60 GARDENING FOE THE SOUTH. 



CHAPTER VI. 



ROTATION OF CROPS. 



The same crops cannot be grown from year to year 

 upon the same soil without decreasing in productiveness. 

 All plants more or less exhaust the soil, but not in the 

 same degree, nor in the same manner ; hence, as different 

 plants appropriate different substances, the rotation of 

 crops has considerable influence in retaining the fertility 

 of a soil. If the same kind of plants is continued upon 

 the same soil, only a portion of the constituents of the ma- 

 nure applied is used ; while by a judicious rotation every- 

 thing, in the soil or in the manure, suitable for vegetable 

 food, is taken up and appropriated by the crop. How- 

 ever plentiful manure may be, a succession of exhausting 

 crops should not be grown upon the same bed, not only 

 because abundance is no excuse for want of economy, but 

 because manure freshly applied is not so immediately bene- 

 ficial as those remains of organized matter which by long 

 continuance in the soil have become impalpably divided 

 and diffused through its texture, and of which each suc- 

 ceeding crop consumes a portion. 



Some crops are so favorable to weeds, that if continued 

 long upon the same bed, the labor of cultivating them is 

 much increased, while if raised but once in a place and 

 followed by a cleaning crop, the weeds are easily kept un- 

 der. Besides, many crops planted continually in the same 

 soil are more liable to be attacked by the insects and 

 parasites which are the peculiar enemies of those plants. 



Many insects injurious to plants deposit their eggs in 

 the soil which produced the plants they have infested, 

 ready to commit their depredations upon the succeeding 

 crop ; but if this is changed to a distant locality, they 

 often perish for want of their proper food. So, many 



