FERTILIZERS IN THE WEST 5 



All of the three elements,, nitrogen, phosphoric acid and 

 potash together are necessary for the successful production of 

 crops and no one of them can take the place of any other, 

 because each one of them has important well defined func- 

 tions. For this reason any fertilizer should, in all but excep- 

 tional cases, contain nitrogen as well as phosphoric acid and 

 potash in suitable proportions. In looking closer over the 

 figures given above it is easily seen that phosphoric acid is the 

 ingredient needed in the smallest quantity, whereas the nec- 

 essary amounts of potash and nitrogen are much higher. 



Each of the three fertilizer elements has special functions 

 to perform which may be mentioned briefly as follows : 



Nitrogen increases growth and favors the formation of 

 the green parts of plants, like stems and leaves. It is the 

 factor that exerts the greatest influence on the size of the 

 plant. The effect of an application of soluble nitrogen mani- 

 fests itself in a few days by a change of the color of the 

 leaves to a dark green. For the reason given, large quantities 

 of nitrogen are called for particularly, where leaves are the 

 principal product, like in the case of certain graden crops, 

 where it also improves the quality by making the leaves more 

 tender and crisp. On the other hand, where the fruit is the 

 important product, too large applications of nitrogen are 

 liable to bring about excessive growth of leaves, to delay or 

 prevent the formation of flowers and fruit, and to retard 

 maturity in general. Plants that are overfed with nitrogen, 

 have a tendency to be vsoft and to be less resistant to the 

 attacks of insects and diseases. 



Phosphorus is an important constituent of the plant cell, 

 especially of certain proteid bodies characteristic of all seeds, 



