SOILS AND FERTILIZERS. 381 



cede in every instance the assimilation of nitrogen, and since animal 

 substances containing it decompose much more readily than vegetable 

 ones, the former are more valuable to the farmer than the latter for 

 manurial purposes, where quick responses are expected and demanded. 

 From this statement, however, horn shavings and hide and leather 

 scraps must be excluded, as these produce scarcely any effect what- 

 ever unless previously subjected to a chemical treatment. 



These facts are recognized in the prices at which a pound of nitro- 

 gen in different fertilizers can be bought; and as several find a sale only 

 in eastern markets, eastern prices are subjoined here: 



Price of One Pound of Niti'ogen in the Following Brands : 



Groimd fish, meat, blood (containing 8% nitrogen), 17^ cents a pound. 

 Ammonia sulphate, " 20% " 17 " " 



Nitrate of soda, " 15|% •' 15^ " " 



Fine ground bone and tarkage (containing 6% nitrogen), 15 cents a pound. 

 Fine gr. medium bone and tank ige, " 4% " 12 " " 



Medium bone and tankage, " 4% •' 7 " " 



The high, and, in fact, the highest price of all paid for the first ar- 

 ticle, is owing to the presence of other valuable constituents, and does 

 not invalidate the general statement made above. Peruvian guano would 

 in all probability rank alongside of it, and for similar reasons. 



The soil, then, is the medium in which the conversion of any form of 

 nitrogenous compounds, whether animal or vegetable, into ammonia, is 

 effected. This is partly absorbed by the plants, partly fixed by the soil, 

 and partly, also, if opportunity offers, carried away by running water. 

 The action of the soil, however, does not stop here. Multitudes of liv- 

 ing and active organisms, constantly present in it, transform with great 

 rapidity the ammonia into nitrate, in which form cultivated crops greed- 

 ily absorb and convert it to their uses, so that the choice of a nitro- 

 genous fertilizer, whether organic, ammonia, or nitrate, depends simply 

 upon the time when it is expected to be of service to the crop. If im- 

 mediately, then nitrate ; if subsequently, with the chance of failure to 

 come to time, and during the interval to sutler loss by washing away, 

 then ammonia or organic manures. The rational nitrogenous fertilizers, 

 and all things considered the cheapest for extensive agriculture, are cer- 

 tainly the nitrates, of which nature has given us vast deposits in some 

 parts of our globe. 



The amounts in pounds of the various fertilizers per acre necessary 

 to furnish the nitrogen of a crop have been calculated, and as the price 

 ^f this differs, as already stated, in proportion to its availability, the 

 cost has been added: 



