1- Trans. Acad. Sci. of St. Louis 



tlieii to provide those conditions and let nature do the 

 rest. In this manner tlie ;j;reatest chemical industry was 

 created, an industry wiiich secures food for men for times 

 to come, by re^uhitin*^: tiie cultivation of tlie soil. W'licn 

 as early as 18.*W Liehiir directed attention to the fact 

 that all plants for their j^rowth rcMjuire carbon, nitro- 

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

 tain mineral substances were necessary for plant life, 

 amon*i: them potash and j)hosphorus. Carbon and nitro- 

 gen could come from the air; phosphorus and potash 

 could come only from the soil, and when these were 

 exhausted, veji:etation necessarily would starve. This 

 led Liebi<>: to the statement that it was the decrease of 

 soil fertility, and neither ]ieace nor war, which was fun- 

 damental in brin,ii:ini2: about the decay of nations. In Lie- 

 biiif's opinion old civilizations in Africa, Asia, and Euroi)e 

 were extinquished by sterilization of the soil, and 

 undoubtedly the same will occur in America if no fer- 

 tilizer is sujiplied 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 Ix- main- 

 tained. Nitroi^en may be derived from the air by cidti- 

 vation of clover in a rotation of cro]is. The early 

 Roman writers on agriculture knew the value of legumi- 

 nous crops as restoratives of soil fertility. Hut the fact 

 that legumes assimilate nitrogen from the air by a bio- 

 logical process has only ])ecome known within the last 

 fifty years. If an uninterrupted succession of large 

 crops is desired, it ])ecomes imj)erative to supjily nitro- 

 geneous fertilizer in a more concentrated form, sucb as 

 Chilean nitre of anunonium salts. Dr. lji))man. Director 

 of the New Jersey Agricultural Kx))eriment Station, was 

 quoted in the hearings before the Senate Connnittee on 

 Agricultuie and Forestry (Senate Document 'XVM)) 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 



