PROFITABLE FARMING 15 



haustive investigations by such well-known 

 agricultural chemists as Mr. John Hughes, a 

 few years ago, and by Professor Hendrick, the 

 chemist to the Highland and Agricultural 

 Society, and more recently by Mr. Morison, at 

 the Rothamsted Experiment Station, have 

 demonstrated that the percentage of free or 

 caustic lime in average British slags does not 

 usually exceed 4 to 5 per cent. From this it is 

 quite evident that whilst basic slag may be used 

 beneficially on soils which are somewhat poor in 

 carbonate of lime, it cannot possibly replace 

 direct applications of lime when soils are in need 

 of that element. 



The principal value of basic slag lies in that 

 it is an alkaline phosphate containing 

 lime, and is most suitable for wet, 

 sour soils rather deficient in lime. Slafl 

 Such soils are also benefited by the 

 application of bone meal, steamed bone flour, 

 or precipitated phosphates. 



Superphosphate 



Superphosphate is the name applied to mineral 

 phosphates (of which there are enormous natural 

 deposits throughout the world) that have under- 

 gone a certain treatment with sulphuric acid, 

 which transforms the insoluble phosphate of 

 lime into a form which is soluble in water. 

 According to the grade of mineral phosphate 

 used, the resultant superphosphate ranges from 

 26 per cent, to as much as 38 per cent, water- 



