THE MONTHLY BULLETIN. 501 



REVIEW OF PRACTICAL EXPERIMENTS IN 

 FERTILIZATION 



By R. S. Vaii.e,* Riverside, California. 



The remarks which I have to make on this subject are entirely non- 

 technical and are the result of personal observations and discussions 

 with various growers regarding certain definite tests which they have 

 made in their own groves, of various fertilizer mediums. I do not pre- 

 tend to go into the scientific cause of the results which I am to describe 

 to you, but merely state the facts as they have been presented to me. 

 It has occurred to the Citrus Experiment Station that in an industry 

 as well established as is the citrus iiuiustry in Southern California, there 

 must be a vast amount of valua])lc knowledge that has been gathered 

 by the men who are making their living from this industry. With this 

 point in mind it is the purpose of the Citrus Experiment Station to 

 gather together, in so far as possible, the results of growers' experiments 

 and experiences along various lines and publish the completed results 

 of our findings. This present report is based on a partial survey of this 

 nature. 



In this survey there are at present three points which stand out with 

 decided clearness. First, there is a great lack of carefully planned and 

 systematically carried out experiments along the line of fertilization. A 

 few days ago a letter came to my desk from a man who desired informa- 

 tion regarding the correct fertilizer to be applied for maximum results. 

 I found on looking into the matter that this man had been in charge of 

 citrus orchards for nearly twenty years. He had been recognized for 

 a number of years as a very successful grower and had given advice 

 regarding this very matter to the writer personally some ten years ago. 

 When questioned, he admitted that he had used all types of fertilizer, 

 but was not at all sure which had given results and which had not. 

 During this convention several men have come to me and have said 

 practically the same thing ; that they have u.sed all kinds of fertilizers at 

 various times but have not as yet determined which ones have returned, 

 in increased crop, the money invested in them. Second, the experiments 

 M'hicli we have been able to check up all show quite clearly the absolute 

 necessity of the addition of nitrogen for optimum results. Third, there 

 is very little actual evidence, if any, of the value of addition of potash 

 or phosphoric acid, at least in the first several years of the growth of 

 an orchard. 



♦Address before the State Fruit Growers' Convention, Los Angeles, California, 

 November 10-14, 1914. 



Owing to the almost universal eagerness for information as to soil treatment we 

 feel more than warranted in publishing this review of actual field work in the use of 

 fertilizers, though it will be also published in the transactions of the convention.— 

 A. J. Cook. 



