8 BACTERIA AND SOIL FERTILITY 



until their shape, function, and various other characteristics were 

 understood. 



Many writers take the date 1882 as the one in which this ad- 

 vance was made as the birth of the new science — bacteriology. 



iSoil Bacteriology. — It was a well-accepted maxim with 

 the older writers on agriculture that "corruption is the mother of 

 vegetation." One of the most illustrious of their number. Lie- 

 big (1855), taught that plant and animal tissues decayed in the 

 soil with the formation of ammonia which he considered so es- 

 sential to plant growth. Part of this he taught was transformed 

 into nitric acid which also served as plant- food. 



Long before the nature of the process by which plant residues 

 and manures were transformed into nitrates was understood the 

 method was used to supply the large quantities of gunpowder con- 

 sumed in the almost incessant wars of Europe. In the eighteenth 

 century the artificial production of saltpetre in beds of decaying 

 organic matter reached a high degree of perfection. Especially 

 was this true in Sweden, Switzerland, and France, where nitrates 

 were collected as a part of each farmer's tax. In the year 1777 

 the French Government issued special instructions for its manu- 

 facture in which there was stressed the form of pit to use, the 

 covering of the organic matter, the arrangement for the free 

 entry of air, the optimum amount of moisture, and the necessity 

 of a base to neutralize the acid as formed. 



Boussingault in the years between i860 and 1878 became inter- 

 ested in the natural-occurring "nitre beds" — especially in those 

 of Peru and Ecuador. He did work which established the origin 

 of the nitrate as the organic matter of the soil. It was consid- 

 ered, however, that the transformation was a chemical change 

 produced through the interaction of ozone or active oxygen on 

 the ammonia coming from the organic matter. The soil was 

 supposed to act as a catalyzer, thus accelerating the speed of the 

 reaction. 



During the sixties and seventies great advances had been made 

 in bacteriology. It had been definitely established that bacteria 

 bring about decay, putrefaction, and fermentation, and it was 



