VERMONT AGRICULTURAL, REPORT. 53 



NITROGEN.* 



Nitrogen is a colorless, tasteless, odorless gas, comprises about four- 

 fifths of the air and is a principal ingredient of flesh, milk, etc. It is 

 useful in agriculture when united with other materials, in order, as it 

 were, to bind it. When in the gaseous state only a few forms of plant 

 life, the legumes, or pod bearing plants, can make use of it. When it is 

 combined with other elements in mineral or organic materials it is more 

 or less available to all plants. 



Nitrogen is used on the soil in three forms, as nitrate, as ammonia 

 salts and in organic matter. 



(1) Nitrates. These are combinations of nitrogen, hydrogen, and 

 oxygen with certain alkalies. When united with sodium (a white alkali 

 metal of common occurrence found in salt, washing and baking soda, 

 etc.), it forms nitrate of soda or Chili saltpetre. This material is a 

 dirty white, coarsely crystalline salt which rapidly gathers moisture from 

 the air. It is mined and purified in northern Chili and carries 16 per 

 cent, of nitrogen. Nitrate nitrogen is soluble in water, diffuses readily 

 through the soil, and, therefore, is immediately available to plants, being 

 taken up by the plant roots as nitrates of lime, soda or potash. It 

 forms no insoluble compounds with soil constituents and may be easily 

 lost by leaching. 



(2) Ammonia Salts. — Ammonia is a gas which, when dissolved in 

 water, makes the well known ammonia water of the drug store. 

 Ammonia salts are soluble in water and the nitrogen is readily avail- 

 able to plants. They are less open to loss by leaching than are the 

 nitrates, but are not in common use in fertilizers as sold in Vermont. 



(3) Organic matter. — This is simply material which has been or is 

 a part of a living plant or animal. Thus cottonseed meal, ground bone 

 and manure are mostly "organic matter." All organic matter does not 

 contain nitrogen, but the seeds of plants as well as some of the 

 seed residues, and the several structures of the animal body are rich 

 therein. Nitrogen derived from organic matter is insoluble in water 

 and may be either quickly or slowly available to plants according to its 

 source and rate of decay. 



Speaking broadly, plants assimilate nitrogen only in the nitrate form. 

 It is necessary, therefore, that such as is present as ammonia or in or- 

 ganic matter be transformed into the nitrate shape before it can become 

 of use. This change is brought about through the agency of bacteria, 

 small living plant organisms found in the soil in great numbers, the 

 process being known as nitrification. I shall, I hope, have a chance 

 next year to say something about this matter to the readers of the 

 report. 



*Much of the matter following is a modified excerpt from Bulletin 99 of the Vermont 

 Experiment Station. Anyoue who is interested in this matter and wishes to pursue it 

 further should send to the station at Burlington for a copy of this issue. It will be 

 sent to any address without charge. 



