1903.} PUBLIC DOCUMENT — No. 33. 15 



The writer wishes to call special attention to Table B, on 

 the preceding page. A comparison of the results in this 

 compilation of analyses of so-called special crop fertilizers 

 reveals a wide diflerence between the maximum and mini- 

 mum amount of nitrogen, phosphoric acid and potassimn 

 oxide claimed and found in the different brands of commer- 

 cial fertilizers. In the different brands of tobacco ferti- 

 lizers, for instance, there is a difference of 4.92 between the 

 highest and lowest percentage of nitrogen, a difference of 

 8.75 between the maximum and minimum percentage of 

 available phosphoric acid, and a difference of 12.61 between 

 the mean and extreme percentage of potassium oxide which 

 was found. A correspondingly great difference will be ob- 

 served between the maximum and minimum percentages of 

 plant food found in the several special crop fertilizers which 

 have been compiled in the table. The average farmer is 

 apt to lay too much stress upon the trade name of a ferti- 

 lizer, and oftentimes buys an inferior article when guided 

 wholly by the name under which it is sold. 



There are many things to be taken into consideration in 

 the judicious selection of a fertilizer for growing special 

 crops. The physical and chemical character of the soil and 

 sub-soil, the previous management of the soil and the system 

 of crop rotation employed should all enter into consideration 

 when selecting a fertilizer. A study of the soil should be 

 made by simple local experiments with the different kinds 

 and forms of plant food, to find what elements have become 

 depleted ; when these facts have become established, then 

 supply the wants of the soil in the most suitable and eco- 

 nomical manner. When the character of a soil is not known 

 and its wants are not manifested, it is advisable to use a fer- 

 tilizer more nearly corresponding to what a chemical analysis 

 of the crop show^s is required for its proper development. 

 For the purpose of illustrating how the chemical composi- 

 tion of a crop may serve as a guide in the compounding of 

 a commercial fertilizer, an example is here inserted. We 

 find the average analysis of potatoes (see compilation of 

 analyses of fruits, garden crops, etc., in annual report of 

 this department for the year 1901) is as follows : — 



