THE GROWING OF CORX. 127 



seems probable that the nitrogen of the soil, or " soil nitro- 

 gen" as it is called, becomes fit for plant-footl, becomes 

 soluble, and thus assumes a form in which it can be appro- 

 priated by the plant through the agency of a ferment in the 

 soil. That seems very probable : many claim that it is 

 proven. We know that some plants seem to acquire nitrogen 

 from the atmosphere in some indirect way, perhaps directly. 

 I refer to leguminous plants, — clover, beans, pease, and 

 things of that sort. The cow-pea of the South very likely 

 would be accepted as a type of this class. But the majority 

 of our agricultural plants do not use this soil nitrogen 

 directly : if they use it at all, it is only indirectly, and in 

 such small quantities, that the finest experiments have not 

 been able to determine it. But I should like to have Pro- 

 fessor Goessmann speak of this, because he is a chemist, 

 and understands more about it than I do. 



Dr. Goessmann. The air contains at all times carbonic 

 acid, and, in most instances, also nitric and nitrous acid and 

 ammonia. The soil absorbs continually more or less of the 

 former, and receives in particular the nitrogen compounds 

 by means of rain and snow. Once absorbed by the soil, they 

 find access to the plants by the roots as carbonates and 

 nitrates, where they assist in the formation of the organic 

 portion of the plant. Besides this direct support of plant- 

 growth, they serve also the very important purpose of in- 

 creasing the supply of inorganic plant-food ; for they aid in 

 the disintegration of the soil, rendering the insoluble mineral 

 constituents of the latter more or less soluble, and thus 

 accessible to the plants. Plants, as well as animals, need 

 certain mineral constituents for their growth. The speedy 

 and complete supply of these substances — as potash, lime, 

 magnesia, phosphoric acid, etc. — is essential for a successful 

 growth. To supply the entire amount of mineral constitu- 

 ents of plants required for the production of any crop by 

 home-made manure, or by commercial fertilizers, is in most 

 instances too expensive an operation to secure a satisfactory 

 pecuniary result. We distinguish, for this reason, as far as 

 the superior chemical composition and general physical condi- 

 tion of the soil is concerned, between various kinds of lands, 

 as first, second, or third class. To devise economical and 

 rational ways to render the latent plant resources of liis soil 



