94 BULLETIN No. 145 [April, 



Hopkins and Pettit (68) reported the total carbon, nitrogen 

 and phosphorus contents of a great number of samples of the soils 

 of Illinois. This work is, thus, made the basis of calculating the 

 relationship of carbon, nitrogen and phosphorus reported in part 

 (B) of this thesis. 



2. NITROGEN IN SOILS 



The nitrogen in soils exists chiefly as organic nitrogen with a 

 very small amount of inorganic nitrogen. The organic nitrogen 

 may exist in some known and probably some unknown forms. 



Mulder (i) believed the nitrogen, found in the humus, to be 

 associated with the organic matter in the form of the ammoniacal 

 salts of the various organic acids obtained by him. 



Miiller (4) thought he detected a tendency for the nitrogen to 

 vary inversely as the carbon. 



Detmer (9) believed that the nitrogen formed a definite com- 

 pound with the organic carbon of the soil since the nitrogen could 

 be liberated only with great difficulty and by the use of the most 

 drastic chemical agents. 



Simon (n) believed that the organic matter of the soil pos- 

 sessed the property of absorbing the free nitrogen of the at- 

 mosphere and of converting it into ammonia which in turn united 

 with the organic acids in the form of their ammoniacal salts. Sos- 

 tegni (19) a little later discussed trie work of Simon and reported 

 a series of experiments to prove that Simon's assumption was un- 

 tenable. 



Berthelot (19), in 1886, reported the carbon and nitrogen con- 

 tents of calcareous clayey soil, originally very deficient in organic 

 carbon and nitrogen but which was gradually increasing in carbon 

 and nitrogen content owing to the action of diatoms. 



Berthelot and Andre (20, 74, 75, 76) later carried on a series 

 of experiments for the purpose of separating the organic nitro- 

 genous material into its various compounds. They reported the 

 amount of total, nitric, amido and ammoniacal nitrogen present in 

 the soil. 



Eggertz (21) differed very materially from Mulder. He con- 

 cluded that Mulder's contention, that the nitrogen associated with 

 the organic matter of the soil existed only as the ammoniacal salts 

 of the various organic acids, was untenable. If the nitrogen ex- 

 isted simply as the ammoniacal salt of the humic acid, treatment 

 with hydrochloric acid should liberate all the nitrogen as ammonia, 

 which, experimental evidence showed, was not the case. 



Furthermore artificial humic acid, treated with ammonia, did 

 form ammonium humate which, however, was readily decomposed 



