CROP ROTATION 



17 



but the reduction in the last 16 years has been going on 

 much slower than at first. 



University op Illinois Experiment Field at Urbana, III. 

 Typical Corn Belt Prairie Soil 



(Three years' averages : bushels per acre) 



Iowa Agricultural Experiment Station, Ames, Iowa. 

 Typical Corn Belt Prairie Soil 



(Figures give bushels per acre) 



Rotation of corn, corn, oats, clover, compared with continuous 



Corn in rotation 

 Continuous cul- 

 ture .... 



1904 



75 

 74 



1905 



87 

 73 



1906 



69 

 53 



1907 



57 

 47 



191% 



60 



47 



The results from nine years of experiments at the Iowa 

 station are even more striking than those from Illinois. 

 They show that, while each system started out with a 

 yield of approximately 75 bushels of corn per acre, con- 

 tinuous cropping never after the first year produced as 

 much by ten bushels per acre as in a four-year rotation 

 c 



