116 



soda, lime or magnesia, phosphoric or sulphuric 

 acid, iron or silica that we can raise any soil to the 

 highest degree of fertility it is capable of attaining. 

 The means to gain this end are within the reach 

 of every one, and the chief question which a 

 farmer must solve, after having selected that crop 

 which practical experience and theoretical know- 

 ledge convince him as being best suited for his 

 fields, is, whether the available inorganic substances 

 which serve as plant-food are present in the propor- 

 tion in which they are required by the plant. To 

 gain this information, a complete analysis, exhibiting 

 all the details I have mentioned, should be made, 

 which will show any deficiency, by supplying 

 which the farmer will induce his lands to yield the 

 highest crops they are capable of producing ; and 

 all that remains for him to do thenceforward, to 

 maintain this fertility, is simply to conscientiously 

 restore year after year the small quantity of in- 

 organic substances withdrawn with each harvest. 



