Food for 



Plants How Money Crops Feed. 



98 The substance of plants is largely water 



p J J and variations of woody fiber, yet these 



comprise no part of what is commonly 

 understood as plant food. More or less by accident was 

 discovered the value of farmyard manures and general farm 

 refuse and roughage as a means of increasing the growth of 

 plants. In the course of time, the supply of these manures 

 failed to equal the need, and it became necessary to search 

 for other means of feeding plants. The steps in the search 

 were many, covering years of careful investigation, and it is 

 needless to go into a lengthy description here; but, as a 

 result we have the established fact that the so-called food 

 of plants consists of three different substances, Ammonia 

 (Nitrogen), Potash and Phosphates. 

 It Pr'nc'oal These words are popular names, and 



T,, _ , are used for the convenience of the general 



Elements, ... . ^ ^ i r i 



Nitrate Ammo- P"^^^^' . ^^ ^ "^^"^'^ °^ ^^^^! plant-food 

 •ni. u • ammonia is not real ammonia, but am- 

 nia, Phosphoric 1 • 1 • 1 1 1 



Ac'd Potash monia combined with other elements,, yet 



* ' the valuable factor is always the ammoniate. 



Nitrate of Soda contains an amount equivalent to about 

 nineteen per cent, of ammonia, or 380 pounds to the ton, 

 and cotton-seed meal, for example, about nine per cent.; as 

 plant food more than two pounds of cotton-seed meal are 

 necessary to furnish as much plant food as one pound of 

 Nitrate of Soda. We value the plant food on the amount 

 of ammoniate it contains, and on this account ammonia has 

 become a popular standard name for this element of plant 

 food. In like manner. Phosphoric Acid and Potash are 

 standards, hence the importance of farmers and planters in 

 familiarizing themselves with these expressions. We always 

 think of fertilizers and manures as just so much Ammonia, 

 Phosphoric Acid and Potash, as we can then at once com- 

 pare the usefulness of all fertilizer materials. No doubt 

 other substances are necessary for the proper development 

 of crops, but soils so generally supply these in ample quan- 

 tities that they may safely be neglected in a consideration 

 of soil needs and plant foods. The food of plants may 

 therefore be understood to mean simply. Ammonia, Phos- 

 phoric Acid and Potash. 



