TUBER CROP PROJECTS 225 



mind that there must be an abundance of soil moisture at the time 

 of transplanting to insure the success of this operation, and all 

 preliminary tillage should be managed with this in view. It is 

 also exceedingly important to follow a system of cropping that 

 will effectively destroy weed seeds. If cultivated crops are grown 

 the preceding year, they should have the most thorough tillage 

 so that no weeds will go to seed. Crimson clover is a desirable 

 manurial crop to plow down for sweet potatoes. 



Commercial fertilizers are universally employed for sweet 

 potatoes. It is customary to use some nitrogen, 3 or 4 per cent, 

 but an excessive amount should be avoided because it stimulates 

 too much vine growth without a corresponding development of 

 tubers. The mineral elements are essential and there should be 

 no uncertainty about the required amount of both potash and 

 phosphoric acid; 1000 pounds to the acre of a 3-7-10 fertilizer 

 should be satisfactory under most conditions. It should be 

 applied before planting and mixed very thoroughly with the soil. 

 Well-decayed stable manure can be used to advantage, especially 

 in thin soils. 



1. What are the best crops to precede sweet potatoes ? 



W-VG : 444. 



2. What preparatory tillage operations are necessary? 



W-VG : 444. Fi : 31. 



3. What fertilizer treatment do you recommend for sweet potatoes ? 



W-VG : 444. C : 423. 



4. What lessons do the Experiment Stations teach relative to fertilizing 



sweet potatoes ? W-VG : 445. 



7. Planting. — Sweet potato plants should not be set out 

 until they are well rooted, and until the ground is thoroughly 

 warm and the danger of frost past. Either before or after a rain 



