306 BOARD OF AGRICULTURE. 



of seasons ; and I am inclined to think it is a law of nature, 

 that the ph3^8ical conditions of soils (conjoined, perhaps, with 

 chemical conditions) determine the amount of nitrogen they 

 are capable of receiving. It may be true, that, if we only 

 knew just what conditions are requisite, the spontaneous 

 supply of nitrogen could be made ample for all our wants. 

 It seems to me that facts and observation point in this 

 direction ; and the suggestion, though new, is worthy of con- 

 sideration. 



I have found that fields kept in high culture by constantly 

 stirring and pulverizing the soil, without the use of nitroge- 

 nous manures, uniformly gave a much higher percentage 

 of nitrogen, upon analysis, than adjacent fields which were 

 comparatively at rest, the crops being the same in kind. It 

 is well known that a crop of clover raised upon a field, and 

 turned under in a green state, adds greatly to the fertility of 

 the field by increasing the supply of nitrogen. I have found, 

 upon analysis of the soils of such fields before and after the 

 decay of the clover, that the nitrogen present was greater 

 after the crop than the amount originally present in the soil 

 added to that contained in the clover. If the leaves and 

 external organs of clover are incapable, as we feel certain 

 they are, of assimilating gaseous nitrogen, it may be they are 

 capable of appropriating nitrogen in the form of nitric acid 

 and ammonia from the air. I have not conducted experi- 

 ments far enough in this direction to settle the matter in my 

 own mind ; but I know the view quite generally prevails 

 among chemists, that it is not through the roots alone that 

 clover, and perhaps some other plants, receive nitrogenous 

 food. We are still much in the dark upon this interesting 

 question : it is a darkness, however, which I am confident 

 will be dissipated by further and more intelligent research. 



As regards the sources of the compounds of nitrogen in 

 the air, I have only to point out the agency of the electrical 

 forces, and the escape of free ammonia from industrial etab- 

 lishments, putrefactive fermentations, and a thousand other 

 natural and artificial sources. How far the play of electri- 

 cal activities in the atmosphere, which are silent and unseen, 

 may conduce to the union of nitrogen with oxygen, we do 

 not know ; but we have good reason to suppose they are by 

 no means insignificant. We do know that nitric acid is pro- 



