512 INVESTIGATION BY CULTURE EXPERIMENTS 



These results may serve as a control or check when comparisons 

 are needed. 1 



Thus, from Table 106, we note that iron sulfate produced a 

 more marked effect upon oats and barley than upon wheat; but 

 in Table 107 we observe that, as a three-year average, iron sulfate 

 decreased the yield of carrots on the wheat series, and increased 

 markedly the carrot crop when grown on the oat series. Likewise, 

 with potatoes, iron sulfate decreased the yield by 8 or 28 bushels 

 on the wheat land, and produced an increase of 8 bushels or a 

 decrease of 13 bushels on the barley series. All of this means that 

 apparent results from treatment not controlled by some sort of 

 repetition are not to be given great confidence, especially when 

 the apparent effect of the treatment is no greater than the difference 

 between the untreated plots, or between any two plots which are 

 fairly comparable, as plots 5 and 10, wherever plot 5 shows the 

 larger yield. 



1 Evidently through a clerical error, the three-year average yield of carrots from 

 the wheat series was credited to the oats series in the 1894 Report of the Dominion 

 Experimental Farms, and this error was continued in the subsequent reports; 

 consequently the above corrected seven-year average does not agree with the data 

 given in the 1897 Report. 



