2S Food for Plants. 



Nitrate as yilaiit food seems to iiiflu- 

 Special Influ- vuqq more especially the development of 

 ence of Nitrate stems, leaves, and roots, which are the 

 on Edible Value framework of the plant, while the for- 

 of Plant. mation 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 framewoi'k, 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 

 ]ilants the greater the relative proportion in the com- 

 ])osition 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 particu- 

 larly 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 produc- 

 tion of seed or grain. Its special use in practical agricul- 

 ture is to help hasten the maturity of crops likely to bo 

 caught by an early fall, and to supplement green manur- 

 ing where grain is to be grown. It is frequently used in 

 altogether unnecessary excess in " complete " fertilizers. 



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 processes supply potash and phos- 

 Sources of phoric acid, hut only the former supplies 



Natural Plant Nitrate. Whether the soil has been fer- 

 Food. tilized 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 



