lo May, 1912.] Infltu'iice of Soil Moisttire tifon Niirificaiioti. 



275 



THE 



INFLUENCE OF SOIL MOISTURE UPON 

 NITRIFICATION. 



By J. 



TF. Paterson, B.Sc, Ph.D., Exferimentalist, aud P. R. Scott, 

 C lie mi St for Agriculture. 



Introduction. 



Xitric acid or nitrate contains nitrogen in the highest state of oxidation. 

 Ammonia is a compound of nitrogen which has no oxygen. To convert 

 ammonia into nitric acid, its nitrogen must be oxidized. This happens in 

 fertile soil, and the oxidation is brought about by certain bacteria. The 

 process of oxidizing ammonia to nitric acid is termed nitrification. 



Besides nitrogen and oxygen plants require eight other elements in their 

 food materials. Each of these must be in the highest state of oxidation 

 commonly occurring in Nature. Phosphites, sulphites, nitrites, and ferrous 

 salts either kill the plant outright, or they give an unsatisfactorv return. 

 This is also true of ammonia for ordinary crop plants. Ammonia is not 

 poisonous in practical amounts, but it gives a much smaller vield than the 



With nitrogen in 

 form of nitrate. 



With nitrogen in 

 form of ammonia. 



highly oxidized nitrogen found in nitrates. The accompanying figure*^ 

 shows very fairly the action of ammonia and nitrate nitrogen under con- 

 ditions where nitrification is impossible. 



The reason why nitrates should be better than ammonium salts as a 

 food of plants is somewhat obscure. The first organic compounds formed 

 by plants from the absorbed nitrogen are amino-acids and their derivatives. 

 As these contain the amidogen radical (XHj) which is closely related to 

 ammonia (NH3), one might have expected the ammonium salts to give the 

 better result. As the primary amide formation always occurs in the plant 

 cell where oxidizable carbohydrate is present along with the absorbed 

 nitrogen compound, it may be that nitrate pos,sesses an advantage in that 



• From A Manual of Agricultural Botany, hy Prof. Frank, Berlin 

 Edinburgh : Wm. Blackwood and Sons. 



translated by John W. Faterson . 



