6 SOILS AND FERTILIZERS 



position of plant-ash, and his emphasizing the import- 

 ance of supplying crops with mineral food, led to the 

 commercial preparation of manures, which in later 

 years has developed into the commercial fertilizer in- 

 dustry. The work of L,iebig was not conducted in 

 connection with field experiments. It had, however, a 

 most stimulating influence upon investigations in agri- 

 cultural chemistry, and to him we owe, in a great de- 

 gree, the summarizing of previous disconnected work 

 and the mapping out of valuable lines for future in- 

 vestigations. 



Iviebig's enthusiasm for agricultural investigations 

 may be judged from the following extract : "I shall 

 be happy if I succeed in attracting the attention of men 

 of science to subjects which so well merit to engage 

 their talents and energies. Perfect agriculture is the 

 true foundation of trade and industry ; it is the founda- 

 tion of the riches of states. But a rational system 

 of agriculture cannot be formed without the applica- 

 tion of scientific principles, for such a system must be 

 based on an exact acquaintance with the means of 

 nutrition of vegetables, and with the influence of soils, 

 and actions of manures upon them. This knowledge 

 we must seek from chemistry, which teaches the mode 

 of investigating the composition and of the study of 

 the character of the different substances from which 

 plants derive their nourishment." 3 



Soon after Liebig's first work appeared, the investi- 

 gations at Rothamsted by Sir J. B. Lawes were under- 

 taken. The most extensive systematic work in both 

 field experiments and laboratory investigations ever 

 conducted have been carried on by Lawes and Gilbert 



