,475 
2,640 
2,920 
2,650 
2,865 
4,031 
4,286 
Disked, surface 
smooth 
4,415 
4,895 
1 Average yields from duplicated tenth-acre plats each year. 
CONTINUOUS CROPPING TO RICE. 
In California three or four crops of rice are all that have been 
profitably grown in succession on the same land. This is due pri- 
marily to the fact that weeds increase so rapidly that it is not possible 
to grow profitable crops on foul land and not because the rice hjas 
robbed the soil of its fertility. Analyses show that wheat and rice 
with equal yields remove from the soil about the same quantity of 
plant food per acre. 
Continuous cropping to rice is hard on the land, for the same 
reasons that continuous cropping to any crop is detrimental. Per- 
manent agriculture is based upon diversification and rotation of crops. 
Every agricultural section has its weed problems, and the solution is 
usually crop rotation. Maximum yields with all cereal crops are 
obtained in rotation systems and not by cropping continuously to 
the same crop year after year. The yields obtained from rice grown 
continuously on the same land for the 7-year period from 1913 to 1919. 
inclusive, were as follows: 1913, 5,677 pounds; 1914, 3,692 pound.-: 
1915, 3,914 pounds; 1916, 3,231 pounds; 1917, 3,690 pounds; 1918, 
2,706 pounds; and 1919, 1,799 pounds. The yield in 1913 was the 
•average from 10 tenth-acre plats; in 1914, 1915, and 1916, from 12 
tenth-acre plats; and in 1917, 1918, and 1919, from 7 tenth-acre plats. 
