534 AGRICULTURE. 



organic matter be remedied, and if it is true that we must 

 depend upon fallow crops and animal manures to resupply the 

 organic matter, we may pass on to the brief discussion of the 

 scientific use of commercial fertilizers. 



We must pass by the question of the disposal of town sewage, 

 without meaning by any means to ignore its prodigious impor- 

 tance. Thirty-five millions of urban population consume, includ- 

 ing waste, more than 1 50,000,000 pounds daily of the products 

 of the soil of the national domain, of which the merest trifle is 

 in any form returned to the soil. A distinguished English 

 scientist is said to have abandoned the study of agricultural 

 chemistry, because he said it afforded no scope for his genius, 

 "being a mere matter of nitrogen and phosphates." If his 

 genius had not scope to see any further into the subject than 

 that, it was well that he went no further. The scope which 

 was lacking appertained rather to the genius than to the chem- 

 istry of agriculture. It is true, however, that the nutrition of 

 plants can never be well understood as long as the solution of 

 its infinitely complex problems is attempted exclusively from the 

 chemical side. The plant, no less than man himself, is a living 

 organism. The presumption that its acts of imbibition, circu- 

 lation, assimilation, secretion, excretion, respiration, are purely 

 chemical phenomena, under the dominion of purely chemical 

 and physical laws, has led many minds far from the truth. All 

 the phenomena in which the plant is concerned, which culmi- 

 nate in the production of living matter from non-living mineral 

 matter, are vital phenomena, and under the dominion of physio- 

 logical law, which, within the sphere of its action, subordinates 

 or supplants the ordinary chemical and physical laws of nature. 



The ordinary chemical view is that the valuable constituents 

 of commercial fertilizers are nitrogen, phosphoric acid, and 

 potash. This dictum is accepted generally in an absolute sense, 

 and the deductions drawn from it are consequently elaborately 

 erroneous. Nitrogen, phosphoric acid, and potash, are arbitrarily 

 valued at so much per pound ; the number of pounds of each in 

 a ton is determined approximately by the approximate deter- 

 minations of an analyzed sample, and the errors of analysis 

 affecting a few grains are multiplied into errors affecting tons ; 

 the resulting figures are multiplied by the arbitrary prices per 



