XII.] INCOMPATIBLE MANURES 353 



It must be remembered that certain fertilisers 

 cannot be mixed together without setting up reactions 

 which are either wasteful or render the mixture difficult 

 to work. Basic slag and basic superphosphate cannot 

 be mixed with sulphate of ammonia or guano or any 

 other fertiliser containing ammonium salts, because the 

 caustic lime reacts with the ammonium salts and sets 

 free ammonia, which escapes as a gas. Superphosphates 

 cannot long remain mixed with nitrate of soda without 

 setting free a certain amount of nitric acid, which is 

 both wasteful and injurious to anyone handling the 

 mixture. It is, however, safe enough to make up the 

 mixture and sow it straight away ; the nitric acid only 

 begins to be in evidence when the mixture is left in a 

 heap or in bags overnight, or when it is sown from a 

 machine which has some moving part working in the 

 manure. Most mixtures containing superphosphate 

 will turn into a paste round machine parts working in 

 the material. Kainit and superphosphate will also 

 begin to set free hydrochloric acid if they are left long 

 together. 



Superphosphate, either mineral or bone, can be 

 safely mixed with sulphate of ammonia or guano or 

 any of the fish or meat compounds, but the only 

 nitrogenous fertiliser that can properly go with basic 

 slag is nitrate of soda. In any case, however, these 

 latter are better sown separately because they differ so 

 much in density and fineness that the mixture would 

 separate very much in sowing ; very rarely, indeed, 

 would anyone want to sow them at the same time. Of 

 course lime, like basic slag, should never be mixed with 

 sulphate of ammonia or any of the guanos or organic 

 nitrogen fertilisers. 



Under ordinary conditions of farming, however, very 

 little mixing will be required, partly because the 



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