NITRIFICATION IN ARABLE SOIL/ 



p. p. Dehkraix. 

 EXCES3IVE NITRIFICATION IN SOILS SENT TO THE GRIGNON STATION. 



Early in 1891 a sample of soil collected on the estate of M. Fizeau, 

 near La Ferte-sous-Jonarre (Seine-et-Marne), was sent to tlie Grignon 

 Station. On analysis this soil was found to contain, per kilogram, total 

 nitrogen, 1.96 gm.; total phosphoric acid, 1.08 gm. ; phosphoric acid 

 soluble in acetic acid, 0.021 gm., and lime, 7.2 gm. It was j)laced in 

 large earthenware pots, and the drainage water which passed through 

 was collected and examined for nitrates. The results were as follows: 



Nitric nitrogen per cubic meter of drainage tvater. 



Collected March 24 

 Collected April 7 . . , 



Xo. 1. 



Grams. 

 584 

 664 



No. 



Grams. 

 5H9 

 466 



These amounts are excessive. As the result of determinations made 

 in 1870, 1872, and 1873 by Dr. Frankland in the drainage water from 

 vegetation boxes at Eothamsted it was found that the nitrogen content 

 I)er cubic meter was 21.95 gm.; the average of Warington's analyses of 

 drainage water from the same boxes 6 years later was only 10.0 gm.; 

 and at Grignon the average during 1891-'92 was 39 gm. 



It was suspected that this excessive amount of nitrates was due to 

 shipping the soil in sacks previously used for nitrate, but inquiry indi- 

 cated that this was not the case. It is probable, however, that in ship- 

 ment the sack of soil came in contact with others containing nitrate, and 

 this suspicion is strengthened by the fact that tlie excessive nitrification 

 indicated by the first determination was not maintained in subsequent 

 experiments. It is true that high amounts of nitrates were observed 

 during the remainder of the year (1891), but they never reached the 

 amount observed at the beginning. October 11, 1891, there was found 

 196 gm. of nitric nitrogen per cubic meter of drainage water, and on 

 July 21, 1892, 144 gm. 



1 Coiitimied froni p. 353. 



491 



