The Sweet Potato and its Cultivation. 845 



Yields of Tubers. 



During' the meeting of tlie British Association for the Advance- 

 ment of Science held in Cardiff last August, Captain A. P. H. 

 Desborough, in a paper on " Industrial Alcohol," alluded to the 

 potentialities of the sweet potato in the tropics in the following 

 terms : — ■ 



" According to good authority, the average yield amounts 



to 4-() tons per acre, or harely that of the potato yield in 



England. '* 



The average yield of sweet potatoes in the United States, where 

 there were 940,000 acres under that crop in 1918, was a total of 

 87,924,000 bushels, equivalent to an average of 93.5 bushels per acre 

 for that season. Taking a bushel of sweet potatoes as 53 lb., this 

 yield amounts to about 5000 lb. per acre. In 1919 the acreage had 

 increased to 1,029,000 acres, the total production to 103,579,000 

 bushels, and the rate per acre to 100.7 bushels or 5337 lb. 



In the Union of South Africa, according to the 1918 Agricultural 

 Census, the acreage under sweet potatoes in the four Provinces and 

 the relative yields were as follows : — 



Province. Acres. Production. Yield per Acre. 



Cape of Good Hope 12,162 46,089,450 lb. 3790 lb. 



Natal 3,643 12,290,850 lb. 3374 lb. 



Transvaal 4,411 10,529,250 lb. 2387 lb. 



Orange Free State 176 231,600 lb. 1316 lb. 



Total 20,392 69,141,150 lb. 3390 lb. 



The annual production of ordinary (Irish) potatoes in the Union 

 is about 117,000 short tons, the yield per acre being approximately : — 

 Cape. 270C 11>. ; Natal, 1200 lb. ; Transvaal and Orange Free State 

 each 1900 lb.; and average for the whole Union, 2200 lb. The chief 

 Irish potato growing district is Thaba 'Nchu, in the Orange Free 

 State, its yield being 17,354,100 lb. at the rate of 3128 lb. per acre. 

 Sweet potatoes are not grown in the Thaba 'Nchu District, while in 

 the principal sweet potato areas in the Union, such as George and 

 Oudtshoorn, the production of sweet potatoes is more than double 

 that of Irish potatoes. 



The Division of Oudtshoorn, with its exceedingly fertile soil, 

 yields heavier sweet potato crops than any other district in the Union. 

 It has only 510 acres under that crop, but its yield in 1918 was 

 3,892,350 lb., an average of 7632 lb. per acre. Of the other sweet 

 potato growing divisions in the Cape Province those giving highest 

 yields per acre are, in order, Paarl, Worcester, Stellenbosch, 

 Ladismith, and Knysna, their returns being as follows: — 



Division. Acres. Production. Yield per Acre. 



Paarl 430 2,459,250 lb. 5719 lb. 



"Worcester 464 2,539,050 lb. 5472 lb. 



Stellenbosch .... 381 1,842,600 lb. 4836 lb. 



Ladismith 478 2,287,500 lb. 4785 lb. 



Knysna 847 3,910,350 lb. 4617 lb. 



