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ROTATION AND CULTURAL METHODS AT EDGELEY, N. DAK. 9 
letter. The crop that is on plat C one year is on plat B the next, and 
so on until from A it moves to the letter marking the end of the 
rotation. The plats are 2 by 8 rods and are separated by 4- foot alleys 
and 20-foot roadways. In the diagram the separation of rotations 
is indicated by heavy lines. The four unnumbered blocks of four 
plats each are the continuous and alternate cropping plats devoted 
to the four crops designated. 
Rotations Nos. 1, 2, 71, and 72, set off by a broken line and desig- 
nated " on hill," are duplications described in the text as being on 
deeper soil. They do not occupy the position indicated on the dia- 
gram, but are detached. The eight plats, also set off by a broken line 
and designated ; ' 1913 fallow series," are also detached. They have 
been devoted to a study of four methods of fallow. 
The circle and square designated " observatory " indicate the loca- 
tion of the instrument yard, in which the meteorological instruments 
are exposed. 
Rotations Nos. 1 and 3 are exactly the same 3-year rotations of 
oats on fall-plowed wheat stubble, corn on fall-plowed oat stubble, 
and wheat on corn ground. In rotation No. 1 the corn ground is 
disked and in rotation No. 3 it is fall plowed in preparation for the 
wheat. The wheat on the disked corn ground has yielded more than 
on the fall-plowed corn ground in 11 out of 13 years, and for the 13 
years it has averaged 2J bushels per acre more. The average yields of 
oats from the two rotations agree within a fraction of a bushel, but the 
corn has averaged slightly more in rotation No. 1. In 1906, when 
the treatment was the same, the yield was about the same, indicating 
no considerable natural advantage of rotation No. 1 over rotation 
No. 3. 
Rotation No. 2 has the same crops, but the ground is spring plowed 
for each of them. The yield of wheat on disked corn ground in 
rotation No. 1 has exceeded that on spring-plowed corn ground in 
rotation No. 2 in 10 out of 13 years, and for the 13 years it has 
averaged 2.4 bushels more per acre. 
The same rotations have been duplicated on deeper soil since 1908. 
In this duplication the disked corn ground has shown less advantage 
over the plowed land than in the original plat field, but its average 
increase for the 11-year period from 1909 to 1919, inclusive, has been 
three-tenths of a bushel per acre. 
Rotation No. 4 is wheat on fall plowing, corn on fall plowing, and 
oats on disked corn ground. Rotation No. 9 has the same crops in 
the same order, but all on spring plowing. The oats on disked corn 
ground in rotation No. 4 has yielded more than the oats on spring 
plowing in rotation No. 9 in 10 out of 13 years. The average in- 
crease on disked corn for the 13 years is 1.1 bushels per acre. 
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