501 
Sept. 9,1918 Deep Tilling and Dynamiting in the Great Plains 
spring wheat, winter wheat, oats, and barley, which range from 94 to 97, 
with probable errors ranging from 2 to 2.6, certainly do not indicate 
any difference in the relative effect of subsoilihg upon these crops. Cora 
Fig. a.—Ratio of the yield for each crop at each station of plot E (subsidled) to the mean of the yield of 
plot B (not subsoiled.) and plot E (subsoiled) and the averageof all crops at each station. The shaded 
areas are delimited by the probable error of each ratio. They mark the zones within which the chances 
are even that the results of a repetition of the experiments would fall. 
at the same stations has a ratio of ioo, with a probable error of 1.8. 
While the difference between this and the other crops is not great enough 
to make it in any way conclusive, it might perhaps indicate a slightly 
better response from this crop. 
70393°—18-* 
