NITRIFICATION IN ARABLE SOIL. 



499 



RESULTS OBTAINED ON VEGETATION BOXES AT GRIGNON DURING 

 THE YEARS 1892 AND 1893. 



Vegetation boxes were constructed on tlie experimental fields of 

 Grigiion during the iiutumn of 1891. Their capacity is 4 cubic meters, 

 the surface being 2 meters square and the depth 1 meter. The walls 

 are made of an impervious cement in whi(;h is embedded a wire netting 

 to give it strength. The fioor dips in the middle so as to form a gutter 

 and slopes toward the northern wall of the box. In the lower end of 

 the gutter a lead pipe is cemented through which the drainage Avater 

 tiows into a large carboy placed in a recess under the box. 



In constructing the boxes it was necessary to remove the soil, which 

 was thrown into heaps, the subsoil and the surface soil being kept sep- 

 arate. The boxes were completed in November, 1891, and drainage 

 waters began to be regularly collected in March, 1892. Four boxes 

 were kept free from vegetation in 1892 and 1893 in order to study nitrifi- 

 cation. The results obtained from March, 1892, to March, 1891, are 

 given in the following table: 



yitrijication in vegetation boxes. 



No. ot liox. 



ilamiriufi 



Cultivation. 



:...< 



n.. 



14 



-1 



1892 Nothing Nothing 



1893 do I do 



1892 12 kg. of niauiirt' ' ... do 



18!)3 Kothing i Forking 



1892 j 12 kg. or manure, lUO I Notliing 



gni. nitrate ol' soda. 



189.3 Nothing | do 



1892 250 gin. nitrate of soda.i do 



1893 Nothing Thorough cultiva- 

 tion and forking. 



Nitrogen 



per 

 hectare. 



Kilograms. 

 221.570 

 79. 198 

 180. 672 

 110.840 

 192. 450 



90. 055 

 248. 197 

 127. 745 



In the preceding table the term "forking" indicates a superficial culti- 

 vation with a fork with bent tines which secured a thorough stirring 

 of only the surface soil. In case of No. 11 the soil had been thoroughly 

 spaded in 1893. 



It will at once be observed that the drainage waters were very much 

 more abundant in 1892 than in 1893, but what is more striking is the 

 enormous difference in the amount of nitric nitrogen formed during the 

 2 years. In the case of box No. 1 the quantity of nitrogen found in 

 1892 was almost three times that obtained in 1893. For box No. 13 

 about double the amount was found, while for boxes Nos. 12 and 14, 

 although the difference is less, it is still considerable. Among the 

 various causes of these differences it appears that the very different 

 treatments to which the soils were submitted during the 2 years were 

 evSi)ecially important. As stated above, the vegetation boxes were coii- 

 strui'tcd in the autumn of 1891; the soil which they contained was 

 removed, thrown into lieaiis, and remained exposed to the air during 

 se\eral months. When il was returned to the boxes in autumn, 



