sept. 9, 1918 Deep Tilling and Dynamiting in the Great Plains 511 
lowest yield from the plot deep-tilled every year. This relation has been 
quite consistent during three of the five years for which results have been 
obtained. During the two other years little difference as a result of the 
different preparations is exhibited. 
From the com crop no significant differences as a result of different 
depths of tillage have been obtained. Between the average of the two 
plots deep-tilled each year and the average of the two plots ordinary- 
plowed each year there is as an average of six years' results a difference 
of only 0.4 bushel of com in favor of one and 60 pounds of fodder in favor 
of the other. In the three years when grain was produced both of these 
averages exceeded those of the plots alternately deep-tilled. In the 
three years in which fodder only was produced, the yields of these plots 
exceeded those of one of the alternately deep-tilled plots, but were in 
turn exceeded by that of the other. 
That these differences are accidental rather than due to the effect of 
the tillage method is shown by the fact that they are determined, in at 
least a part of the cases, by differences in 1911 in the yield of plots ex¬ 
actly similar in their preparation. The only differences of cultivation or 
sequence that year were that the four plots F, E, D, and C, being the four 
which appear under the headings “Deep tillage each year" and “First 
crop after deep tillage," were deep-tilled, while the other four plots were 
given ordinary plowing. Two of the deep-tilled plots and two of those 
shallow-plowed produced some grain, while the other four did not. The 
yields are given, however, as total weights of fodder. In no other year 
has there been observed in plots of different treatment such great differ¬ 
ences as were evidenced this year between plots of similar treatment. 
From the evidence presented by this experiment it is safe to say that 
at this station deep tillage has no efficacy either in overcoming drouth or 
in increasing the yields of wheat or com in the average of a series of 
years. There is, indeed, strong indication that the yields of wheat may 
be materially reduced by this practice. The conclusiveness of this evi¬ 
dence is strengthened by its general agreement with the results of the 
shorter experiment in the use of dynamite and the longer and more ex¬ 
tensive experiment with subsoiling. 
ARDMORE FIELD STATION 
* 
DEEP TILLAGE BY THE USE OP DYNAMITE 
The deep tillage with dynamite experiment at Ardmore, S. Dak., is 
similar to the one at the Judith Basin Field Station, and in every par¬ 
ticular except the size of the plots and their grouping in the field is the 
same as the deep-tillage experiment at Akron. Figure 4 illustrates the 
manner in which the plots are laid out. In preparation for the crop 
raised in the odd years the two center tiers of plots running north and 
south are dynamited. In preparation for the crop raised in the even 
