12 Trans. Acad. Sci. of St. Louis 



then to provide these conditions and let nature do the 

 rest. In this manner the greatest chemical industry was 

 created, an industry which secures food for men for times 

 to come, by regulating the cultivation of the soil. When 

 as early as 1838 Liebig directed attention to the fact 

 that all plants for their growth require carbon, nitro- 

 gen, and the elements of water, he also proved that cer- 

 tain mineral substances were necessary for plant life, 

 among them potash and phosphorus. Carbon and nitro- 

 gen could come from the air; phosphorus and potash 

 could come only from the soil, and when these were 

 exhausted, vegetation necessarily would starve. This 

 led Liebig to the statement that it was the decrease of 

 soil fertility, and neither peace nor war, which was fun- 

 damental in bringing about the decay of nations. In Lie- 

 big's opinion old civilizations in Africa, Asia, and Europe 

 were extinquished by sterilization of the soil, and 

 undoubtedly the same will occur in America if no fer- 

 tilizer is supplied to our fields. It is recognized that 

 phosphates and other mineral fertilizers in some form 

 must be added to the soil if its fertility is to be main- 

 tained. Nitrogen may be derived from the air by culti- 

 vation of clover in a rotation of crops. The early 

 Roman writers on agriculture knew the value of legumi- 

 nous crops as restoratives of soil fertility. But the fact 

 that legumes assimilate nitrogen from the air by a bio- 

 logical process has only become known within the last 

 fifty years. If an uninterrupted succession of large 

 crops is desired, it becomes imperative to supply nitro- 

 geneous fertilizer in a more concentrated form, such as 

 Chilean nitre of ammonium salts. Dr. Lipman, Director 

 of the New Jersey Agricultural Experiment Station, was 

 quoted in the hearings before the Senate Committee on 

 Agriculture and Forestry (Senate Document 3390) as 

 having estimated that the total annual loss of nitrogen 

 from all land under cultivation in the United States, 

 after allowance for all returns to the soil, was between 

 three and four million tons. Considering only the lower 



