chapter xiv 

 no-njsymbiotic nitrogen fixation 



Native rocks are usually free from nitrogen. Soils produced 

 by the grinding of them are poor in it. Therefore, in many 

 respects nitrogen stands apart from the other elements. It is inert 

 and does not readily enter into chemical compounds. Its natural 

 home is the atmosphere to which it is always attempting to return. 

 In all arable soils it is found in greater or less quantities. How 

 did it get there? "The lightnings of a billion storms have com- 

 bined it in the air; the rains of hundreds of millions of years 

 have washed it combined from the air into the soil; billions upon 

 billions of microbes in plants and in the soil have ceaselessly ab- 

 sorbed it during unnumbered ages; consequently, the nitrogen 

 combined in our soil represents the united efforts of all Nature 

 working continually for unthinkably vast periods of time. 



"What do we do with the earth's precious store of nitrogen? 

 We filch it from the soil immensely faster than it is restored by 

 natural processes; and the land grows sick and barren and refuses 

 to grow our crops. Vast tracts of land in Sicily, in the broad 

 plains of North Africa, in the Great Valley of the Euphrates, 

 once the richest corn-producing region of the world, have within 

 historical times grown barren largely owing to this cause." 



This condition was sensed to its fullest extent by Sir William 

 Crooks when he made his famous address to the British Associa- 

 tion in 1898 in which he predicted that the world in thirty or 

 forty years from that date was doomed to suffer from a wheat 

 famine unequalled in history if the men of science did not find 

 a practical method of inducing the inert nitrogen of the air to 

 enter into combination with oxygen and produce the nitrates es- 

 sential for plant growth. 



How successful science has been in meeting this dilemma is 

 answered by the results portrayed in Figure 29. 



