382 STATE BOARD OF AGRICULTURE. 



iuoj crops and to make s:oocl the natural waste of combined nitrogen constantly 

 going on. There must be some restorative force at work beyond anything we 

 have named, to preserve the stately poise and balance which characterize 

 nature's handiwork. 



INFEKENCES FROM FIELD-CULTURE. 



AVhen we examine and scrutinize closely the results of field operations in 

 agriculture, the French school seem to score a still stronger point in favor of 

 their theory of plant accumulation of nitrogen from its free form. Two 

 propositions have been laid down as axioms in agricultural chemistry : 1st. 

 The composition of the manurial matters to be used to secure the best develop- 

 ment of any plant is to be determined by the composition of such plant ; if 

 the plant is especially rich in phosphorus, potassium, silicon, or nitrogen, 

 then such predominant substance should be abundantly supplied in the manure, 

 unless the soil already contains a sufficient amount in available form. 2d. 

 The exhausting influence of any crop is to be measured with reference to any 

 element by the amount of this substance which the crop removes from the 

 soil. These propositions appear like self-evident truths, but when tested by 

 actual trial in field practice they often break down in ignominious failure. 

 Take two representative crops such as wheat and clover: A crop of wheat of 

 30 bushels and 25 cwc. of straw, removes about 45 pounds of nitrogen per 

 acre ; a crop of clover hay of 2|- tons removes about 108 pounds of nitrogen. 

 The wheat contains a relatively small amount of nitrogen, and should not be 

 benefited by nitrogenous manures; but the clover contains a relatively large 

 amount of nitrogen, and should be especially benefited by such manures ; but 

 in actual practice we find the facts are the reverse of this. The wheat is 

 especially benefited by increased supplies of active nitrogen, whereas clover is 

 not appreciably benefited thereby. Again, the clover removing so large an 

 amount of combined nitrogen, which the wheat so much needs for its full 

 development, the wheat crop following clover should give a much smaller pro- 

 duction than it would when following some crop less exacting in its demands 

 for available nitrogen; but in practice we find the wheat much better after a 

 crop of clover. These self-evident truths are found to be evidently false so 

 far as nitrogen is concerned. How shall we explain the anomaly that a crop 

 which is indifferent to nitrogenous manures, but removes the largest amount 

 of nitrogen in its product, should yet be the best preparative for a crop 

 requiring an abundant supply of combined nitrogen for its full develop- 

 ment? Ville explains it easily and satisfactorily by saying that the clover 

 obtains its supply of nitrogen from the air, and leaves a surplus of this air- 

 derived nitrogen in the soil in the form of roots and stems for the use of the 

 subsequent wheat crop, which lacks this power of air-accumulation. The 

 clover is thus a "producer" and wheat a "consumer" ofcombined nitrogen. 

 Boussingault and Lawes reply: *' The explanation is inadmissible, because 

 plants cannot assimilate free nitrogen, as our experiments have abundantly 

 demonstrated." The answer is silencing if not satisfying, but it is merely 

 negative where we want positive information — it is giving us a stone where 

 we ask for bread. 



If we concede that clover cannot obtain its supply of nitrogen from the free 

 nitrogen of air, the question remains whence does the clover derive its large 

 supply of nitrogen under circumstances where wheat would fail to secure its 

 smaller supply? ISTot from atmospheric ammonia and nitrates; not from 

 nitrates or ammonia existing in or formed within the soil, because these forms 



