30 Subtropical Vegetable-Gardening 



Certain crops are able to grow repeatedly on the same 

 land without showing any falling off in quantity or quality 

 of yield. For example, in an onion-raising district, a 

 certain piece of land has grown more than thirty crops of 

 onions, and that plot is preferred to-day to any of the sur- 

 rounding land. Lawes and Gilbert grew wheat on the 

 same carefully weeded plot for forty consecutive years, 

 and at the end of that time the land seemed about as good 

 for wheat as it was at the beginning of the experiment. 



It is always a good practice, however, to change the crop 

 grown in any field from year to year. In making changes 

 of crops, they should be as different as possible. It is 

 well to plant a field that has just received a good green 

 soiling with some gross-feeding crop, as the small grains or 

 corn, and then to follow this with vegetables. To follow a 

 crop of eggplant with a crop of tomatoes could hardly have 

 the force of rotation, inasmuch as the plants use about the 

 same fertilizer and harbor about the same insects and 

 fungi; cabbage following cauliflower could not be con- 

 sidered a rotation for the same reason, but cabbage follow- 

 ing tomatoes would be a good rotation. 



In the southern United States, near the Gulf, it is 

 possible to have three or even four crops in rotation in a 

 single year. Thus at Hastings, Florida, a crop of Irish 

 potatoes may be planted in February, and immediately 

 after digging the potatoes, corn may be planted. When 

 the corn is cultivated for the last time, cowpeas may be 

 sown. When these have been harvested, a fall crop of 

 Irish potatoes may be planted. These are harvested be- 

 fore Christmas. This rotation has been carried out in 

 practice. If some other crop, such as fall lettuce, be sub- 



