126 



COBN CROPS 



yield. When additional minerals have been added, the 

 crop production has been actually increased about 20 

 per cent. 



At the Indiana station ' five cropping systems have been 

 compared for 20 years, with and without commercial 

 fertihzers. Without giving details, the following table 

 shows clearly enough the comparative effect of different 

 cropping systems on the maintenance of production. 



TABLE XXIII 



Indiana Expebiments, comparing Coen Yields at Begin- 

 ning AND End of Twenty-year Period in Different 

 Rotations 



Treatment 



Cropping Systems and Yields in Bushels per Acre 



Continuous 

 Corn 



II 



Corn and 

 Wheat 



III 



Corn, Oats, 

 Wheat- 

 Clover 



IV 



Corn, Oats, 

 Wheat, 

 Clover- 

 Grass 



V 

 Corn-roots, 

 Oate, 

 Wheat, 

 Clover- 

 Grass 



Unfertilized . 

 Fertilized 



Yields in 1889 "when the Experiments were Begttn 



61.1 

 62.1 



50.0 

 49.3 



54.6 

 54.8 



54.2 

 56.4 



58.4 

 58.1 



Yields in 1909 after 20 Yeahb' Chopping 



1 Ind. Agr. Exp. Sta., Circ. 25. 1911. 



