238 Fertilizers 



FERTILIZERS FOR POTATOES, EARLY CROP 



It has been demonstrated, both by experiment and 

 practical experience, that good crops of early potatoes 

 require an abundance of plant-food, and that on soils of 

 good character a heavy fertilization is usually more profit- 

 able than a medium or light application. 



The plant-food removed by a fair crop 200 bushels to 

 the acre of tubers will, on the average, consist of 27 

 pounds of nitrogen, 12 pounds of phosphoric acid and 60 

 of potash. Even though the increase from the application 

 of fertilizers is less than 100 bushels to the acre, it is always 

 advisable to add plant-food in considerable excess of these 

 amounts : first, because the crop must be grown quickly ; 

 and second, because a large part of its growth must be 

 made in the early season, before the natural conditions 

 are favorable for soil activities. A study of the fertility 

 composition of the potato shows that of the three essential 

 constituents, the potash is contained in the greatest 

 amount and the nitrogen next, while the amount of phos- 

 phoric acid contained in it is comparatively small. Most 

 fertilizer formulas for potatoes are therefore prepared with 

 the idea of furnishing a greater amount of potash than of 

 nitrogen or phosphoric acid. Studies made by the Geneva 

 Experiment Station shows that the formulas prepared to 

 contain the plant-food in nearly the proportions used by 

 the entire potato plant, excepting that the phosphoric 

 acid is in considerable excess, were less useful than 

 those containing very different proportions of the con- 

 stituents, and which were based upon the experience 

 of observing growers. That is, a formula of the first 

 class, furnishing 



