establishing the crop against heat and moderate drouth. This Food for 

 method of manuring is simply Top-Dressing, familiar to us Plants 

 all. 35 



Nitrate as plant food seems to influ- , f C1 



. ,, ., , i Special Influ- 



ence more especially the development or . M . 



i i i i f ence or fNitrate 



stems, leaves, roots, etc., while the rorma- T-J-UI w 



' r , . I , . , , j . . t on Edible Value 



tion or fruit buds is held in reserve; in fact, . p. 



the growth of the framework of the plant. 

 This action is, of course, a necessary preliminary to the ma- 

 turity of the plant, and the broader the framework 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 composi- 

 tion of the plant itself, and the most valuable part of all 

 vegetable substance, for food purposes, is that produced by 

 Nitrate of Soda. Nitrate is seldom used in sufficient quan- 

 tity in the manufacture of "complete fertilizers." Hence 

 the general dissatisfaction with their use. 



Potash as plant food seems to influence more particu- 

 larly the development of the woody parts of stems and the 

 pulp of fruits. The flavor and color of fruits is also credited 

 to potash. In fact, this element of plant food seems to sup- 

 plement 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. 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 supplement green manuring where grain 

 is to be grown. It is frequently used in 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 Phosphoric 

 Acid, but only the former supplies Nitrate. Sources of 

 Whether the soil has been fertilized or not, Natural Plant 

 there are certain signs which indicate the ' 



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



