112 



THE rillNCIl'LES OF ACililCLI/rURE. 



4. It secures the varied advantages of cultivating the 

 soil. 



When luiul is contiuiially occiiiiicd with one crop, like 

 grass, it may become too hard and eonii)act, and the for- 

 mation of i)huit food may be checked. By stirring such 

 soil, and exposing it to the atmosphere in cultivation, we 

 hasten the chemical changes, and unlock the sui)])ly of 

 food which nature has in store. 



There are many old meadows and pastui-es, regaided as 

 worn out and w^orthless, which, if subjected to thorough 

 cultivation, might yield profitable returns. 



5. It prevents the increase of zveeds and injurious 

 insects. 



In cultivating certain crops, we may supjdy conditions 

 •favorable to the growth of certain varieties of weeds. If 

 the crop is continued in the same soil, tlicse weeds will 

 naturally increase. Proper management requires a 

 change to some other crop with which such weeds will 

 not thrive. 



It is well known that injui'ious insects, like the potato 

 beetle, will tend to Increase on land whicli is repeatedly 

 occu|>ied by the particular crop upon which they arc 

 accustomed to ])i-('y. 



The following are exam})les of rotations which are 

 sometimes adopted : — 



Indian corn 

 Potatoes 

 Wlieat . . 

 Clover . . 



Clover . 

 Tobacro 

 Wheat . 



One year. 

 One year. 

 One year. 

 Two years. 



Two years. 

 One year. 

 < )ne Near. 



Wheat 

 Potatoe? 

 P.arley 

 Clover. 



Cotton . . 

 ^^'lleat - . 

 CloMT (ir ])eas 



One year. 

 One year. 

 One year. 

 One year. 



One year. 

 One year. 

 ( )ne \-ear. 



