v.] 



BONE MEAL 



153 



because of the lack of carbonate of lime. Otherwise 

 the choice between these different phosphates is very 

 much one of price, since, phosphoric acid for phosphoric 

 acid, they have proved to be about equally effective. 



Raw bones or bone meal, though the price has been 

 at a low level fur some years, still seems to be rated too 

 highly, the nitrogen of the phosphoric acid it contains 

 being over-valued if we take into account the low 

 availability which field experiments indicate it possesses. 

 Most of the experiments go to show bone meal to be so 

 slow in its action that excessive amounts have to be 

 applied and locked up in the soil if any immediately 

 appreciable result is to be obtained. 



For example. Table XL I. shows the results of one 

 series of experiments carried out by the Highland and 



Table XLI.— Returns from Bonk Meal and other Phosphatic 



Manures. 



Agricultural Society, wherein bone meal was less 

 effective than fertilisers of the superphosphate class, 

 not only in the year of its application but afterwards 

 also, when further crops were grown without the 

 application of fresh manure. It is probably on grass 



