352 VALUATION AND PURCHASE [chap. 



of fertiliser he wants for the crop in question, so that he 

 can compound the available materials in the right propor- 

 tions and not be dependent upon the much more limited 

 range of fertilisers already mixed by the manufacturer. 

 For example, every merchant's catalogue will show 

 examples of turnip manures, barley manures, mangold 

 or grass manures, containing such mixtures of nitrogen, 

 phosphoric acid, and potash as experience has shown to 

 be generally suitable to the crops in question. In such 

 cases the farmer gets the advantage of the knowlege of 

 the merchant and also obtains a carefully mixed 

 fertiliser of even composition throughout, which can 

 be distributed without further trouble. Such mixtures, 

 however, can only represent a certain average adapta- 

 bility to the crop and cannot take into account either 

 the particular kind of land or the condition it has been 

 left in by previous cropping. The farmer who has 

 really made himself acquainted with the theory of 

 manuring and with the special conditions of his own 

 land can always manure both more cheaply and 

 more effectively by purchasing unmixed fertilisers. 

 These he must either sow separately, or by paying 

 a little extra to the merchant he may get made 

 up whatever mixture he desires before delivery. 

 It should not, indeed, be a matter of any difficulty to 

 make up a sufficiently accurate mixture on the farm 

 itself, all that is necessary being a suitable weighing 

 machine and a floor with a space cemented or paved, on 

 which lumps can be crushed. The heaps of separate 

 manures should be weighed out and thrown into a 

 common heap by alternate shovelfuls ; the mixture should 

 be then passed through a half-inch screen and the lumps 

 broken down with a wooden rammer or the back of a 

 shovel, the resulting heap being cast down and remade 

 two or three times until it is uniform in appearance. 



