450 



[December, 1912. 



SWEET POTATOES. 



Some data from Western Australia. 



This plant which belongs to the Convolvulacece does best in warm 

 climates where it replaces the Irish potato, says the Bulletin of the Depart- 

 ment of Agriculture, Western Australia: There it is cultivated as a field 

 crop whereas the Irish potato is regarded as a garden crop, which is the 

 opposite of the practice of the cooler districts of the South. 



It does best where the land is moist or where frequent rain is recorded 

 during the period of growth. Wet weather at the time of ripening induces 

 a second growth and is injurious to the raising of a profitable crop. 



Although the plant is perennial it is treated as an annual. As it 

 flowers rarely and the seeds give rise to a variety of types, slips or sets 

 about four inches long growing on roots placed in hot-beds are used when 

 sufficiently developed and one single sweet potato will produce quite a 

 number of these slips. 



Compared with Irish potatoes as a foodstuff, sweet potatoes show 

 about one and a half times as much nutritive matter ; they contain about 

 10 per cent, less water, the same proportion of mineral constituents, a 

 little less protein, more fat and about 10 per cent, more carbohydrates as 

 starch and sugar. 



One or two bushels of small potatoes will produce enough slips to 

 plant an acre. A second and sometimes a third growth of slips will show 

 after the fiist one is ready to pull. If green vines are available cuttings 

 may be used instead of slips grown on the tubers. When slips are pulled 

 they should be dipped at the base in liquid mud made of clay and cow 

 manure. 



In the human diet it should be supplemented by an addition of foods 

 rich in protein, such as lean meat, eggs, milk, peas and beans. In feeding 

 stock, a proportion of cowpeas, soy beans or any of the legumes should 

 be added. 



The varieties are numerous ; they are either syrupy, mealy or inter- 

 mediate. The flesh is yellow or white; the leaves deeply indented, 

 shouldered or round ; the skin is white, yellowish, light-red or purple. 



The soil most suitable as regards its texture for the growth of that 

 root is a sandy loam which remains friable and does net bake. It does 

 well also in limestone clay, but there the crop is harder to dig. 



A four-ton crop removes in the roots alone 30 lbs. of nitrogen, 13 lbs. of 

 phosphoric acid, 64 lbs. of potash. The vines which weigh more than half 

 the weight of the crop are richer in nitrogen. It is thus seen that heavy 

 fertilising is required to ensure a large crop ; humus is very desirable and 

 can be provided by growing the sweet potatoes after a leguminous crop or 

 a green crop fed off on the ground. A wide interval in the rotation is 

 desirable to guard against pests and diseases. If the soil is not wet at the 

 time of planting, some water should be poured over the slip so as to settle 

 the soil around it ; in that case some dry earth is raked over to check 

 evaporation. Shallow cultivation is necessary after planting to break the 

 crust and root out weeds, 



