430 



SOUTHERN FIELD CROPS 



of sweet-potatoes is expected to make nearly one gallon 

 of industrial alcohol. Moreover, in the manufacture of 

 starch, after this substance is removed, alcohol could be 

 made as a by-product from some of the waste material. 



399. Draft on soil fertility. — The sweet-potato removes 

 much potash and also rather large amounts of other plant 

 food, as shown by analyses : — 



Nitrogen 

 Per Cent 



Phosphobic 



Acid 

 Feb Cent 



Potash 

 Per Cent 



Sweet-potatoes, edible roots (N. J.) 

 Sweet-potatoes, edible roots (S. C.) 

 Sweet-potatoes, edible roots (Cal.) 

 Sweet-potatoes, edible roots, aver- 

 age of above 



Sweet-potato, fresh vines (Md., 



water 83 %)' 



Sweet-potato, fresh vines (S. C, 



83 % water)^ 



lYesh vines, average of above . . 



0.23 

 .25 

 .30 



.26 



0.42 



0.34 

 .38 



0.10 

 .07 

 .17 



.11 



0.07 



0.05 

 .06 



0.50 

 .45 

 .63 



.63 



0.73 



0.48 

 .60 



1 Farmer's Bui. No. 26, U. S. Dept. Agr. 

 ' S. C. Expr. Sta., Bui. No. 146, p. 18. 



The roots of sweet-potatoes remove about twice as much 

 potash as nitrogen and about five times as much potash as phos- 

 phoric acid. The fresh vines have been found to weigh consid- 

 erably more than half of the weight of the edible roots and to be 

 richer in nitrogen. 



According to the average figures in the above table a crop of 

 200 bushels would remove in the edible roots alone 



31 pounds of nitrogen, 



13 pounds of phosphoric acid, 



64 pounds of potash. 



