PURCHASE AND USE OF FERTILIZERS 



33* 



He also shows the effect of the fertilizer to increase from year 

 to year, as per the following results on a plot receiving a complete 

 fertilizer. 



Thorne 1 corrects for variations in the soil by assuming that 

 variations in fertility are regular from one check to the next. 

 The difference between this method and the method of deducting 



If 



309* 



Pig, 77. The same fertilizers give the same increase if the land decreases 



regularly (CD) from the checks, but not if the average of 



the checks (A B) is deducted. Ohio Station. 



the average of all plots, is well brought out in Thome's diagram. 

 This represents four plots fertilized alike and three check plots. 

 The increase in the average crop is regular if the soil varies uni- 

 formly, but the results are unconsistent if the average yield of 

 the plots are deducted. 



1 Circular 96, Ohio Station. 



