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Tankage must be examined from two standpoints to determine iti 

 Talue as a fertiliser, viz., mechanically and chemically. On account of 

 the bone present as a constant ingredient, a mechanical analysis is al- 

 ways in order, since the availability of bone, slow in its best condition, 

 is iDelieved to be directly as its pulverisation. Fragments of bone, or 

 even coarsely ground bones, are very slow in decomposing. " Too slow 

 in this busy age when every hour must chase its sixty minutes to its 

 death." Therefore, it is of first consideration that all tankage be very 

 finely ground. 



Chemically, tankage is a mixture of blood and meat, substances rich 

 in nitrogen, and of bone high in phosphoric acid. Therefore it may 

 Tary greatly in composition, between wide extremes ; bone with 4 per 

 cent, nitrogen, and 24 per cent, phosphoric acid, and blood with 16 per 

 cent, nitrogen (only). Usually it is sold, as it should be, by chemical 

 analysis ©nly. The higher the nitrogen content, the more valuable the 

 tankage, both in dollars and cents', and in availability in the field, 

 since this high content indicates an excess of dried blood or meat, both 

 highly available forms of nitrogen, over bone, a very slowly availabl© 

 form. 



When an analysis of tankage is given, the percentage of bone pre- 

 sent may be roughly calculated. Suppose analysis shows 9 per cent, 

 of nitrogen and 9 per cent, phosphoric acid, what part of tankage is 

 bone ? Bone contains on an average, 4 per cent, nitrogen and 24 per 

 per cent, phosphoric acid. Therefore, the nitrogen corresponding to 

 the 9 per cent, of phosphoric acid is 1 5 pounds, calculated by follow- 

 ing proportion : 24 : 9 : : 4 : x=1.5 pounds. Since there are 9 pounds of 

 nitrogen present, and 1.5 pounds of this adheres to the bone, then 7.5 

 pounds, or the remainder, comes from the blood and meat. Since 100 

 pounds of bone contain 24 pounds phosphoric acid and 4 pounds nitro- 

 gen therefore, it will require 37.5 pounds of bone to furnish the 1.5 

 pounds nitrogen and 9 pounds phosphoric acid found in the tankage. 

 Therefore, the tankage consists of 37.5 parts of bone and 62.5 parts of 

 blood and meat scrap. 



This example is given to illustrate the difference in values between 

 different grades of tankage and to show that its value as a fertiliser 

 largely depends upon the amount of nitrogen furnished by the blood 

 and meat scrap, and not that supplied by the bone. Tankage is a pop- 

 ular fertiliser with our planters just now, and the difference of opinion 

 prevailing as to its value is doubtless largely due to the difference in 

 composition of the various brands offered on our markets. Low grades 

 are universally unsatisfactory in their results, while high grades fre- 

 quently give most excellent returns. 



Fish Scrap, the dried and ground residue from fish after the oil has 

 been extracted, is used more to ammoniate manipulated fertilisers than 

 as a direct fertiliser in the south. Like tankage, its value depends 

 upon the relative proportion of meat to bone in the fish worked. A 

 part of the nitrogen always present, is inherent in the bone and is 

 therefore not as available as that in the meat. The action then of fish 

 scrap as a fertiliser is necessarily slower than the highly active formi 

 of cotton seed meal and dried blood. 



