THE USE OF FERTILIZERS 1 K - 



157 



WHAT FERTILIZERS TO APPLY TO FRUIT TREES 



RAND VINES 

 i 



A discussion of this subject from a chemist's point of view is 

 eyond the scope of this volume. The results of research at the 

 University Experiment Station at Berkeley are summarized in the 

 treatise on soils by Dr. E. W. Hilgard, who maintains the position 

 that the most intelligent and economical choice of fertilizers is to 

 be made after ascertaining by analysis in what constituents the 

 soil is deficient and in what it is well supplied. Some applications 

 made in conformity with suggestions based upon analysis have 

 proved very satisfactory. But as soils vary within narrow limits of 

 area, there must be analysis for each soil in question. 



Approaching the matter of choosing fertilizers without soil 

 analysis, the method by local trial is open. In this recourse there 

 is danger of error, as pointed out by Dr. Hilgard, arising from local 

 differences in soil and subsoil, and must be checked by several 

 check plots so interposed between the others as to not only check 

 them by direct comparison, and to prevent the washing of fertil- 

 izers from one fertilized plot to another, but they must also be 

 compared, first of all, among themselves, to determine what is the 

 normal product of the unfertilized land. It will frequently be found 

 that these unfertilized check plots differ more widely between them- 

 selves than do the fertilized ones from them or from each other. 

 It usually takes several seasons to come to definite results. 



From these statements it must appear that the prescription of 

 fertilizers is not an easy matter. Disappointments will naturally 

 be encountered, but unquestionably the advantage is on the side 

 of patient trial and wise investment in fertilizers honestly made 

 and honestly sold. The observing grower must learn all that 

 he can from experience. The University of California at its Citrus 

 Experiment Station at Riverside began in 1907 a series of experi- 

 ments in the course of which trees, specially planted in plots 

 guarded from interference, will be grown on various diets in order 

 that close comparisons may be made, from which it is expected 

 that important conclusions in plant nutrition can be drawn. It is 

 obviously the duty of the grower to constantly study fertilizer 

 questions as presented in books and journals and to be alert 

 for observation of the behavior of his own trees with the applica- 

 tions he may make. The publications of responsible fertilizer 

 manufacturers and dealers, also convey important information when 

 read discriminately. 



Though the deficiencies of the soil, as learned by analysis, or by 

 practical test, must be the basis of prescription of fertilizers, the 

 analyses of fruits, as showing the special needs of the plants, are 

 of the highest importance. The following analyses of the different 



