FOOD FOR PLANTS 31 



case the use of Nitrate of Soda alone will force growth 

 to the extent of fully establishing the crop against 

 heat and moderate drouth. 



Nitrate as plant food seems to influence more 

 especially the development of stems, leaves, and roots, 

 which are the framework of the plant, while the 

 formation of fruit buds is held in reserve. This 

 action is, of course, a necessary preliminary to the 

 maturity of the plant, and the broader the frame- 

 work, the greater the yield at maturity. The color 

 of the foliage is deepened, indicating health and 

 activity in the forces at work on the structure of the 

 plant. Nitrates also show markedly in the economic 

 value of the crop ; the more freely Nitrates are given 

 to plants the greater the relative proportion in the 

 composition of the plant itself, and the most valuable 

 part of all vegetable substances, for food purposes, is 

 that produced by Nitrate of Soda. Nitrate is seldom 

 used in sufficient quantities in the manufacture of 

 "complete fertilizers." 



Potash as plant food seems to influence more par- 

 ticularly the development of the woody parts of 

 stems and the pulp of fruits. In fact, this element 

 of plant food seems to supplement the action of 

 Nitrate by filling out the framework established by 

 the latter. 



Phosphoric acid as a plant food seems to influence 

 more particularly the maturity of plants and the 

 production of seed or grain. Its special use in prac- 

 tical agriculture is to help hasten the maturity of 

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

 plement green manuring where grain is to be grown. 



