SWEET POTATOES 423 



part of April. After the land has been deeply plowed and thor- 

 oughly pulverized, a disk harrow should be used at intervals of six 

 or eight days until the season for planting arrives. A week or ten 

 days previous to planting, the commercial fertilizer which is to be 

 used should be distributed broadcast with a grain drill. The drill- 

 ing should be done with a common hoe or disk drill and will take 

 the place of one cultivation with the disk harrow. The fertilizer 

 should be of a high grade, carrying about 3 per cent of nitrogen, 

 6 per cent of phosphoric acid, and 10 or 12 per cent of potash. 

 The quantity per acre for highest commercial results should range 

 between 600 and 1500 pounds to the acre, 1000 pounds usually 

 being a satisfactory amount. 



After broadcasting the fertilizer, the rows are laid off about 4 feet 

 apart. The first step in this operation is to open a furrow about 

 4 inches deep with a one-horse turning plow. A liberal dressing 

 of well-rotted stable manure is then scattered in the furrow, after 

 which a back furrow should be run to throw the earth from each 

 side upon the manure, thus forming a low, comparatively flat ridge, 

 which can be struck off with a board, garden rake, or weeder. In 

 this way a suitable bed for planting the potato sets is prepared. In 

 some instances the land is left flat, but when manure or fertilizer 

 is used in the furrow the bed is considered an advantage, and in 

 localities where the land is liable to wash and where heavy rains 

 prevail during the growing season a list or ridge is necessary. 



Propagation. The success of the sweet-potato crop is dependent 

 on the quality of the seed and the sets produced from it, as well 

 as on the stand of plants in the field. 



While the sweet potato is propagated from vegetative parts like 

 the white potato, the method of procedure is different. The seed 

 of the sweet potato consists of small-sized roots selected and stored 

 in separate bins at harvest time. It is seldom planted in place as 

 is the seed of white potatoes. In the northern part of the sweet- 

 potato region the sets are grown by bedding the seed in either 

 manure or fire-heated hotbeds. Extensive growers maintain their 

 own propagating beds, but small planters often purchase the sets 

 tkey need. The hotbeds are prepared late in March or early in 

 April, and in the latitude of Washington, D.C., the potatoes are 

 bedded between April I and April 15 as shown in figure 160. 



