December, 1908.] 



545 



Edible Products' 



The sweet potato industry in this 

 country is readily divided into two 

 classes of production : (1) For home use ; 

 and (2), for market. A quantity suffi- 

 cient for home use can be grown under 

 a wide range of conditions, while pro- 

 duction on a commercial scale is some- 

 what restricted by climate and soil and 

 also by market and transportation 

 facilities. The larger eastern markets 

 are now well supplied, but there are 

 sections where the people have not as 

 yet become accustomed to the use of 

 sweet potatoes in large quantities. The 

 field for the production and use of 

 sweet potatoes is very broad, and this 

 crop promises to become of more general 

 farm importance. 



In view of the constantly increasing 

 interest in sweet potatoes, it is the 

 purpose of this bulletin to give simple 

 cultural directions covering their pro- 

 duction both for home use and for 

 market, including the soil and its 

 preparation, the propagation of the 

 plants, planting, harvesting, storing, and 

 marketing, together with the uses of 

 sweet potatoes for stock feeding and 

 for similar purposes. 



The sweet potato is of a tropica^ 

 nature, its original home probably being 

 the West Indies and Central America. 

 The true sweet potato, as we have it 

 growing in the United States, belongs 

 to the morning-glory family, its botanical 

 name being Ipomcea batatas. Through- 

 out the Southern States the sweet pota- 

 toes having moist flesh are commonly 

 known as " yams," and those having 

 dry flesh as sweet potatoes. The name 

 "yam" is misleading, and properly be- 

 longs to a distinct class of plants that 

 are confined almost entirely to the 

 Tropics. 



Climatic Conditions Required. 

 The climatic requirements for the pro- 

 duction of sweet potatoes on a com- 

 mercial scale are (I) a growing period of 

 at least four and a half mouths without 

 frost ; (2), warm nights and abundant 

 sunshine during the day ; and (3), a 

 moderate rainfall during the growing 

 period. 



Where irrigation is depended upon 

 for the supply of moisture, the greatest 

 quantitly of water should be applied 

 between the time the plants are set in 

 the field and the time when the vines 

 practically cover the ground. If too 

 much water is applied during the latter 

 part of the season the result may be an 

 abundant growth of vine and a small 

 yield of stringy potatoes. For some- 

 time before harvesting the crop the 

 water should be withheld altogether, in 

 order that the roots may ripen properly. 



69 



Character op Soil Adapted to 



Sweet Potatoes. 



Sweet potatoes thrive on a moderately 

 fertile sandy loam which does not con- 

 tain an excess of organic matter. They 

 are frequently grown upon almost pure 

 sand, especially where the sub-soil is a 

 yellow clay. Soils containing consider- 

 able calcium or underlain with lime- 

 stone are well adapted to the growing 

 of the crop. The sweet potato is excep- 

 tional in that a fairly good crop can be 

 grown upon soils that are too poor for 

 the production of the majority of farm 

 crops. Sweet potatoes yield a fair crop 

 on the "wornout" tobacco and cotton 

 lands of the South, especially when used 

 in a rotation including some leguminous 

 crop for increasing the humus in the 

 soil. Like many other crops, the sweet 

 potato thrives on newly-cleared land, 

 but the crop should not be planted con- 

 tinuously in the same place. With the 

 sweet potato, as with other crops, rota- 

 tion is the keynote of success. 



Good drainage is essential, the original 

 idea of planting upon high ridges being 

 for the purpose of securing better drain- 

 age. The surface soil should extend to a 

 depth of 6 or 8 inches, and the subsoil 

 should be of such a nature that it will 

 carry off excessive moisture without 

 leaching away the fertilizers applied to 

 the land. Too great a depth of loose 

 surface soil or an alluvial soil having no 

 subsoil will produce long, irregular 

 potatoes that are undesirable for market- 

 ing. Planting upon land having a loose, 

 sandy surface soil underlain by a well- 

 drained clay subsoil will tend to produce 

 the type of rather thick, spindle-formed 

 potato that commands the highest price. 

 The depth of ploughing is a prominent 

 factor in the preparation of land for 

 sweet potatoes, and on soils of too great 

 depth before the subsoil is reached very 

 shallow ploughing should be practised, 

 leaving the soil firm beneath, against 

 which the roots must force their way. 

 If the surface soil is of insufficient depth, 

 it should be gradually increased by 

 ploughing a little deeper each year or by 

 subsoiling in the furrow behind the 

 regular turning plough. 



Fertilizers por Sweet Potatoes. 



As already noted, the sweet potato 

 will thrive on soils that are only moder- 

 ately fertile. The root portion of the 

 plant is the part having the greatest 

 value, though the foliage and vines have 

 some value as foods for certain kinds of 

 stock. It has been found that an ex- 

 cessive amount of organic matter in the 

 soil will frequently produce an abundant 

 growth of vines at the expense of the 

 roots. It has also been noted that the 



