500 EXPERIMENT STATION RECORD. 



tlierefore, it was as tliorouglily pulverized as the soil sent from 

 Seiue-et-Marue, from the Limague of Auvergne, or those wiiich had 

 been exjiosed to the air during 6 weeks in the station building in the 

 autumn of 1892. It is to this thorough aeration and mixing of the soil 

 that the author attributes the activity of nitrification in 1892. 



"This activity was such that it almost completely masked the influence 

 of the manure, for we observe that No. I, which had not been manured, 

 furnished more nitric nitrogen than Nos. 12 and 13, which had been 

 manured. The amount obtained from No. 14, it is true, exceeded that 

 from No. 1 during the year 1892, but it should be borne in mind that 

 No. 14 received 37 gm. of nitric nitrogen, while No. 1 had received no 

 manure. The averages of the amounts ot nitrogen removed in the 

 drainage water per hectare during the 2 years are as follows: 1892, 

 210.722 kg.; 1893,101.959 kg. Nitrification therefore decreased one- 

 half during 1893. 



Without doubt the meteorological conditions of 1893 were very 

 unfavorable, and the persistent drought of the spring may possibly 

 have contributed to produce the slow nitrification during this year. 

 However, it did not mask the influence of cultivation during this year. 

 Box No. 1, which received no cultivation, furnished 31.679 gm. of nitric 

 nitrogen; No. 13, which received no cultivation and remained undis- 

 turbed, yielded only 30.22 gm., while it was increased to 44.339 gm. on 

 No. 12 by simply stirring with a fork, and to 51.098 on No. 14, which 

 received a spading in addition to the forking. This superficial cultiva- 

 tion, however, is not equivalent to the aeration to which the soils were 

 subjected during the construction of the boxes and to the very complete 

 mixing which they underwent before being i)laced in the boxes in the 

 autumn of 1891, as is shown by the superiority of the nitrification in 

 1892 over that of 1893. 



RESUME AND CONCLUSIONS. 



The experiments reported in the preceding article clearly demonstrate 

 that those agriculturists who have long attributed to cultivation of 

 the soil a decisive influence on nitrification have held a correct view of 

 the subject. This influence is, in fact, much greater than might be 

 supposed. A soil properly stirred and aerated is capable of producing 

 much greater amounts of nitrates than are required to sustain the most 

 abundant crops. 



The enormous reserves of nitrogenous matter which arable soils con- 

 tain are therefore not destined to remain indefinitely inactive. We 

 will not always be reduced to the necessity of paying cash down for 

 assimilable niti'ogen and of importing each year large amounts of, 

 nitrogen compounds to make up the deficiency in the production of 

 assimilable nitrogen in tlie soil. Nitrogen compounds are found in 

 profusion in the soil, and the experiments which we have reviewed 

 show that the transformation of inert organic matter in nitrates 

 may be greatly accelerated by cultivation of the soil. 



