NITRIFICATION IN ARABLE SOIL. 495 



Although all the soils did not furnish drainage water January 25 

 and March 8, an examination of the table is very instructive wherever 

 a comparison between the results on stirred and unstirred soil is j)os- 

 sible. There is a wide variation between the nitric nitrogen furnished 

 in the differently treated soils. The amounts per cubic meter obtained 

 for the stirred soil are often excessive. For instance, the Grignon soil 

 yielded on March 8 the exceptionally high amount of 2,380 gm. 



On submitting the drainage water to a complete analysis, to deter- 

 mine the bases with which nitric acid was combined, it was found that 

 a large part of this acid was in combination with lime, a smaller 

 amount with magnesia, and a still smaller amount with potash. On 

 calculating the amounts of nitric acid required by these bases it was 

 found that a slight excess of nitric acid was present. The amount of 

 nitric acid found was o.S^) gm. ; the amount required by the above bases 

 was 5.35 gm. It is very f)robable that the 0,5 gm. in excess was com- 

 bined wdth soda or possibly oxid of iron. 



The above results lead to the important and highly interesting con- 

 clusion that nitrification is extremely active in different kinds of soils, 

 and that it is capable of furnishing quantities of assimilable nitrogen 

 largely in excess of that required by the most exacting crops. In order 

 to obtain this result is it simply necessary to furnish a humid soil, the 

 proper temperature, and thorough pulverization ? Further experiments 

 are necessary to answer this question. 



NITRIFICATION IN SAMPLES OF SOIL COLLECTED DURING WINTEK 



AND SPRING. 



Samples of frozen soils were collected in January, 1893, at the Museum 

 of Paris and at Grignon. They were exposed to a moderate tempera- 

 ture until they crumbled, and were then pulverized and sifted. Although 

 one series of samples was exposed to the temperature of the labora- 

 tory from January 20 until February 16, and the second series from 

 February 14 to May 9, the quantities of nitrates formed remained very 

 small in every case. 



A third series o± samples was collected in March, when the temi^era- 

 ture was beginning to rise. The soils were pulverized with care, sifted, 

 and one lot of samples of each spread out in a dish kept in a closet at 

 the temperature of the laboratory, while the second lot was placed in an 

 oven kept at a uniform temperature of 30° C. Water was added when- 

 ever the samples commenced to dry out. When the samples were pul- 

 verized a certain xwrtion of each was extracted with water, and these 

 extracts were submitted to analysis, with the following results: 



