4 BULLETIN 595, U. S. DEPARTMENT OF AGRICULTURE. 
GENERAL PLAN OF THE INVESTIGATIONS. 
The same variety.of winter wheat is used on all plats at a station 
during any one year. The intention is to use the best variety that 
is available for general use. Changes are made only when seed 
breeding, selection, or varietal testing make available for general 
use a better variety. No attempt is made to use the same variety 
at different stations. The only varieties that have been used, 
however, have been strains of Turkey and Kharkof. The rate, 
time, and manner of seeding are the same for all plats at a station in 
any one year. As compared with more humid sections, the seeding 
is light, the usual rate being 3 pecks per acre. All seeding is done 
with a drill, the rows being spaced from 6 to 8 inches apart, depend- 
ing upon the locality. In different places different styles of drills 
are used. 
At each station the plats are one-tenth acre in size. Their dimen- 
sions are 2 by 8 rods. Along their larger dimension the plats are 
separated by bare alleys 4 feet in width. The ends of the plats are 
separated by roads 20 feet wide. 
There are as many field plats devoted to each rotation as there 
are years required to complete the cycle of the rotation. Each crop 
in a rotation is thus grown each year. 
Each rotation is given a number, and each plat within the rotation 
is designated by a letter. 
In Gagan to rotations or different cabana of crops and 
cultural methods, there is at each station a series of plats contmu- 
ously cropped ie different methods to each of the important crops. 
With each crop in this series two plats, known as C and D, are alter- 
nately cropped and summer tilled. 
In the present study a table is presented for each station. The 
first part of such table shows the yields that have been obtained in 
each year by each of the different methods under which winter 
wheat has been grown, considering only the variations in the one 
year preceding the crop. The previous crop whose stubble was 
treated as specified is also shown. Where more than one plat has 
been under the same treatment for the previous year, only the 
average yield of the whole number of plats so grown is given. Col- 
umn 2 of the table shows the number of plats so averaged. The 
succeeding columns need no explanation, as they show the yields 
for each year as indicated and the averages of each method for the 
whole period of years. In the last column, where the average 
appears under the heading ‘‘Average,” the calculation is from the 
left. The averages of the different methods of treatment are the 
averages of the whole number of plats that entered into their com- 
position. For a rough comparison of seasons the bottom line of 
the first half of the table gives the averages of alli plats for each 
