I. AGRICULTURE AND RURAL ECONOMY. 381 



DOES THE FREE NITROGEN" OF THE AIR CONTRIBUTE TO THE 

 FORMATION OF NITRATES IN THE SOIL? 



Boussingault, long famous for his researches upon the 

 question whether the plant assimilates the free nitrogen of 

 the air, has lately performed some experiments to determine 

 whether the free gaseous nitrogen of the air can take part in 

 the formation of nitric acid in the soil. 



It is a familiar fact that saltpetre is found in soil contain- 

 ing alkali and nitrogenous organic matter, from the decom- 

 position of the organic matter, and oxidation of the nitrogen 

 contained therein. The principle involved is the same 

 whether the operation takes place in a nitre bed or an ordi- 

 nary fertile soil. 



The atmosphere is also a source of an immense amount of 

 nitrates for the soil. Under the influence of electrical dis- 

 turbances, nitrogen, hydrogen, and oxygen are chemically 

 combined, and the compounds thus formed are conveyed by 

 rain to the soil, and thus the latter is fertilized. 



It is, however, a question whether the free gaseous nitro- 

 gen of the air does not also contribute to the formation of 

 nitrates in the soil, by oxidation and union with the bases 

 therein contained. 



To test this question experimentally, Boussingault took 

 two glass globes of one hundred litres' (a little over twenty- 

 five gallons') capacity each, and placed in the bottom of one 

 a quantity of dry earth mixed with quartz sand, and in the 

 other the same materials with the addition of non-nitrogenous 

 organic matter, in the form of woody fibre. The amounts of 

 nitrogen, nitric acid, and carbon in the soils thus formed had 

 been accurately determined by analysis. The globes were 

 tightly closed, and set aside in a cellar, and remained un- 

 opened for eleven years. There was, then, in the globes, dur- 

 ing this time, organic matter in the earth containing known 

 amounts of nitrogen and nitric acid exposed to the action of 

 air. It was to be expected that the nitric acid would be in- 

 creased by oxidation of the nitrogen in the organic matter 

 of the earth. The question was whether the free nitrogen of 

 the air would also be taken into the soil and oxidized, and 

 whether this process would be furthered by the oxidation of 

 the woody fibre. A comparison of the total amounts of ni- 



