Ratio of Increase in Crop to Ammonia Supplied. 55 



most nearly represent those which may be expected in 

 ordinary practice, and, further, that the results obtained by 

 these amounts in the cases -where the mineral constituents 

 (unless silica) are not in relative defect are also such as are 

 most likely to be obtained in ordinary farm practice, the 

 authors subject the tabulated results to a thorough exami- 

 nation. The figures show how very striking is the difference 



TABLE XI. 



of effect upon the immediate increase of a given amount of 

 nitrogen in manure, whether used in the form of ammonia- 

 salts or of nitrate, according to the available supply of 

 mineral constituents in the soil. With the overwhelming 

 evidence before him which such a comprehensive summary of 

 experimental results on the point affords, the grower cannot 

 fail to see that he not only very injuriously further reduces 



