THE POTATO 213 



This part is very important, however, so much so 

 that in many instances success or failure depends 

 on how it is looked after. 



In stating the part the elements have in the 

 growth of the plant it must be considered that the 

 statements are relative and not absolute. 



Nitrogen is largely instrumental in providing 

 growth in plants, heavy, luxuriant stems and 

 leaves being credited to a liberal supply of this 

 element in available form. A deficiency is shown 

 by weak, yellow growth. The elements of plant 

 food in the soil are transformed or manufactured 

 in the leaves in combination with sunlight and the 

 gases of the air into the substances that form the 

 edible tubers. In order that these processes be 

 carried on with the best results there must be a 

 strong, healthy manufacturing establishment — the 

 plant. 



Phosphoric acid hastens the maturity of crops 

 and influences the production of seeds in fruits. 

 In the potato it is supposed to influence the pro- 

 duction of starch. 



Potash is supposed to influence yield, and be a 

 factor in the formation of starch. 



Like many other things concerned with the pro- 

 duction of crops and the working of the various 

 elements in nature's laboratory, the exact offices of 

 potash and phosphoric acid are not known, but 

 can only be judged and estimated by experiments 

 and results. In general, it is known that nitrogen 

 is mostly concerned with growth of plants, and 

 phosphoric acid and potash with the fruit or 

 crop. 



Nitrogen is obtained from the following sources: 



(1) Organic — Natural products in which ni- 

 trogen is combined with other elements such as 



