THE MONTI 1 1 A' BULLETIN. 227 



The IcMions arc not included in this ta])lc, as there has not l)cen suffi- 

 cient time since the conii)]etion of last year's crop to iict the data 

 t()tieth<'r, and the crops of the ])recedin<i- years were so much injured 

 by the freezes of December, 1!)11. and January, 1913, that the data 

 can not be considered satisfactory. 'I'he oranije yields, howcvei-. arc; 

 thouiiht in <ieneral to be as fair and as conclusive as yields from such 

 comparative plats can l)e. 



Tlies(» experiments wei'e reviewed l).\ the writer a year ago at the 

 First Annual Horticultural Assembly of the Citrus Experiment 

 Station; see paper entitled "Fertilizer Experiments with Citrus 

 Fruits," California Cultivator, Vol. 41, No. 24, page 596, December 11, 

 1913. The present paper is intended to bring the results up to date, 

 and to call attention to the most important suggestions that can at 

 present be drawn from the expei-iments. It nuist be remembered by 

 the readers that the experiments have only been inider way seven years 

 and that the i-esults in future years may be different and lead to very 

 differcMit conclusions. 



Table I sliows the avei'age yield per tree in numl)er of fruits. In 

 Table II the average yield per tree in pounds of fruit, navels and 

 Valencias combined, is given, and, as will be seen, compares very closely 

 with the yields in inunbers of fi'uits. In arriving at a judgment of 

 which treatment has given the best results, it is also necessai'y to know 

 the grade and sizes of the fi-uit pr-oduced on each plat, and in Table II 

 the ])er cent of fancy and choic(> fruits and the per cent of the best 

 sizes arc also given. The ])er cent of best sizes includes the 150. 17f) 

 and 200 sizes. As further indicating the effect of the dift'erent ferti- 

 lizers, the per cent of leaves showing mottling and the per cent of 

 the surface discolored by mottling are also given. These figures are 

 not based on actual counts and measurements, but are the best judg- 

 ment of four investigatoi-s. 



From the data given in the tables, certain things stand out promi- 

 nently. The two plats A and Q. receiving a complete fertilizer, gave an 

 average yield per tree of 133.38 pounds and 132.02 pounds, respec- 

 tively ; while the three plats, B, ]\I and T, receiving no fertilizer, gave, 

 respectively, 32.91 pounds, 87.50 pounds, and 104.25 pounds per tree. 

 This is a very considerable difference, considering that the trees are 

 only seven years old. The difference is so marked that it can readily 

 be seen in the field, the trees of the unfertilized plats being much 

 smaller in size and having smaller leaves of lighter green color. The 

 grade and size of the fruit on the complete fertilizer plat, it will also 

 be noticed, are mainly much better than on the unfertilized plats, 

 though plat ]\I, unfertilized, has very good fruit. 



The superiority of the fertilized over the unfertilized plats in the 

 first seven years indicates very clearly that in the light, disintegrated 

 granite soils, such as are common around Riverside, fertilization from 

 the time the trees are planted is doubtless necessary. This is an 

 important result in view of the fact that many growers in various 

 parts of the State are inclined to doubt whether fertilization is neces- 

 sary in the early life of the tree up to an age of about ten years. 

 Doubtless there are some soils in every locality that are so rich in 

 organic and mineral matter as to require no fertilization for a con- 



2—17154 



