4 SOILS AND FERTILIZERS 



About 1830 there was renewed interest in scientific 

 investigations relating to agriculture. At this time 

 Boussingault, a French investigator, became actively 

 engaged in agricultural research. He was the first to 

 establish a chemical laboratory upon a farm, and to 

 make practical investigations in connection with agri- 

 culture. This marks the establishment of the first 

 agricultural experiment station. Boussingault's work 

 upon the assimilation of the free nitrogen of the air is 

 reviewed in Chapter IV. His study of the rotation of 

 crops was a valuable contribution to agricultural 

 science. He discovered many important facts relating 

 to the chemical characteristics of foods, and was the 

 first to make a comparative study of the amount of 

 nitrogen in different kinds of foods and to determine 

 the value of foods on the basis of the nitrogen con- 

 tent. His study of the production of saltpeter did 

 much to prepare the way for later work on nitrifica- 

 tion. The investigations of Boussingault covered a 

 variety of subjects relating to plant growth. He re- 

 peated and verified much of the earlier work of 

 DeSaussure, and also secured many additional facts 

 relating to the chemistry of crop growth. As to the 

 source of nitrogen in crops, he states that : " The soil 

 furnishes the crops with mineral alkaline substances, 

 provides them with nitrogen, by ammonia and by 

 nitrates, which are formed in the soil at the expense 

 of the nitrogenous matters contained in diluvium, 

 which is the basis of vegetable earth ; compounds in 

 which nitrogen exists in stable combination, only be- 

 coming fertilizing by the effect of time." As to the 



