Food for materials containing the essential plant-food elements in 



such a manner as to contribute to the best growth and devel- 



^^4 opment of the plants under the wide variety of conditions 



that exist, and thus secure the largest financial return from 



their application. 



T...^ 01 u While the three constituents — Nitrogen, 



ruitrogen Should 1 1 • • 1 1 1 n ^ 



_, . o • , phosphoric acid and potash — are all essen- 



Receive Special • 1 1 n i- 1 1 1 



.^^ ^. tial, because all are liable to exhaustion. 



Attention. -.j. . , , 111 



iNitrogen is the one that should receive more 



careful attention than the others, first, because it is the most 

 expensive of the three to supply. Nitrogen is more expen- 

 sive than either phosphoric acid or potash, largely because 

 it costs more to produce it. The great natural deposits of 

 phosphates in America and other countries make the possi- 

 bilities of their exhaustion very remote; besides, the com- 

 parative ease of mining, combined with the facilities with 

 which these phosphates may be converted into superphos- 

 phates, materially reduces the cost of immediately available 

 phosphoric acid. In the case of potash, the vast deposits 

 of Germany furnish unlimited quantities of crude material, 

 which are readily converted into concentrated salts of potash, 

 free from deleterious substances, and which furnish potash 

 in immediately available forms, and, because of their high 

 content of the essential element, the transportation charges 

 • are relatively low per unit of constituent. Nitrogen, on the 

 other hand, is less abundant, and even though fouiid in the 

 form of Nitrate of Soda as a tTatural deposit, the quantity is 

 limited in extent, as compared with the deposits of phosphates 

 and potash salts. The location of the deposits in a barren 

 country makes it more expensive, too, to concentrate and to 

 remove impurities, and even when in its most concentrated 

 commercial form, it is comparatively bulky, as compared with 

 the manufactured poiash salts, thus increasing the cost of 

 transportation per unit of the constituent. 



Second, because Nitrogen exists in three forms — as 

 organic matter, as ammonia and as Nitrate — and which 

 differ widely in their rate of availability or immediate use- 

 fulness to the plant. The Nitrogen in the first and most 

 common form (organic) generally undergoes a change into a 

 Nitrate before plants can make a large use of it; this change 

 requires a longer or shorter time, according to the character 

 of the material. If, therefore, we desire a large and reason- 



