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 : 



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



2 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. 



