The Purchase of Artificial Manures. 



Where, therefore, a farmer wants to use the latter substance, 

 he may find it to his advantage to employ this manure. 



Sulphate of potash is offered in various degrees of 

 strength, containing from 25 to over 40 per cent, of potash. 

 Muriate or chloride of potash often holds over 50 per cent, of 

 potash. 



All potash manures are apt to be lumpy, and if they are 

 stored long they may become so hard as to be almost un- 

 manageable. Poor mechanical condition is here quite as 

 undesirable as in the case of other manures. 



Potash manures are most important for root and 

 leguminous crops, less so for grass and cereals. There are 

 many well-authenticated instances of potash manures doing 

 positive harm to meadows, though in other cases they have 

 been used effectively. Whether they are wanted on any 

 particular farm or not can only be determined by experiment. 



Valuation of Artificial Manures. 



There are various methods of valuing artificial manures, of 

 which that known as valuation by units is most employed by 

 farmers and dealers. The general trend of prices is deter- 

 mined by market influences, and is largely beyond the 

 farmer's control, but a reliable method of valuation enables 

 him quickly and accurately to conclude which of several 

 samples of the same class of manure is the cheapest. 



For the purposes of the valuation of artificial manures, a 

 unit may be taken as synonymous w<ith 1 per cent, of the 

 valuable substance in a manure. To find the value of 

 a unit we divide the price of a ton by the percentage compo- 

 sition of the manure. Thus sulphate Of ammonia containing 

 20 per cent, nitrogen, and costing £11 per ton, carriage paid, 

 offers nitrogen at £ 1 ±=ns. per unit. Or as 20 per cent, of 

 nitrogen is equivalent to about 2\\ per cent, of ammonia, the 

 cost of a unit of ammonia is 9s. id. We can use one or other 

 of these unit-values to enable us to determine which of 

 several samples of sulphate of ammonia is the cheapest. 

 Suppose that we are offered two other samples, the one 

 guaranteed i8-| per cent., and the other 16 per cent, of 

 nitrogen ; the price per ton of the former, on the same 



