16 BULLETIN 1387, U. S. DEPARTMENT OF AGRICULTURE 
broadcast and drilled plats were inclosed within the same lev- 
ees, to handle the water in such a manner that maximum stands 
would be obtained on both plats. Drilled rice does not germinate 
well if excessive moisture is present, while broadcast rice needs a 
very wet soil to insure a high percentage of germination and good 
stands. The stands each year were better for the drilled plats in these 
and the preceding experiments, probably because moisture condi- 
tions were better suited for drilled than for broadcast rice during 
the period of germination. 
The average acre yields for plats sown broadcast and drilled on 
spring-plowed and on disked stubble land submerged 4, 6, and 8 
inches after the rice emerged, decreased in each case with increased 
depths of submergence. The three-year average acre yield of the 
drilled plats for all depths of submergence on spring-plowed land 
was 2,227 pounds, of the broadcast plats on spring-plowed land 1,925 
pounds, of the drilled plats on disked stubble land 1,434 pounds, and 
of the broadcast plats on disked stubble land 1,223 pounds. The 
three-year average acre yield for all plats, including drilled and 
broadcast, on spring-plowed land submerged 2, 4, 6, and 8 inches 
was 2,098 pounds and on disked stubble land 1,344 pounds, or an 
average difference of 754 pounds per acre in favor of the spring- 
plowed plats. This increase in yield (754 pounds per acre) is signif- 
icant and shows the advantage of plowing for rice. The chief 
benefits of plowing are probably due to the control of such weeds 
as spike rush, cat-tail, slender aster, canary grass, and perennial 
sedge, which were largely responsible for the low annual yields on 
the disked stubble land. 
The method of irrigation used in this series of experiments, as pre- 
viously stated, is inferior to continuous submergence immediately 
after broadcasting, both in the control of weeds and in rice yields. 
EXPERIMENTS ON RATE OF SEEDING AND METHOD OF IRRIGATION 
Rate-of-seeding and method-of-irrigation experiments were con- 
ducted on land previously used in the irrigation experiments. The 
land was fallowed in 1921. The 1922 crop was the sixth rice crop 
in 9 years, the 1923 crop was the seventh rice crop in 10 years, and 
the 1924 crop was the eighth rice crop on this land in 11 years. In 
the spring of 1922 the land was twice double disked, harrowed, and 
dragged. For the 1923 and the 1924 crops the land was spring plowed, 
double disked, harrowed, and dragged. These tillage operations 
resulted in a good seed bed each year. 
On series 1 the rice was sown broadcast and the plats were immedi- 
ately submerged about 6 inches. On series 2 the rice was drilled and 
irrigated and drained twice before emergence. It was then sub- 
merged about 6 inches. On series 3 the rice was drilled and irrigated 
and drained at 10-day intervals until 30 days after emergence. It 
was then submerged about 6 inches. 
The plats on which the rice was sown broadcast and immediately 
submerged (series 1) were practically free of water grass and spran- 
gletop each year. There was some annual sedge on certain of these 
plats each year, due to thin stands of rice. Plats on which the rice 
was drilled and irrigated and drained twice before submergence (se- 
