20 BULLETIN 698, U. S. DEPARTMENT OF AGRICULTURE. 
EXPERIMENTAL CONDITIONS. 
In order that the experimental results may be properly inter- 
preted, descriptions of the methods of obtaining data and of the 
environing conditions prevailing in each season are given here. 
MetTHops EMPLOYED. 
The size and arrangement of plats, the method and rate of seeding, 
the date when the crop was sown each year, the rotation of crops 
on the experimental area, and the methods of obtaining certain data 
are explained in the following paragraphs.. 
SIZE AND ARRANGEMENT OF PLATS. 
The plats used in these experiments were 8 rods long by 2 rods 
wide, containing a tenth of an acre each. These plats were laid out 
in blocks of 10. Each block was bordered on all four sides by a road 
19.2 feet wide. Each plat, therefore, had a road at each end, and — 
the first and tenth plats in each group or block had a road on one 
side. A guard row usually is placed between the first and tenth 
plats and the adjacent roads. 
In the experiments with small grains, definite alleys are left 
between plats, to prevent mixing and to facilitate the handling of 
the crop. Since the grain sorghums are sown in widely spaced rows 
no alleys were needed for these purposes, and usually none were 
left. The regular 42-inch space between rows served as an alley. 
In 1910, however, 5-foot alleys were left between the plats, thus 
giving the crop thereon the benefit of 9 inches of extra space on each 
side of the plat. 
Each plat contamed 10 rows, 132 feet long and 42 inches apart. 
Usually each variety occupied 10 rows, or a tenth of an acre. Some- 
times, however, fewer than 10 rows were sown. In 1914 all varieties 
were sown on 5-row or twentieth-acre plats. In sowing the varieties 
the rows were made longer than 132 feet. When the plants were 
15 to 20 inches (4 to 5 dm.) in height, the ends of the rows were 
trimmed to the proper limits. 
METHOD AND RATE OF SEEDING. 
A 1-row corn drill, fitted with special sorghum plates, was used for 
sowing the crop until 1910. Since then a 2-row corn drill, fitted in 
the same manner, has been used. The plates for sowing milo and 
durra contain 18 holes, each three-sixteenths of an inch in diameter. 
Yor kafir the plates have 16 holes, each five thirty-seconds of an inch 
in diameter, and for kaoliang 25 holes the same size as for kafir. The 
feed was run on high gear, which drops at intervals of 6.4, 7.2, and 
4.6 inches, respectively, with plates bored as stated above. 
It was the intention to have only one kernel dropped at a time, but 
in many cases two and sometimes three kernels were dropped because 
of the thickness of the plates and the varying size of the kernels. 
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