178 Bacteria in Relation to Country Life 



monia by ammonifying bacteria before it can be util- 

 ized by the nitrous and nitric ferments. The nitrogen 

 of ammonium sulfate can be attacked directly. It fol- 

 lows from these facts that there must exist a certain 

 relation between the ammonifying and nitrifying bac- 

 teria in the soil, of which we know very little. 



The determination of the nitrates, at Rothamsted, 

 in the drainage wastes from soils that had been kept 

 fallow, showed an average annual removal of 40.2 

 pounds of nitrate nitrogen per acre. The least amount 

 of nitrate nitrogen in the drainage waste was found in 

 the spring, the greatest amount in July. In the soil 

 which had borne crops, and received applications of 

 nitrogenous materials, the production of nitrate bore 

 a direct relation to the amount and character of the 

 substances applied. The least amount of nitrates was 

 found in the soil receiving annual applications of barn- 

 yard manure at the rate of fourteen tons per acre. 

 The soils receiving applications of nitrate of soda and 

 of ammonium salts showed a higher content of nitrate 

 than the corresponding unmanured soil. 



The differences may be due to two causes. In the 

 first place, the soils receiving nitrogenous materials 

 contain more nitrate because these substances contribute 

 directly some nitrogen to the soil. The nitrogen thus 

 added may be in the^nitrate form, as in the case of the 

 applications of nitrate of soda, or it may be in a form 

 capable of more or less rapid conversion into nitrate, 

 e.g ., sulfate of ammonia, or barnyard manure. Not 

 all of the nitrate nitrogen thus contributed is removed 

 by the crops or in drainage. In the second place, the 



