CHAPTEE XXXVIL 

 SWEET POTATOES. 



Our sweet potato is a member of the morning glory family and is not of 

 the same family as the Irish potato. Unlike the Irish potato, too, it is a 

 true root and not a tuber, though tuberous in form. The sweet potato de- 

 lights in a warm, sandy soil, and will not reach its best condition in any 

 other, though fair success can be had in heavier loams. Though differing in 

 character from the Irish potato its manurial requirements are very similar. 

 But as the plant grows through the long, hot season, when nitrification is 

 active in the soil and is still further promoted by the rank cover of the vines, 

 the crop needs far less nitrogenous manures than the early crop of Irish 

 potatoes. In fact, any excess of nitrogen will lead to a rank development 

 of tops at the expense of the roots, and while these rank vines are capable of 

 storing large quantities of the starch and sugar so important in the tuberous 

 roots, they cannot do this unless there is plenty of the mineral elements over 

 and above that needed for the perfection of the top-growth. Hence phos- 

 phoric acid and potash are far more important for the crop than nitrogen, 

 and the slowly available organic matter is better than the immediately avail- 

 able nitrogen of a nitrate. While on the northern limit of the culture of the 

 sweet potato it may be desirable to use stable manure in its production, such 

 would be rather a hindrance than a help in the South. The large market 

 growers understand the requirements of the plant very well and they under- 

 stand that the humus forming matter in the rakings of a pine forest are de- 

 sirable as an application to the soil, not alone for their manurial effect but for 

 the mechanical lightening of the soil and the retention of moisture. There- 

 fore the skilled market grower of sweet potatoes uses the forest mold only, 

 as the organic matter, and supplements it with liberal applications of the 

 mineral elements. 



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