IX. 



THE ANALYSIS AND VALUATION OF MANUEES 



177 



the Highland and Agricultural Society of Scotland, 1910, may serve as- 

 an example. It is based on the prices current at Glasgow or Leith, except 

 in the case of basic slag, where prices are those at place of production. 



The figures in brackets after the name of the manure indicate the 

 trade guarantees. Obviously such tables can only have a transient 

 and local importance, since prices of manures are subject to consider- 

 able fluctuation. 



In ordinary tables of this kind, the values per unit of " ammonia " 

 and "phosphates" (i.e., Ca 3 P 2 8 ) are usually given, and not those of 

 nitrogen and phosphorus pentoxide, as in the above table. The latter 

 plan certainly appears preferable, except on the ground of custom, 

 since such substances as nitrate of soda and many organic manures 

 contain none of their nitrogen in the form of ammonia ; and, similarly, 

 superphosphate and basic slag contain most of their phosphorus 

 pentoxide in forms other than tricalcium phosphate. Perhaps the 

 same argument applies to the other manurial constituent potassium 

 (though to a less degree), since in some manures it exists as 

 chloride and not as potash. 



It may perhaps be useful to give an example of the application of 

 the table of " unit value " to the calculation of the money value of a 

 manure from its analysis. 



Suppose a sample of dissolved bones to yield the following 

 numbers on analysis : 



Total phosphorus pentoxide ..... 



Soluble 



Insoluble ,, ,, 



Nitrogen 



Its value per ton would be calculated as follows : 



Per cent. Value " per unit ". 



8-6 x 4s. lOd. Value of soluble phosphorus pentoxide = 

 8-5 x 3s. 7d. ,, insoluble ,, = 



2-5 x 15s. 6d. ,, nitrogen = 



Per cent. 

 17-1 

 8-6 

 8-5 

 2-5 



5 10 9J 



In America, the plan of expressing the trade value of manurial in- 

 gredients in price per pound is general. The following table gives the 

 estimated trade values l : 



Nitrogen in ammonium salts ... 

 nitrates ..... 



dry and fine fish, meat, blood, etc. 

 fine bone and tankage . . 

 cotton-seed meal, castor cake, etc. 

 medium bone and tankage . . 

 coarse bone and tankage . 

 hair, horn and coarse fish refuse 

 Phosphorus pentoxide, soluble in water . 



,, ,, ammonium citrate 

 in fine bone and tankage . 

 ,, medium bone and tankage 

 , , coarse bone and tankage 

 ,, fish, oil-seed cakes and wood ashes . 

 ,, mixed fertilisers, insoluble in ammonium 

 citrate ...... 



Potash in sulphates and mixtures free from chlorine ... 

 ,, chloride ......... 



1 Quoted by Wiley from Bull. 51, 1894, of the Mass. Agric. Exp. Station. 



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