SOILS AND FERTILIZERS 421 



four and one half months without frost for its growth, with 

 plenty of warm weather both day and night, its culture is 

 confined largely to the Southern states, though it may be 

 grown for home use as far north as southern New York and 

 from there westward to Iowa and Nebraska. Sweet potatoes 

 are grown principally in the South Atlantic and Gulf states, 

 the leading states being Alabama, with 178,000 acres in 1917, 

 producing 16,020,000 bushels; Georgia, with 125,000 acres; 

 North Carolina, 90,000 acres; Mississippi, 85,000 acres; and 

 Texas, 84,000 acres. Among the other districts where the 

 crop is grown on a large scale for market are New Jersey, 

 eastern Maryland and Virginia, and near Merced, California. 



575. Soils and Fertilizers. The best soil for sweet pota- 

 toes is a sand or sandy loam with a clay or clay loam subsoil. 

 The loose surface soil allows the roots to develop, while the 

 heavy subsoil retains the moisture and prevents the forma- 

 tion of long slender roots which are not marketable. Soils 

 of this nature tend to produce the rather short, spindle-shaped 

 potatoes so much desired for the market, of the type shown 

 at the center in Figure 141. The sweet potato will grow in 

 veiy poor soils, though it will yield better in those of moder- 

 ate fertility. The lands should be rich enough to produce a 

 good growth of vines and foliage, but too much manure or 

 too rich soil will tend toward the production of a heavy top 

 growth with only a few small, undesirable potatoes. The 

 quantity of commercial fertilizer which is ordinarily used is 

 small, only from 200 to 500 pounds to the acre. The use of 

 crimson clover or some other legume in the rotation is de- 

 sirable to furnish the necessary vegetable matter in the soil. 



576. Growing the Plants. Sweet potatoes are ordinarily 

 grown from sprouts from the roots rather than by planting 

 the roots themselves in the field, though this latter practice 

 is followed to some extent in the South. The usual plan is 

 to start the plants in a bed of warm soil or in a hotbed and 

 remove them for setting in the field as they become large 



