434 SOUTHERN FIELD CROPS 



or mottled white and yellow. Each of these last subdivisions 

 can be still further separated into four divisions, according as the 

 skin of the potato is white, yellowish, light red, or purple (dark 

 reddish). If all of these classes should have representatives, 

 there would be 144 different classes. However, the vineless 

 has only a few subdivisions at the time when this is written. 



Examples of the bunch varieties are found in the several 

 strains of vineless, which appear to differ somewhat in quality 

 and yield. 



Among the varieties of the cut-leaf type, with long vines, 

 are the following. Sugar, or Yellow Yam, and its synonyms, 

 all of which have a sirupy quality, but are relatively unproduc- 

 tive ; the Spanish has cut leaves and a mealy texture. 



Among varieties having shouldered leaves is the Yellow Nan- 

 semond which has a mealy texture. 



Among the varieties with leaves almost entire are Pumpkin 

 Yam, or Dooley, which has a sirupy flavor ; and among those 

 with a starchy texture are Southern Queen and Hayman. 



SOILS, FERTILIZERS, AND ROTATION 



404. Soils. For the best results in quantity and 

 quality, the soil for sweet-potatoes should have the fol- 

 lowing properties : (1) It should be mellow, so as not 

 to bake, and so that the roots may easily penetrate it, 

 and fully develop without undue pressure; (2) it should 

 be warm, so as to promote a long period of active growth ; 

 and (3) it should be well drained, so that growth may be 

 vigorous and the quality of the crop good. These con- 

 ditions are best filled by a sandy loam or sandy soil. On 

 a given farm, the soil which contains the largest proportion 

 of sand is usually devoted to the cultivation of sweet-i 

 potatoes. 



However, this crop is not confined to sandy land. On 



