EXPERIMENT STATION BULLETINS. 



COMMERCIAL FERTILIZERS. 



R. C. KEDZIE. 



Bulletin 145, Chemical Department. 



COMMERCIAL FERTILIZERS A MODERN PRODUCT. 



Concentrated manures as commercial articles are very modern and 

 were unknown fifty years ago. Their starting point was the suggestion 

 of Liebig, that bones could be made more active by treating them with 

 sulphuric acid. This was in 1840; J. B. Lawes of Rothamsted, Eng., 

 took advantage of the hint by using the acid to convert mineral phos- 

 phates into soluble or superhosphates, about 1850,, and the manufacture 

 of superphosphates and other artificial manures on the commercial scale 

 was soon established and grew to vast proportions, laying the foundation 

 for the large fortune which has enabled Sir J. B. Lawes to endow the 

 Experimental Farm of Lawes & Gilbert at Rothamsted. Thus commer- 

 cial fertilizers laid the foundation of the greatest experiment station in 

 the world. 



One reason why superphosphates came so speedily into favor with 

 British farmers was the special beneficial influence in the growth of the 

 turnip crop — the special manurial crop in British agriculture. They 

 found that superphosphates greatly promoted the growth of the turnip 

 in its earliest growth, carrying the plant beyond its critical stage before 

 the true leaves are formed at which time it is liable to be destroyed by 

 the turnip fly. In the English system of rotation of crops, the turnip is 

 the manurial crop, on which the other crops in the rotation depend, 

 occupying in British agriculture about the same position that red clover 

 does with us. Hence the early favor and great popularity of these con- 

 centrated manures in England. 



In this country the introduction of concentrated manures has been 

 slower for two reasons: 1, we have no such specialized crop as the 

 turnip which becomes the pivot of the whole rotation and for which a 



