^° pi ^°^ Potash as plant food seems to influence more particularly 

 the development of the woody parts of stems and the pulp 



1 02 



of fruits. It is also essential to the formation of sugar and 

 How Nitrate starch. The flavor and color of fruits is 



]yjay Be ^^^° credited to potash. In fact, this ele- 



Supplemented ment of plant food seems to supplement 

 by Potash. ^^^ action of Nitrogen by filling out the 



■framework established by the latter. Potash 

 with Nitrate is always an important fertilizer with special 

 crops where the object is to produce sugar, starch, or other 

 products usually more or less a result of the manufacture 

 of agricultural produce. 



How Nitrate Phosphoric Acid as a plant food seems 



May Be Aided ^° influence more particularly the maturity 

 by Phosphoric °^ plants, and the production of seed or 

 j^cid. grain. It seems to aid the assimilation of 



the other plant food elements. Its special 

 use in practical agriculture is to help hasten the maturity of 

 crops likely to be caught by an early fall, and to supple- 

 ment green manuring where grain is to be grown. It seems 

 to be used in excess in commercial fertilizers, because it is 

 prone to take insoluble and therefore unavailable forms in 

 the soil. 



The natural plant food of the soil comes from many 

 sources, but chiefly from decaying vegetable matter and the 

 weathering of the mineral matter of the soil. Both these 

 Sources of processes are somewhat slow except under 



Natural Plant ^^^^ favorable conditions, and both supply 

 jtqqjj^ Potash and Phosphoric Acid, but only the 



former supplies Nitrate. Whether the soil 

 has been fertilized or not, there are certain signs which 

 indicate the need of plant food more or less early in the 

 growth of the crop. If a crop appears to make a slow 

 How They May growth, or seems sickly in color, it does not 

 Be Supple- greatly matter whether the soil is deficient 



mented with ^" Nitrate or simply that the ammoniates 



Profit. present have not been Nitrated and so are 



not available; the remedy lies in top-dress- 

 ings of the immediately available form of Nitrated ammo- 

 niate, of which class of plant food materials Nitrate of Soda 

 alone is commercially available. 



