6 BULLETIN 214, U. S. DEPARTMENT OF AGRICULTURE. 
varietal tests, breeding, or seed selection makes available for general 
use a better variety. The same seed is used on all plats at any one 
station in any particular year. 
All seeding is done with, a drill. Drill rows are spaced from 6 to 8 
inches. As compared with more humid sections, light seeding is 
practiced*. The rate varies from 2 to 4 pecks, depending upon the 
location and the consequent average climatic conditions. At "Edgeley 
N. Dak., where summer rains are more frequent and weeds more 
troublesome, the seeding rate is 6 pecks per acre. . Generally speaking, 
the drier the condition the lighter the seeding. The seeding rate, 
date, and mamier of seeding are the same for all plats at the same 
station in any one year. 
For comparative study of the effect of environment and for securing 
data on production certain of the work is made uniform at all stations. 
This results in the attempted growth of spring wheat and other crops 
in sections to which they are not adapted and in their growth at 
certain stations by methods not adapted to the conditions obtaining 
there. Such work, however, is limited, the most intensive studies at 
each station being undertaken on the crops which are of greatest 
promise in that locality. 
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 wheat has 
been grown, considering only the treatment during the one year imme- 
diately preceding the crop. The reasons for not differentiating the 
study further have already been stated. 
Where more than one plat has been grown under the same treatment 
for the previous year, only the average yield of the whole number 
of plats so grown is given. Column 2 of the table shows the number 
of plats so averaged. In the presentation of yields, the column 
headed " Treatment and previous crop" indicates the method of 
preparation, whether fall plowed, spring plowed, listed, subsoiled, 
disked, green manured, or summer tilled. Some of these are again 
subdivided to show the previous crop. To illustrate: The table for 
Judith Basin (Table V) shows that there were five plats of whea^. 
each year grown on fall-plowed land. On two of these the wheat 
followed corn, on two it followed oats, and on one it followed wheat. 
The average yield on fall plowing as given is the average of the five 
plats, not the average of the given averages. To obtain these aver- 
ages it is necessary to use the figures as many times as there were 
plats averaged in obtaining them. The succeeding columns need 
no explanation, as they are the yields for each year as indicated and 
the average of each method for the whole period of years. In the 
last column, where the average appears under the heading "Average," 
