PHOSPHO-NITROGENOUS MANURES 24o 



10 to 20 per cent, of tricalcic phosphate rendered soluble, 

 a similar quantity undissolved the total phosphate varies 

 from about 25 to 35 per cent. and from 2J to 3J per 

 cent, of nitrogen. 



The following analysis shows the composition of a 

 typical sample: 



Per cent. 



Phosphoric acid (soluble) 1 5*76 



(insoluble) 2 8*38 



Organic matter 3 and combined water .... 27*43 



Moisture ......... 12*15 



Lime, magnesia, etc 42*86 



Sand and insoluble matter . 3 '42 



100*00 



1 Equal to tricalcic phosphate rendered soluble 12'57 ) QQ.gg 



2 Equal to tricalcic phosphate undissolved . 18*29 ; 



3 Containing nitrogen . . . . . 2*40 

 Equal to ammonia 2*91 



The soluble phosphate in dissolved bones is of no 

 greater value than that of ordinary mineral superphos- 

 phate, but the insoluble portion, i.e., insoluble in water, 

 is to a large extent soluble in ammonium citrate, and 

 is not only more valuable than raw mineral phosphate, 

 but is probably much more readily available than the 

 phosphates in untreated bones. The. nitrogenous matter 

 is also partially acted upon and rendered more readily 

 available. 



It appears, therefore, that dissolved bones contain the 

 fertilising ingredients in varying degrees of solubility. 

 A portion is soluble in water, and directly available to 

 the plants, and the remainder, though insoluble in water, 

 probably becomes gradually available as required. It is 

 doubtless to this graduated solubility that dissolved bone 

 largely owes its valuable fertilising properties. Similar 

 conditions prevail in farmyard manure, and as will be 



