94 FARMERS' INSTITUTES. 



position they now hold in Michigan farming. When to buy and when to- 

 abstain is a question of highest importance to the farmer, and requires careful 

 consideration and mature Judgment. A kind-hearted duchess was shocked to 

 hear that some of her poor neighbors had died for want of bread. " How 

 dreadful ! If these poor people c uld not get bread, why did they not bvy calces 

 and not starve in this absurd way ! " Tl)e farmer Avho neglects to make availa- 

 ble the natural supplies of these prime factors of fertility lying dormant in his 

 soil, but rushes off to get commercial fertilizers to take their place, is buying 

 cakes of the duchess. The farming that pays (the only farming worth consid- 

 eration) derives the bulk of these three materials from the soil; and commer- 

 cial fertilizers, if used at all, come in to supplement the soil supply, not to take 

 it place. 



But the theme for discussion this evening is not manures in general or com- 

 mercial fertilizers in particular, but the sources from which plants derive their 

 supply of nitrogen. No subject has awakened keener controversy than the 

 sources of nitrogen for plants. For more than a hundred years this matter has 

 been before the supreme court of science for adjudication, and chemists of 

 highest rank have appeared on the witness stand to give the results of years of 

 laborious investigation and experiment on this subject. It was easy enough to 

 show that nitrogen " in the active form," in the condition of ammonia or nitric- 

 acid, or in combinations capable of ready conversion into ammonia or nitrates,, 

 would readily contribute to plant growth. Yet the question continually came 

 up, " Are these the only sources of nitrogen for plants? Can nitrogen in the 

 so called inert form — as humose nitrogen of the soil, or free nitrogen of the 

 air — contribute to plant nutrition ?" 



To one unacquainted with the peculiarities of this most peculiar substance, 

 these questions would seem frivolous. The great reservoir of nitrogen is the 

 atmosphere. The leaves of agricultural plants, representing in many respects 

 both tlie mouth and stomach of the living organism, are surrounded and 

 floo-led with nitrogen every moment of their life. Why, then, cannot the plant 

 drink from the cup thus constantly pressed to its lips the needed element for 

 which it languishes ? Yet the almost unanimous verdict of chemists is that 

 atmospheric nitrogen is not the source of nitrogen for plants. A few chemists, 

 such as Vielle of France, and lately Atwater of this country, teach that the free 

 nitrogen of the air is one source of supply for growing plants. Yet the great 

 body of chemists consider atmospheric nitrogen incapable of contributing 

 directly to plant nutrition. Though dying for the nitrogen that penetrates it 

 at every pore, the plant must yet take up the poet's wail, " Thou art so near, 

 and yet so far." 



Wliile thus summarily dismissing the plant supply of atmospheric or free 

 nitrogen, the question comes up about the humose nitrogen of the soil, or " the 

 inert nitrogen of the vegetable matter of the soil." It seems to have been taken 

 for granted that this combined nitrogen belongs to the same class of inactive 

 materials as the free nitrogen of air. The question for our consideration this 

 evening is whether this classification of the nitrogen of the soil with free nitrogen 

 of the air as alike and equally incapable of contributing to plant life, holds 

 true of every kind of plants grown on the farm ? 



It is a significant fact that the organic matter of the soil contains an aver- 

 age of 2 per cent of combinations of nitrogen, about the same amount that is 

 found in well fermented barnyard manure. The humus of the soil thus con- 

 tains from 2,500 to 6,000 pounds of nitrogen to each acre of arable soil taken 

 to a depth of 12 inches, more than enough to supply the nitrogen for a score- 



