278 THE FARMER OF TO-MORROW 



failed, just as cow-peas following cow-peas 

 without intermission failed. 



Then this soil, which first refused to grow a 

 second crop of wheat, but grew a crop of 

 cow-peas, and then refused to produce a sec- 

 ond crop, responded readily when it was 

 asked to take care of a potato seedling. Thus, 

 in succession it would grow wheat, cow-peas 

 and potatoes, but not a second crop of either 

 in succession. 



After the potato sprout had thrived it was 

 taken from this pot and a wheat seedling 

 was planted. It grew to perfection ! 



Thus, wheat would not follow wheat, but 

 when two other crops had intervened, the soil 

 responded to wheat as readily as it had in the 

 first place. 



Had the originators of this simple experi- 

 ment stumbled on the secret of the good 

 usage of crop rotation? The same conditions 

 are met with in field practice. Old land, well 

 manured though it may be, sickens, gets tired, 

 when it is asked to grow one crop season after 

 season. But when the crop is changed every 

 year the soil responds perfectly. The same 

 crop can be grown continuously every third 

 or fourth year without diminution of yield, 



