80 THE CULTURE OF FARM CROPS. 



Any reasonable person will be impelled to reply, the atmos- 

 phere must have been the first source of it; that all these 

 plants must have existed upon such carbon as they could 

 gather from the air, and that as they perished, they left a 

 supply in the soil which was not fit to nourish succeeding 

 generations, and hence accumulated during the vast periods 

 of time which have elapsed since vegetable growth first 

 began. 



This reasoning is plausible and seems free from objection, 

 and would seem to justify us in concluding that plants de- 

 rive their carbon directly from the atmosphere. In some 

 cases this must be certainly true, for there is no other ex- 

 planation to be given of the circumstances. But as regards 

 the culture of farm crops it would not be safe to conclude 

 that the vegetable matter of the soil has no relation to the 

 growth of plants, and that the carbon existing in the soil 

 does not contribute to the carbonaceous substance of vege- 

 tables. For facts prove otherwise. Just now the public 

 interest is in a lively condition of agitation in regard to the 

 question, whence do plants gather their nitrogen, and the 

 equally important question in regard to carbon is neglected. 

 Farmers are actively engaged in procuring nitrogen in va- 

 rious forms at very considerable expense, believing this to be 

 the chiefly indispensable agent in fertilizing their crops. 

 But a few farmers of intelligence, and used to closely ob- 

 serve what is going' on in their fields, have not lost sight of 

 the importance of a large supply of combined carbon, and 

 are adding to their fields as large a quantity of carbona- 

 ceous matter as they can procure, with such nitrogen as 

 may seem to be adequate, and are thus avoiding the ex- 

 treme to which the popular belief seems to have turned. 



In considering this question in the light of present expe- 

 rience, it may be considered that at first only a very poor 

 and weak growth of inferior plants covered the soil; or that 

 by reason of the exceedingly active chemical changes which 

 were then occurring, the soil was highly charged with 

 carbon in such forms as were available for plant food. In 

 the one case vegetable growth would proceed slowly to fill 



