of blood is far greater. If a quickly acting manure 

 was wanted the nitrate of soda would have the 

 higher agricultural value. 



Again, if phosphoric acid was not needed for a 

 particular soil and crop, it would then have no agri- 

 cultural value in that case, but would still have a 

 market, or commercial, value. 



In the selection of a fertilizer, the agricultural 

 value should be considered first and the commercial 

 value second. Good results are of first importance 

 as they repay the cost many- times. 



THE USE OF FERTILIZERS. 



In order to use fertilizers intelligently, it is 

 necesssary to know the specific action of the three 

 plant foods, nitrogen, phosphoric acid, and potash, 

 and when and how to apply them. So far as the 

 author knows, there have never been any exhaustive 

 experiments made to this end in California with 

 special reference to citrus fruits. However, by the 

 help of agricultural colleges, certan general principles 

 have been discovered, and certain conclusive results 

 obtained, in connection with deciduous fruits and 

 other plants, which are a guide and help in citrus 

 culture. The few experiments which have been made 

 with various fertilizers on citrus trees confirm these 

 same general principles. They will be briefly stated. 



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