Relative Importance of Denitrification 329 



nitrifying power. The more rapid decomposition of 

 the manure brought about by loose storing or by ad- 

 ditions of substances like lime is equivalent to a more 

 rapid decline of the denitrifying power. 



The danger from denitrification. ^Since nitrates do not 

 appear in the manure until the organic matter is largely 

 decomposed and its denitrifying power greatly reduced, 

 it follows that the danger from denitrification in the 

 manure cannot be great. Moreover, the claim of some 

 of the German investigators that denitrification in the 

 soil, following the application of large quantities of 

 manure, is brought about by the addition of large num- 

 bers of denitrifying bacteria, is hardly in accord with the 

 facts just noted. The soil itself possesses an abundance 

 of these organisms and it is only the supply of much 

 easily decomposable organic matter that enables them 

 to destroy the nitrates in the soil. 



Further light is thro.wn on this question by other 

 experiments performed by Wagner and his associates. 

 They found that, when manure was exposed to the action 

 of carbon bisulfide and later incorporated into the soil, 

 the return from the nitrate used with it was smaller 

 than that when untreated manure was applied. This 

 result was contrary to the expectations of Wagner, for 

 he had believed that the manure treated with carbon 

 bisulfide, and deprived thus of its denitrifying bacteria, 

 would prove less injurious than the untreated manure. 

 In still other experiments, when the carbon bisulfide 

 was applied directly to the soil, the returns from nitrate 

 were increased instead of diminished. 



These conflicting returns, that appeared very 



