348 FIELD AND GARDEN PRODUCTS 



By this method the manure will become thoroughly incorporated 

 with the soil and become somewhat reduced before the sweet potatoes 

 are planted upon the land. Stable manure will be found most bene- 

 ficial on worn-out soils, but on the more fertile soils its use should 

 be retsricted and the method of application carefully studied. 



The sweet potato is one of the few crops that thrive equally as 

 well (or better) upon commercial fertilizers as upon stable manure. 

 A fertilizer for use on the majority of sweet potato lands should con- 

 tain 3 to 6 per cent of nitrogen, 6 or 7 per cent of phosphoric acid, 

 and 8 to 10 per cent of potash. Every grower should make a study 

 of the requirements of his soil and apply the fertilizer that will give 

 the best results. Many growers purchase the ingredients and mix 

 their own special fertilizers, or use a standard fertilizer as a base and 

 increase the percentage of certain elements by adding high-grade 

 elementary ingredients. Some soils require that certain elements 

 should be in a more available form than others ; in the case of nitro- 

 gen it is often desirable to have a portion of that contained in the 

 fertilizer quickly available and the remainder more slowly in order 

 to feed the plants throughout the season. A mixture adapted to the 

 growing of sweet potatoes on most soils may be made by combining 

 the following: 



200 pounds of high-grade sulphate of ammonia, 25 per cent pure. 



200 pounds of dried blood, or 300 pounds of fish scrap. 

 1,200 pounds of acid phosphate, 11 per cent pure. 



400 pounds of high-grade muriate of potash, 50 per cent pure. 



The quantity of fertilizer that may be profitably applied will be 

 governed entirely by local conditions. Many growers do not depend 

 upon commercial fertilizers, but merely apply from 200 to 300 

 pounds to each acre as a supplement to the organic matter and 

 natural fertility of the soil. Others apply from 300 to 1,000 pounds, 

 according to the condition of the soil, while a few growers use a ton 

 to the acre. The general rule is to apply the fertilizer in the row 

 where the crop is to be grown, but where large quantities are used it 

 should be distributed at least ten days before planting and thoroughly 

 incorporated with the soil. An application of 1,000 pounds of high- 

 grade fertilizer placed in the row at planting time has been known 

 to injure seriously or kill the plants. For the best results the fer- 

 tilizer should be applied at least ten days before planting, or a portion 

 of the fertilizer may be applied a month or more in advance and the 

 remainder at the time of preparing the land for planting. Hardwood 

 ashes are desirable for use on sweet potato land and may be applied 

 at the rate of from 1,200 to 2,000 pounds to the acre. The value of 

 wood ashes depends upon how much they have become leached, but 

 hardwood ashes should contain from 6 to 8 per cent of available pot- 

 ash. Wood ashes also contain considerable lime. 



Where large quantities of any green crop are plowed into the 

 soil there is a tendency to sourness, and occasional applications of 

 from 1 to 2 tons of lime to the acre are beneficial. The presence of 

 an abundance of lime in soils devoted to the growing of sweet pota- 

 toes hastens the maturity of the crop and increases the yield. On 



