49 2 Journal of Agricultural Research voi. xiv, no. » 
Table IV presents eight years’ results with spring wheat, winter wheat, 
oats, bailey, and com. During these years conditions have ranged from 
the drouth of 1911, which was so severe that all crops on all methods of 
preparation were total failures, to the favorable conditions of 1915, when 
the highest yields of spring grains yet recorded in experimental work in 
the Great Plains were obtained. 
Of the 40 comparisons offered, only 11 are in favor of subsoiling. 
These are so evenly distributed throughout the different crops and years 
that no positive conclusion can be derived from them. A negative con¬ 
clusion that subsoiling has afforded no protection against drouth is very 
clearly indicated. In the average of the eight years the differences in 
yield as a result of the two methods are measured in fractions of a bushel 
with every crop. The departures of the average ratios from 100 are all 
less than the probable error except in the case of barley, where the 
departure is less than twice the probable error. With this crop the 
difference in average number of bushels per acre is in one direction, while 
the departure of the average ratios is in the other. This is partly 
explained by the fact that in 1910 there was a production of nearly 5 
bushels per acre on the fall plowing, while the subsoiled plot was a total 
failure. The mean ratio of all crops is 98, with a probable error of 2.5 
This shows practically no effect in either direction as an average result of 
subsoiling. 
ARDMORE FIELD STATION 
The soil on the Ardmore (S. Dak.) Field Station is a heavy clay loam 
with a lighter subsoil. The subsoil is not uniform, but at depths of 3 
feet or more it generally breaks into sand or gravel. 
Three years’ results, exclusive of the year 1914, when the crop was 
completely destroyed by hail, are available for study. One year the 
crops from many methods, including the two under study, were total 
failures. One year the yields were good, and one year the yields were 
very high. 
Table V presents in detail the results with spring wheat, winter wheat, 
oats, barley, and com at this station. With all crops except winter 
wheat, with which the better yield both years has been from subsoiling, 
the evidence is all against that practice. It failed with all crops to 
overcome the drouth of 1913, and actually appeared to reduce the yields 
of all crops but winter wheat both in the exceptionally productive year 
of 1915 and in the more normal year of 1916. The average ratio of all 
crops is 93, with a probable error of 3.1. There apparently is at this 
station a detrimental effect from subsoiling. The decrease in yield is 
not, however, enough greater than its probable error to make it all 
certain that it might not be effaced by continuation of the record. 
