58 BULLETIN 1155, U. S. DEPARTMENT OF AGRICULTURE. 
for June, July, and August for the 9-vear period. 1913 to 1921, was 
25.696 inches. 
In the depth-of-seeding experiments the highest average yield, 
4,423 pounds of rice per acre, was obtained from the 2-inch depth. 
Shallow seeding is better than deep seeding. 
The highest average yields when rice was drilled or broadcasted 
were obtained from the heaviest rates of seeding, the 100-pound 
rate in the first period and the 150-pound rate in the second period. 
Drilling gave much better results than broadcasting in the first 
period, but the 150-pound rate during the second period produced 
about the same yield from both methods of seeding. 
Rate-of-seeding experiments conducted during 1921 with three 
varieties of rice indicate that 150 pounds per acre is probably the 
best rate on old rice land. 
In the date-of-seeding experiments there has been a marked 
decrease in yield with each successive date. Early seeding should 
be more generally practiced. 
In a comparison of rough and smooth seed beds, there was a 
small increase in the average yield for the smooth seed bed. 
The average yield by continuous cropping to rice for the 7-year 
period, 1913 to 1919, was 3,528 pounds per acre. 
In the time-of-submergence experiments, the highest average 
yield, 3,699 pounds of rice per acre, was obtained by submerging 
30 days after the rice emerged. 
In the depth-of-submergence experiments, the highest average 
yield, 3,925 pounds per acre, was obtained by submerging the land 
6 inches deep during the submergence period. 
Slowly changing water gave a higher average yield than stagnant 
water. Fluctuation in the depth of submergence gave a higher aver- 
age yield than slowly changing or stagnant water. 
Land kept moist but not submerged during the usual submergence 
period produced dwarfed plants, small heads, and low yields of poor 
quality. 
The best irrigation practice consists of irrigating the rice as often 
as necessary until 30 days after emergence: then submerging the 
land 6 inches deep continuously until the cro]) is ready to drain for 
harvest. 
The fertilizer experiments conducted during the 3-year period, 
1914 to 1916, inclusive, show that manure increased the average 
yield 879 pounds, sulphate of ammonia 651 pounds, dried blood 646 
pounds, and cottonseed meal 583 pounds per acre. 
After deducting the cost, the average increase in yield from the 
use of manure was worth $ 12.70; sulphate of ammonia, $9.09; dried 
blood, $8.16; and cottonseed meal, $5.85 per acre. 
The fertilizer experiments indicate that nonnitrog'enous fertilizers 
are unprofitable on Stockton clay adobe soil, while all nitrogenous 
fertilizers except nitrate of soda produced increased yields which were 
profitable. 
Combinations of nitrogenous and nonnitrogenous fertilizers did not 
increase the yields as much as when the nitrogenous fertilizers alone 
were applied, and the increased cost of such combinations usually 
resulted in no profit and often a loss. 
