Methods of Use of Fertilizers 211 



rests with the farmer to select the best points from each, 

 or rather to use the suggestions in each which are in his 

 judgment more applicable to his conditions. They are 

 all based upon underlying principles, and pre-suppose a 

 knowledge of them on the part of the farmer. They are, 

 at best, but guides or sign-posts pointing toward better 

 methods in the use of fertilizers, rather than absolute rules 

 to be followed blindly. 



It may be pointed out that these systems do not take 

 into consideration the character of the soil. Vast differ- 

 ences exist between soils, not only in their natural content 

 of plant-food but also in their physical and mechanical 

 character, which is so important in the retention and libera- 

 tion of plant-food. Nor do these systems give apprecia- 

 tion to rational farm practices such as green-manuring 

 and liming which have such a material effect upon the soil 

 stores of plant-food. In view of these facts the good 

 points of the various systems should not only be utilized 

 but they should also be fortified by experimentation. A 

 more complete discussion of simple experiments for this 

 purpose may be found in the following chapter. 



The suggestions here and in subsequent chapters, in 

 reference to the use of fertilizers, are formulated from the 

 best information obtainable by the writer, and mainly from 

 two sources: First, the results of experimental inquiry, 

 and, second, the results of the observation and experience 

 of practical men. In no case can absolute rules be laid 

 down. Farmers may safely rely on the well-established 

 principles, but each must remember that the use of the 

 principles must be modified according to his own condi- 

 tions. 



