28 BULLETIN 214, U. S. DEPARTMENT OF AGRICULTURE. 
wheat crops raised on corn ground, oat stubble, and wheat stubble 
with those on spring-plowed or fall-plowed ground after any crop, or 
on disked-corn ground as a preparation for wheat, shows no wide 
differences in yields. A small average difference in favor of fall 
over spring plowing is shown. Fall plowing of corn ground in prepa- 
ration for wheat appears from the returns of two plats so treated to 
have been considerably better than either disking or spring plow- 
ing it. 
The one plat of wheat on spring plowing following wheat has given 
an average yield of 12.2 bushels per acre. This plat is plowed shal- 
low while the others are plowed deep, as heretofore explained. The 
departure of this method from the others in yield appears to have 
been dependent upon the seasons and is not consistent from year to 
year. 
Summer tillage for wheat at this station seems to stand by itself 
as a means of increasing the yield. The largest increases in bushels 
from this method have been obtained in the best years. After the 
first year of a period of dry years, which began in 1910, summer tillage 
has not been able, except in 1914, to increase yields or even, in some 
cases, to maintain them at the standard set by less expensive methods. 
While it is not shown in the present study, a much greater response 
to summer tillage is obtained with winter wheat. 1 Consequently, 
in spite of the fact that this method has been productive on the 
average of more bushels per acre of spring wheat than any other, it 
will not find favor in farm management as a general practice for the 
growth of spring wheat. 
When the cost of production is considered, it is seen that the yield 
obtained by summer tillage has been enough to pay for the cost of 
the method. For the eight years under study it shows an average 
profit of 26 cents per acre. Fall plowing and spring plowing show 
profits of only $1.56 and $1.33 per acre for the same period. The low 
cost of preparation is responsible for making disked corn ground show 
an average annual profit of $2.53. 
While the spring wheat crop has been raised without much net 
profit, it seems that it might afford a market for the labor of men 
and teams and pay for the use of the land. 
AKRON FIELD STATION. 
The soil at the field station at Akron, Colo., is of a clay-loam type, 
locally known as " tight land.' 7 It is characterized in the native 
vegetation by a growth of short grass. As it carries in each unit sec- 
tion a considerable proportion of water available to the crop and as 
it offers no physical resistance to the development of roots, it is pos- 
sible to store in it a large quantity of water available to a crop. It 
1 See Nebraska Experiment Station Bulletin 135. 
