THE ROTATION OF CROPS 211 



*" O 



and upper roots to the surface soil, and thus help to 

 maintain or increase fertility. 



Rotation tends to protect crops from injurious in- 

 sects and diseases. If one kind of crop is grown 

 continuously on one piece of land the soil becomes 

 infested with the insects and diseases which injure 

 that particular crop. If the crop is changed, the 

 insects and diseases find difficulty in adapting them- 

 selves to the change and consequently diminish in 

 numbers. 



Rotation helps to keep the soil free from weeds. 

 " If the same kind of crop were grown year after 

 year on the same field, the weeds which grow most 

 readily along with that crop would soon take pos- 

 session of the soil." For example, chick weed, dock, 

 thistle, weeds peculiar to grain and grain crops tend 

 to increase if the land is long occupied by these 

 crops. 



Rotation helps the farmer to make a more even 

 distribution of labor throughout the year. This is 

 because crops differ as to the time of year at which 

 they are planted and harvested. 



Rotation of crops enables the farmer to provide 

 for his stock more economically. Live stock fares 

 better on a variety of food, which is more cheaply 

 secured by a system of rotation than otherwise. 



THE TYPICAL ROTATION 



A typical rotation for general farming should 

 contain at least : 



