CHAPTER V 



Crop Rotation 



The importance of crop rotation has long been 

 recognized in connection with the growing of farm 

 crops, but its value in vegetable growing has too 

 often been overlooked or ignored. This has doubt- 

 less come about largely from the fact that the only 

 advantage of rotation usually considered is that 

 which has to do with the supply of plant food avail- 

 able in the soil. It is known that certain crops take 

 out particular elements in larger quantities than 

 others. The heavy applications of manures 

 and fertilizers to vegetable crops have led the grower 

 to feel that this factor is largely under his control, 

 and, therefore, rotation is not as necessary for him as 

 it is for the general farmer. One of the principal rea- 

 sons for rotation, however, is the elimination of 

 insect pests and diseases which are peculiarly de- 

 structive to the vegetable crops on account of thef 

 fact that conditions are made ideal for their develop- 

 ment. These difficulties are largely obviated by 

 growing different kinds of crops which allow the 

 insects and diseases feeding upon one crop to starve 

 out and die, while another crop is being grown. 



Vegetable crops also differ greatly in the amount 

 of humus destroyed by cultivation and likewise in 

 the amount of humus-making materials left upon 

 the soil when the crop is harvested. Cabbage, 

 cucumbers, melons and squash leave rather large 

 quantities of vegetable materials to be returned to 

 the soil, while onions, beets, spinach and lettuce 



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