40 Fertilizers 



ground fish from this source contains from 7 to 8 per cent 

 of nitrogen, and from 6 to 8 per cent of phosphoric acid. 

 The former, owing to the varying proportions of bone, 

 skin and flesh contained in it, varies widely in its content of 

 nitrogen. Fish, besides affording a considerable supply of 

 nitrogen, is also regarded as a good source of this element, 

 ranking in availability well up to blood. 



The use of these materials is more common along the 

 coast, where fishing is an important industry. The supply 

 of fish pomace is to a marked degree regulated by the 

 abundance of Menhaden, which varies greatly from year 

 to year. More profitable use may be made of these prod^ 

 ucts if applied a few days before planting upon soils 

 which present conditions favorable to decomposition. 



TANKAGE 



Tankage is a highly nitrogenous product, and consists 

 chiefly of the dried animal wastes from the large abattoirs 

 and slaughtering establishments. It is variable in its 

 composition, since it includes the otherwise unusable 

 parts of the carcass, as bone, tendons, flesh, hair and the 

 like. The portions of this from the different animals not 

 only vary in their composition, but they are used in vary- 

 ing proportions, which naturally results in an extremely 

 variable product. What is known as "concentrated 

 tankage," which is obtained by evaporating the fluids 

 which contain certain extractive animal matter, is the 

 richest in nitrogen, and is more uniform in character than 

 the others; and because of its fineness of division and 

 physical character, the nitrogen contained in it is also more 

 active than in the other forms. Two distinct kinds of 

 tankage can, therefore, be obtained : first, concentrated 



