EFFECT OF NITROGEN. 



The presence of available nitrogen is shown by a 

 dark, healthy, green color of leaves and stems. 

 Growth is vigorous. The feeding power of the plant 

 is increased. If an excess of nitrogen is available at 

 the time of flowering, and the supply of phosphoric 

 acid insufficient, the bud and bloom and fruit will be 

 imperfect and the total amount of fruit lessened. The 

 fruit will then be rough and thick-skinned. Constant 

 use of stable manure, without the addition of phos- 

 phoric acid, will produce thick-rind fruit, as manure is 

 relatively high in nitrogen. The size of fruit may be 

 increased by nitrogen. A lack of nitrogen is shown 

 by yellow trees and small growth, or lack of vigor. 

 Nitrogen will not give its best effect unless phos- 

 phoric acid is present. 



EFFECT OF PHOSPHORIC ACID. 



Phosphoric acid helps a plant to assimilate other 

 plant foods. It is also essential to the final maturity 

 of the plant or its seed production, and hastens this 

 maturity, if abundant and available at blossoming 

 time. Although the navel orange contains no seed, 

 phosphoric acid is as essential as though it did. 

 What usually thus goes into seed is needed elsewhere 

 in the development of the fruit. 



If maturity is hastened by the presence of an 

 abundance of available phosphoric acid at the time 



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