Tillage, Fertilizing and Rotation 97 



and at the same time maintains or even increases the 

 productivity of the soil. A most important factor in 

 the determination of profits which must necessarily be 

 considered by the business farmer of to-day is the rela- 

 tion of the annual outgoing and incoming of plant-food. 

 Sound business principles do not warrant the produc- 

 tion of increased crops unless they can be grown at a 

 genuine profit, which embodies more than a margin 

 over and above the production cost in the way of 

 manures and labor and should take into account the per- 

 manent effect on the productive power of the soil. 

 These facts have been realized in a practical way, per- 

 haps without any special understanding of the scien- 

 tific principles involved, by many of the sweet potato 

 growers in the coromercial producton centers. This 

 is especially true of the New Jersey, Delaware and Vir- 

 ginia growers who have by many years of practical pro- 

 duction and observation learned that diligence must be 

 exercised in the rotation of crops and the annual appli- 

 cation of manures if the quality of their " Nansemond 

 sweets " is to meet the expectation of discriminating 

 markets and the productivity of their land is to be 

 maintained. In areas where this practical observation 

 has not been facilitated by systematic commercial pro- 

 duction, a vast improvement in the proper manuring 

 of the sweet potato crop must be effected by producers if 

 they are to compete successfully with their more ex- 

 perienced neighbors. This phase of production is of 

 especial importance to the naturally favored areas of 

 the cut-over pine-belt, and on the depleted cotton and 

 tobacco farms of the South where the prevailing 

 climate and soil conditions aided by intelligent and 

 judicious use of the proper manures would make 



